Dual RCD Consumer Unit
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- Опубликовано: 5 окт 2024
- A look inside a typical dual RCD consumer unit as used in the UK.
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Mr Ward your videos are better then evening classes. Your videos are really a full course in electrical installation.
John I’ve been an avid follower of yours for a very long time. Not only are you exceptionally knowledgeable, you provide clear and concise explanation that the view is able to understand apply to their own given situation. I’m very grateful and enjoy looking forward to new videos as and when you post them. Again, thank you!
The bus bar tip is brilliant thanks so much for explaining it so clearly. I’ve just checked this on a new consumer unit and one leg was wrong side of the slot! Who’d have thought eh? New out of the box too! Respect
Outstanding! If I'd had a teacher like you at school I might of done something with my life instead of skiving off and wasting the chance of a decent education.
John.. A very well explained video. yours is by far the best explanation of this topic I have found to date. Thank you for taking the time to create this.
Just about to fit one of these new plastic CU myself - bringing greenhouse, shed, garage and cellar together, which are then connected to the house, so thank you for your clear explanation, it is a great help.
I have a 1970 house. I had the Wylex box replaced when I moved in because my surveyor red-flagged it. The lights are all on one circuit, and the sockets are all on another. The electrician put them on the same RCD. So now, if I trip my sockets at night, all the lights in the house go out. Genius!
Another video said downstairs sockets and upstairs lights on 1 RCD, and opposite for the other RCD...then if there's a power out there is still at least residual light. Or just RCBOs like this no nonsense man says
I feel like I should leave electrical work upto the experts, but then when you look at some so called experts work, it makes you glad people like this man put these videos out there so we have a chance of putting things right
Your electrician has no common sense, If one breaker or fuse trips you have no light, He should have split the lighting in two.
@@chestermartin2356 That is why I do as much work myself as I can. Then I know it is done to the standard that I want.
Great vid, as always *JW* - I've found that heatshrink can be cut and 'rewelded' using cyanocryolate... Carefully done, those copper Line (L) bus plates could be shrouded in brown heatshrink if a cover was not existent.
Hi there John thank you for the instruction on the consumer unit I've just replaced my old unit with a modern one but it kept tripping when I plugged any think in. It was just a case of the neutral wires it the the correct bus bar. Cheer's Jon.
Excellent video. I think the reason for the overhang described is so that part of the unit can be neatly recessed into a wall.
Just Excellent!!! Just what I needed. I'm installing an automatic transfer switch for my back up generator and I don't know how to wire it, this has been a great help. Thank you
Our house has a much older consumer unit from the early 1980s with bottle fuses. I think it's 4 x 6A for lights, 4 x 16A for sockets, 1 x 40A for the shed welder outlet and 1 x 65A master fuse. It has an 30mA rated chunky RCD that covers the sockets only and it is surprising the range of appliances that developed an earth fault over the years. Thankfully not many appliances go short circuit as replacing a bottle fuse is not fun, particularly if an appliance/lead develops an intermittent short.
Well done on the explanation of the buzz bar and installing it. You done a better job in comparison to ghs electrical
JW thanks for explaining that each rcd circuit needs its own neutral bar.
Excellent video as always John. This is certainly a lot better than having no RCD's at all like so many older houses in the UK. I replaced my old MK fuse board with one of these last week and it started tripping due to a borrowed neutral. Thanks to you I knew exactly what was happening. Thanks and keep up the good work.
+hyperion8008 As changing a CU is notifiable how did you deal with it?
+Graham Langley in your own home.... who cares? I'm a electrician by trade and if I installed it in my own home I wouldn't do any certification at all!
+tittytwister5251 An 'electrician by trade' who didn't know about borrowed neutrals until they saw John's video?
im not the original poster of that comment... of course i know about borrowed neutrals..
+tittytwister5251 Oops - sorry.
A cam pleasant explanation and the walkthrough made it easy to understand.
Glad I came across you!
RCBOS All the way, more videos on domestic electrics john, love your videos
Excellent and well explained videos as always. Keep doing, I know a lot of people are learning from your videos Thank you John
Thank you Mr.JW
Interesting. We have RCDs built into some of the sockets which protect any sockets down the line from them. Required by our NEC for kitchen, bathroom, and outdoor sockets. We also have breakers with built-in RCDs, but as you said they are very expensive. And of course being that we use both 120v and 240v, we have different breakers for 120 and 240. Our main switch is required to be a breaker, just in case the individual breakers that have been fitted are loaded up as such that they are not individually overloaded, but combined exceed the mains input (typically 100, 150, or 200 amp for residences)
***** the most powerful home kettles are 1500w here. Although I did find a KitchenAid 3000w, it was 230v which we would have to install its own socket in the kitchen. Not very common though, most people in the US generally have only a small stovetop teapot, or use the coffeemaker for hot water. We're a bit strange ;-)
Interesting, in germany we have light and sockets connected to the same breaker, but we have a breaker for every single room.
