SEE ALL - To view a list of all our LearnElectrics videos, click on the link below. There are many videos on many electrical topics including Installation, Part P, 18th Edition, Testing, Certification, Lighting, Sockets, Ring Circuits and much more. ua-cam.com/channels/YaJQnpO4XAp0yCgqzMkmfA.html
You make some interesting videos explained in praical terms that new learners would find very useful. I have to say though that everything causes debate amongst these young Sparks that seem to spend more time on UA-cam than on a building site! I'm so glad to be retired now because I simply wouldn't be able to stand them on the same job, they'd be leaving via the nearest window whether open or not!
I am going to take a spur from a ring main to use MK grid switches. I am planning on putting a MK grid 13a FCU prior to the two proceeding switches. These two appliances are less than 13a, but this approach will avoid me having to extend the ring through the MK grid switches. Thanks for the video!
@@learnelectrics4402 does my thought process sound about right. Providing I use the 13a grid prior to the next two switches I’ve effectively made an FCU. However, I will use 2.5mm for the full wire up for good practice. The two appliances will only draw 11a total so no risk in the fuse going.
@@learnelectrics4402 thanks watched, explained so well. I believe my plan creates a fused spur situation as the appliance switches are after the 13a fuse. However, if it was just one switch with a plug for the appliance this would only be 1 spur, so wouldn’t need the fuse prior as the plug is fused. Will run it past a sparky, but think I’ve got that right
A lot of cable, particularly sockets on an outside wall on a timber framed house is buried in insulation. In which case the 27amp rating which is “clipped direct” no longer applies. I don’t have the table in front of me, but I seem to recall that the rating drops down to “conduit in insulated wall” which I think was somewhere around 20 amps. I think the modern building standard is to incorporate a service void for electrics and plumbing on the outside wall, but older timber framed houses it’s common to see the ring circuit wiring buried right in with the fibreglass material.
@@learnelectrics4402 I have followed your guidance to install wall light with L, N. E wires which is working fine. However I tried to install dimmer smart switches between lights and spur switch ( with 3a ) but it didn’t work. I tried 3 different types of smart switches but no results. My wall light is dimmable that I bought. I’m not sure where did I make mistakes, any recommendation would be helpful, Jay
Are you sure you have a neutral wire in the switch box and not just a blue being used as a phase switch wire. A smart switch will usually need a neutral.
@@learnelectrics4402 thanks for quick reply. I used spur socket where it wires blue, brown and earth. I used these wires to connect a smart switches but it didn’t work. I have another smart switch where it doesn’t require N wire and I tried but still not working.
A concise and easily understandable explanation, thank you. I have fitted an rcd wall plate externally to a shower room fed from the ring using a 2.5 cable. It is to supply a heated towel rail that has a 600W element. Can I feed the towel rail with 1mm cable to a flex outlet box adjacent to the towel rail? Additionally, could I also wire an extractor fan and LED lighting into this rcd so that all electrics in the shower room are protected by the rcd? I'm enjoying learning from your excellent videos.👍
David, yes, you can feed from the new RCD but the extractor, lights, towel rail must be fed through Fused Connection Units (fused spurs). Towel rail with a 3amp fuse and the extractor/fan on a separate FCU rated accordingly (possibly 3 amp) as per the demand. Glad you are enjoying our videos, lots more coming.
An RCD is not fused. It will be fused by the 32 amp or 40 amp breaker back at the CU I assume. You should not have a 2 amp towel rail protected by a 40 amp breaker, hence we use FCUs and fit 3 or 5 amp fuses. Hope this helps.
@@learnelectrics4402 thanks again for your on going support, I appreciate your efforts. The rcd I have fitted IS fused, it's this one www.toolstation.com/rcd-spur-white/p48767 So will this fuse suffice for the towel rail or do I still need to fit a secondary fused spur?
Righto David, this is an RCD SPUR, which is different to just an RCD. An RCD on its own not fused but an RCD spur is yes. OK we're sorted now. As long as the RCD spur has a 3 amp or 5 amp fuse (the towel rail will draw about 2.5 amps) you will be ok. We always fuse as close as possible for safety and you may find the RCD spur comes with a 13 amp fuse fitted, in which case change it. Glad you got back to me. loads more to come. Dave
No, no, no. Leave the 4mm in place. Bigger cable is always safer than smaller cable. It's just that it costs more money. Keep watching, loads more to come.
Love your channel and just subbed. One question I have is - how come the lighting is protected by a 3 amp (or even 1 amp) fuse in this arrangement..... but lighting circuits themselves are protected (generally speaking) by 6 amp MCB's? I would have thought a fuse up to a maximum of 6 amp would be correct....
Good question Billy and thanks for watching. We always fuse for safety and close to the max needed. A 6 amp lighting circuit might have 10 or 12 lights on it. In the example here, it is a small extension/sun lounge and maybe only has 2 or 3 lamps. The current demand is therefore a lot lower so we can reduce the fuse size accordingly. Why protect a half amp lighting circuit (2 x 60W lamps) with a 6 amp fuse, 12 times bigger than needed. Hope this helps. Dave.
I you have, say, a FCU going to a double socket with 2 high powered appliances like a washer and a dishwasher and it exceeds the 13A causing the fuse to go in the FCU could you add another FCU after the dbl socket and then add another socket?
No. One accessory from each socket on the ring, whether its single or double doesn't matter. just one. You can run a second FCU off another socket though. Remember, the fuses are there to protect the cable. Thanks for asking. Dave.
