Reusing BS 3871's

[vxwestie]

I realise I should probably know the answer to this, but I'll ask away anyhow...
I'm having to quote for some major refurbishment to an existing commercial kitchen for a local charity organisation. It'll include additional sockets to the ring, relocation of existing and relocation of a couple of 3phase appliances and control gear.
The problem is, the existing install is via a MEM board with N range 3871 Mcbs. Although applying RCD protection to the additional works is going to be bad enough, What are my responsibilities for overload protection, can I utilise the existing 3871's or do I NEED to replace the board?
Ordinarily I wouldn't muck around and even consider it, simply replacing the board, but as its a charity and the previous install was certainly up to 15-16th regs and in superb condition, I contemplating leaving the board to save them some money.
Any opinions?

 

[telectrix]

can't see a problem with retaining the 3871's, but what's the chance of fitting RCBOs to socket circuit?

 

[Andy78]

Why would you not be able to use the BS3871 OCPD that is already in place protecting the circuit ?

RCD protection should be easy enough adding a small enclosure next to the CU.

 

[Richard Burns]

So long as the circuits comply with the Zs requirements for those breakers and the breakers do switch off then the only problem will be RCD protection, and the cost of that may exceed the cost of a new board if you have lots of circuits to RCD protect.

 

[vxwestie]

My thoughts exactly. I cannot see a problem either with using the 3871's but I will have to take in account the cost of the RcD protection verses a new board. ... Unless I can come up with a RCBO to fit the MEM.
Purely because of the age of the 3871's I would normally change the unit and I've discussed this with the clients. As money is tight, it's only something they'll/I do if really needed.
I'll only have to apply RCD protection to the circuits im modifying, which is around 3, so won't be too bad.
I knew I had answered Motown question really, but thanks for the replies...

 

[telectrix]

alternatively you could feed your new sockets from a RCD FCU.

 

[Deleted member 26818]

Or use RCD sockets?

 

[telectrix]

Or use RCD sockets?

as long as he's not burying cables to them <50mm.

 

[westward10]

People will curse me for saying this but you should note them as a deviation from BS7671.

 

[Deleted member 26818]

You mean departure.
No need to list it as a departure for two reasons.
One they are already there.
Two they comply with BS7671