The way I have always seen this is, the earth terminal on the socket must get priority of all incoming earth wires, the fact that the socket fixing screws and plate are there as a belt and braces approach, the flying earth lead must come from the socket terminal and connect to the backbox, Why? because when you remove the socket and leave it hanging, the backbox is then left unprotected,.You cannot now rely on conduit screwed connections to provide earthing, the couplings and connections can give resistance, esp when old and over long runs, hence the need for wired earthing at terminals, as far as the recessed socket and switch screws are concerned, don't forget toddlers running around with their tiny fingers exploring every nook and cranny, it might only go wrong once in ten million, but that is too much so get it all earthed, not hard is it?
@glyn hodges The regulations are a guide, a way to achieve a minimum standard for very specific situations, there is nothing wrong with deviating from the regulations if it increases safety in other situations that the regulations do not cover. Just because the regulations say you dont have to earth the backbox because of reasons, it doesnt mean you shouldn't.
I'm experienced in the electrical field, though not qualified and what I get from this is that it's not compulsory to earth a metal backbox, but there is no harm if you do, and no harm if you don't. Of course depending on whether metal conduit is being used as a CPC.
The new sockets have 2 separate earth points. CPC (earth) from each of the ring cables to separate terminals. Back box earthed through screw and not contactable in normal use.
Also true with new all metal fronted sockets with the earth strap across the back between screw holes, the screws being the connection to the back box, which takes the earth forward to the back box.
Always earth just like in this video, where I live there are lots of cottages and back boxes rust like nobody’s business due to damp. I have see countless screw lugs rusted completely away. So it’s even more important with the current quality of materials these days to do it as the boxes will not last 5 minutes.
I never understood this earthed back box fetish in UK, and why there is a metal box in the wall. What is wrong with the plastic? And the big fear about fire, but the fire problem is coming only from poor quality work, or the UK legendary rings like seven sockets with 32 Amps circuit breaker, that is a real fire hazard.
This is the worst way too earth a back box best and easiest way is using a 1.0mm single from the front plate to the back box when looping the cpc to the box first without breaking the cable is the worst I work in local housing associations housing where lots of people are moving in and moving out well nearly every single one of those redecorate well that solid cpc conductor to the box eventually will fail or snap every time the accessories is loosened and refitted I've found many rings with very high cpc continuity or none because the sparky has looped to the box first before the face plate. I teach every apprentice I have had to east the faceplate first then fly lead the box second.
I couldn't disagree more. I worked in local authorities for over 10 years - I understand your statement on the decorating - that has nothing to do with a reason why one connection is better than another though IMO. Ring final continuity or simple R2 tests will determine this.
30+ years in the industry i agree , always go to socket terminals with cpc conductors and fit bond seperatley, also doubling over of cpc compromises allowable radius of size of copper conductor ,however that is something that has always been done to achieve a better connection
Well said mate, I ALWAYS wire direct to the socket / device. And understand the use of a "fixed" log is acceptable since the late 16th / early 17th (2008) and also take a "fly" lead from the socket to the backbox. MORE so for a metalclad socket / device.
I agree. Its not REQUIRED but it takes but a moment. Only thing from my experience would be to take both legs to the faceplate and a return let to the back box. Only reason being I have had terminations that have severely weakened the unbroken bend "doubled over" under the fixing screw. Which puts doubt in my mind in the double over to withstand a dismantle and refit say during a periodic or fault finding exercise heavens forbid.
Always was told it's best practice to earth the box. Never understood why you wouldn't do it as it takes a matter of seconds to do. Fella I work for now never earths the back box and it annoys the fuk out of me.
A very interesting video Ninja. As ever you raise some interesting points. I would always earth a back box as best practice but its good to be clear on the latest technicalities. I was also taught to maintain a continuous earth (cpc) wherever possible, which in the event of a failed or loose connection, obviously maintains the fault path, so it is good to see it suggested here. Please keep up the good work.
My view on this is that, if for instance you are working on an existing fused spur or similar accessory that cannot be tested without removing it from the back box, you cannot guarantee that is dead until you have removed it from the back box to carry out the relevant tests (which now and again results in a live conductor popping out of the accessory and landing on the back box itself). If the back box was not earthed in this scenario the box would be live and the protective device wouldn't know anything about it. Its more of a risk to the diy'er or electrician than the end user. I always earth them regardless, and I'll be doing it in the way its been done in that first picture from now on!
Supersparks I carry on mainly because of arthritis which if I didn’t stay active would take over so to carry on working helps and of course the extra money helps
The old first types of metal back boxes didn't have earth terminals( especially the light switch boxes ) . If you wanted to earth them you used a fixing screw. While I agree safety first and would earth them anyway, I wish box manufacturers would improve the earth terminals especially in plaster boxes!!
I always take everything to the plate and take a stranded fly lead back to the back box. The house I moved into a few years ago had the CPCs terminated on the back box and NO CPC connected to the terminal on the plate, relying on the screws for continuity - potentially lethal! Every socket in the house was connected like this, I assume by the builder who refurbished the house, hopefully not by a proper electrician. All in red & black, so no paper trail...
Interesting. Personally I like to terminate the CPCs into the socket. I think connections should be kept to a minimum. To me this is another connection that could go wrong. If you terminated the two CPCs into the socket you only have one connection that can fail. If you connect into the back box, then into the socket, thats two point of possible failure. So if you have 30 sockets for e.g, thats 60 possible fail points. The little lug in the back box has such a small little screw, and cuts through the conductor quite easily.
Hi Ninja interesting stuff as always. I always earth the back box mainly because it's easy and it is better for lots of reasons. BS7671 should be the starting point for best practices not where safety standards finish.
@@nicholaspratt7934 I suspect not current standards. But I don't have the docs to check, so can't say definitively. If it isn't then I'm certain that the requirement is relatively recent so it might well have been to spec whenever it was manufactured. Back in the 70s we were taught to run an earth* fly to metal back boxes every time which was a right pain on a ring circuit because earth in, earth out and earth to the box meant 3 wires in a connector. (* CPC or Circuit Protective Conductor, for the formal.)
What happens when the diy customer changes the sockets to metal ones the back box becomes live and the screws connecting become live making the accessory also live and you can then place your whole hand on the accessory, a diy customer generally copies what he removed in most circumstances so if you don't wire the back box neither is the diy customer? I also make sure the back is earthed out of principal. p.s. sorry for reviving a dead comment section :D
GREAT VIDEO 👍 The Issue I have is on lighting circuits with no CPC, but class 2 fittings installed. Im happy with the regulation as class 2 is a method of protection but... where flush metal backboxes are not earthed on plastic switches then under common fault conditions (pinched cable) screws would become a live part, although you could apply the regulation mentioned above about a small surface area I wouldnt feel comfortable letting someone take 30mA (which still hurts and is enough to stop/damage a pacemaker) I would rather fit nylon screws or change the backbox then argue about a non-statuary document in court. I posted a pic on a Facebook group recently of a switch in a new build where cpc were terminated in floating connector blocks in all metal KO boxes, however plastic caps (a whole other debate barrier or decoration ?) was provided.
I'd agree that the faceplace screws meet the criteria to not be earthed, but given the small cost of materials and time to earth them, electricians who are aiming to provide their clients with the safest possible installation should earth the backbox. It will also prevent anyone you does not know the regulations from casting aspersions on the electrician because they have not earthed the backbox.
