Are Split Load Consumer Units Compliant with BS7671 Amd 2?
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- Опубликовано: 4 июн 2024
- The latest edition of the UK Wiring Regulations BS7671 Amd introduced major changes related to circuit protection within residential electrical installations. How do these changes affect the installation of split-load consumer units?
BS7671 Circuit Protection - www.efixx.co.uk/Know%20How/am...
🕐 TIME STAMPS 🕕
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00:00 Can we still fit split load consumer units?
00:39 What does BS7671 say
01:14 BUT maybe
01:51 Natural earth leakage current
02:31 Could have unwanted tripping
02:44 Maximum natural earth leakage current
03:30 Consider RCBO on high leakage circuits
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Dual rcd boards still have there place in my opinion. Many rcbos are still only single pole , a 2 pole rcd will clear a neutral to earth fault a single pole rcbo will not . Therefore with regards to circuit protection the dual rcd board is better . Many " electricians " will not even understand what I mean which is concerning
That is a really good point I hadn't thought of to be fair. 💪
Great video,happen to have a MK split load board,& having nusiance triping,been considering fitting DP RCBO's to solve issue.
Yur, that sounds like a good solution, I take it everything's tested out OK?
@@efixx Off the tools now, but everything tested ok, had sparky mate to confirm my results just to be sure.
@Boznivich
No. *The all DP RCBO board is far better.*
In France, Germany, Switzerland, etc, all main panel circuit _interrupters_ are mandatory DP. This means in those countries they can have dual L&N bus bars, which are referred to as combs. In France they have the _combs_ at the top of the RCBOs/MCBs/RCDs, with conductors to the circuits at the bottom of the _interrupters._ Far better. Not this hodge-podge nonsense we have. We are still in the 1950s in some respects.
The French/German DIN rail mounted _interrupters_ are available in the UK as are the combs, usually via mail order.
Very interesting! My mother is in the process of buying a new build house (won't mention the developer, but one of the major nationwide ones) which they have decided to fit with a split load board.
Found this a bit odd, but not as odd as pre-wiring for an EV charger with a 6mm to the back garden (as there's no driveway and there's car ports for multiple properties a few houses down)- the db is at the front of the house too, and the garden is surrounded by other gardens.
I have RCBOs and it was the best thing for the last 20 years that weve had them in our consumer unit,
Great video Joe
Thanks James! 😃
The increasing amount of non-linear loads on circuits, including controllers in domestic appliances like washing machines etc are presenting more harmonic distortion of the supply voltage waveform. Although standards restrict the amount of distortion an appliance should create, the triplen harmonics create an additive effect that can appear to earth-leakage protection devices as a “fault current”. These currents should be fairly small in a domestic installation but they don’t help by adding to the overall leakage measured by RCCBs etc.
Great insightful comments as always Craig, thanks much. 😊
How about the manufacturers design equipment not to leak to earth ?
@@raychambers3646 not as easy as it sounds without over-engineering the insulation and adding significantly to the cost. Also, some of the current “seen” by RCCBs, RCBOs etc is not actually current leaking to earth, it is due to harmonic currents (particularly 3rd harmonic) drawn by the equipment. Inrush currents on wound components like motors and transformers can also be asymmetric and appear to the devices as faults too. Careful design is the key and, as Joe points out in the video, the regs make contingency for the selection of protective devices and how circuits are grouped in DBs.
@@raychambers3646 Not possible. Earth is used as a reference to 0v in electronics.
My house is all RCBO , oh yeah they're also all double pole! And imfitted it about 5 years ago...always ahead of the curve. Just a pity they weren't type A 😉😂😂😂
Ahead of the curve is having all AFDDs.
I haven't installed a split load board in 3 years, When giving the customer the option and they penny pinch, I'm more than happy not to get the job. Experience has taught me it's a good indication that it's probably not worth the potential hassle, for what ever reason
Reece totally agree with you. We to never install dual rcd boards as we have alway considered not to be good wiring practice. The dual board will be gone for the regs as was that stupid reg where there was no need to protect lighting circuits
Does this mean you have only 1 RCD? If such is the case how you split Lighting (using 100mA) to Sockets (using 30mA) and Water Heaters (using 10mA)?
Millions of split load boards fitted to the 17th & 18th eddition, is it really a problem now ?
FREE Training module 👉 BS7671 Circuit Protection - www.efixx.co.uk/Know%20How/amendment-2-circuit-protection-cpd
I have not worked as an electrician for over 25 years, but it was my practice never to put lighting circuits on the same RCD as power under the guise if you were using for example an iron and it tripped causing the lights to go off also, that was potentially dangerous. Perhaps I was wrong. What do you think?
