Bs3871

peck06 · Mar 16, 2011

Come across an old MEM board today, first time i've seen BS3871 MCB's other than at college. Obviously I know these are old and obsolete.

Basically today I extended the socket circuit in a boiler room just to add a fused spur for a CCTV camera to be wired to. I've done the work, but told the client that the board need's changing as it doesn't comply with 17th edition and I was always told that the 'push-button' type MCB's were obsolete because they used to blow the sides out when they failed. I'm now quoting for the board change.

My question is, should I have done the work, or should I have refused until the board is changed? What would you have done?

I will say this was for a commercial client of mine who give's me 70% of my work so I really didn't want to upset him.

Whats your view???

These are the one's i'm talking about.

Guest123 · Mar 16, 2011

With the situation you have described, I cant initially see a problem with you having done the work prior to the CU upgrade.

You havn't added a socket outlet so no requirement for additional RCD protection there, I assume the cableing is surface mounted being in a boiler room so requirement there either.

As long as earthing & bonding is up to standard then I probably would have done it too.

nickblake · Mar 16, 2011

Agree with lenny on this , these breakers were used to replace the old rewirable ones , only problem is is the fuse cover should still be in place , reason being is these would fit straight into the existing carrier so it would be possible to have an exposed conductive part on the existing fuse carrier

IQ Electrical · Mar 16, 2011

peck06 said:
Come across an old MEM board today, first time i've seen BS3871 MCB's other than at college. Obviously I know these are old and obsolete.

Basically today I extended the socket circuit in a boiler room just to add a fused spur for a CCTV camera to be wired to. I've done the work, but told the client that the board need's changing as it doesn't comply with 17th edition and I was always told that the 'push-button' type MCB's were obsolete because they used to blow the sides out when they failed. I'm now quoting for the board change.

My question is, should I have done the work, or should I have refused until the board is changed? What would you have done?

I will say this was for a commercial client of mine who give's me 70% of my work so I really didn't want to upset him.

Whats your view???

These are the one's i'm talking about.

View attachment 4742

Just to clarify, although BS 3871 devices were superseded with BS 60898 devices, the presence of the older devices alone is no reason to change a board.

There is specific mention of this in the ESC Best Practice Guide on periodic inspection.

peck06 · Mar 16, 2011

Just to clarify, although BS 3871 devices were superseded with BS 60898 devices, the presence of the older devices alone is no reason to change a board.

Ah ok, I just thought I remember being at college (about 5 years ago) they showed these to us and made a big deal about them blowing the sides out. Maybe I've got that wrong, my memory is not the best. Oh well, looks like I've talked myself into some extra works with what I've already told my client, not to worry its more money in the bank.

Yes all surface wiring in Galv 20mm Conduit, with metal clad accessories, all earthing/bonding is good.

nickblake · Mar 16, 2011

It can happen especially if you have a high PFC as if im not mistaken they only have a 3 ka rating compaired to 60898's being 6 and 10 ka

pushrod · Mar 17, 2011

peck06 said:
Come across an old MEM board today, first time i've seen BS3871 MCB's other than at college. Obviously I know these are old and obsolete.

Basically today I extended the socket circuit in a boiler room just to add a fused spur for a CCTV camera to be wired to. I've done the work, but told the client that the board need's changing as it doesn't comply with 17th edition and I was always told that the 'push-button' type MCB's were obsolete because they used to blow the sides out when they failed. I'm now quoting for the board change.

Whats your view???

View attachment 4742