Yes but the problem is often getting two 2.5mm coppers and one 4mm copper into the same hole. Because they are different sizes there is always a chance of one being loose.
great explanation! question: taking spur from a socket (not ring) with 13A FCU, can I add few more sockets? Am I aloud or just limited to one socket? Thanks
Thanks for watching. This is the video you need to look at, it gives all the explanation you need, cable size, fuse size etc. Dave. RADIAL SOCKET SPURS, click on the link below ua-cam.com/video/Et7CpEwFEzg/v-deo.html
Yet again another great video. Thank you. 1 question, at 8.42 mins you show a junction box on the ring then down to the fused spur. Is it OK to leave the socket that was there before and just connect a 2.5mm cable into the back of the socket out to the fused spur? I have a room that I need to take a spur off for a heater but I also need the sockets still in that room. So I was going to add a fused spur next to the socket on the wall. But your image shows you have taken away the socket and replaced with a junction box.... Is there a reason? TIA
Yes, add a Fused spur next to the socket that is on the ring and then you can add as many sockets as you wish. Don't worry about how I've drawn it as long as a fused spur is the first item off the ring. Hope this helps, and thanks for watching. Dave.
Can you install the FCU via cable from socket. 2.5 T&E from single socket to FCU and then 2.5 T&E from FCU to New single socket. The ring is on a 30A fuse.
@@learnelectrics4402 if the fixed load connected isn’t going to exceed the maximum current carry capacity of the leg what’s the need to fuse it down if the Zs for the protective device is met?
Great channel love the videos, just a quick question regarding spurring off of the ring with two single sockets as you explain at 3:20 I have never heard of this not being allowed before. What is the difference in spurring from the ring with one double socket or two single sockets? Is it not the same thing? you can not exceed the rated 27a of the cable as anything plugged in to either socket will have a maximum rated 13a fuse in the plug top, which in turn would have a total max load of 26amps? Could you explain a little bit more please, thank you and keep up the great work it is much appreciated
One accessory only. A single socket is one accessory. A double socket is one accessory. 2 single sockets could be some distance apart and both loaded to 13 amps. A double socket is unlikely to have two 13amp devices plugged into it. Their rules not ours. Thanks for watching. Dave.
my novice understanding can't quite grasp the diagram at 4.52 mins. The fused connection is showing the supply coming in and the load going to four additional sockets. But it also shows supply to the other sockets? Does that mean the 2.5mm wiring share the same supply terminals? I.e. two wires into the same supply terminals to allow the continuing of the ring?
That is correct, the 2.5 passes through the FCU to the rest of the ring and also feed the 4 sockets below. take a look at the video on the link below. ua-cam.com/video/fj9cc1U9Re0/v-deo.html
No. An immersion heater must be on its own circuit. A 16A circuit breaker and then a 13A switched fused spur. page 505 (ii) of the Regs. Good question though. Thanks for watching. Dave.
Is it possible to go from main ring socket to a socket which would be a spur then after that put a FCU for lighting? Also is it possible to go from a FCU to a outside garage consumer unit?? Sorry if these are stupid
The Regs say only one accessory of the ring, so that would be your socket. The FCU for the lights is then not permitted. Instead, change the socket for a 13A FCU and then add a socket after the FCU and a 3A FCU for the lights. Have another look at the video, there is an example of this in the video. Dave.
Thanks for the video. I have a couple of questions. I would like to convert to a 2 gang socket an immersion heater switch that still turns on but is not connected to a now gone boiler. I saw under the floorboards the cable to it is connected to a junction box. It looks like a 2.5mm2 cable. Can that be converted? Also I would like to add two new 2 gang sockets side by side in another part of the room. Should I put in two junction boxes and a spur each or should I go the fuse connection unit way then add the sockets? In that room, I will also be creating a spur from the socket already present. Hope you can advise. Cheers.
Firstly, it is not permitted to install junction boxes under floor boards as it is difficult to reach them for testing and inspection (screwed joints). You can use junction boxes but they must be accessible for maintenance, the same with fused connection units. Follow the advice on the video and you shouldn't go wrong. Good luck. Dave
@@learnelectrics4402This isn't strictly true. The regulations allow for maintenance free junction boxes to be installed in an inaccessible location(s). A correctly configured and installed Wagobox XLA junction box for example may be so installed and will still be BS5733 compliant.
Yes you can, that's the correct way. And then 1.5 or 1.0 after the 3A FCU. You might also find this video useful. ua-cam.com/video/bW44Ie4jOHc/v-deo.html
Good practice says that we always fuse as close to the actual demand as possible. At 5A that's 1200 watts of lighting. Is there really 1200 watts on that circuit or can we reduce the fuse to 3A - about 700 watts and that is still 10 lamps at 60W, even more if they are LEDs. Always try to fuse for safety and choose a fuse close to the actual demand. If the fuse rating is too big, the circuit could be on fire before the fuse blows. Hope this helps. Dave.
Only if the spurs off a spurs it has to be a fixed appliance,as an Industrial electrician of 50 years I've never wired a final ring circuit in cable less than 4mm and that's from a spec and drawings from an electrical design engineer,so my answer to house bashers wire your rings in 4mm twin and earth and if you lose one line cable therefore everything on the circuit is being fed by only 1 cable in the ring ,this is no problem because with one leg being 4mm it will easerly take the load but allowing for diversity the likelihood of all sources being on at the same time is very unlikely ,and if you house bashers say the cost of 4mm is too expensive my answer to you is I know contractors get up to 75% deducted off the gross price,so pass that saving on to your customer,simple
Whatever length doesn't make Zs exceed the permitted maximum. It will be different for every circuit. See our video - Cable Lengths and R1+R2 - on this link. ua-cam.com/video/Qq_9MNH8XxU/v-deo.html
@@learnelectrics4402 OSG 7.2.2 Infused spur lengths should not exceed 1/8 the cable length from the spur to the futherest point of the ring. ok its a rule of thumb and guide , but it's worth noting.