410.3.9 ii. '... and provided that a connection with a protective conductor could only be made with difficulty or would prove unreliable'. Wouldn't the fact that an earthing terminal is provided mean this exemption is not applicable in this case?
so for those that don't earth the backbox in a flush installation the question is do you earth a metal clad surface box where a twin and earth is wired into the top by a stuffing gland or through a grommet via back entry ?
Is the requirement to earth the back box in the regs? If not then surely its up to the spark although i dont understand why we have regs then people do their own thing. If it is in the regs then it must be done regardless of your views. The same as were supposed to stick to the speed limit! Never trust an electrician with no eye brows
I do take CPC's direct to the socket and then a flyleaf to the back box if a metal socket NIC didn't used to insist on on the latter ie if a plastic socket but NAPIT did. However the metal conduit system presents what I would consider a huge danger if relying on the metal of the conduit providing a CPC and in this scenario I encountered a situation whereupon the metal conduit had been severed and 2.5 had been used in between. Remember in galvanised conduit you are dealing with threads, cutting compound etc all of which can circumvent the continuity. My first flat had one of these infrastructures and I completely re-wired it again with singles but with a CPC within the conduit.
Obviously with a plastic face plate you need to earth the backbox. If the Live becomes loose an comes into contact with the backbox, an earthed backbox with allow enough current to flow to trip the MCB. If it's not earthed you just have a Live! backbox.
I agree it’s personal preference and a minor detail. Back boxes when a socket circuit is energised is not an exposed conductive part as it’s concealed behind the socket anyway. But how many times do electricians and DIY enthusiasts take socket fronts off live ! A fly lead will ensure the back box is still earthed even when others like poking around live parts.
The starting point should be that the power to the socket MUST be off BEFORE the socket cover is removed. There are plenty of regs, acts, instructions etc which state this point. However, in the real world, this does not happen. Let's presume the socket remains energised, an earth fault COULD occur when the cover is off, and if no rubber grommet is protecting the metal entry hole, an earth fault is MORE likely to occur. 'AHH, RCD would trip' I hear you say..... How many RCDs have you come across that DO NOT trip. LOADS, I mean who tests them periodically anyway?
Best practice is the way forward, I've always earthed the back box, with a 'flyinglead' cpc (ie. always multi-stranded conduit wire) this is more robust than single strand cpc. I should say metal cover light switches would be given the 'flying lead' cpc treatment too.
SparkyNinja If there is at least one fixed lug it’s really not necessary. If you have a socket with a spur, introducing yet another cable just makes things more cumbersome than they [functionally] need to be.
Is an extra earth needed for a metal face plate? I would have assumed so (similar light switches have an earth screw to earth) but my new plug socket doesn't have an obvious earth screw for the faceplate
How many times have you seen missing grommets? No grommets = possible live backbox so always Earth the box before you even get the socket out of the wrapper
Always done my mentor and lecturer taught me to make the installation as safe a possible. Better to sleep easy at night. Say the end user changes over to steel or brass finished fittings. As it's already in place you give a greater conductivity back to ground in the event of a fault occurring. Thanks for sharing. 👍
I think you are very wrong to say the screws can not be griped, as for instance a child holding (gripping) a metal implement such as dads standard screw driver, only has to make contact with the plate screw head. Also I have often witnessed decorators both professional and DIYer’s just loosening the screws without removing switches or sockets, while the circuit is live, the screws could certainly be griped. In both scenarios if there was a live touching the back box there would be a shock hazard. Hey I know fark hall, Don’t listen to me. Love your videos. Regards Norfolkngood
Child would loose contact between the screw and the tool at the first perception of energy. Other trades loosening screws fails the fundamental principles outright and no installation is designed to operate safely in that condition.
“... _and_ provided that connection with a protective conductor could only be made with difficulty...” - I fail to see the difficulty here, so the connection is still required, isn’t it?
Steel has a significantly lower conductivity than copper but the cross sectional area of a steel conduit is so massively greater than a copper CPC could provide that, if *correctly* jointed, conduit is just about always guaranteed to outperform s separate CPC.
Wow! NO NO NO. The fly lead has to be there to comply and its a breach of regulations not to add it. And, a point in case my daughter touched two recessed exposed screws and a latent fault in the system shocked her badly. I agree its unlikely and is as unlikely as the latent fault that nearly killed her.
@@SparkyNinja I believe the regulation he is referring to was what you have been saying... where certain conditions are met then no need to bond... on some sockets where the earth bars don't earth the screws then they become exposed conductive parts in which case the only way for that to comply with regs is to bond the back box. I always bond it anyway... then I'm covered.
When I was training for my C&G 236 (part 1 & 2) we were using 16th edition (I qualified early 1990's) and you had to connect an earth wire to the backbox. I believe this was relaxed when the 17th edition was released. The argument was that under normal circumstances a domestic user would not be touching the backbox and that it was earthed via the screws that connected the earth on the socket to the backbox.
I was qualified around same time as you, I seem to remember that because you will lose the earth connection to the back box for example when painters remove the sockets during painting
Wondering as the bending ratio of the CPC is greatly exceeded when terminating to the back box and taking it on to the socket, can you call it a continuous circuit?
Solid conductors are often bent completely back on themselves when terminated under a screw so I don't think bending the copper to that extreme is an issue. However, I prefer to use a double ferrule to crimp the fly lead and one of the CPCs together. This saves on the waste of extra length on the line and neutral of the cable with the longer earth and maintains a constant connection just the same. I don't know if it counts as a continuous connection, perhaps Sparky could ponder that one for us and let us know his opinion. It is an extra component, so there's an extra cost, but pennies... As far as time taken to do it, I can't imagine it takes any longer than the longer CPC and bending it over method.
This was brought up in my last NICEIC inspection in december the examiner was joyfully showing me pics he had taken of sockets that had the earthing bar of the socket just connected to the earth terminals but not to the screw head. So if i line conductor had came out and would hit the back box it would become live and not trip out if the back box was not earthed. 1st time i have seen sockets like that in 30 years.
Funny enough earthing the back boxes is the most hateful, aggravating and annoying part of the job for me, I'd rather be pulling cables through inaccessible blind holes or bashing rock hard concrete. I have a full rewire in progress and all boxes, have been wired and finished... Apart from, as of this moment only half the boxes have been earthed. I did half and was expecting to finish off and do the rest next visit - Because I don't enjoy that bit, after hearing your very sensible and authoritative appraisal I was quite tempted to just leave them.. I mean the great Sparky Ninja has removed any guilt.. Of course it would be impossible for me to leave site without completing the blinkin' back boxes. Grrr. For some reason I couldn't do it. Excellent channel and what a great name too. Subbed.
Inspecting behind a socket that is energised isn't recognised in Regulation or Legislation though. If you are live working via a sanction to comply with EaWR 14 (c) then you would be applying additional protective measures. Again as I said, I would still do it too, but this is the bullshit that would be used to interpret that work.
I don't think you're interpretation of 410.3.9(iii) is correct. For the exemption to apply 2 criteria are required. Exposed conductive parts need to be of reduced dimensions AND connection with the CPC would need to be difficult or unreliable. Whilst the first requirement is met as you describe, the latter is not IMO since I think it is neither difficult nor unreliable to use the back-box terminal, therefor the exemption does not apply. I think this is really clear with careful reading. Regardless of the regs, I would also ALWAYS run the CPC via the back box and into the front plate exactly as you show.