I do a lot of fault finding and dont think it really matters, just try not to have more than 4 MCBs per RCD and the more double pole switches used the better.
I always thought that was best practice. My house is downstairs ring, upstairs lighting on one RCD and vice versa on the other. Makes perfect sense.
Best practice is to split power and lighting so if one RCD tripped you didn't lose all power or all lighting. RCBO solves that. They're one of the few things coming down in price.
@@antlane365 Are you saying you use Double Poles MCB for Loads would help in nuisance tripping
@@Pgan803 Double pole MCBs make fault finding much easier but any double pole switches around help. Like the cooker switch, if you turn it off and the fault clears its in the cooker.
So what is the down side of split load boards bar the trip leakage issue? If only this then outlaw a little strong?
We had a new board just before metal boards came in, 9 years ago (ish). Is it not going to get to the stage where a re wire is ‘current’ about as long as your iPhone?
Not really, a new set of regs doesn't necessarily require an upgraded board.
Most rewires are done because the existing system does not meet the needs of the customer.
Not be because it’s “not current”. It’s customer choice that drives most of this.
@@MrIbib fair point Phil. Just for the record I think RCBO’s look like the way forward to me. I am nothing more than a DIY’er who likes to be informed as much as I can.
The argument around tripping circuits makes sense to me as a person who has the issue
BS7671 states the regulations aren't retrospective.
Another sneak source of earth leakage is ovens. They normally have a layer of mineral wool insulation between the inner and outer shells. Over time fat/grease can leak into this insulation and wick up to where the elements poke through the insulation. In physical conduct with the hot element the fat chars and turns to a conductive substance very like graphite, providing a path between phase and the earthed shell that leaks more and more current over time... But usually only on one element. Causes a fun intermittent nuisance trip to find.
The oldschool way to avoid these nuisance trips is to hang the oven MCBs off the bus bar before an RCD. A dodgy bodgy fix IMHO that is better fixed with a RCBO instead of a MCB in this day and age.
I can’t understand why in this day and age it’s acceptable to have any appliance or fitting designed to produce a fault current on the earth in the first place. Surely there is a better way .
The problem is the requirement to minimise conducted and radiated noise for EMC requirements - especially on devices required to have power factor correction - requires a lot of filtering and that filtering inherently results in earth leakage.
Technically the RCD 'leakage' current is the imbalance between the hot and neutral wires - which can occur even without an earth wire. We see more of this these days because fewer loads are purely resistive. A lot of loads now have integrated circuits and there has to be AC to DC conversion to power them. I have a forced air gas furnace in my USA home and it is by far the largest source of 'leakage' current in my home. It has a large DC variable speed blower motor to circulate the air in my home. It is great in that it uses significantly less electricity to run. But, I measure significant leakage current both on the earth wire and the natural gas pipe (not a comforting thought). The second largest leakage current comes in on the ground shield of the cable television coaxial cable that enters my home. We have to bond these other utility cables to our electrical service's ground system, which is bonded to the neutral cable in the main breaker panel.
I've yet to see a good article/video from an experienced circuit designer that discussed this topic in depth. I'm curious how much of the 'leakage' is due to poor design or cost constraints as opposed to the natural limitations of dealing with non-resistive loads. But, if I were in the UK I'd stop installing split load boards as I'd expect 'leakage' to get worse not better.
@@JasonEDragon great comment
@@JasonEDragon For clarity: leakage is always to ground/earth but an RCD does not need to monitor ground/earth to detect such leakage and therefore operate.
It's not exactly down to poor design but is somewhat linked to practicability and cost. Leakage comes from dielectrtic barriers within electronics, i,e capacitor plates. There is no such thing as a perfect insulator so some current will always 'leak' through. In order to make a 'perfect' insulator, the costs would be astronomical and unobtainable for most consumer-pupose electronics. Hence why it is 'dumped' through the protective earth circuit. Otherwise circulating currents would simply rise to mains potential.
But if split load boards are ‘outlawed’ what will the Saturday morning Screwfix 1/2 price hero gang do?? 🤔
I think the split load CU will be around for a long time yet.
@@efixx considering that ring final circuits, choc blocks, bakelite junction boxes and other things that probably should have been consigned to history are still a thing I agree with you!
All breakers being DP RCBOs is far better to fault find.
Where are you from ?
Can I use this colour code in Poland Europe union county?
Please let me know.
I am from India.
We are in the UK. Not sure about Poland...
Just a quick & cheap to install these dual RCDs.