For the purposes outlined in this video is there any difference between an FCU and a switched FCU? Side from the ability to kill power to spurs after the switched FCU?
@@learnelectrics4402 Agreed. Whenever I have connected a single appliance to a FCU I have always used a switched type for isolation purposes, as there would be no plug to be pull out for isolation like you would do normally. When using a FCU to supply multiple sockets, I have usually used an unswitched FCU, simply because there shouldn't be any need to isolate the circuit in that way under normal conditions, and quite apart from anything else when the FCU is on show an unswitched one is less to look at. However, in the house I am in now I have used a switched FCU simply because it was all I had at the time I did the job, and in fact over the years it's proved to be quite handy to isolate a whole bunch of sockets in that room, when decorating etc, because what with the switch being double-pole it saves switching off the whole circuit at the consumer unit. I should add that before starting work I also remove the 13 amp fuse for extra safety.
Its your choice as long as you stay within the rules. This video has a lot more information, it shows you several ways of adding sockets. Good luck, thanks for watching. Dave. To see EXTENDING SOCKET CIRCUITS, click on the link below ua-cam.com/video/3mBXNBwpxXo/v-deo.html
I posed a question on your radial circuits video today, but looking here I perceive a different answer. In the summary at 7:32, the graphic says a spur from a 32A protected ring final can be wired in 2.5mm T&E. That would assume the spur terminates at a double 13A socket, max load possible being 2 x 13 = 26A which is ok for the cable in non fault conditions. What happens in this configuration if a short L/N occurs, can we safely rely on the 32A protective device ?
Yes Mike. It is assumed by the Wiring Regulations that you would not normally fully load both plugged in appliances in one double socket outlet. I.E. you wouldn't normally plug two 13 amp kettles in to the same socket or two 3 kW heaters on full chatt at the same time. Even if you did, the max load would be 13 Amps on each plug top or 26A total as you say and 2.5 twin and earth will take 27A clipped direct. A L/N short would be a massive current, hundreds of amps so a 32A mcb will trip in less than 0.4 seconds, long before the cable overheats and becomes damaged. Remember the fuse or breaker is there to protect the cable from overheating, not to protect the appliance. We also have a video on Choosing breaker and cable sizes. Your getting your money's worth out of our videos. Love it, keep watching Mike. That's what they are there for. The more we can help the happier we are. Dave.
@@learnelectrics4402 Thanks Dave, sounds like I’ll have to send you some biscuits soon! Seriously this channel is the most clear and concise I have found. Others are either out to show how clever they are, or just muddled and confusing. Brilliant work, thank you.
Nothing to stop you doing that, but you will be maxing out the current loading if it is clipped direct. If there is any insulation around the cable route, trunking, conduit etc. then two ovens will exceed the max permitted.
How about if you do Zs test , and if it’s let say 1.25 ohms at the light pendant and it is on 32A breaker . But we know it has 3A fuse protecting it . Can I put the test result as 1.25 ohms but will mention on test cert that it was taken from the light pendant protected by 3A FCU ?
A 3A BS1362 fuse has a Zs(m) of 12.4 ohms. But do take a look at the video below on some of the problems with BS1362 fuses as used in plugs and FCUs. ua-cam.com/video/ojI7vX7u6_A/v-deo.html
Good question Keiran Regulation 554.3.3 may apply, use of a double pole switch and NOT plugged Consider what is rarely, and what other loads are connected. Think about it - a 3kW kettle is a water heater Dave
You cannot just change the breaker size without knowing that the cables are the correct size for the new breaker. I suspect at 16A this is a radial circuit, have a look at our video on Ring and Radial differences on the link below. ua-cam.com/video/6GNb1SSEjQg/v-deo.html We also have a video on Extending Radial circuits. Dave.
@@learnelectrics4402 thank you. I have checked all the sockets in the garage and is a closed loop circuit 2.5 cable. I will be using the garage as a workshop
Can i add a 13A FCU in a 2,5mm cable size then adding spur socket with same size of cable (2,5mm T&E)? Or is it only correct if I reduced the cable size after the 13A FCU???
You can supply an FCU from a 2.5mm ring in 2,5mm cable as you say. You do not have to reduce the cable size after the FCU, it can be left as 2.5mm if you wish.
If you mean can you add a spur directly to the 32 amp circuit breaker then yes you can but it must be in 4mm cable. If it comes off a 16mm or 20mm breaker then 2.5mm is ok.
@@learnelectrics4402 Thank-you for your reply. I hear what you say but do not understand why it needs to be 4mm cable. If that is the case then all the single spur's on the ring main will need to be 4mm cable as well. The best way to explain it on a drawing is to think of the CU connection as just another JB on the ring main.
Yes Roy, you are right. It depends how you view the "spur" and I like your JB analogy. If it will only ever be one double socket for all time then yes you can use 2.5. and treat it as a spur off the ring. But if you think it may be considered as a radial circuit now or in the future and have more sockets added to that original socket, then it should really be 4mm. I've seen a few where the spur has been extended with a second socket box. Their excuse was that one more wouldn't hurt. It sounds like you know what your doing, keep going. Good luck and stay in touch. Thanks for watching, thanks for the comments. Dave
@@learnelectrics4402 Thank-you for your reply, my angst for raising the question was due to a recent EICR report which categorised that ring main circuit as a C2 (unsatisfactory) "Multiple circuits in MCB" and having a hard time convincing him he is wrong.
Roy, when I was assessing for one of the big schemes I would have accepted what you describe as ok. It makes sense, it's safe, you can explain coherently why it is done that way, so there shouldn't be a problem. The Electricity at Work Regulations require that the connections are good, the conductors are installed correctly and suitable means are provided for overcurrent protection (a circuit breaker), etc. Nice "chatting" to you. Take care. Dave.
