Perhaps if the manufacturer had not cut materials down of the main switch and bus bar to the absolute minimum a few Amps over the optimistic rated current wouldn’t be an issue.
I think that because solar PV installations have only become popular in the last few months, the IET can be forgiven for only addressing this issue now. It is not that solar PV installations have been seen in the UK for years or even decades, so they should be given some latitude about this issue. BEAMA, being the association representing manufacturers of electrical equipment in the UK should also not be criticised for its members not uprating the electrical equipment such as consumer units and switchgear/ equipment to cope with 116A, over 100A when it comes to type testing, as this is also a recent development for them in the PV market that they could never have foreseen up until now.
IET have lost control. It is getting silly now. That "Could" is carrying a lot of theorised weight whilst apparently completely ignoring installation diversity. Setting domestic installs up for mandatory 3ph and load management I suspect.
Consumer units also could become rusty. We need new regulations about it. What about making consumer units from pure gold? Sorry, but ever increasing number of "electrical safety" regulations making any electrical work prohibitorily expensive for the end client from general public. It leads to the even worse situation with most of the home electrical installations.
Its a tricky one and all about balance. I have been a spark for 40 years and I do agree that work now is incredibly expensive for customers. Every year just more and more regulation. I plan to give it up in a couple of years. I think they just don`t want sole trader sparks anymore. It has become just so much more difficult to trade now. I am seeing a lot more DIY work around and jobs not done because of cost.
I'm tempted to agree. I'm sure if I went right now and tried to pull 116A from my 100A consumer unit (I have no microgeneration), it would deliver that for several hours without any chance of the main fuse rupturing - It would probably also do so without becoming unsafe. The idea that the busbar in a 100A consumer unit would become unsafe at 116A is unrealistic. The idea that a household might consume this much current for a long period even more so. I get that this could be a problem where the microgeneration is 32A or more, but for 16A it does appear to be a hair-splitting thing.
Safety has to be paid for. Safety is normally a compromise taking into account practicality. If you really wanted to improve the safety of consumer units, the DNO service fuse should be *supplemented* by a 100A (or other suitable rating as appropriate) circuit breaker for every domestic installation. But that’s not gonna happen. If the bus bar in the CU is really only capable of safety handling 100A, then the extra CB should be down rated to 80A for example.
Im not sure how a property drawing 100A , with 16A supplied by solar on top of this = 116A. Surely the solar reduces the current draw from the grid, resulting in 16 A from solar, 84A from the grid? Am i missing something!
How often is a house with 100a cut out fuse going to be drawing 100a or close? Also, why isn’t the PV being used locally rather than being exported and if it is being exported surely there is something software related that the inverter can use to manage this so the install stays below 100a in either direction?
OMG, the UK starts to be dumb I think. Here on the continent in EU and in Kingdom of Thailand we install two meter, one for the solar panel and one for the house. 😂 If you force to give 100% solar power to the grid do you earn in EU around € 0.40 per kw/h and from the grid pay € 0.36 per kw/h. If you use all solar power or only 50% do you loose more money as you win. 🤦♂️😉 Before 20 years my friend earn around € 1.20 per kw/h but at this time the solar panels was more expensive then they was made in Germany. In Kingdom of Thailand it isn't so big difference in earn money but the installation is more easier too. 😮
What normal house has a load approaching 100 (or even 80) Amps for anything other than a few seconds? TBH perhaps the approach of a second connection between the main consumer unit and the solar system should be mandated? It would be a lot cheaper than messing around in the existing CU and possibly causing more mayhem. Circumstances mean that is my installation - the meter / incomer is in the garage connected by SWA to the house CU so the solar / battery install connects at the meter in the garage. No CU was harmed in the installation! 😂😂
Solar inverters all have CT clamps on the incoming supply, why not limit generation based on import from grid + generation from solar PV? Easy software update.
@Monkeh616 the inverter needs to know where the current flows, to load or grid. Reasons could be: monitoring on the app and statistics, no export mode, limit export to 3.7kW to comply with DNO requirements.
@@Mircea007 Ah. So.. optional features. With the sole exception of limiting export to account for poor infrastructure, all unnecessary. So, they don't all have CTs.
