Supply for Combi Boiler - RCD required ?

[Dave OCD]

Allright chaps

I have to connect a new Combi this Saturday morning, intending to fit a 3 amp fused switched FCU and take the supply off a handy socket [about 2 feet away and on a RFC not a spur]

The consumer unit is an old MEM with cartridge fuses and there's no RCD, [TNCS system with Ze of 0.14]
Now assuming the owner doesn't want a new CU [yet anyway] would you be happy to connect up as is or would you fit an RCD spur ?
I have an opinion but just wondered what other people might think ?

 

[Darkwood]

What do the manufacturers guidelines say about the electrical requirements?

 

[LankyWill]

i would just fit a standard spur, 3A wont cause too much damage

 

[Dave OCD]

What do the manufacturers guidelines say about the electrical requirements?

Just double pole isolation and 3 amp fuse, no mention of RCD.

 

[Leesparkykent]

I wouldn't worry about it as long as the installation method of the spur you are putting in doesn't require it.

 

[Dave OCD]

i would just fit a standard spur, 3A wont cause too much damage

Well in the event of a fault it'll certainly blow pretty fast Will.

 

[Pete999]

If you are that concerned put a RCD fused spur in £17 from Screwfix I think

 

[Dave OCD]

I wouldn't worry about it as long as the installation method of the spur you are putting in doesn't require it.

Exactly my thoughts Lee. :smiley2:

 

[Leesparkykent]

Exactly my thoughts Lee. :smiley2:

Any way from next Wednesday you only have to take into account of the manufacturer's relevant instructions, if any. Haha :clap:

 

[NoSparks]

My understanding is that any NEW work, which would include this, was required to comply with Current Regs. The regs only require that cable burried in walls etc be protected by an RCD, specifically surface wireing is not required to be RCD protected. so will there be any new wire passing through walls?

 

[telectrix]

My understanding is that any NEW work, which would include this, was required to comply with Current Regs. The regs only require that cable burried in walls etc be protected by an RCD, specifically surface wireing is not required to be RCD protected. so will there be any new wire passing through walls?

not quite right. passing through walls don't need RCD. buried in the plaster < 2" deep does.

 

[Dave OCD]

My understanding is that any NEW work, which would include this, was required to comply with Current Regs. The regs only require that cable burried in walls etc be protected by an RCD, specifically surface wireing is not required to be RCD protected. so will there be any new wire passing through walls?

Not in this case, it'll be about 2 feet of 0.75mm H/R flex from a fused spur right next to an existing socket.

 

[Redvanman]

is the cable to the stat buried

 

[NoSparks]

My understanding is that any NEW work, which would include this, was required to comply with Current Regs. The regs only require that cable burried in walls etc be protected by an RCD, specifically surface wireing is not required to be RCD protected. so will there be any new wire passing through walls?

Well you tel that to my NICEIC inspector! In fact maybe the word "buried" might have more exactly expressed what I ment.

 

[NoSparks]

not quite right. passing through walls don't need RCD. buried in the plaster < 2" deep does.

So in that case an RCD is not strictly needed, but of course you will have checked that the supplementary bonding that was required by the previous standards to which the boiler was first installed are present!!! The problem being that if an earth fault developed then it would be to the boiler which is connected to the metal work of the water and the gas and these cannot be allowed to become live. So in the end it's your decision which way to go.

 

[Leesparkykent]

So in that case an RCD is not strictly needed, but of course you will have checked that the supplementary bonding that was required by the previous standards to which the boiler was first installed are present!!! The problem being that if an earth fault developed then it would be to the boiler which is connected to the metal work of the water and the gas and these cannot be allowed to become live. So in the end it's your decision which way to go.

So everything has to be RCD protected in your book then?

 

[NoSparks]

So everything has to be RCD protected in your book then?

That is too sweeping. There are exceptions as we all know but discussion of those is outside the OP.

 

[Dave OCD]

Well it's all done, and with a Zs at the socket right next to my new fused spur of 0.28 and a 3 amp fuse in said FCU I'll sleep soundly even though there isn't currently an RCD.
In reply to the other questions there are 10mm main bonds to both gas and water and the room stat is wireless RF, did that this morning as well.

 

[Deleted member 26818]

Might require 30mA RCD protection, if the Combi is in a bathroom.
30mA RCD protection is an acceptable method of providing additional protection for cables concealed in walls, as long as the cables are in prescribed zones.

 

[Dave OCD]

Had that been the case then I would definitely have fitted an RCD but this one was in a kitchen.