Is there a limit to sockets in the ring? I have just moved in and I know they had work done before. I’m trying to figure out how many for each ring and check nothing has been double spurred, but also if there is a ring limit I want to check that’s not exceeded either.
hi I have external caravan type plug off fcu freezer connection from kitchen thru wall to outside .I want to connect inflatable hot tub from outside but keep caravan plug spare for charging etc.should I use a mains controller outlet on outside
@@learnelectrics4402 thought be better to run fsu off socket in house already got one cable they kitchen wall or can I run it off cable already there is that ok 👌 hot tub be on all time well weekends about 2kw plus caravan plus is just for charge now and Again plus jet washer
hi...where can i find information on the current carrying capacity for a 13 amp 3036 fuse...cant find it in the regs...i can see fuse sizes that are not commonly used but not 13
It can be the maximum current that (say) the kettle will consume. It can be the maximum current that a cable can allow to pass though before it overheats Or it can be the maximum current that the protective device (fuse or breaker) can carry 24 hours a day/7days a week - often called the fuse or breaker rating. Just because a circuit breaker is rated at 32A maximum current, it doesn't mean it HAS to draw 32A. It can draw just 5 amps or perhaps half an amp if connected to a 100W table lamp. I hope this helps, it does confuse new folk at times. But keep watching the videos, keep learning. There are nearly 200 videos on the website at LearnElectrics.com. We all started off as dummies at one time. Dave.
SEE ALL - To view a list of all our LearnElectrics videos, click on the link below.
There are many videos on many electrical topics including Installation, Part P, 18th Edition, Testing, Certification, Lighting, Sockets, Ring Circuits and much more.
ua-cam.com/channels/YaJQnpO4XAp0yCgqzMkmfA.html
I am a DIY guy and your explanations of the topics are simply brilliant and backed up by great examples. Thank you for sharing
Great feedback, truly appreciated. Thanks for watching and lots more to come. Dave.
Very clear and concise - Thanks. I struggle to keep up with all the new revs that come out, but this is no-nonsense instruction.I am just a DIYer
Thank you Adrian, great feedback for us. Glad you are enjoying the videos, lots more to come. Dave.
Keep them coming, great info explained in easy to understand diagrams/wording
Thanks for the encouraging comment. Yes, more videos to come.
Fantastic explanation ! It has resolved an ongoing issue Ive had with an underfloor installation
So glad we could help. This is exactly why we set up this UA-cam channel.
Pass the word on. Thank you so much for the positive feedback. Dave
You make some interesting videos explained in praical terms that new learners would find very useful.
I have to say though that everything causes debate amongst these young Sparks that seem to spend more time on UA-cam than on a building site! I'm so glad to be retired now because I simply wouldn't be able to stand them on the same job, they'd be leaving via the nearest window whether open or not!
I know what you mean. I had a rule with my guys that phones were off in work periods. It worked, we respected each others needs. And no windows!
The best video I've watched on this subject by far. it was explained sooo clearly. thank you very much.
You're very welcome, thanks for watching.
Excellent video. It's good to have all this confirmed and explained so clearly.
So happy you liked it Mark. Thanks for the great comments.
Dave
great explanation on Ring Final with different scenarios. wow
Thank you Iqbal. Great comments. Dave.
Just happened upon this channel---excellent explanations of key areas whilst installing electrical circuits--
Thank you David. Glad you found us, there are 70 videos on the channel at the moment.
Glad to have you with us. Dave.
Fantastic channel!! Learnt just what I needed from way going your tutorials....thanks
Great that we have helped. Your comments are appreciated. Dave.
You are great sir
Your explanation is awaysome 👍👍👍
Thank you Akash, your comments are much appreciated. Dave
Excellent description really enjoyed that. great advice on the changing the 13 amp fuse to a 6 amp fuse if feeding a light.
Glad it was helpful, thanks for watching.
I am going to take a spur from a ring main to use MK grid switches. I am planning on putting a MK grid 13a FCU prior to the two proceeding switches. These two appliances are less than 13a, but this approach will avoid me having to extend the ring through the MK grid switches. Thanks for the video!
You may find the video on the link below useful too. Thanks.
ua-cam.com/video/fj9cc1U9Re0/v-deo.html
@@learnelectrics4402 does my thought process sound about right. Providing I use the 13a grid prior to the next two switches I’ve effectively made an FCU. However, I will use 2.5mm for the full wire up for good practice. The two appliances will only draw 11a total so no risk in the fuse going.
@@learnelectrics4402 thanks watched, explained so well. I believe my plan creates a fused spur situation as the appliance switches are after the 13a fuse. However, if it was just one switch with a plug for the appliance this would only be 1 spur, so wouldn’t need the fuse prior as the plug is fused. Will run it past a sparky, but think I’ve got that right
Another great video!
Glad you enjoyed it, thank you. Dave.
Thanks for the clear explanation, great video
Thanks for the comments and support, appreciated.
Very helpful and reassuring. Thanks.
Thank you Norman, thanks for watching. Dave.
Thank you, sir. Great explanation 👌
You are welcome, thanks for watching, appreciated. Dave.
Solved my problem. Thanks L E.
Glad you are sorted. Dave.
Great video, well done.
Thankyou. We try our best. Keep watching. Dave.
Straight forward , thank you
Thanks Robert, nice feedback. Dave.
Great thanks!
Glad it was useful Steve. Appreciated.
A lot of cable, particularly sockets on an outside wall on a timber framed house is buried in insulation. In which case the 27amp rating which is “clipped direct” no longer applies. I don’t have the table in front of me, but I seem to recall that the rating drops down to “conduit in insulated wall” which I think was somewhere around 20 amps.