I know I know but 16 extra amps on a busbar come on people get real. It’s not even affecting the rating of the main switch as that can’t increase due to solar. Bearing in mind you could draw 150 amps through your 100A dno fuse for a considerable amount of time and 125 for many hours. So many people think a 100a fuse blows at 110a Who pays the electrician to go replace the time switch and how are they expected to know where they have fitted one 🤷♂️. This sort of recall is garbage, who even knows about it🤷♂️ time people could sign up to some sort of database that emails you or something from the wholesaler
2:05 Can someone explain why the consumer unit could not draw/pull 100A from the DNO whilst the Solar PV also exports 16A on top of the 100A load, meaning there would be 116A going through the DNO's cut out fuse? Would the solar PV always be used locally for what it can provide before any excess is exported to the DNO?
I believe the issue is not that 116A could go through the service cutout, rather that 116A could be drawn through the busbar (16A from the solar plus 100A from the service cutout) by customer circuits, exceeding the 100A manufacturer's rating of that bar.
Er... yes! I have recently been wondering this, in fact the rating of a DB is almost academic nowadays because there can be so many sources, thinking through the weakest link is not easy, particularly due to direct offsetting as opposed to export you mentioned. Personally (and I know everyones going to shoot me!) the days of traditional CU's are dissapearing for this very reason. I always start with a giant 3-phase DB, this contains the current limiting MCBs to/from the grid, the feeds to/from all the inverters/chargers, the heat pump feeds, the aircon DB feed and EV feeds together with more traditional feeds to the conventional CU's. This initial DB has no internals or junction strips etc so its purely wire size / module limited in current capacity. But... you have to have unlimited time, unlimited budget, have unreasonable skills and tools and access to a decent workshop. So I wont be upset if you reply 'what a crap solution!'
If the PV is generating 16A, and 100A is coming into the CU through the DNO fuse then 116A (~27kW) is being consumed locally and there is only 100A in the DNO fuse. If the PV export is going back through the fuse to the grid then there is only 100A being consumed in the house and only 84A going back though the cutout. The inverter causes export by raising the local voltage so the power flows the other way. But essentially yes, PV power is always used locally unless more is being generated than is being used locally. At that point it is possible for the excess to go back into the grid.
Yes, but the problem is that the bus bar and other components inside the consumer unit are rated for, say, 100 A. But then you can draw 100A from the grid without blowing the fuse, and also get an extra 16A from the solar, so the total current you can draw can exceed the capacity of the consumer unit.
@@jamesmillward6286 it should be doable with an upstream CU with 125A busbar if that works out cheaper than replacing the whole CU. Feed the main CU from a 63A MCB, PV from a 16A RCBO, possibly put another "heavy hitter" like an EV charger on its own RCBO in there too, leaving the original CU and 63A MCB to deal with everything else. Schneider have a 125A single-phase board range, I don't know who else does. It'd be nice of course if the suppliers were able to get their boards re-certified for 125A, even if it means a busbar upgrade.
Busbar issue ??? Install TWO IDENTICAL busbars as a sandwich pair - it's that simple Use the same busbar so it matches sits perfectly on top of each other - job done Busbars "should" be 3mm thick I think but often they're more like 2.5mm or less and for PV stuff the IET is flapping about they should be I reckon 4mm at least So until manufacturers offer a higher current busbar 4mm thick instead of 2.5mm, just double up the busbar to enable the double busbar to safely carry more current at rare peak intervals on certain instances like PV installs into one existing CS (Really just fit an additional CS for solar & EV stuff - but double busbar if using existing sinlge CS)
Love your content, one day after I have gotten and a apprenticeship and eventually become a electrician. I would like to start my own business too any advice to starting your own business?
What is this diversity you mention, when energy suppliers are incentivising people to pull 20+ kW for a couple of hours at a time, and rewarding them for consuming well above their in usual demand? It looks a bit reckless to me!
@@AintBigAintClever how do you know this? There are people putting pictures on social media of 25 or 26 kW and boasting about having as much on as possible, and their windows open, because they are being paid to consume. Back in September, the only house in a street near me with an EV, had National Grid digging up the drive, one Sunday afternoon / evening, to do a cable repair. Guess what? It was low demand, and high generation period, with lots of wind and solar, and energy suppliers paying for excess consumption. The NG engineer told me the likely cause on a cable which is around 70 years old. As I said.......... reckless!