Best practice - Blah... Most domestic use modern sockets are earthed via the screws anyway. Many ‘loose’ back box wires become faulty or are not cut/stripped/fitted property. Most modern sockets have TWO earth sockets. As long as they are connected up here then its happy days. Yours screws work as an earth anyway. However, like you point out, it’s good practice.
The backbox doesn't need a CPC it may be good practice to bond; take the CPC where it's required to the socket. Your adding a point of failure in the cpc - I've seen the cpc failed at the bonding connection (overtightened termination/ damaged copper). With large volumes of sockets, this may have a detrimental, maybe small, effect on R2 - R2.
I used to think that this procedure was unnecessary because the back box is earthed through the lugs, however this only protects you when the socket is fully connected and when it’s removed you loose the earth path..but then you shouldn’t be removing the socket unless power is isolated… so I just don’t know… FYI I always earth metal back boxes just to avoid dispute
A very interesting video!!! I would do exactly how you say ,keeping a continuous earth, but another reason I can see is that you're using a plastic socket so if at a later date it goes to a metal one then u are covered ??? Would like your opinion on this please!! Rgds your friendly neighbourhood trucker!!!
i think its good practice NOT to earth the back box with the fly lead because when dead testing -its best to take the face plates off the wall,(to exclude any parallel paths from metal stud work).how do we know we are measuring the cpc and not a fortuitous earth from cable tray or metal studs etc which can change if the builder was to make an alteration (I dont do domestic work,I'm talking commercial here) The back box will be earthed through the screw
have always done this and always will, belt and braces on SOCKETS cant hurt. I say sockets, because no one ever talks about switches, which is where it makes the most sense, unless you are using a metal switch plate, there is no way to earth the screws, and if the backbox isnt earthed the screws could become live and stay that way until someone gets a belt.
The question is answered by admitting that a flying lead from a besa box, back box, spur box is to earth them in absence of an integral cps within containment which when mechanically sound is electrically continuous as the earthing requirement. My opinion differs somewhat. The TNC system being somewhat inadequate because of bad mechanics lost the concept of being electrically continuous and therefore became hazardous. The TNC-S's integral separate earth made the flying lead nothing more than a bit of supplementary bonding. Now here, in my opinion, is the anomaly. The picture presumably shows one leg of a ring final circuit's cpc being split from the accessory and replaced with a supplementary bonding flying lead to the terminal of a back box where it is made to join the other leg of the ring final circuit's cpc. That to me, says that a cpc which should be in the form of a ring is made up two cpc legs from the board to the back box+accessory and joined between with a flying lead of supplementary bonding. Supplementary bonding, as far as I can reckon, is not a circuit protective conductor.
The other reason to have this lug is for cases where the front plate isn't earthed, say for a plastic 3 gang light switch. It gives you a place to park the cpc in the case that the switch is changed for a metal one in future. Doing it for sockets seems pointless and silly. I don't think it adds any safety, it just wastes a bit of cable.
In my opinion if you really want to earth the back box then its better to have a saprate wire from backbox terminal to the spare earth terminal on the socket , and keep both cpc together in one terminal.
Interesting subject, personally I would earth back box. I have seen too many "fixed lugs" that I would not call fixed, many of these are separate pieces of metal crimped to the box. It doesn't take much for these lugs to become excessively loose or detached. What about a situation where a small child / baby is exploring there surroundings? Sat on the floor, possibly with a wet nappy and bare legs also in contact with floor, sees a small shiny thing and goes to touch it. Unfortunately the screw has become live, unfortunately for the child who through no fault of there own has a very good ground and conductance is now dead. This may seem excessive but having seen and worked in houses that fit both criteria I'm surprised it hasn't happened to my knowledge (im sure it has at some point). Perhaps the TV in front of socket has helped. With regard to using the conduit as earth conductor, has this been reverted? I thought the conduit was to protect the cables and had to be earthed in the same way as the function of steel armour cable, and not function as the cpc. Does corrosion not occur these days with steel conduit in a damp wall? Seen some nasty situations over the years, still shudder at the thought of some of them and wonder how people haven't been injured or killed... I get this funny tingling when I lean on this wall by here (attached garage converted to spare downstairs room, ex council house). That job ended with complete rewire (after moving and replacing the old *fuse* board from under the kitchen sink worktop that leaked water down the wall).
Yes because some of the sockets, switches and other do not have a ring of metal at the screw hole. As in the old day's the screw hole was not earthed as now. (Me. Socket first then lead to back box)
I agree with everything you said and would further a reason for this good practice that if the two screws are removed from the socket plate with it flapping around the backbox would not be earthed. Ive seen socket plates flapping around in badly maintained properties and situations where decorators take them off to paint. Like the guy a few comments down I always feed back to the backbox and not the backbox first.
I'm not on the business of finding excuses to cut corners in good practice but I know many people who are, the guidance note 8 has a few pages and illustrations dedicated to this scenario explaining about the adjustable lug and fixed lug etc.
I am not an electrician but have a passing interest. So what I am hearing there is zero downside to doing this from a safety point of view, so why should an electrician argue that he / she won't do it? To save a bit of copper and about a minute per socket wiring to the back box? If so, then that is an electrician I would not want wiring my house if those are seen to be real reasons.
If you fit a socket to a plastic back box do you earth the screws?? No you don't.... If you earth the Metal box technically you are only earthing 1 screw as only 1 lug is fixed the other isn't.
If one screw on the fixed lug creates that equipotential then the other screw doesn't matter as long as you screw it in Only concern is that the earth bar must be covering the screws too as some earth bars don't cover the screw holes
If wired correctly and on a rcd then testing and subsequent tripping will occur unless screws are left out say while decorating,and during that time the box becomes a live conductor. Nothing is perfect but belt and braces,screws and earth cable earthing double bubble.less trouble
@mr little, can you point me in the direction of the sockets you talk about which don’t connect too cpc thought the screws. I’m interested to see them. Not interested in old ones as I never install old ones.
Always go with the belt & braces approach when dealing with electrics imho. Nothing wrong with having multiple earth routes to the BB, a failsafe is always a good thing :-)
@@supersparks9466 I'll answer on behalf of him.. ua-cam.com/video/kPpX1YXvGcg/v-deo.html from 7:42 you will find a cheap but fully compliant BS1363 twin socket outlet with no strap across to the screw holes
if you take the face plate off with the power still on and you get a shock you got what you deserved dead tests before live tests so even on an eicr you should have all the covers off and inspect them before the power goes back on the fixings holes on most decent socket outlets are connected to an earth bar in the back of the socket so the screws are earthed via the cpc connection on the faceplate
andy ? This is my thinking but I’m not sure it’d stand up in court (got what they deserved) ha ha. I never earth my back boxes as like you say, power should be off before removing anyway. I’ve been doing it without for 23 years
@@tommochelsea72 in court id quote the eawr etc, you shouldnt work live unless it is unreasonable to do so. sockets can be tested from the front so there is no need to remove them with the power on
You never drop sockets down when they are live? I will occasionally drop them to have a quick peak at what is going on. Maybe an initial check to see if it has 1 or 2 t&e cables present if planning to add a socket to the ring. Just exercise a bit of caution in case the cables drop out and also depending on the environment. Obviously not in a nursery or something!