I think the modern building standard is to incorporate a service void for electrics and plumbing on the outside wall, but older timber framed houses it’s common to see the ring circuit wiring buried right in with the fibreglass material.
Absolutely Anthony. Lots of methods in use. Dave.
Thanks for the video, very well explained.
Glad you like it John and thanks for the positive comments. lots more to come.
Dave
Many thanks for your effort
We are so glad you enjoyed this video. Thanks for the positive comments. Dave.
Thanks for this video i have been looking for months how to wire a TV of the ring as wasn't sure i need a fused sure, seems i don't
Thanks for watching. Glad you found the information you needed. Dave.
Thanks
Thank you to you for watching, appreciated. Dave.
thank you
My pleasure Mary, thanks for watching.
Excellent video and well explained
Thank you Jay.
@@learnelectrics4402 I have followed your guidance to install wall light with L, N. E wires which is working fine. However I tried to install dimmer smart switches between lights and spur switch ( with 3a ) but it didn’t work. I tried 3 different types of smart switches but no results. My wall light is dimmable that I bought. I’m not sure where did I make mistakes, any recommendation would be helpful, Jay
Are you sure you have a neutral wire in the switch box and not just a blue being used as a phase switch wire. A smart switch will usually need a neutral.
@@learnelectrics4402 thanks for quick reply. I used spur socket where it wires blue, brown and earth. I used these wires to connect a smart switches but it didn’t work. I have another smart switch where it doesn’t require N wire and I tried but still not working.
Nice clear explanation
Thanks for your encouraging comment. We try our best. Dave
Though i am qualified, but you answered most of doubts
We try our best. Thanks for the positive comments.
Dave
excellent video - thank you
Thanks for your great response. Dave.
Thank
Thank you for watching.
Brilliant!
Thanks for the great feedback. Dave.
A concise and easily understandable explanation, thank you.
I have fitted an rcd wall plate externally to a shower room fed from the ring using a 2.5 cable. It is to supply a heated towel rail that has a 600W element.
Can I feed the towel rail with 1mm cable to a flex outlet box adjacent to the towel rail?
Additionally, could I also wire an extractor fan and LED lighting into this rcd so that all electrics in the shower room are protected by the rcd?
I'm enjoying learning from your excellent videos.👍
David, yes, you can feed from the new RCD but the extractor, lights, towel rail must be fed through Fused Connection Units (fused spurs). Towel rail with a 3amp fuse and the extractor/fan on a separate FCU rated accordingly (possibly 3 amp) as per the demand.
Glad you are enjoying our videos, lots more coming.
@@learnelectrics4402 thanks for your prompt response.
Is this the case even if the rcd plate is fused?
An RCD is not fused. It will be fused by the 32 amp or 40 amp breaker back at the CU I assume. You should not have a 2 amp towel rail protected by a 40 amp breaker, hence we use FCUs and fit 3 or 5 amp fuses. Hope this helps.
@@learnelectrics4402 thanks again for your on going support, I appreciate your efforts.
The rcd I have fitted IS fused, it's this one www.toolstation.com/rcd-spur-white/p48767
So will this fuse suffice for the towel rail or do I still need to fit a secondary fused spur?
Righto David, this is an RCD SPUR, which is different to just an RCD.
An RCD on its own not fused but an RCD spur is yes.
OK we're sorted now.
As long as the RCD spur has a 3 amp or 5 amp fuse (the towel rail will draw about 2.5 amps) you will be ok. We always fuse as close as possible for safety and you may find the RCD spur comes with a 13 amp fuse fitted, in which case change it.
Glad you got back to me. loads more to come.
Dave
Great video, i always thought you had to use 4mm2 to connect a new twin socket as a spur..! Can it be left in or should i swap it for 2.5mm2 cheers
No, no, no. Leave the 4mm in place. Bigger cable is always safer than smaller cable. It's just that it costs more money. Keep watching, loads more to come.
Thanks sir
You are very welcome Mintu. Lots more videos to come. Dave.
Love your channel and just subbed. One question I have is - how come the lighting is protected by a 3 amp (or even 1 amp) fuse in this arrangement..... but lighting circuits themselves are protected (generally speaking) by 6 amp MCB's? I would have thought a fuse up to a maximum of 6 amp would be correct....
Good question Billy and thanks for watching. We always fuse for safety and close to the max needed. A 6 amp lighting circuit might have 10 or 12 lights on it. In the example here, it is a small extension/sun lounge and maybe only has 2 or 3 lamps. The current demand is therefore a lot lower so we can reduce the fuse size accordingly. Why protect a half amp lighting circuit (2 x 60W lamps) with a 6 amp fuse, 12 times bigger than needed. Hope this helps. Dave.
I you have, say, a FCU going to a double socket with 2 high powered appliances like a washer and a dishwasher and it exceeds the 13A causing the fuse to go in the FCU could you add another FCU after the dbl socket and then add another socket?
No. One accessory from each socket on the ring, whether its single or double doesn't matter. just one. You can run a second FCU off another socket though. Remember, the fuses are there to protect the cable. Thanks for asking. Dave.
in theory could you not use 4mm cable for the link between the ring and spur to stop overloading cable?
Yes but the problem is often getting two 2.5mm coppers and one 4mm copper into the same hole. Because they are different sizes there is always a chance of one being loose.
great explanation! question: taking spur from a socket (not ring) with 13A FCU, can I add few more sockets? Am I aloud or just limited to one socket? Thanks
Thanks for watching.
This is the video you need to look at, it gives all the explanation you need, cable size, fuse size etc. Dave.