Is quick and cheap an exclusively bad thing? 🤔
Well with the festive period upon us, I am sure some stressed out people will be wishing that fault on their lights hadn't ruined their lunch, by taking out the oven and sockets 🤣🤣, rcbos don't look that bad now👍
RCBOs are definitely the best option as we've stayed many times, the point is that split load boards can still be compliant with some thought.
Really?! If the lights are KNOWN to be a problem ... Turn off the lighting breaker, light some candles (it's Christmas), plug in a table lamp (or two - save energy), switch the oven back on and enjoy your Christmas lunch 5-10 minutes later than planned. Remember to fix the faulty lights ASAP as a New Year resolution! 🤔😋😲🤣🤣
@@boblewis5558 what about neutral to earth fault 😉
@@acelectricalsecurity WHAT neutral to earth fault? DP breakers old chap! None of this SP crap! No Neutral connection ... No fault!
When a superior ISO standard DP RCBO OR standard breaker is available in standard 18mm width AND frequently available at a lower price than standard single pole, WHY use inferior, more expensive SP breakers that are MORE time consuming to fit?
The UK electrical industry is still WAY behind elsewhere in the world when it comes to breaker & RCBO fittings and their utterly ridiculous antiquated wiring format.
WHY is there STILL a STUPID Neutral tail dangling out of double height 18mm RCBO's TWICE the size of Euro & Asian ISO standard 18mm sized devices? Bloody ludicrous!
WHY do we STILL have breaker inputs at the bottom causing output feeds to have to cross underneath the DIN rail? Again bloody ludicrous.
WHY do we have single busbar systems and have SO MUCH clutter in a CU because of all the Neutral feeds going to one bar at the top? Again bloody ridiculous!
The UK CU is, pure and simple, a complete shambles, requiring WAY too much time to implement and even greater time to test and fault find.
Compare the simplicity of testing a suspect or faulty circuit on a DP standard breaker to an SP breaker as a simple example:
DP: isolate the breaker, disconnect the earth/s only and test the fully isolated wiring as normal, without ever touching the live or neutral inputs, without disturbing either of the output terminals and only have to reconnect the earth terminal and re torque.
Final ring circuits being the exception to the above for obvious reasons, but there is a solution to that problem too, although too much detail for this post which is already long.
SP: work out WHICH Neutral is which in a poorly wired, non dressed unit and disconnect (a reconnection which has to be retorqued on reassembly), disconnect the CP/Earth lead (after finding it in the mess), disconnect live output (not necessary or essential but everyone seems to do it. Now you have THREE connections to be retorqued instead of one, increasing the opportunity for reconnection error.
If the release torque wasn't checked, and recorded, of there may be too much compression having been on the wire damaging or crushing it too much, so retorquing (correctly) may weaken it even more.
Safer to leave connections alone OR measure & record release torque OR cut cable ends and remake. The latter is clearly impractical long term once cable ends become too short to remake ... ANOTHER reason in my view why solid as well as stranded cable should have ferrules fitted for more consistent connections and better long term physical protection.
@@boblewis5558 yeah if it's double you are hot to trot, but I have never come across double pole breakers in a domestic property, it's all cheap as chips £60 twin RCD board from Screwfix or some brand you have never heard of and all single pole mcbs .
5 years ago when I had a motley collection of fuse boards/8way consumer unit changed out, my electrician didn't mention that RCBOs existed so I have dual split boards 2x21way To swap this out for RCBOs doesn't make economic sense at £700+ by the time you add in the labour for retesting all the circuits. My plan is to upgrade the system when changes are made - would I benefit from adding arc fault / is arc fault need on all circuits
Eight RCBOs is nowhere near £700! FuseBox are around £18 and also DP.
@@johnburns4017 2x21way almost full is about 25 circuits
I guess as a landlord i'll be chucking away more consumer unit in 5 years
Er, not necessarily. 🤔
Already thrown away 6 or 7 in houses with no issues.... 2 this year. And electrical fires on the rise.... Any connection?
*Just. Say. No.* Or at least do everything possible to convince the client not to have one fitted, even if they are cheap as chips. 😀
Our thanks to the Grange Hill generation! 😂 Good points though, thanks much.
I wouldn't fit a split load anymore. Fusebox do double pole rcbos for pretty cheap.
Fair does, thanks for commenting! 😊
Fusebox is the boss
Cheap but are they quality? A Hager rcbo is around £30 where as a lewden is say £15! I’m regularly doing jobs with around 15-20 circuits. That’s £450-£600 just on rcbo’s if I want to fit a quality brand. We are in a financial crisis and because the iet rule makers need to keep themselves in employment the consumer has to pay for it. Realistically how often after a rewire do we have rcds tripping out because of the reasons they are giving? I’ve not had 1 as of yet
@@ToffeenoseToffee hold on, we can’t fit RCBO’s because of price but rewires are okay.