Also true with new all metal fronted sockets with the earth strap across the back between screw holes, the screws being the connection to the back box, which takes the earth forward to the back box.
Quick question for you sir, does it matter from which cable is the earthing wire connecting to the backbox ? ( In the picture it seems the incoming wire si connecting the earthing to the socket, and the outgoing is connected to the backbox linked with the socket )
It's for Ferrous reasons......Why would you earth the frontplate to the back box when the screws in the frontplate run through the face plate earthing strip anyway.
I am a retired electrician and I find when friends ask me to change electrical fittings for them I find that 80% of houses have wiring interfered with by previous homeowners for e.g. grommets missing and sharp screws in back boxes. So I like to use 4mm earth fly lead from back box to E terminal on sock/outlet.
I was trained by CEGB many moons ago (up to 11 kv). The 'qualified ' electrician who just rewired my house did the earth wire to box randomly, never clipped any trunking, never used grommets, stuffed three 2.5 T&E in one backing box hole (one two in trunk), slit the outer cover on a 2.5 and hid it, patched the floor so well that my wife nearly went through it. Don't ever use Adept Electrical and their authority!
Hi, I have considered this too, and I agree with your reasoning, but you know l would also consider if the wall is subject to any dampness and also some sockets provide those little plastic caps! That said these days as we have R.C.D's which would sense imbalance really reduces potential danger to a minimum, whereas back in the day would have been a bit more involved, That said I also make a long CPC into a box tail as it makes the process simple and done all in one go, I think what you have highlighted is that if you know your reg's then you have more options and it's always better to have options Right on Kind regards Warren
The screws will be earthed regardless of damp, only consideration here is if we're talking about if the cpc was a conduit system or if the sockets have earth bars that don't earth the screws which will turn them into exposed conductive parts
Could you tell me why I'm getting over a 100 volts when I connect my multimeter to the outside screws obetween 2 sockets if i put one probe on the kitchen sink and one to the metal case of the socket I get around 60v the sockets are metal not plastic I have a cut on my finger and I just noticed when I was doing the dishes that I was getting an electric shock when I touch to the tap and the water in the sink
Sounds like you have some potential earthing issues. I'd recommend you call an electrician in to test the effectiveness of the protective conductors in your kitchen.
@@SparkyNinja I know the sink taps are not earthed i just found that out looks like sumone forgot to do it wen the new kitchen went in would that have anything to do with the sockets given a reading
@@SparkyNinja I took the isolation switch socket cover for the dishwasher off and 2x earth wires from the socket to the left were not connected and one of the black wires had come out of the connector and I have a feeling it was touching the metal faceplate cover on it
As much as I applaud the method of earthing the back box, the 'respected electrician's' choice of fixing screw and the resulting sharp edge is not brilliant.
Hi! guys, tell me please, by regulations do I have to earth backbox or not? it's more important what regulations says, becouse the contractor will don't pay you if you did the job wrong and does not matter how safe is your job done. when you working on price, the speed matter.... Thank you!
I don't know about iee/iet regs and recs, but ieee regs require all metal panels and enclosures containing or supporting mains wiring has to be earthed.
Surely you’re original theory that the lug is used to provide the PE connection to the socket where the back box and conduit provide the PE could be wrong as the screws would in fact make that connection. Gordon
@@derekwade7471 Hi Derek, That's a good point, the only reason I can think of is, if a (metal) backbox is fitted into an insulated cavity (say a stud partition), and the item being fitted to the box was for example, a plastic plate switch without an earth connection or bar, and then for some reason the back box became live (e.g the insulation on the live wire being compromised), then the screws on the faceplate could be live, but as sparky mentioned, the regs seem to think that's OK if they are small and recessed. But as many have mention here, if your charging £100 to fit whatever it is (just joking), why wouldn't you just spend a couple of minutes fitting an PE for safety's sake. Cheers, Gordon
Yes!..i ALWAYS connect metal back boxes to cpc.. I have seen and repaired socket outlets with live conductors popped out of a 32A ring circuit and touching the back box which was not earthed.. The screw heads on the front plate were live!.. It's a no brainer.
How the fuck can the screws be live? If the socket is connected to cpc then the screws will also be connected thought the metal strip on the back of the socket.
@@supersparks9466 humidity/damp in the wall, over a period of months because it wasn't fully tightened, and corroded, caused a high resistance between the screw head and back box lugs, in tandem with a screw penetrating the live conductor insulation made 1 screw head live! I'm not making it up. It also failed an IR test. It's not made up!
Great points. I don’t double over the cps. I usually take a separate conductor from the box just so I’m not disturbing the cps too much.
Half the time the earth connection on the back box is loose or poorly fixed.
The way I have always seen this is, the earth terminal on the socket must get priority of all incoming earth wires, the fact that the socket fixing screws and plate are there as a belt and braces approach, the flying earth lead must come from the socket terminal and connect to the backbox, Why? because when you remove the socket and leave it hanging, the backbox is then left unprotected,.You cannot now rely on conduit screwed connections to provide earthing, the couplings and connections can give resistance, esp when old and over long runs, hence the need for wired earthing at terminals, as far as the recessed socket and switch screws are concerned, don't forget toddlers running around with their tiny fingers exploring every nook and cranny, it might only go wrong once in ten million, but that is too much so get it all earthed, not hard is it?
@glyn hodges The regulations are a guide, a way to achieve a minimum standard for very specific situations, there is nothing wrong with deviating from the regulations if it increases safety in other situations that the regulations do not cover. Just because the regulations say you dont have to earth the backbox because of reasons, it doesnt mean you shouldn't.
I'm experienced in the electrical field, though not qualified and what I get from this is that it's not compulsory to earth a metal backbox, but there is no harm if you do, and no harm if you don't. Of course depending on whether metal conduit is being used as a CPC.
There is harm but quite limited
As my college lecturer always says a good spark goes above and beyond.
I'd personally do it that way also as I was always taught you can never be too safe.
The new sockets have 2 separate earth points. CPC (earth) from each of the ring cables to separate terminals. Back box earthed through screw and not contactable in normal use.
Also true with new all metal fronted sockets with the earth strap across the back between screw holes, the screws being the connection to the back box, which takes the earth forward to the back box.
Always earth just like in this video, where I live there are lots of cottages and back boxes rust like nobody’s business due to damp.
I have see countless screw lugs rusted completely away. So it’s even more important with the current quality of materials these days to do it as the boxes will not last 5 minutes.
Takes 10 seconds to earth it ; I do out of principle
I never understood this earthed back box fetish in UK, and why there is a metal box in the wall. What is wrong with the plastic? And the big fear about fire, but the fire problem is coming only from poor quality work, or the UK legendary rings like seven sockets with 32 Amps circuit breaker, that is a real fire hazard.
This is the worst way too earth a back box best and easiest way is using a 1.0mm single from the front plate to the back box when looping the cpc to the box first without breaking the cable is the worst I work in local housing associations housing where lots of people are moving in and moving out well nearly every single one of those redecorate well that solid cpc conductor to the box eventually will fail or snap every time the accessories is loosened and refitted I've found many rings with very high cpc continuity or none because the sparky has looped to the box first before the face plate.