RADIAL SOCKET SPURS, click on the link below
ua-cam.com/video/Et7CpEwFEzg/v-deo.html
Brilliant
Thank you, really appreciate your feedback.
Dave
Yet again another great video. Thank you. 1 question, at 8.42 mins you show a junction box on the ring then down to the fused spur. Is it OK to leave the socket that was there before and just connect a 2.5mm cable into the back of the socket out to the fused spur? I have a room that I need to take a spur off for a heater but I also need the sockets still in that room. So I was going to add a fused spur next to the socket on the wall.
But your image shows you have taken away the socket and replaced with a junction box.... Is there a reason?
TIA
Yes, add a Fused spur next to the socket that is on the ring and then you can add as many sockets as you wish. Don't worry about how I've drawn it as long as a fused spur is the first item off the ring. Hope this helps, and thanks for watching. Dave.
Can you make a video on explaining the wiring of the consumer unit?
That's a good one. We've put it on the list of future videos. Thanks.
Can you install the FCU via cable from socket. 2.5 T&E from single socket to FCU and then 2.5 T&E from FCU to New single socket. The ring is on a 30A fuse.
Yes you can. Always pay attention to cable sizes.
If you fit an FCU and then say four switches off this, is there a reason why you should use 1.5mm cable? Or should you continue to use 2.5mm? Thankyou
Because you have a 13A FCU, you can drop the cable size to 1.5mm.
Take a look at this video on the link below.
ua-cam.com/video/fj9cc1U9Re0/v-deo.html
5:58 what is best practice? Junction box, then FCU, then socket? Or just FCU straight on the ring main, then socket? Thanks in advance
Either way will work as long as you respect the cable sizes.
U EXPLAIN THE WHOLE ONE SEMESTER SUBJECT
Glad you found it useful. Thanks for watching and lots more to come.
Wow! This is very informative, thanks for sharing it with us Dave. It worth it and the best tutorial on the topic for me...dl
Glad it was helpful Daniel.
Since lights are a fixed load are you fusing it down, for overload or to ensure max zs is achieved?
We are fusing it down for over-current protection. We should always fuse close to the maximum load for that leg.
@@learnelectrics4402 if the fixed load connected isn’t going to exceed the maximum current carry capacity of the leg what’s the need to fuse it down if the Zs for the protective device is met?
Great channel love the videos, just a quick question regarding spurring off of the ring with two single sockets as you explain at 3:20 I have never heard of this not being allowed before.
What is the difference in spurring from the ring with one double socket or two single sockets? Is it not the same thing? you can not exceed the rated 27a of the cable as anything plugged in to either socket will have a maximum rated 13a fuse in the plug top, which in turn would have a total max load of 26amps?
Could you explain a little bit more please, thank you and keep up the great work it is much appreciated
One accessory only. A single socket is one accessory. A double socket is one accessory.
2 single sockets could be some distance apart and both loaded to 13 amps. A double socket is unlikely to have two 13amp devices plugged into it.
Their rules not ours. Thanks for watching. Dave.
my novice understanding can't quite grasp the diagram at 4.52 mins. The fused connection is showing the supply coming in and the load going to four additional sockets. But it also shows supply to the other sockets? Does that mean the 2.5mm wiring share the same supply terminals? I.e. two wires into the same supply terminals to allow the continuing of the ring?
That is correct, the 2.5 passes through the FCU to the rest of the ring and also feed the 4 sockets below.
take a look at the video on the link below.
ua-cam.com/video/fj9cc1U9Re0/v-deo.html
@@learnelectrics4402 Many thanks for that! I have a clear grasp of this now.
Nice easy vid thanks.Can I add an emmersion to a 13a fused spur?
No. An immersion heater must be on its own circuit. A 16A circuit breaker and then a 13A switched fused spur. page 505 (ii) of the Regs. Good question though. Thanks for watching. Dave.
Is it possible to go from main ring socket to a socket which would be a spur then after that put a FCU for lighting?
Also is it possible to go from a FCU to a outside garage consumer unit??
Sorry if these are stupid
The Regs say only one accessory of the ring, so that would be your socket. The FCU for the lights is then not permitted.
Instead, change the socket for a 13A FCU and then add a socket after the FCU and a 3A FCU for the lights. Have another look at the video, there is an example of this in the video. Dave.
Thanks for the video. I have a couple of questions. I would like to convert to a 2 gang socket an immersion heater switch that still turns on but is not connected to a now gone boiler. I saw under the floorboards the cable to it is connected to a junction box. It looks like a 2.5mm2 cable. Can that be converted?
Also I would like to add two new 2 gang sockets side by side in another part of the room. Should I put in two junction boxes and a spur each or should I go the fuse connection unit way then add the sockets? In that room, I will also be creating a spur from the socket already present.
Hope you can advise. Cheers.
Firstly, it is not permitted to install junction boxes under floor boards as it is difficult to reach them for testing and inspection (screwed joints). You can use junction boxes but they must be accessible for maintenance, the same with fused connection units. Follow the advice on the video and you shouldn't go wrong. Good luck. Dave
@@learnelectrics4402This isn't strictly true. The regulations allow for maintenance free junction boxes to be installed in an inaccessible location(s). A correctly configured and installed Wagobox XLA junction box for example may be so installed and will still be BS5733 compliant.
For the lighting spur... can you take a 2.5mm from the ring straight to a 3amp FCU?
Yes you can, that's the correct way. And then 1.5 or 1.0 after the 3A FCU.
You might also find this video useful.
ua-cam.com/video/bW44Ie4jOHc/v-deo.html
@learnelectrics4402 Thank you so much for the replies and the help. It's🙏 really incredible
Why can't you use a 5amp fuse for the switched FCU for lighting?