Also we have 3 phase design for high power applications. Nice to know.
Daft idea really, if you lose that circuit then all your lighting, table lamps everything goes off. Could be quite dangerous actually.
Another great video JW, thanks. I'm surprised those un-insulated live bus bars are still allowed - in this day and age of health & safety.
Some makes have a plastic cover to clip over the busbars, however many do not.
Not really a problem as the main switch should be off before removing the cover.
John, also can you do a video on just how many times a solid core wire can be disturbed inside a patress box, or CU, before it breaks. What is the fatigue characteristic of a solid copper core and how can that fatigue life be extended without annealing or some other form of heat treatment.
Well Done John it is very clear and all information needed, Thank you
Excellent, just what I needed thank-you! Just got back from Screwfix with the exact same model of CU - but metal of course.
This guy is great. I wish my electrician was as good as him!
Hey JW. Great video - you mentioned your preference for RCBO units. How about doing a video about the internals of an RCBO consumer unit? It would be interesting to see the difference in wiring regimes as I would assume each RCBO would need their own neutral connection. Cheers
+Bob Fish
Look them up, there are loads of images... its' really simple -- main switch feeding line busbar into the RCBOs, then all the flying neutral leads go back to a neutral bar... Each circuits' line+neutral connections go directly into output terminals on the RCBO. Simple... There are many videos on fitting those, too!.
Many thanks for this very instructive video, Great Work
... .and just to complete it include steel and brass screws onto copper wire. Copper wire necking creating a fracture point. Screws loosening inside (concealed) junction boxes. Comparison between steel and brass screws, perhaps stainless too. The ideal method for soldering copper cores together. I'll show you mine, if you show me yours.
Excellent video as always John
Do not suppose you could possibly do a video segment covering Din Rail Surge Protective Devices (SPD's)? I am curious and also now does appear to make reference in the new wiring regs 18th edition draft. Cheers.
Why is that panel designed with 2 extra spaces to the right, out of interest? It looks like with an alternative cover the main switch could move 2 positions to the right, so as to allow the board to easily take 2 further breakers (e.g. 2 RCBOs to complement the 2 small RCD groups), not too bad a config at all if carefully thought out layout.
WoW, here in Belgium they're a lot bigger, mine is even a floor model that is 2 meters in height... (But then I'm an electrician, so that's more geekiness I think)
+Joy Van Acker Yeah, I think much of the EU has it much better than we do for design. While there are sufficient circuit ways, the amount of wiring space is TINY, not conducive to neat workmanship. It CAN be done but it's a lot more effort than it would be on a larger panel. Does Belgium follow what many EU countries do and have 3 phase 230/400v into the house/flat? That could explain the larger size too, keeping separation between phases? (guessing!)
+TheChipmunk2008 Here in Belgium you can choose betwoin 1f230+N, 3f230 or 3f400+N, that will give you larger panels also. But it's like you're saying, making your installation future proof by installing enough circuits is key I think. And neat cabling/installation is always a must! :-)
+Joy Van Acker Thanks for the fast response, yes, you can tell a true craftsperson when you see them take that little extra time to make things neat.
Incidentally, the 3phase 230v without neutral you speak of, is that the old 127v to ground with 220 between phases that much of Europe used to use?
(Which also freaks out younger people with old stereo gear wondering why it has such an odd voltage option on the selector, 127v!)
+TheChipmunk2008 That's correct, 3f230 is 230v between the phases, 3f400+N is 230 between phase and neutral and 400 between phases.
One reason why they are bigger in Belgium is because 2 pole breakers are mandatory (or more if 3f or 3f+N). Even N must go thru the breaker. Also your light and sockets must be kept separate (exceptions are possible) and the number of sockets per breaker is limited. Even in a smal house or apartment you will often need a 2x12 modules or more.
Thank you John for all your videos, really helpful.
Great video John.
I would like to see a 2021 version of this video as now I'm advised (still not done 18th Ed due to Covid) that each circuit requires an RCBO now and a anti surge device.
I have googled 18th Edition complete C/U's and I haven't as yet found one that has all this stuff, just the same ones as you were using in this 6yr old video.
