Like for Like wherever you like....

[DaveyD]

Hi Boys and Girls.
Got a call out tonight, lovely older couple - no lights up or down. Push button CB, 100Ma RCD. TT.
Turns out it was the bathroom fan shorting. Made safe and put a barrier for protection.
I know its not notifiable as its a replacement. But here the thing. No 3 pole isolation and no 30Ma RCD. There is a 230v overun timer fan rated at IPX4. I would replace with the Xpelair IPx5 (think its 100T I usually fit). I dont want to rip off this couple. RBCO and Isolatior. All they want is a like for like replacement and I understand that.
What do you think?
T.I.A, Dave

 

[Richard Burns]

As a simple method of (just) conforming to the regulations without too much cost, if the existing fan has a FCU, as the manufacturers normally require, then you could replace this with an RCD FCU and exchange the fan for the 100T. You do not need to fit a 3pole switch as you have double pole isolation from the FCU.
Not sure if it would still be a like for like but I would think it would be close and avoids the need to fit an RCBO for the lighting circuit which would be more costly and would shift up to notifiable.

 

[Deleted member 26818]

Go for it.
This like for like stipulation for Part P doesn't really exist.
You don't need to install 30mA RCD protection, as it's not an addition, alteration or new circuit, just maintenance, although the lack should be noted on any certification.
There's no requirement for a 3 pole isolator in BS7671.
I wouldn't install an RCD FCU, as I don't believe it complies with BS7671.

 

[DaveyD]

Thanks guys. No, there is no FCU and no window. Only way to isolate the permanent live is via the lighting circuits on the consumer unit.

 

[Octopus]

IMHO - If its a like for like replacement then there's no need to update the circuit (unless its actually unsafe)

 

[High Tower]

If the bathroom has its supplementary bonding, then it complys with the 16th, The fan doesn't always need a isolator, there is a post about it on here somewhere.

I would change it out, like for like and not the lack of rcd on the cert, just as spin suggested.

 

[La Poste]

I wouldn't install an RCD FCU, as I don't believe it complies with BS7671.

Why is that?

Is it because an earth fault on the supply side of the RCD FCU would not trip the RCD FCU and the fault would transfer to the earth circuit on the load side of the RCD FCU thus making the earth circuit in the bathroom live?

Thanks.

 

[telectrix]

something like that. was in a previous thread.

 

[Octopus]

Why is that?

Is it because an earth fault on the supply side of the RCD FCU would not trip the RCD FCU and the fault would transfer to the earth circuit on the load side of the RCD FCU thus making the earth circuit in the bathroom live?

Thanks.

OK, so when you fit a RCD socket inside or outside a property and a fault develops "before" said socket then the earth could go live. So why are we allowed to fit such devices?? Surely BS7671 should forbid ANY additions or changes unless a dual RCD board is fitted!!!!!!!!

The RCD FCU or socket is to protect the circuit "after" said device.

Just debating.

Tin hat on

 

[telectrix]

i suppose it's because, by fitting a RCDFCU or a RCD s/o, you will have left the installation (or part of it) safer than it was before.

 

[La Poste]

But it shouldn't be allowed for certain special locations such as bathrooms and gardens.
A garden supply to outside sockets should only be allowed from a separate circuit protected by an RCD at the origin of the circuit namely the board.
Not by adding an RCDFCU tapped into a non RCD protected circuit in the house.

 

[Octopus]

But it shouldn't be allowed for certain special locations such as bathrooms and gardens.
A garden supply should only be allowed from a separate circuit protected by an RCD at the origin of the circuit namely the board.
Not by adding an RCDFCU tapped into a non RCD protected circuit in the house.

I'm sorry but on this occassion I have to disagree with you. Such interpretations of the regs is exactly why the DIY installer continues to install poor/unsafe additions into residences in the UK.

Whether it be a RCD socket added on the outside of a house with a BS3036 board or a RCD FCU protecting a section of a circuit after such a device then clearly the residence is better protected.

 

[La Poste]

But we are talking about laying a new circuit in a garden, brand new.
Not making an existing circuit safer.

How about a bathroom fed from a RCDFCU, surely that would be quite dangerous.

 

[Octopus]

Why? If previously, say 35 years, its been attached to a 3036 board, then a RCD FCU isn't going to make it dangerous, surely!!

Just debating.

 

[La Poste]

I like debating.
I can see your point about making an existing installation safer but laying a new circuit, brand new should only be allowed if the RCD is at the origin of the circuit.
That's just my opinion, it would help me sleep better at night.