@@BROOMEngineeringTMIET ah, I was thinking of off-peak EV charging (where 7kW would be the maximum unless on a 3-phase supply), I forgot about the flexi tariffs where they plug the hot tubs in and stuff. I suppose it depends on whether those on flexi tariffs get individual offers (which could - or at least should - be distributed so as not to overload particular roads or areas) or whether it's a blanket offering to all customers simultaneously which could cause problems.
@@AintBigAintClever yep - on a local level it could be a bigger issue, as you could have people loading up phases, well out of balance on a street / area level, depending on their energy suppliers, and the tariffs those people have chosen.
Perhaps if the manufacturer had not cut materials down of the main switch and bus bar to the absolute minimum a few Amps over the optimistic rated current wouldn’t be an issue.
I think that because solar PV installations have only become popular in the last few months, the IET can be forgiven for only addressing this issue now. It is not that solar PV installations have been seen in the UK for years or even decades, so they should be given some latitude about this issue.
BEAMA, being the association representing manufacturers of electrical equipment in the UK should also not be criticised for its members not uprating the electrical equipment such as consumer units and switchgear/ equipment to cope with 116A, over 100A when it comes to type testing, as this is also a recent development for them in the PV market that they could never have foreseen up until now.
IET have lost control. It is getting silly now. That "Could" is carrying a lot of theorised weight whilst apparently completely ignoring installation diversity.
Setting domestic installs up for mandatory 3ph and load management I suspect.
Consumer units also could become rusty. We need new regulations about it. What about making consumer units from pure gold?
Sorry, but ever increasing number of "electrical safety" regulations making any electrical work prohibitorily expensive for the end client from general public. It leads to the even worse situation with most of the home electrical installations.
Its a tricky one and all about balance. I have been a spark for 40 years and I do agree that work now is incredibly expensive for customers. Every year just more and more regulation. I plan to give it up in a couple of years. I think they just don`t want sole trader sparks anymore. It has become just so much more difficult to trade now. I am seeing a lot more DIY work around and jobs not done because of cost.
I'm tempted to agree. I'm sure if I went right now and tried to pull 116A from my 100A consumer unit (I have no microgeneration), it would deliver that for several hours without any chance of the main fuse rupturing - It would probably also do so without becoming unsafe. The idea that the busbar in a 100A consumer unit would become unsafe at 116A is unrealistic. The idea that a household might consume this much current for a long period even more so.
I get that this could be a problem where the microgeneration is 32A or more, but for 16A it does appear to be a hair-splitting thing.
Completely agree
Imagine the mark up on 24ct consumer unit... 😂🪙🪙🪙 Seriously though it's a tricky balance between anarchy and safety.
Safety has to be paid for. Safety is normally a compromise taking into account practicality. If you really wanted to improve the safety of consumer units, the DNO service fuse should be *supplemented* by a 100A (or other suitable rating as appropriate) circuit breaker for every domestic installation. But that’s not gonna happen. If the bus bar in the CU is really only capable of safety handling 100A, then the extra CB should be down rated to 80A for example.
This is nonsense as taking diversity plus 16amps does not equal 116amps.
Im not sure how a property drawing 100A , with 16A supplied by solar on top of this = 116A.
Surely the solar reduces the current draw from the grid, resulting in 16 A from solar, 84A from the grid?
Am i missing something!
How often is a house with 100a cut out fuse going to be drawing 100a or close? Also, why isn’t the PV being used locally rather than being exported and if it is being exported surely there is something software related that the inverter can use to manage this so the install stays below 100a in either direction?
OMG, the UK starts to be dumb I think. Here on the continent in EU and in Kingdom of Thailand we install two meter, one for the solar panel and one for the house. 😂 If you force to give 100% solar power to the grid do you earn in EU around € 0.40 per kw/h and from the grid pay € 0.36 per kw/h. If you use all solar power or only 50% do you loose more money as you win. 🤦♂️😉 Before 20 years my friend earn around € 1.20 per kw/h but at this time the solar panels was more expensive then they was made in Germany.
In Kingdom of Thailand it isn't so big difference in earn money but the installation is more easier too. 😮
What normal house has a load approaching 100 (or even 80) Amps for anything other than a few seconds? TBH perhaps the approach of a second connection between the main consumer unit and the solar system should be mandated? It would be a lot cheaper than messing around in the existing CU and possibly causing more mayhem.