Good practice says that we always fuse as close to the actual demand as possible. At 5A that's 1200 watts of lighting. Is there really 1200 watts on that circuit or can we reduce the fuse to 3A - about 700 watts and that is still 10 lamps at 60W, even more if they are LEDs. Always try to fuse for safety and choose a fuse close to the actual demand. If the fuse rating is too big, the circuit could be on fire before the fuse blows. Hope this helps. Dave.
Why do you need a junction box on the diagram at 6:10 can’t you just have the fuse, followed by the socket, switched fuse and then light bulb?
Yes you can Tazer, I was just showing you different options according to the Regs, and what they permit. Good question. Dave.
Why do you have to put 3 amp fuse for lighting circuit if the cable is still 1.5mm2 .. Is it to protect the housing unit of the bulb ?
We always fuse as close as possible to maximum load. A lighting circuit in an extension might only need 2 amps.
@@learnelectrics4402 Thank you. That makes sense
Oh, hi. Nicely done.BobUK
Thanks, your comments are appreciated. Dave.
Only if the spurs off a spurs it has to be a fixed appliance,as an Industrial electrician of 50 years I've never wired a final ring circuit in cable less than 4mm and that's from a spec and drawings from an electrical design engineer,so my answer to house bashers wire your rings in 4mm twin and earth and if you lose one line cable therefore everything on the circuit is being fed by only 1 cable in the ring ,this is no problem because with one leg being 4mm it will easerly take the load but allowing for diversity the likelihood of all sources being on at the same time is very unlikely ,and if you house bashers say the cost of 4mm is too expensive my answer to you is I know contractors get up to 75% deducted off the gross price,so pass that saving on to your customer,simple
Thanks for your input, appreciated.
you never mentioned the maximum length of the cable going to a spur.
Whatever length doesn't make Zs exceed the permitted maximum. It will be different for every circuit.
See our video - Cable Lengths and R1+R2 - on this link.
ua-cam.com/video/Qq_9MNH8XxU/v-deo.html
@@learnelectrics4402 OSG 7.2.2
Infused spur lengths should not exceed 1/8 the cable length from the spur to the futherest point of the ring.
ok its a rule of thumb and guide , but it's worth noting.
For the purposes outlined in this video is there any difference between an FCU and a switched FCU? Side from the ability to kill power to spurs after the switched FCU?
No difference Saleem. Just personal choice. You might put a bathroom towel rail on a switched spur, but a boiler circuit would be unswitched.
@@learnelectrics4402 Agreed. Whenever I have connected a single appliance to a FCU I have always used a switched type for isolation purposes, as there would be no plug to be pull out for isolation like you would do normally. When using a FCU to supply multiple sockets, I have usually used an unswitched FCU, simply because there shouldn't be any need to isolate the circuit in that way under normal conditions, and quite apart from anything else when the FCU is on show an unswitched one is less to look at. However, in the house I am in now I have used a switched FCU simply because it was all I had at the time I did the job, and in fact over the years it's proved to be quite handy to isolate a whole bunch of sockets in that room, when decorating etc, because what with the switch being double-pole it saves switching off the whole circuit at the consumer unit. I should add that before starting work I also remove the 13 amp fuse for extra safety.
So if you were adding a socket would it be best to add this to the ring rather than spur off?
Its your choice as long as you stay within the rules.
This video has a lot more information, it shows you several ways of adding sockets.
Good luck, thanks for watching. Dave.
To see EXTENDING SOCKET CIRCUITS, click on the link below
ua-cam.com/video/3mBXNBwpxXo/v-deo.html
I posed a question on your radial circuits video today, but looking here I perceive a different answer. In the summary at 7:32, the graphic says a spur from a 32A protected ring final can be wired in 2.5mm T&E. That would assume the spur terminates at a double 13A socket, max load possible being 2 x 13 = 26A which is ok for the cable in non fault conditions. What happens in this configuration if a short L/N occurs, can we safely rely on the 32A protective device ?
Yes Mike. It is assumed by the Wiring Regulations that you would not normally fully load both plugged in appliances in one double socket outlet. I.E. you wouldn't normally plug two 13 amp kettles in to the same socket or two 3 kW heaters on full chatt at the same time. Even if you did, the max load would be 13 Amps on each plug top or 26A total as you say and 2.5 twin and earth will take 27A clipped direct.
A L/N short would be a massive current, hundreds of amps so a 32A mcb will trip in less than 0.4 seconds, long before the cable overheats and becomes damaged. Remember the fuse or breaker is there to protect the cable from overheating, not to protect the appliance. We also have a video on Choosing breaker and cable sizes.
Your getting your money's worth out of our videos. Love it, keep watching Mike. That's what they are there for. The more we can help the happier we are. Dave.
@@learnelectrics4402 Thanks Dave, sounds like I’ll have to send you some biscuits soon! Seriously this channel is the most clear and concise I have found. Others are either out to show how clever they are, or just muddled and confusing. Brilliant work, thank you.
Hi. If I have a spur with a (13amp fused spur switch) that has 4 double sockets. Can I plug 2 13 am ovens into one socket or should it be one each?
Nothing to stop you doing that, but you will be maxing out the current loading if it is clipped direct. If there is any insulation around the cable route, trunking, conduit etc. then two ovens will exceed the max permitted.
@@learnelectrics4402 thank u that’s what I thought I’ll run two fused spur’s and have them on separate ones👍🏻
How about if you do Zs test , and if it’s let say 1.25 ohms at the light pendant and it is on 32A breaker . But we know it has 3A fuse protecting it . Can I put the test result as 1.25 ohms but will mention on test cert that it was taken from the light pendant protected by 3A FCU ?
Yes, you should make a comment on the schedule of test results that a 3A FCU is installed.