It is fascinating to see how different the electric distribution panels are in the UK ("consumer unit") and US ("load center"). Very surprising to see that the UK unit is basically just a plastic box with a DIN rail inside it. I do like the rails, actually, because it eliminates the need for bussing.
I see everything is on the same line there. Are there any installations with split-phase power in the UK or is it typical to receive only a single leg of the circuit?
The majority of homes have single phase 230V, supplied as two wires, a neutral and 230V.
For anything larger you get 3 phase & neutral, 230V between each phase and neutral, 400V between any two phases.
No need for anything else as all appliances are 230V.
JW man I love you so much. Thank you
Best explanation regarding fuse box 👍
Perfect vid John, Fitting a BG metal this weekend.
British General brand.
When testing an installation with one of those consumer units fitted, I found that the RCDs were adding about 0.5 Ohms to the Zs figures. It made a couple of circuits only borderline pass.
Strange, I've never found any other brands with such a problem.
Anyone else encountered this?
There's something very strange about that. I, say, 20 amps was flowing through an RCD with a 0.5 ohm resistance, then the power dissipation would be 20 x 20 x 0.5 = 200 watts. Naturally 200 watts dissipated in an RCD (or in a CU in total) would be disastrous. If the current from a 10 kW electric shower passed through it (about 40 A), then that would be 800 watts.
Thanks for putting these vids up, very helpful!!
Hi ,
thank you for all your great videos. can you tell be the best practice to extend cables to a new consumer unit 3 metres away. All cables are required to be extended.
thanks in advance
Adaptable box with all connections ?
Excellent explanation
Brilliant. So clear that I'm determined to install my own myself. But is it still legal in the UK for a handyman (aka recreational electrician) to install a pre-wired consumer unit, rather than a qualified electrical tradesman. Fortunately I have installed one previously under the supervision of a qualified electrical tradesman so your refresher is much appreciated.
Love your videos, John. I am confused about why you can jump line wires from main switch to the two RCDs. I think from main switch to RCDs, there should be separate feed.
That isnt necessary as your not separating anything.
John has some good knowledge on Circuit Panels. If I could ask him to speak up a bit and try not to mumble, that would be excellent. Looking forward to more videos from John.
John, Can you do a video on the use of torque set screwdrivers on the terminals please?
+whitefields5595 FWIW the CU here got changed recently and the sparks went round every terminal with his torque driver. Next day I checked them all. About half were still OK, most of the rest less tight than I'd like and a couple were now actually loose.
+Graham Langley ... indeed, I found similar, hence the question. It is almost as though you have to overtighten to make sure everything is seated, then back right off then tighten again to the right torque. Or at least that's what I do, but I do not use a torque set screwdriver
Nice video John, thanks for sharing.
can you show us how you personally would set one up?
The 18th edition OSG states that such an arrangement (i.e.2 RCDs in one CU) is "Generally [...] not suitable for an installation forming part of a TT system as there is insufficient fault protection of the single insulated conductors which connect the load side of the double-pole main switch to the supply side of the RCCB." (p.37 in relation to Figure 3.6.3(ii) on p.36). I am not sure I understand why this is so. I would have thought that if there were a problem with a 2nd RCD there should also be a problem with RCBOs. I would be very grateful for your thoughts on this matter. Thank you.
The supply side conductors are not protected by the RCD, and on a TT system the earth fault loop impedance will be high, so a fault between line and earth will not blow the main fuse.
It's more of a problem with dual RCD efforts because they have single insulated flexible wires from the main switch to the RCDs, and one of those being damaged could make contact with the earthed metal case of the consumer unit.
With an all RCBO board, line is on a solid fixed busbar so very unlikely to cause a fault to earth.
However for all TT installations, there is still the possibility of a fault between the incoming line and the metal case of a consumer unit, there are various plastic glands and similar which are intended to avoid that happening. Or an time delayed RCD could be fitted before the consumer unit, although that can lead to other problems such as when used with single pole RCBOs.
very helpful as always very well explained john Thanks
You are the best sir!
Great video, really helpful, thanks for taking the time to post up.
One of my pet hates is rising clamp terminal blocks like this that leave a gap beneath the clamp.
we have an older type of consumer unit with one rcd protecting all rcd protected circuties and we have a switch under the consumer unit which when it trips all our electric is cut off we once had a boiler pipe leak and early in the morning the fuse under the consumer unit tripped and we was in a house without electric early in the morning when it was still dark it was winter i think at the time.