Circumstances mean that is my installation - the meter / incomer is in the garage connected by SWA to the house CU so the solar / battery install connects at the meter in the garage. No CU was harmed in the installation! 😂😂
Solar inverters all have CT clamps on the incoming supply, why not limit generation based on import from grid + generation from solar PV? Easy software update.
They do? Mine certainly doesn't. What function does it serve for a simple inverter?
@Monkeh616 the inverter needs to know where the current flows, to load or grid. Reasons could be: monitoring on the app and statistics, no export mode, limit export to 3.7kW to comply with DNO requirements.
@@Mircea007 Ah. So.. optional features. With the sole exception of limiting export to account for poor infrastructure, all unnecessary. So, they don't all have CTs.
@Monkeh616 and limiting the current thru your consumer unit could be another use more simpler to implement that fuses and switchgear.
I know I know but 16 extra amps on a busbar come on people get real. It’s not even affecting the rating of the main switch as that can’t increase due to solar. Bearing in mind you could draw 150 amps through your 100A dno fuse for a considerable amount of time and 125 for many hours. So many people think a 100a fuse blows at 110a
Who pays the electrician to go replace the time switch and how are they expected to know where they have fitted one 🤷♂️. This sort of recall is garbage, who even knows about it🤷♂️ time people could sign up to some sort of database that emails you or something from the wholesaler
Yay more rules and regulations, that'll fix it! 🎉
2:05 Can someone explain why the consumer unit could not draw/pull 100A from the DNO whilst the Solar PV also exports 16A on top of the 100A load, meaning there would be 116A going through the DNO's cut out fuse? Would the solar PV always be used locally for what it can provide before any excess is exported to the DNO?
I believe the issue is not that 116A could go through the service cutout, rather that 116A could be drawn through the busbar (16A from the solar plus 100A from the service cutout) by customer circuits, exceeding the 100A manufacturer's rating of that bar.
Er... yes! I have recently been wondering this, in fact the rating of a DB is almost academic nowadays because there can be so many sources, thinking through the weakest link is not easy, particularly due to direct offsetting as opposed to export you mentioned. Personally (and I know everyones going to shoot me!) the days of traditional CU's are dissapearing for this very reason. I always start with a giant 3-phase DB, this contains the current limiting MCBs to/from the grid, the feeds to/from all the inverters/chargers, the heat pump feeds, the aircon DB feed and EV feeds together with more traditional feeds to the conventional CU's. This initial DB has no internals or junction strips etc so its purely wire size / module limited in current capacity. But... you have to have unlimited time, unlimited budget, have unreasonable skills and tools and access to a decent workshop. So I wont be upset if you reply 'what a crap solution!'
If the PV is generating 16A, and 100A is coming into the CU through the DNO fuse then 116A (~27kW) is being consumed locally and there is only 100A in the DNO fuse. If the PV export is going back through the fuse to the grid then there is only 100A being consumed in the house and only 84A going back though the cutout. The inverter causes export by raising the local voltage so the power flows the other way. But essentially yes, PV power is always used locally unless more is being generated than is being used locally. At that point it is possible for the excess to go back into the grid.
If the house is using 100A, and the solar is generating 16A, surely only 84A is coming from the grid?
Issue is that the house could use 116A, exceeding the rating of the busbar without exceeding the rating of the two overcurrent devices supplying it.
Yes, but the problem is that the bus bar and other components inside the consumer unit are rated for, say, 100 A. But then you can draw 100A from the grid without blowing the fuse, and also get an extra 16A from the solar, so the total current you can draw can exceed the capacity of the consumer unit.
I see, makes sense. Maybe the PV should always be on its own dedicated CU then to avoid this issue.
@@jamesmillward6286 it should be doable with an upstream CU with 125A busbar if that works out cheaper than replacing the whole CU. Feed the main CU from a 63A MCB, PV from a 16A RCBO, possibly put another "heavy hitter" like an EV charger on its own RCBO in there too, leaving the original CU and 63A MCB to deal with everything else. Schneider have a 125A single-phase board range, I don't know who else does. It'd be nice of course if the suppliers were able to get their boards re-certified for 125A, even if it means a busbar upgrade.
@@MrOpenGLJust put the solar mcb at the opposite end to the main switch. Bus bar won’t be overloaded then. (Or devices. )
Re your Torque Calibrated Arm, do all of your sponsors specify torque settings for all their products?
