RCB rating

[jonifife]

Hi

We are having an electrician do some wiring for an extension. THe RCBs on the consumer unit are rated at 100 milli amps. (I hope this is the right terminology right?!)

The sparky says should be smaller, around 30 ma I think and so need a new board.

As our building works are subject to building con approval will this be a Part P requirement or is it something else? Can this be insisted on?

Cheers

 

[ban-all-sheds]

To cut a long story short, yes, the RCD(s) will have to be changed to 30mA for any new circuits, or new concealed wiring.

The circuits not being worked on don't have to be upgraded.

But a complete CU replacement might not be necessary - swappjng MCBs for RCBOs on the affected circuit(s) might also be an option.

How old is the CU? What make?

Post a photo?

 

[jonifife]

I can't find the usb to connect my phone to take a pic at the mo!

The make is MK sentry done to bs en 439 - we moved into the house about a year ago and I think the CU is about 10 years old as the property was overhauled then including rewiring by the looks of things.

The new circuit for the extension is being taken of a spare blank 'point' (sorry don't not correct word) on the CU

I will ask the spark if this can just done for the new circuit as this is the only new one.

Cheers

 

[ericmark]

The regulations does not say you have to have a 30ma RCD in the consumer unit. What it says is sockets under 20A and wires buried less than 50mm in the wall need protection by either a 30ma RCD or with wires could be by using Ali-tube cable. There is likely a host of methods to comply and what has to be done is select the most appropriate method in your case.

So if there was just one socket in the extension then ali-tube cable and a RCD socket likely best method. But RCD sockets are expensive so with two sockets then we start to look at the idea of protecting at the source.

If you can use RCBO's then that's easy way out but if the CU is too old to be able to use them one has to consider either a box that will take them or renewing whole consumer unit.

As well as cost today one must also consider cost in the future and unless you have RCD protection at 30ma any other work will run into the same problem. Also of course your safety and that of your family.

So although there are ways around it you may still be better to have a new consumer unit.

For the new kitchen fitted for my parents a sub-main was used and the RCBO's for the kitchen are in the kitchen. But it was not to reduce cost it was so my disabled mother could re-set the RCBO's if they tripped as she could not get under the stairs.

 

[Paul_C]

Put this into perspective: The 30mA RCD requirement for all sockets is a recent introduction to BS7671, compliance with BS7671 is not mandatory, and you already have 100mA protection, so adding a few extra sockets in the extension which are protected similarly to the existing sockets is not a big deal. Many British electricians can't see beyond what their current edition of BS7671 says though, so you may have difficult convincing them otherwise.

But that aside, if this is going to be run as a new circuit, you could just fit a 30mA RCBO in the spare position which is going to be used anyway.

 

[jonifife]

Thanks- I think what you say Paul c sounds sensible although can see the other points raised are all valid.

I don't think we are likely to expand further and maybe would change the board at a later date if its not part p requirement. I will see what our spark says but your suggestions give me something to go on for now

Cheers

 

[JohnD]

Having a 100mA RCD usually indicates either an eccentric electrician, or the absence of a good eath. See if the electricity company provides, or can provide, an earthing point. They mostly can these days, even in country districts with overhead supplies. Sometimes they will charge for it, but even if it costs £100 or so, it will be money well spent and will save you needing an earth spike.

 

[Paul_C]

Having a 100mA RCD usually indicates either an eccentric electrician, or the absence of a good eath.

Or simply that it's an installation which was done some years ago before 30mA RCD protection became the norm.

 

[jonifife]

I think there is an earth spike by the front door- its a black box with a red strip saying electricity earth do not remove

I think it was just done a few years ago when 30ma wasn't the norm IMO 10 years doesn't seem that old - I bet there are thousand of houses with older installations.

 

[JohnD]

See if the electricity company provides, or can provide, an earthing point.

 

[RF Lighting]

Put this into perspective: The 30mA RCD requirement for all sockets is a recent introduction to BS7671, compliance with BS7671 is not mandatory, and you already have 100mA protection, so adding a few extra sockets in the extension which are protected similarly to the existing sockets is not a big deal. Many British electricians can't see beyond what their current edition of BS7671 says though, so you may have difficult convincing them otherwise.