Talk sense lad, if you’re already doing a rewire then a RCBO board is hardly going to break the bank.
And RCBO’s don’t really add that much to the price of a board swap.
You should be doing a full EICR prior to the swap any way. So the days of £500 swaps are long gone.
@@MrIbib in some instances no we can’t fit rcbos because of cost, believe it or not some people don’t have the funds of an extra ££££ for rcbos. I’m fitting a full rcbo board to a new factory shower block because the funds are there so in that instance it’s the best thing to do. And doing an eicr before a mains change is just conning the customer in most circumstances if I’m doing my work and I recognise it needs changing I’ll change it
And give an installation certificate after carrying out the same tests and inspections as I would on an eicr. I’m busy enough without making work for the sake of it and costing the customer. You 6 week crash course sparks with your logo on your vans might work that way because the iet tell you so but some of us do the right thing tailored to the customers needs
So RCBOs where "required" no need to use them across the board.
Who puts "shall be considered" into a rule and makes it mean "must be done this way"? Every normal person would read this as "the following is your arsenal to prevent unwanted tripping, check each one before selecting whichever makes sense in your case"...
Hello! how are you. I'm Abdelghani I'm from Morocco I'm a student, I study FP middle grade electricity in Spain at the Felipe Trigo institute, this is my first year of electricity, can you help me with some of the material🙏
Lots of content on the channel to help! 😃
Hi how are things? In the institute they ask us for material to do the practices, I do not have the capacity to buy all the material. Thank you
Maximum of 9mA per 30mA RCD and each appliance could be leaking up to 5mA naturally. So every appliance should be on its own circuit by that logic shouldn’t it?
RCBO appears very good. But costs seem to dictate the use of RCBO compared to Dual RCD. In 3 phase board, Dual RCD more common again due to cost. Perhaps a Video on comparative costs would be great.
If you look into who makes up the panel of contributors to the bs7671 you will find many captains of industry not surprising the electrical manufacturing industry
ie. Those who make RCBO
MCB
Consumer units
Distribution boards and everything else in-between
So they dictate the rules and everything else .
Not surprising realy
Remember the Golden rule
He who ownes the Gold makes the rules
Not a fan of split load boards , I call them Union boards, I out all out .
😂 Love that. 💪
so the side that doesn't trip are 'the splitters'?
We don't need rcd protection for fixed appliances and lighting circuits. Socket circuits yes as you could be holding a faulty appliance. But fixed equipment like immersion heaters , ovens and hobs etc don't need rcd protection. A good CPC connection and a low Zs is all you need . We have gone too far down the road to change now I know this but it doesn't change my mind. I know others will disagree .
Yeah, the RCD protection on fixed loads and lighting is more about the cables buried in the walls really. The intention is if someone whacks a nail through a cable it'll protect anyone touching the nail. 👍
In short....yes
I don't know what the obsession is with electricians with wanting to rip out perfectly functional split load RCD boards to replace with new CU & individual RCBO's. Well I say I don't know - I do know, it's nothing to do with nuisance tripping (which is almost never an issue) or 'selectivity' - it's all to do with making a nice chunk of money from an unnecessary job, conveniently citing 'this board is not to reg's'.
New job to replace a very old CU - sure go with individual RCBO's, but don't rip one out that's not causing a problem....seen that done too many times and people charged an arm & a leg for the privilege.
I think a major problem with an all RCBO board is the extra amount of time that the customer will need to spend doing periodic manual testing.
I would say that it would add up to 0 extra time, I've never met a single customer who tests their RCDs or RCBOs
@@100tinsoldiers It was an attempt at humour.
@@fredquimby5409 I must admit I thought it was, I thought you can’t be serious, in my best McEnroe voice
They’ve been outdated for a while, and okay they might not be against the letter of the regulations in some circumstances, but what’s the point really?
We just need to consign them to the history bin and move forward.
A fair point, I only have RCBOs and AFDDs on my own board. 👍
Sir hinde me
far to much talk of nuisance tripping very rare and normally a faulty white goods
and no one wants a faulty white good taking out half their electrics.
The amount of split-load RCD board I've had to reconfig and reload because the customer recently had an LED conversion or upgraded their appliances to modern equivalents. All nuisance tripping from overcrowding the RCD.
Don't worry, you will be welcome to the dark side when all the circuits will require AFDD's (AFCI's) like here in the USA in the next revsion! 🤦♂🤠
dual rcd consumer units should be outlawed in the 16th edition as in my experience they cause nusiance tripping and many hours extra fault finding unecessarily needed on an installation RCBO is the way of the future.