RCD Protection for submains

[TJC1]

Evening all

We have been asked to do some redial work picked up by a testing company i a hostel. It has been picked up that is no RCD protection in the rooms

There are 5 submain circuits that feed the 20 consumer units, 4 consumers units per submain (B32) Each room have a consumer unit which has two double sockets off a 16a radial and a lighting.

They asked my advice on whether to change the submain MCB to RCBOs or whether to change the consumer units for main switch and RCBOs

They supply cables to each consumer unit are above a plasterboard ceiling but cant be sure of the installation method, does the submain need to be RCD protected? As i dont want to put RCBOs on each circuit and also on the submain also

Thanks

 

[Deleted member 26818]

The date of installation bears zero alliance with how safe it is.

Exactly.
So why advise that older installations are unsafe?
Take for instance something mentioned today:
RCD sockets and RCD FCUs do not comply with the 18th Edition requirements for additional protection.
Does that mean any installation which has RCD sockets is now unsafe?
Does that mean any of the construction projects started last year are now unsafe if the design specified RCD sockets?

 

[Toneyz]

Exactly.
So why advise that older installations are unsafe?
Take for instance something mentioned today:
RCD sockets and RCD FCUs do not comply with the 18th Edition requirements for additional protection.
Does that mean any installation which has RCD sockets is now unsafe?
Does that mean any of the construction projects started last year are now unsafe if the design specified RCD sockets?

As long as the sub-mains were installed correctly to the previous edition of BS7671 the installation is safe. What has happened over the years is more and more layers of safety have been added. Years ago all was relied upon was a fuse then came RCD's and RCBO's for outdoor equipment then they were introduced into circuits to protect if someone is stupid enough to drill a hole in the wall above a socket.trades and maintenance staff should be aware of cable zones. The risk is that to the person using the sockets in each room.

 

[45140]

I think that there are misconceptions about what BS7671 really requires given conversations I have had with people in the Industry, such as time-served electricians trainers, trainees, etc. I am also surprised at the number of people whom I have met who either do not know about the 18th or more widely have not undertaken any training to update themselves, even to 16th or 17th Editions. Thus in some cases there is a genuine surprise at some of the latest requirements.

I then find that there is a misunderstanding about the need for compliance with changes to BS7671 with some people thinking that just because an installation now does not meet the 18th Edition that somehow it has suddenly become unsafe overnight and everything needs to be changed. Here we go back to the lack of briefing.

I think it would be foolish and quite wrong for anyone to infer that just because BS7671 now requires a specific means or method and type of equipment, that any previous arrangement is now per se unsafe. Modifying an existing installation to meet the 18th will bring about an incremental enhancement in safety but there is NO absolute requirement for this to occur until modifications are made, and then the need is only for the circuits involved to be brought up to the 18th Edition. As I understand it only certain requirements are absolute. This was my training.

 

[DPG]

I think most of us realise that the regs are not retrospective to be fair.

 

[Nigel]

Exactly.
So why advise that older installations are unsafe?
Take for instance something mentioned today:
RCD sockets and RCD FCUs do not comply with the 18th Edition requirements for additional protection.
Does that mean any installation which has RCD sockets is now unsafe?
Does that mean any of the construction projects started last year are now unsafe if the design specified RCD sockets?

If I come across a socket that is likely to feed portable equipment outside without an RCD installed that was installed prior to RCDs being a requirement that will be a C2. End of.

Just as if I come across a fused neutral that was installed when they were allowed.

 

[Deleted member 26818]

If I come across a socket that is likely to feed portable equipment outside without an RCD installed that was installed prior to RCDs being a requirement that will be a C2. End of.

Are you saying that it would be a different code, if the socket was not likely to feed portable equipment outside?

 

[Nigel]

Are you saying that it would be a different code, if the socket was not likely to feed portable equipment outside?

Yes. I would code that C3.

 

[Deleted member 26818]

Yes. I would code that C3.

So what, you use a mishmash of 16th and 18th editions when conducting EICRs?

 

[Nigel]

So what, you use a mishmash of 16th and 18th editions when conducting EICRs?

No. I use the current version of BS7671 only. I do not use any other versions when doing EICRs.

 

[Bait Account]

That is a ridiculous comment.

If so then why are you agreeing with it?

Yes. I would code that C3.

 

[Deleted member 26818]

No. I use the current version of BS7671 only. I do not use any other versions when doing EICRs.

So where does it say in the 18th that sockets likely to be used to feed portable equipment outside require RCD protection?

 

[Nigel]

If so then why are you agreeing with it?

When it was installed will not change my coding. You would change your coding based on when it was installed. Very odd.

 

[Nigel]

So where does it say in the 18th that sockets likely to be used to feed portable equipment outside require RCD protection?

411.3.3

 

[Deleted member 26818]

411.3.3

Nope.

 

[mydigitalhome]

Discrimination between the boards is required possibly 100mA and 30mA at the local DB. As others have said it’s in the regs.