A 3A BS1362 fuse has a Zs(m) of 12.4 ohms. But do take a look at the video below on some of the problems with BS1362 fuses as used in plugs and FCUs.
ua-cam.com/video/ojI7vX7u6_A/v-deo.html
Hi learn electrics, can you spur off a ring circuit to 3kw instantaneous water heater that would be used rarely in a outbuilding? Cheers
Good question Keiran
Regulation 554.3.3 may apply, use of a double pole switch and NOT plugged
Consider what is rarely, and what other loads are connected.
Think about it - a 3kW kettle is a water heater
Dave
My garage has 4 sockets I wish to add more. The breaker is 16amp is this normal? Should it be changed
You cannot just change the breaker size without knowing that the cables are the correct size for the new breaker. I suspect at 16A this is a radial circuit, have a look at our video on Ring and Radial differences on the link below.
ua-cam.com/video/6GNb1SSEjQg/v-deo.html
We also have a video on Extending Radial circuits. Dave.
@@learnelectrics4402 thank you. I have checked all the sockets in the garage and is a closed loop circuit 2.5 cable. I will be using the garage as a workshop
Can i add a 13A FCU in a 2,5mm cable size then adding spur socket with same size of cable (2,5mm T&E)? Or is it only correct if I reduced the cable size after the 13A FCU???
You can supply an FCU from a 2.5mm ring in 2,5mm cable as you say. You do not have to reduce the cable size after the FCU, it can be left as 2.5mm if you wish.
Can you add one double socket spur to the 32 amp switch in the Consumer Unit feeding the ring main?
If you mean can you add a spur directly to the 32 amp circuit breaker then yes you can but it must be in 4mm cable. If it comes off a 16mm or 20mm breaker then 2.5mm is ok.
@@learnelectrics4402 Thank-you for your reply. I hear what you say but do not understand why it needs to be 4mm cable. If that is the case then all the single spur's on the ring main will need to be 4mm cable as well. The best way to explain it on a drawing is to think of the CU connection as just another JB on the ring main.
Yes Roy, you are right. It depends how you view the "spur" and I like your JB analogy. If it will only ever be one double socket for all time then yes you can use 2.5. and treat it as a spur off the ring. But if you think it may be considered as a radial circuit now or in the future and have more sockets added to that original socket, then it should really be 4mm. I've seen a few where the spur has been extended with a second socket box. Their excuse was that one more wouldn't hurt.
It sounds like you know what your doing, keep going.
Good luck and stay in touch. Thanks for watching, thanks for the comments.
Dave
@@learnelectrics4402 Thank-you for your reply, my angst for raising the question was due to a recent EICR report which categorised that ring main circuit as a C2 (unsatisfactory) "Multiple circuits in MCB" and having a hard time convincing him he is wrong.
Roy, when I was assessing for one of the big schemes I would have accepted what you describe as ok. It makes sense, it's safe, you can explain coherently why it is done that way, so there shouldn't be a problem. The Electricity at Work Regulations require that the connections are good, the conductors are installed correctly and suitable means are provided for overcurrent protection (a circuit breaker), etc. Nice "chatting" to you.
Take care. Dave.
Is there a limit to sockets in the ring? I have just moved in and I know they had work done before. I’m trying to figure out how many for each ring and check nothing has been double spurred, but also if there is a ring limit I want to check that’s not exceeded either.
Sockets in the ring, no limit except common sense. The theory is that the breaker will trip before you can plug everything into all the sockets.
@@learnelectrics4402 Thanks for the reply!
You're very welcome.
I assumed that if you have 2 or more spurs from a ring that you have to reduce the breaker down to a 20A. !!
No. take a look at the video on this link. Dave.
ua-cam.com/video/wKCxgEWleHk/v-deo.html
hi I have external caravan type plug off fcu freezer connection from kitchen thru wall to outside .I want to connect inflatable hot tub from outside but keep caravan plug spare for charging etc.should I use a mains controller outlet on outside
You would be best installing an IP55 outdoor socket.
@@learnelectrics4402 thought be better to run fsu off socket in house already got one cable they kitchen wall or can I run it off cable already there is that ok 👌 hot tub be on all time well weekends about 2kw plus caravan plus is just for charge now and Again plus jet washer
@@learnelectrics4402 thjnk the hot tub plug module has rcd on it already
Have a look at our video SPURS ON SPURS, it should help and thanks for watching. Dave.
ua-cam.com/video/0lP8C6ZU_R8/v-deo.html
hi...where can i find information on the current carrying capacity for a 13 amp 3036 fuse...cant find it in the regs...i can see fuse sizes that are not commonly used but not 13
13 amps, as printed on the fuse. That is a nominal current or In. That will be 13 amps 7 days a week 24 hours a day. Tables 41.2 and 41.4 in the Regs
what do you mean by maximum current?the appliance plugged in?dummie here lol
It can be the maximum current that (say) the kettle will consume.
It can be the maximum current that a cable can allow to pass though before it overheats
Or it can be the maximum current that the protective device (fuse or breaker) can carry 24 hours a day/7days a week - often called the fuse or breaker rating.
Just because a circuit breaker is rated at 32A maximum current, it doesn't mean it HAS to draw 32A. It can draw just 5 amps or perhaps half an amp if connected to a 100W table lamp.
I hope this helps, it does confuse new folk at times. But keep watching the videos, keep learning. There are nearly 200 videos on the website at LearnElectrics.com. We all started off as dummies at one time. Dave.
@@learnelectrics4402 if we say only 2 x55 inch new led tvs and 2 xdesktop computer would be in that below the max current?
use 4mm
Thanks for watching, appreciated, Dave.
Spurs are shit mate. Up the villa
Thanks for watching.