Yes, and that's the problem with single RCDs. My preference is to use RCBOs. The way each circuit has it's own residual current protection so only that circuit is lost in the event of a fault and, as a bonus, it's easier to fault find.
Retrofitting RCBOs is relatively simple, albeit that the box can get a bit cramped with the extra wiring involved and the larger devices, albeit that two slots are gained. The other issue is the cost, but as an installation is likely to be there for decades, it's not a ridiculously expensive job.
How about doing a more expensive consumer unit that is "not usually sold in diy sheds" as you put it.
There isn't a massive amount of difference with them. They usually just fit together in a nicer fashion, look better and have fewer RCD's fail. The actual wiring inside is the same and they physically are no different.
they all have to meet strict regs
Is the UK banning plastic boxes? What's the reasoning behind that? I mean, the plastic you've got there looks flimsy and thin, but in principle I think I'd rather have my mains stuff in plastic than in metal...
Since January 2016, they must be 'non-combustible', with an example of that being steel. No other examples are given and no definition of 'non-combustible' is provided either, so in practice they are all steel now.
This only applies in homes, commercial and industrial ones can still be plastic, however they are typically metal anyway and have been for decades.
Bakelite is pretty non-combustible. Maybe some of the fuse box manufacturers still have their machines from fifty years ago.
b.
The answer is twofold. Firstly, in most domestic applications, the consumer unit is sited either under stairs, or in entrance hallway. This causes major problems in the event of a consumer unit fire, and increases the risk of not getting out of the property. Sadly, it appears that it is also widely accepted, that the standard of installation in consumer unit replacement leaves much to be desired. Price work, fast track project delivery, and no quality control, means the shite standard will continue as the norm. This has more or less been said, without saying it! Introducing something which doesn't melt and keep burning is a sad way to have to combat it. Obviously it must be easier than raising installation standards.
Nice work sir
Nice layout
Cheers, Very helpful and clear.
+Adam Day If i was to put an extra rcb between the main switch as you stated for the Fridge freezer i.e if something trips the main ring I assume the 'singlr rcb would be okay for the Fridge freezer. Also how will the from fit on?
Really useful. Thanks.
ths s the most helpful video i ever watched, thnx sir
Many thanks great John
Excellent video Thanks
Very good, very clear!
Hi JW, I am moving my mains and will install a new C/U. I used to swear by MK in my contracting days but to be honest I think they have cheapened in quality and not even sure if they are made in UK anymore.
Have you ever come across or used BG (British General) on your jobs and if so what do you think. I used a small 6 way DB in our temporary kitchen set up at home and to be honest I thought the quality was rather good but not 100% sure if it is really entirely British. That is one reason I would now convert to BG.
MK consumer units and devices previously made in China, and now are still made in China under licence to a UK company set up to represent the Chinese manufacturer. www.circpro.co.uk/
BG are a lower priced option.
Hi John, I know this is a fairly old video, but maybe you still monitor questions..? The incoming DP switch is rated at 100A, but do the latest regulations say what the consumer circuit loads can add up to? I mean even in your example, you have a potential load of 148A total? I know this is unrealistic, but I'd be surprised if the regulations don't have something to say?!
It's unusual for a circuit to ever be loaded to it's maximum rating for any length of time, and pretty much unheard of for all of them to be simultaneously fully loaded. Even if that did happen, the whole lot is protected by the electricity supplier's fuse, which is typically 80A or 100A, so that would disconnect the supply long before the main switch was damaged by overloading.
Excellent!!
Thank you!
well explained thank you
great explanation , thank you Sir
Excellent video, thank you !!
thank you for your incredible movies. any chance of doing one about insulation testing? any point trying to do insulation testing with an ohmmeter?
Interesting they are sold at DIY stores over there. Here in New Zealand I've only been able to find them at specialist electrician stores/warehouses as DIY stores mostly sell outlets and switches.
TradeMe has thousands for sale.
Bare copper plate for live connection between rcd and breakers, didn't think that would be allowed..
Such an arrangement won't meet italian code, as 32 + 40 + 6 = 78 > 63 (RCD) so RCD isn't protected from overload. Also 32 + 32 +6 = 70 > 63 isn't up to code. Obviously this doesn't apply if 63 RCD are acrually RCBO; in that case overcurrent protection is guaranteed. Also single-pole breakers sound odd to me: I always seen 1P+N, 2P and 3P+N, rarely 3P, but never a 1P that on TT system isn't considered safe (you may have voltage on neutral).
Fantastic. Thank you! 👍👍
? listening to you say that you fuse the Neutral wire. we don,t do that in the US.