When are you going to stop trotting out this irresponsible and misleading advice??

It is nearly 4 years since the requirement to protect ALL sockets was introduced, but even so, 30mA protection for sockets is hardly a recent idea. It was a requirement to protect all sockets which may supply equipment for use outdoors almost 20 years ago. All the time I have been working in this trade it has been regarded as good practice to RCD protect ALL sockets even though it was not a requirement of the current regulations.

What standard do you propose the electrician works to then if not the current edition of BS7671?

If there's no bonding in the house should this be ignored too because it didn't used to be required?

 

[ban-all-sheds]

When are you going to stop trotting out this irresponsible and misleading advice??

When he lets go of the idea that governments and regulations are bad, and that people should be allowed to do what they want without "interference".

No doubt if he and this forum had been around 45 years ago he'd have been telling people that the 13th was good enough, and not to bother with all that nonsense about needing a cpc in lighting circuits....

 

[Paul_C]

When are you going to stop trotting out this irresponsible and misleading advice??

Maybe when those who can't seem to see back beyond the current edition of BS7671 accept that a new edition of the Wiring Regs. which introduces new (non-mandatory) requirements doesn't automatically render any installation done to an earlier version dangerous or somehow in desperate need of replacement.

It is nearly 4 years since the requirement to protect ALL sockets was introduced,

As I said - A recent change.

but even so, 30mA protection for sockets is hardly a recent idea. It was a requirement to protect all sockets which may supply equipment for use outdoors almost 20 years ago.

Yes, but as you've just noted, not for all sockets. And again, if you would put this into perspective, while I'm not saying that a 30mA RCD doesn't provide additional protection, that doesn't mean that even a socket used for outdoor equipment is unsafe without it.

The 30mA RCD requirement (for external use) was introduced with the 16th edition in 1992. That's 1992, yet to hear the response of some people to lack of an RCD on this circuit or that circuit you'd think they were condemning something from 1892 when there was much still to be discovered about basic protective measures.

What standard do you propose the electrician works to then if not the current edition of BS7671?

As I said, that's the problem in this country - Finding anyone from the "normal" electrical installation industry who can actually look at things in a reasonable manner and put things into perspective, and not just trot out what BS7671 says at this moment.

One has only to look through some recent posts on this forum to see the response of some people to running as much as new switch drop in wall without RCD-protecting the circuit. Yet these same people were no doubt installing just such cables a mere 4 years ago and declaring them to be perfectly safe, and not in any way suggesting that it would be "good practice" to add an RCD anyway.

If there's no bonding in the house should this be ignored too because it didn't used to be required?

Well, there have been posts on here suggesting not to bond things which older editions of the Wiring Regs. always stipulated must be bonded, so I'm not sure that's a good example.

 

[Paul_C]

When he lets go of the idea that governments and regulations are bad, and that people should be allowed to do what they want without "interference".

I never deny that in my opinion there are far too many statutes which interfere with freedom of choice.

But in this particular case, that's not really relevant, is it? There is no statutory regulation which says new sockets must have 30mA RCD protection. Unless, of course, you want to try and come up with some ridiculous argument that they would not be "reasonably safe" as required by the Building Regs.

No doubt if he and this forum had been around 45 years ago he'd have been telling people that the 13th was good enough, and not to bother with all that nonsense about needing a cpc in lighting circuits....

And I would probably also have been pointing out that in some respects the 14th edition relaxed requirements which were absolute in the 13th edition, as was being discussed here a short while ago with regard to warning notices etc.

I'm just saying that minor matters should be put into perspective and regarded as the minor matters that they are.

 

[EFLImpudence]

When he lets go of the idea that governments and regulations are bad

Surely it is undeniable that a lot of governments ARE bad (and populated by idiots) and by default some of the regulations they impose are not good.
There are many laws throughout the world that are definitely bad.

Blindly stating you should do something, merely because it is THE LAW, without stating whether that law is in itself good cannot be wise.
Blindly stating you should do something, even though it is not law and you are allowed to work out equally satisfactory methods without stating whether that method is in itself bad cannot be wise.