I teach every apprentice I have had to east the faceplate first then fly lead the box second.
Asa Mitchell
Is your keyboard missing it’s punctuation keys?
That is hard to read.
If I had a keyboard I watch videos on my phone not a laptop or pc.
Mr punctuation officer.
Asa Mitchell, your phone or tablet also has commas and full stops. Mr Badger has a point, I too found it hard to follow.
I couldn't disagree more. I worked in local authorities for over 10 years - I understand your statement on the decorating - that has nothing to do with a reason why one connection is better than another though IMO. Ring final continuity or simple R2 tests will determine this.
30+ years in the industry i agree , always go to socket terminals with cpc conductors and fit bond seperatley, also doubling over of cpc compromises allowable radius of size of copper conductor ,however that is something that has always been done to achieve a better connection
Well said mate, I ALWAYS wire direct to the socket / device. And understand the use of a "fixed" log is acceptable since the late 16th / early 17th (2008) and also take a "fly" lead from the socket to the backbox. MORE so for a metalclad socket / device.
It’s a reg to earth surface mounted metal clad boxes
I agree. Its not REQUIRED but it takes but a moment.
Only thing from my experience would be to take both legs to the faceplate and a return let to the back box. Only reason being I have had terminations that have severely weakened the unbroken bend "doubled over" under the fixing screw. Which puts doubt in my mind in the double over to withstand a dismantle and refit say during a periodic or fault finding exercise heavens forbid.
Alternatively, as in my apprenticeship days the boss would have urged JUST F***ING DO IT which tends to suffice
Ban mains electric in residential dwellings. We can all be super super-safe then.
I agree with the ninja. Good topic of discussion.
Always was told it's best practice to earth the box. Never understood why you wouldn't do it as it takes a matter of seconds to do. Fella I work for now never earths the back box and it annoys the fuk out of me.
Probably because there is no need. It'll be earthed through the fixed lug so an extra conductor does nothing
At last sdg, someone’s on my side
A very interesting video Ninja. As ever you raise some interesting points. I would always earth a back box as best practice but its good to be clear on the latest technicalities. I was also taught to maintain a continuous earth (cpc) wherever possible, which in the event of a failed or loose connection, obviously maintains the fault path, so it is good to see it suggested here. Please keep up the good work.
My view on this is that, if for instance you are working on an existing fused spur or similar accessory that cannot be tested without removing it from the back box, you cannot guarantee that is dead until you have removed it from the back box to carry out the relevant tests (which now and again results in a live conductor popping out of the accessory and landing on the back box itself). If the back box was not earthed in this scenario the box would be live and the protective device wouldn't know anything about it. Its more of a risk to the diy'er or electrician than the end user.
I always earth them regardless, and I'll be doing it in the way its been done in that first picture from now on!
If the main switch is off I think you can guarantee that your spur will be off.
I’ve been doing that from an apprentice and I’m 66 now , the old ways are always the best ways there are no room for short cuts in this industry
Why havnt you retired yet, the thought of still installing cables at 66 is depressing me
Supersparks I carry on mainly because of arthritis which if I didn’t stay active would take over so to carry on working helps and of course the extra money helps
Fair enough Brian, I’m looking to retire at 60, or at least semi retire. The knees and back have had enough.
Oh like ring mains? LOL
The old first types of metal back boxes didn't have earth terminals( especially the light switch boxes )
. If you wanted to earth them you used a fixing screw.
While I agree safety first and would earth them anyway, I wish box manufacturers would improve the earth terminals especially in plaster boxes!!
I always take everything to the plate and take a stranded fly lead back to the back box. The house I moved into a few years ago had the CPCs terminated on the back box and NO CPC connected to the terminal on the plate, relying on the screws for continuity - potentially lethal! Every socket in the house was connected like this, I assume by the builder who refurbished the house, hopefully not by a proper electrician. All in red & black, so no paper trail...
Interesting.
Personally I like to terminate the CPCs into the socket. I think connections should be kept to a minimum. To me this is another connection that could go wrong. If you terminated the two CPCs into the socket you only have one connection that can fail. If you connect into the back box, then into the socket, thats two point of possible failure. So if you have 30 sockets for e.g, thats 60 possible fail points.
The little lug in the back box has such a small little screw, and cuts through the conductor quite easily.
Hi Ninja interesting stuff as always. I always earth the back box mainly because it's easy and it is better for lots of reasons.
BS7671 should be the starting point for best practices not where safety standards finish.
The faceplate screws will earth the back box....or am I missing something?
People fitting things like this where they won't because they're not connected to the CPC... i.ytimg.com/vi/kPpX1YXvGcg/maxresdefault.jpg
@@calmeilles Is that socket to British Standards?
@@nicholaspratt7934 I suspect not current standards. But I don't have the docs to check, so can't say definitively.
If it isn't then I'm certain that the requirement is relatively recent so it might well have been to spec whenever it was manufactured.
Back in the 70s we were taught to run an earth* fly to metal back boxes every time which was a right pain on a ring circuit because earth in, earth out and earth to the box meant 3 wires in a connector.
(* CPC or Circuit Protective Conductor, for the formal.)
What happens when the diy customer changes the sockets to metal ones the back box becomes live and the screws connecting become live making the accessory also live and you can then place your whole hand on the accessory, a diy customer generally copies what he removed in most circumstances so if you don't wire the back box neither is the diy customer? I also make sure the back is earthed out of principal. p.s. sorry for reviving a dead comment section :D
I always Earth the back boxes
GREAT VIDEO 👍
The Issue I have is on lighting circuits with no CPC, but class 2 fittings installed.
Im happy with the regulation as class 2 is a method of protection but...
where flush metal backboxes are not earthed on plastic switches then under common fault conditions (pinched cable) screws would become a live part, although you could apply the regulation mentioned above about a small surface area I wouldnt feel comfortable letting someone take 30mA (which still hurts and is enough to stop/damage a pacemaker) I would rather fit nylon screws or change the backbox then argue about a non-statuary document in court.
I posted a pic on a Facebook group recently of a switch in a new build where cpc were terminated in floating connector blocks in all metal KO boxes, however plastic caps (a whole other debate barrier or decoration ?) was provided.
Andy Shepherd Can you buy plastic accessory screws?
@@stevekeys262 yeah, google 3.5mm nylon screws :)
Andy Shepherd Thanks.
I used to do it this way until my niceic inspector asked me what the rating of the earth lug was . Was it 32A rated ?
Earthing to most metal casings of appliances or whatever is expected so what's the difference?
NICEIC are the Gamekeepers?
I'd agree that the faceplace screws meet the criteria to not be earthed, but given the small cost of materials and time to earth them, electricians who are aiming to provide their clients with the safest possible installation should earth the backbox. It will also prevent anyone you does not know the regulations from casting aspersions on the electrician because they have not earthed the backbox.
You can't be wrong for earthing the box.
Earth the box !
410.3.9 ii. '... and provided that a connection with a protective conductor could only be made with difficulty or would prove unreliable'.
Wouldn't the fact that an earthing terminal is provided mean this exemption is not applicable in this case?
so for those that don't earth the backbox in a flush installation the question is do you earth a metal clad surface box where a twin and earth is wired into the top by a stuffing gland or through a grommet via back entry ?