+John ward can can you do a video on cable sizing.working out the tabulated current carrying capacity
thanks for this
Such nice touch protected breakers and then you defeat them with that horrible busbar.
It is weird to see a distribution panel wired right to left instead of left to right. But then you also drive on the wrong side of the road so maybe that's to be expected ;-)
+stefantrethan One manufacturer (Crabtree and there may be others) does a shrouded busbar with plug-in RCDs etc. As for the R/L order, some manufacturers have the main switch on the right, e.g. Hager, Contactum, Wylex, BG as here, and others have it on the left, e.g. Crabtree, MK.
+Graham Langley By all means let's have that $1 in plastic and save the electrician.
At low voltage contact surface area makes all the difference between a mild zap and serious injury or death.
Also avoids those razor sharp corners where the copper was snipped off.
+stefantrethan No electrician is going to use a hacksaw and file when he's got a pair of BFO side cutters to hand.
Hi John, what size are the main cables coming into the cunsumer unit?
Job well done
Curious to know what 3- phase supply to a residence would be in the UK. Here in the US in some situations residential installations can receive 208Y/120 service if requested, rather than the usual split -phase 120
+Kyle Shady Single phase is neutral & 230V,
3 phase is neutral & 3 phases, 400V between phases, 230V between each phase and neutral.
Most residential installations are single phase, 3p is available in some areas but is rarely needed or used.
Most commercial/industrial is 3 phase.
+John Ward ok thanks, the only way to get single phase 240 here is through the use of step up transformers, or step down in the case of a 480Y/277v service. I'm surprised there are actually household appliances over there that use 400v
+Kyle Shady There are no 400V household appliances - 3 phase would be used as 3 single phases where additional capacity was required, or for 3 phase items such as motors.
Nice sir
It's a helpful video.
When choosing an RCD, does it have to be equal or larger(Amp-wise) than the MCB's connected on its circuit, does it have to be equal to the Main Switch?...
Excellent 🔥🔥🔥🔥
Hi John great video, what would cause the RCD to have burn marks at the bottom? Electricity trips but no fuses or RCD actually trip?
Almost certainly loose connections, which cause overheating.
The inside of that unit just looks scary. Is it legal in the UK to have the busbars for phase and neutral exposed like that? (I don't consider the flimsy panel over the phase busbar decent :p)
+DJefke RBBS Yes, most are constructed like that.
+DJefke RBBS Thats safe compared to some of the old boards i've worked on. You literally take your life in your hands when trying to add additional circuits, or work on them. Hate the things.
Some have plastic covers for the live busbar. Neutral connectors block/s is always exposed.
Ok here is a Shocker for you :))
The Neutral will not show voltage as long as its connected to the Neutral Bar then if you take a Neutral Wire from any Circuit even the mains Neutral then test the End it is a deadly Live Wire because the Returning current has no where to go so the Neutral wire becomes an extention to the Live wire. Scary Shit ay.
So don't assume the Neutral is safe ever
Well explained thank you .
Wait, plastic switchboard enclosures are being banned? Did I hear that right?
Yes, four years ago. Consumer units in domestic premises must be 'non-combustible'
from January 2016. In reality, that means they are all made of steel now.
Super! Many thanks.
Hi jw . Reg: Consumer units .
What brands are the best / easy to install cable / arrangement- Rcds + . And
A garage unit (c.u ).
Thanks johan
Sir your one thing i cud not understand that what is the benefit of using two RCB in one single phase distribution board?? There may be only one RCB and even it was properly worked. And if you wanna break circuit then u can do it via MCB
There are two so that if a fault occurs, it doesn't disconnect power to the whole house - each RCD only covers half of the circuits.
John Ward It would also reduce the frequency of nuisance tripping, yes?
Circuits power for gas cooker power ratings? How do you know which rating is required
the cable from the bottom of the isolating switch then goes to the top of the right rcd. what is the thing called at the top of the right rcd that then sends the cable to the top of the left rcd?
wait, only single pole breakers in the UK? Bit odd, i'm only used to double pole breakers in the Netherlands. Is it also normal for the bridge to be exposed like that?
+FoodOnCrack Yes, most are designed like that. Some have a plastic cover over the copper bar, but plenty do not.
Double pole breakers are available here but rarely used.
Hi John, good video, so would the neutrals from the TOP of the RCDs go into the neutral bar on the far right as well as the neutral from the bottom of the main isolator switch and the neutrals from the BOTTOM of the 2 RCDs into the 2 separate remaining neutral bars?
Panasonic HC-X900, now discontinued. The X920 is the current equivalent.