Busbar issue ??? Install TWO IDENTICAL busbars as a sandwich pair - it's that simple
Use the same busbar so it matches sits perfectly on top of each other - job done
Busbars "should" be 3mm thick I think but often they're more like 2.5mm or less and for PV stuff the IET is flapping about they should be I reckon 4mm at least
So until manufacturers offer a higher current busbar 4mm thick instead of 2.5mm, just double up the busbar to enable the double busbar to safely carry more current at rare peak intervals on certain instances like PV installs into one existing CS
(Really just fit an additional CS for solar & EV stuff - but double busbar if using existing sinlge CS)
Hard to see how adding pv, which reduces the current from the grid, can exceed ratings.
Hello there, glad to have the weekly news back again :) My guess this week for the hidden words - "techspeak" and "gotcha". Cheers!
Thanks
You're welcome! 😊
Love your content, one day after I have gotten and a apprenticeship and eventually become a electrician. I would like to start my own business too any advice to starting your own business?
MCB mainswitch, that sounds oddly familiar.
Bus bar, not buzz bar 🙄
In three phase world we are choosing between 25 and 40 Amps :D
What is this diversity you mention, when energy suppliers are incentivising people to pull 20+ kW for a couple of hours at a time, and rewarding them for consuming well above their in usual demand?
It looks a bit reckless to me!
They'll only get to do that with a three-phase supply, in any case they've been doing that for decades, remember the Heat Electric campaign?
@@AintBigAintClever how do you know this?
There are people putting pictures on social media of 25 or 26 kW and boasting about having as much on as possible, and their windows open, because they are being paid to consume.
Back in September, the only house in a street near me with an EV, had National Grid digging up the drive, one Sunday afternoon / evening, to do a cable repair.
Guess what? It was low demand, and high generation period, with lots of wind and solar, and energy suppliers paying for excess consumption. The NG engineer told me the likely cause on a cable which is around 70 years old.
As I said.......... reckless!
Interesting point. 😊
@@BROOMEngineeringTMIET ah, I was thinking of off-peak EV charging (where 7kW would be the maximum unless on a 3-phase supply), I forgot about the flexi tariffs where they plug the hot tubs in and stuff.
I suppose it depends on whether those on flexi tariffs get individual offers (which could - or at least should - be distributed so as not to overload particular roads or areas) or whether it's a blanket offering to all customers simultaneously which could cause problems.
@@AintBigAintClever yep - on a local level it could be a bigger issue, as you could have people loading up phases, well out of balance on a street / area level, depending on their energy suppliers, and the tariffs those people have chosen.
Nissan Leafs have been capable of bi-directional charging for more than a decade.
Bilingual and face
Happy new year Joe and a great first news weekly of 2025 👍
Good to be back, thanks Sean! 😃
People shouldn’t put such shit in, I always try and use Eaton gear 125A main switch.
Vertical solar panels eh...WIND!
Try charcoal tablets... 🤔
Hello, I believe i won the award and I applied for the award but haven’t heard from you guys. Unless I done it wrong 😂. Can someone help me please
I'll get in touch with the postal department. 😊
@ amazing! I hope all my details are there, thank you 😃
Thank you very much, all sorted ! 😃
Bilingual and Gotcha
Bilingual, Gotcha
techspeak gotcha
❤❤❤❤❤
Bilingual cusp
nuggets and gotcha
5:14 Was he wearing a Hat, with a chin strap?
Bilingual, nuggets
bi-lingual and gotcha
I am going for "Spate" & "Gotcha".
Bilingual and gotcha
Nice guesses, listen to next week's show to see if you got it! 😃
bilingual and hats
I honestly don't remember saying hats but I'll take your word for it! 😂 Tune in next week to see if you're right and my memory is that bad... 😊
@@efixx hmm I don't fancy my chances then 🤣
BS what you expect?
Brilliant more Ev chargers - more black outs and no travel #Net Zero
Klaus’s dream is soon to be a reality!
sorceress and baklava
Everything OK at home mate? 🤔😂
Bilingual and Gotcha
Bilingual, nuggets
Bilingual and gotcha
Nice guesses Peter, listen to next Monday's show to see if you're right. 😊
Bilingual and gotcha
Bilingual and gotcha