I'm sure they do as it will be an exposed conductive part on surface
Well if they don't then they should
No, it’s not a requirement under 18th regs but most sparkles do as standard practice
Is the requirement to earth the back box in the regs? If not then surely its up to the spark although i dont understand why we have regs then people do their own thing. If it is in the regs then it must be done regardless of your views. The same as were supposed to stick to the speed limit!
Never trust an electrician with no eye brows
I do take CPC's direct to the socket and then a flyleaf to the back box if a metal socket NIC didn't used to insist on on the latter ie if a plastic socket but NAPIT did. However the metal conduit system presents what I would consider a huge danger if relying on the metal of the conduit providing a CPC and in this scenario I encountered a situation whereupon the metal conduit had been severed and 2.5 had been used in between. Remember in galvanised conduit you are dealing with threads, cutting compound etc all of which can circumvent the continuity. My first flat had one of these infrastructures and I completely re-wired it again with singles but with a CPC within the conduit.
Obviously with a plastic face plate you need to earth the backbox. If the Live becomes loose an comes into contact with the backbox, an earthed backbox with allow enough current to flow to trip the MCB. If it's not earthed you just have a Live! backbox.
Makes sense. But can't see the need for fly lead but we all still do it!
I agree it’s personal preference and a minor detail. Back boxes when a socket circuit is energised is not an exposed conductive part as it’s concealed behind the socket anyway. But how many times do electricians and DIY enthusiasts take socket fronts off live ! A fly lead will ensure the back box is still earthed even when others like poking around live parts.
First of all, get rid of those crazy ring circuits then we can talk.
The starting point should be that the power to the socket MUST be off BEFORE the socket cover is removed. There are plenty of regs, acts, instructions etc which state this point.
However, in the real world, this does not happen.
Let's presume the socket remains energised, an earth fault COULD occur when the cover is off, and if no rubber grommet is protecting the metal entry hole, an earth fault is MORE likely to occur.
'AHH, RCD would trip' I hear you say..... How many RCDs have you come across that DO NOT trip. LOADS, I mean who tests them periodically anyway?
I understand your angle, and this is why I still do it as 'best practice'.. but obviously the regs are not written for this scenario.
Best practice is the way forward, I've always earthed the back box, with a 'flyinglead' cpc (ie. always multi-stranded conduit wire) this is more robust than single strand cpc.
I should say metal cover light switches would be given the 'flying lead' cpc treatment too.
SparkyNinja
If there is at least one fixed lug it’s really not necessary. If you have a socket with a spur, introducing yet another cable just makes things more cumbersome than they [functionally] need to be.
@loose cannon, Ive not come across “ loads “ of rcd that do not trip, I suggest you are exaggerating, and I’ve told you a million times not to do it.
Is an extra earth needed for a metal face plate? I would have assumed so (similar light switches have an earth screw to earth) but my new plug socket doesn't have an obvious earth screw for the faceplate
How many times have you seen missing grommets? No grommets = possible live backbox so always Earth the box before you even get the socket out of the wrapper
Why not twist conductors to get a more secure ring, long term and possibly a lower loop impedance?
Because its a pain in the arse to fault find ,test or alter .
Twisting solid conductors can cause weaknesses to the cable
Always done my mentor and lecturer taught me to make the installation as safe a possible. Better to sleep easy at night. Say the end user changes over to steel or brass finished fittings. As it's already in place you give a greater conductivity back to ground in the event of a fault occurring.
Thanks for sharing. 👍
Why not Join all three Earths to the socket earth rather than loop one ?
I think you are very wrong to say the screws can not be griped, as for instance a child holding (gripping) a metal implement such as dads standard screw driver, only has to make contact with the plate screw head.
Also I have often witnessed decorators both professional and DIYer’s just loosening the screws without removing switches or sockets, while the circuit is live, the screws could certainly be griped.
In both scenarios if there was a live touching the back box there would be a shock hazard.
Hey I know fark hall, Don’t listen to me.
Love your videos.
Regards Norfolkngood
Child would loose contact between the screw and the tool at the first perception of energy.
Other trades loosening screws fails the fundamental principles outright and no installation is designed to operate safely in that condition.
“... _and_ provided that connection with a protective conductor could only be made with difficulty...” - I fail to see the difficulty here, so the connection is still required, isn’t it?
I would not use conduit without an earth conductor as the resistance measured in a conduit run may be to great for fault protection
Steel has a significantly lower conductivity than copper but the cross sectional area of a steel conduit is so massively greater than a copper CPC could provide that, if *correctly* jointed, conduit is just about always guaranteed to outperform s separate CPC.
Wow! NO NO NO. The fly lead has to be there to comply and its a breach of regulations not to add it. And, a point in case my daughter touched two recessed exposed screws and a latent fault in the system shocked her badly. I agree its unlikely and is as unlikely as the latent fault that nearly killed her.
Which regulation?
@@SparkyNinja I believe the regulation he is referring to was what you have been saying... where certain conditions are met then no need to bond... on some sockets where the earth bars don't earth the screws then they become exposed conductive parts in which case the only way for that to comply with regs is to bond the back box. I always bond it anyway... then I'm covered.
When I was training for my C&G 236 (part 1 & 2) we were using 16th edition (I qualified early 1990's) and you had to connect an earth wire to the backbox. I believe this was relaxed when the 17th edition was released. The argument was that under normal circumstances a domestic user would not be touching the backbox and that it was earthed via the screws that connected the earth on the socket to the backbox.
I was qualified around same time as you, I seem to remember that because you will lose the earth connection to the back box for example when painters remove the sockets during painting
One word: Corrosion!
Two words... "replace it". You shouldn't be leaving corroded boxes in place.
Wondering as the bending ratio of the CPC is greatly exceeded when terminating to the back box and taking it on to the socket, can you call it a continuous circuit?
Solid conductors are often bent completely back on themselves when terminated under a screw so I don't think bending the copper to that extreme is an issue.
However, I prefer to use a double ferrule to crimp the fly lead and one of the CPCs together. This saves on the waste of extra length on the line and neutral of the cable with the longer earth and maintains a constant connection just the same.
I don't know if it counts as a continuous connection, perhaps Sparky could ponder that one for us and let us know his opinion.
It is an extra component, so there's an extra cost, but pennies... As far as time taken to do it, I can't imagine it takes any longer than the longer CPC and bending it over method.
This was brought up in my last NICEIC inspection in december the examiner was joyfully showing me pics he had taken of sockets that had the earthing bar of the socket just connected to the earth terminals but not to the screw head.
So if i line conductor had came out and would hit the back box it would become live and not trip out if the back box was not earthed.
1st time i have seen sockets like that in 30 years.
In cases like that you would defo need to bond back metal box as the screws will become exposed conductive parts.
Great vid thanks
Funny enough earthing the back boxes is the most hateful, aggravating and annoying part of the job for me, I'd rather be pulling cables through inaccessible blind holes or bashing rock hard concrete. I have a full rewire in progress and all boxes, have been wired and finished... Apart from, as of this moment only half the boxes have been earthed. I did half and was expecting to finish off and do the rest next visit - Because I don't enjoy that bit, after hearing your very sensible and authoritative appraisal I was quite tempted to just leave them.. I mean the great Sparky Ninja has removed any guilt.. Of course it would be impossible for me to leave site without completing the blinkin' back boxes. Grrr. For some reason I couldn't do it. Excellent channel and what a great name too. Subbed.
