Installation of bathroom heater with no earth terminal

[moretea]

I am installing a Dimplex downflow heater in zone 3 of our bathroom, and am intending to take a spur off the ring main which runs just above our bathroom ceiling down to a fused spur unit then onto a double pole isolator ceiling switch, then on to the heater itself (which only contains a live and neutral as it has a plastic body). However I am concerned about how the earth should be wired. We do not have an RCD/CU only a traditional fuse box - I did wonder if I should use an RCD spur rather than a fused spur in the bathroom, or do I simply terminate the earth in the spur or switch?
I did contact Dimplex who simply said 'contact a qualified electrician'!

 

[1john]

Have you informed building control about this notifiable work?

What is the rating of the heater? If the heater is class two (pic of a square within a square) then it must not be earthed. The CPC of the ring final circuit must be kept intact throughout it's run. How did you plan on extending the ring final circuit?

 

[moretea]

I haven't notified building control on this yet.

The model in question is an FX20EIPX4, which I believe is class 2. I'm not sure what you mean by extending the final ring main, as all I am intending to do is take a spur off it. As for the earth bonding in the bathroom, this goes back to the fuse box.

 

[ajrobb]

Does the OP mean something like http://www.tlc-direct.co.uk/Products/CM4904.html ?

 

[moretea]

Yes instead of a fused spur, but I am not sure if there is any point with this if there is no RCD protection on the CU.

 

[ban-all-sheds]

£20 for that, vs not much more than twice that to add RCD protection to the entire socket circuit.

I know which I'd do.

 

[ajrobb]

As it is an addition to bathroom wiring, I think you'll be required to introduce an RCD. However, the wiring up to the RCD will not be protected. Does this mean the RCD will have to be outside the bathroom (or accessible only with tools)?

If you follow BAS's advice, you get RCD protection for the whole circuit and the FCU can go adjacent to the heater in the bathroom outside zone 2, I think.

Anyway, it's all notifiable to LABC.

 

[ban-all-sheds]

However, the wiring up to the RCD will not be protected. Does this mean the RCD will have to be outside the bathroom (or accessible only with tools)?

Yes, although if the RCD spur was also on the ceiling, or on the wall near it that would be OK.

But the biggest problem would be that the RCD would not operate on any upstream fault, so a L-E fault before it could raise the potential of extraneous-conductive-parts in the bathroom.