What if the back box became live on inspection due to a break in a live conductor. No Cpc no protection I say.
Inspecting behind a socket that is energised isn't recognised in Regulation or Legislation though. If you are live working via a sanction to comply with EaWR 14 (c) then you would be applying additional protective measures. Again as I said, I would still do it too, but this is the bullshit that would be used to interpret that work.
I don't think you're interpretation of 410.3.9(iii) is correct. For the exemption to apply 2 criteria are required. Exposed conductive parts need to be of reduced dimensions AND connection with the CPC would need to be difficult or unreliable. Whilst the first requirement is met as you describe, the latter is not IMO since I think it is neither difficult nor unreliable to use the back-box terminal, therefor the exemption does not apply. I think this is really clear with careful reading. Regardless of the regs, I would also ALWAYS run the CPC via the back box and into the front plate exactly as you show.
Best practice - Blah... Most domestic use modern sockets are earthed via the screws anyway. Many ‘loose’ back box wires become faulty or are not cut/stripped/fitted property. Most modern sockets have TWO earth sockets. As long as they are connected up here then its happy days. Yours screws work as an earth anyway. However, like you point out, it’s good practice.
The backbox doesn't need a CPC it may be good practice to bond; take the CPC where it's required to the socket. Your adding a point of failure in the cpc - I've seen the cpc failed at the bonding connection (overtightened termination/ damaged copper). With large volumes of sockets, this may have a detrimental, maybe small, effect on R2 - R2.
I used to think that this procedure was unnecessary because the back box is earthed through the lugs, however this only protects you when the socket is fully connected and when it’s removed you loose the earth path..but then you shouldn’t be removing the socket unless power is isolated… so I just don’t know… FYI I always earth metal back boxes just to avoid dispute
A very interesting video!!! I would do exactly how you say ,keeping a continuous earth, but another reason I can see is that you're using a plastic socket so if at a later date it goes to a metal one then u are covered ??? Would like your opinion on this please!!
Rgds your friendly neighbourhood trucker!!!
i think its good practice NOT to earth the back box with the fly lead because when dead testing -its best to take the face plates off the wall,(to exclude any parallel paths from metal stud work).how do we know we are measuring the cpc and not a fortuitous earth from cable tray or metal studs etc which can change if the builder was to make an alteration (I dont do domestic work,I'm talking commercial here) The back box will be earthed through the screw
have always done this and always will, belt and braces on SOCKETS cant hurt.
I say sockets, because no one ever talks about switches, which is where it makes the most sense, unless you are using a metal switch plate, there is no way to earth the screws, and if the backbox isnt earthed the screws could become live and stay that way until someone gets a belt.
The question is answered by admitting that a flying lead from a besa box, back box, spur box is to earth them in absence of an integral cps within containment which when mechanically sound is electrically continuous as the earthing requirement. My opinion differs somewhat. The TNC system being somewhat inadequate because of bad mechanics lost the concept of being electrically continuous and therefore became hazardous. The TNC-S's integral separate earth made the flying lead nothing more than a bit of supplementary bonding. Now here, in my opinion, is the anomaly. The picture presumably shows one leg of a ring final circuit's cpc being split from the accessory and replaced with a supplementary bonding flying lead to the terminal of a back box where it is made to join the other leg of the ring final circuit's cpc. That to me, says that a cpc which should be in the form of a ring is made up two cpc legs from the board to the back box+accessory and joined between with a flying lead of supplementary bonding. Supplementary bonding, as far as I can reckon, is not a circuit protective conductor.
I cannot understand why you would not do it anyway. Good practice
Personally, I'd always earth a socket back box. Always assumed this was actually a requirement. 😕
Never assume...
Assumsion can be a killer
The other reason to have this lug is for cases where the front plate isn't earthed, say for a plastic 3 gang light switch. It gives you a place to park the cpc in the case that the switch is changed for a metal one in future. Doing it for sockets seems pointless and silly. I don't think it adds any safety, it just wastes a bit of cable.
who is the respected spark you refer too
Always done, ... just how I was tought
In my opinion if you really want to earth the back box then its better to have a saprate wire from backbox terminal to the spare earth terminal on the socket , and keep both cpc together in one terminal.
Interesting subject, personally I would earth back box. I have seen too many "fixed lugs" that I would not call fixed, many of these are separate pieces of metal crimped to the box. It doesn't take much for these lugs to become excessively loose or detached.
What about a situation where a small child / baby is exploring there surroundings? Sat on the floor, possibly with a wet nappy and bare legs also in contact with floor, sees a small shiny thing and goes to touch it. Unfortunately the screw has become live, unfortunately for the child who through no fault of there own has a very good ground and conductance is now dead.
This may seem excessive but having seen and worked in houses that fit both criteria I'm surprised it hasn't happened to my knowledge (im sure it has at some point). Perhaps the TV in front of socket has helped.
With regard to using the conduit as earth conductor, has this been reverted? I thought the conduit was to protect the cables and had to be earthed in the same way as the function of steel armour cable, and not function as the cpc. Does corrosion not occur these days with steel conduit in a damp wall?
Seen some nasty situations over the years, still shudder at the thought of some of them and wonder how people haven't been injured or killed... I get this funny tingling when I lean on this wall by here (attached garage converted to spare downstairs room, ex council house). That job ended with complete rewire (after moving and replacing the old *fuse* board from under the kitchen sink worktop that leaked water down the wall).
Yes because some of the sockets, switches and other do not have a ring of metal at the screw hole. As in the old day's the screw hole was not earthed as now. (Me. Socket first then lead to back box)
I agree with everything you said and would further a reason for this good practice that if the two screws are removed from the socket plate with it flapping around the backbox would not be earthed. Ive seen socket plates flapping around in badly maintained properties and situations where decorators take them off to paint. Like the guy a few comments down I always feed back to the backbox and not the backbox first.
I'm not on the business of finding excuses to cut corners in good practice but I know many people who are, the guidance note 8 has a few pages and illustrations dedicated to this scenario explaining about the adjustable lug and fixed lug etc.
I am not an electrician but have a passing interest. So what I am hearing there is zero downside to doing this from a safety point of view, so why should an electrician argue that he / she won't do it? To save a bit of copper and about a minute per socket wiring to the back box? If so, then that is an electrician I would not want wiring my house if those are seen to be real reasons.
Agree totlly and sadly belatedly
Horses for courses. Personally I do it this way too but mainly because I learned it this way under C&G236.
If you fit a socket to a plastic back box do you earth the screws?? No you don't.... If you earth the Metal box technically you are only earthing 1 screw as only 1 lug is fixed the other isn't.
If one screw on the fixed lug creates that equipotential then the other screw doesn't matter as long as you screw it in
Only concern is that the earth bar must be covering the screws too as some earth bars don't cover the screw holes
If wired correctly and on a rcd then testing and subsequent tripping will occur unless screws are left out say while decorating,and during that time the box becomes a live conductor.
Nothing is perfect but belt and braces,screws and earth cable earthing double bubble.less trouble
For a task that takes an extra 20seconds, why even bother trying to excuse not doing it?
Always do it as good for our check
You do not need to earth the back box it's earthed through the fixed lug in this system why make more work for yourself when you don't need two
Bullshit some old and my be new sockets do not use an earth at the screw holes so check......
@mr little, can you point me in the direction of the sockets you talk about which don’t connect too cpc thought the screws. I’m interested to see them. Not interested in old ones as I never install old ones.
@mr little, u still haven’t answered my question about the sockets without a earth strap too the screws, or it you that is the bullshitter?
Always go with the belt & braces approach when dealing with electrics imho.
Nothing wrong with having multiple earth routes to the BB, a failsafe is always a good thing :-)
@@supersparks9466 I'll answer on behalf of him.. ua-cam.com/video/kPpX1YXvGcg/v-deo.html from 7:42 you will find a cheap but fully compliant BS1363 twin socket outlet with no strap across to the screw holes
if you take the face plate off with the power still on and you get a shock you got what you deserved
dead tests before live tests so even on an eicr you should have all the covers off and inspect them before the power goes back on
the fixings holes on most decent socket outlets are connected to an earth bar in the back of the socket so the screws are earthed via the cpc connection on the faceplate
andy ? This is my thinking but I’m not sure it’d stand up in court (got what they deserved) ha ha.
I never earth my back boxes as like you say, power should be off before removing anyway. I’ve been doing it without for 23 years
@@tommochelsea72 in court id quote the eawr etc, you shouldnt work live unless it is unreasonable to do so.
sockets can be tested from the front so there is no need to remove them with the power on
You never drop sockets down when they are live?
I will occasionally drop them to have a quick peak at what is going on. Maybe an initial check to see if it has 1 or 2 t&e cables present if planning to add a socket to the ring. Just exercise a bit of caution in case the cables drop out and also depending on the environment. Obviously not in a nursery or something!
@@mrbadger9920 that is totally stupid and dangerous
Also true with new all metal fronted sockets with the earth strap across the back between screw holes, the screws being the connection to the back box, which takes the earth forward to the back box.
Quick question for you sir, does it matter from which cable is the earthing wire connecting to the backbox ? ( In the picture it seems the incoming wire si connecting the earthing to the socket, and the outgoing is connected to the backbox linked with the socket )
It's for Ferrous reasons......Why would you earth the frontplate to the back box when the screws in the frontplate run through the face plate earthing strip anyway.
Some sockets have bars not connected to the screw holes
Been doing it that way for over 40 years, one less cable connected to socket.
I am a retired electrician and I find when friends ask me to change electrical fittings for them I find that 80% of houses have wiring interfered with by previous homeowners for e.g. grommets missing and sharp screws in back boxes. So I like to use 4mm earth fly lead from back box to E terminal on sock/outlet.
I was trained by CEGB many moons ago (up to 11 kv). The 'qualified ' electrician who just rewired my house did the earth wire to box randomly, never clipped any trunking, never used grommets, stuffed three 2.5 T&E in one backing box hole (one two in trunk), slit the outer cover on a 2.5 and hid it, patched the floor so well that my wife nearly went through it. Don't ever use Adept Electrical and their authority!
Hi, I have considered this too, and I agree with your reasoning, but you know l would also consider if the wall is subject to any dampness and also some sockets provide those little plastic caps!
That said these days as we
have R.C.D's which would sense imbalance really reduces potential danger to a minimum, whereas back in the day would have been a bit more involved,
That said I also make a long CPC into a box tail as it makes the process simple and done all in one go,
I think what you have highlighted is that if you know your reg's then you have more options and it's always better to have options
Right on
Kind regards Warren
The screws will be earthed regardless of damp, only consideration here is if we're talking about if the cpc was a conduit system or if the sockets have earth bars that don't earth the screws which will turn them into exposed conductive parts
Could you tell me why I'm getting over a 100 volts when I connect my multimeter to the outside screws obetween 2 sockets if i put one probe on the kitchen sink and one to the metal case of the socket I get around 60v the sockets are metal not plastic I have a cut on my finger and I just noticed when I was doing the dishes that I was getting an electric shock when I touch to the tap and the water in the sink
Sounds like you have some potential earthing issues. I'd recommend you call an electrician in to test the effectiveness of the protective conductors in your kitchen.
@@SparkyNinja I know the sink taps are not earthed i just found that out looks like sumone forgot to do it wen the new kitchen went in would that have anything to do with the sockets given a reading
@@SparkyNinja I took the isolation switch socket cover for the dishwasher off and 2x earth wires from the socket to the left were not connected and one of the black wires had come out of the connector and I have a feeling it was touching the metal faceplate cover on it
I've connected then all bk up and no reading at all so job dun
Would this have been wasting electricity All this time It's just my electricity smart metre Seems to be using a lot less
As much as I applaud the method of earthing the back box, the 'respected electrician's' choice of fixing screw and the resulting sharp edge is not brilliant.
Well put dave. There is a paragraph in guidance note:selection and erection thats states exactly what you mentioned.
I always earth the back box
Hi! guys, tell me please, by regulations do I have to earth backbox or not? it's more important what regulations says, becouse the contractor will don't pay you if you did the job wrong and does not matter how safe is your job done. when you working on price, the speed matter.... Thank you!
Did you watch the video?
Belt and braces approach, earth the backbox, you know it makes sense.
So say a tiler takes off the socket to tile and the live conductor is knicked touches the back box that is not earthed? then what!!
Then the back box will be at mains potential and will go bang when the tiler re fixes . In both scenarios the tiler is at fault .
Good point, well made!
I don't know about iee/iet regs and recs, but ieee regs require all metal panels and enclosures containing or supporting mains wiring has to be earthed.
It is earthed through the fixed back box lug .
Surely you’re original theory that the lug is used to provide the PE connection to the socket where the back box and conduit provide the PE could be wrong as the screws would in fact make that connection. Gordon
Surely the back box makers would not waste money providing earth lug and it's space nuisance if it was of no definite value?
@@derekwade7471 Hi Derek, That's a good point, the only reason I can think of is, if a (metal) backbox is fitted into an insulated cavity (say a stud partition), and the item being fitted to the box was for example, a plastic plate switch without an earth connection or bar, and then for some reason the back box became live (e.g the insulation on the live wire being compromised), then the screws on the faceplate could be live, but as sparky mentioned, the regs seem to think that's OK if they are small and recessed. But as many have mention here, if your charging £100 to fit whatever it is (just joking), why wouldn't you just spend a couple of minutes fitting an PE for safety's sake. Cheers, Gordon
Would it make a difference if using a metal socket ie the face is now metal not plastic, as you could touch more of it
The faceplate is where the cpc is already do its already earthed at the plate
makes total sense
Yes!..i ALWAYS connect metal back boxes to cpc.. I have seen and repaired socket outlets with live conductors popped out of a 32A ring circuit and touching the back box which was not earthed.. The screw heads on the front plate were live!.. It's a no brainer.
How the fuck can the screws be live? If the socket is connected to cpc then the screws will also be connected thought the metal strip on the back of the socket.
@@supersparks9466 humidity/damp in the wall, over a period of months because it wasn't fully tightened, and corroded, caused a high resistance between the screw head and back box lugs, in tandem with a screw penetrating the live conductor insulation made 1 screw head live! I'm not making it up. It also failed an IR test. It's not made up!
@@muzikman2008 award for thing on the internet that didnt happen goes to......
What if the socket being installed has a metal front?
Yawn, it’s earthed by the cpc
And cpc stands for
Circuit protective conductor
Thankyou.