Cable run under floorboards

[Iain123]

Hi Group

Had a third party inspection by a NAPIT tester, to get building control approval for a pv installation.
He has failed the cable run in Twin and Earth under my floorboards even though its greater than 50mm from surface. No 30ma RCD fitted to this circuit.

I though it was acceptable if the cable was 50mm or greater from the top of the joists?
Thanks for advice in advance

Iain

 

[andyb]

Did he give you a reg No that you are falling foul of?

Unless it's relevant to PV which I have no experience of, there's nothing wrong with running cables below floorboards.
Your biggest concern would be building regs.

 

[Darkwood]

Is it 50mm from the ceiling below too? Edit - as Dave points out its not applicable anyway to running through floors.

Likewise I have no PV experience so leave that to the PV guys.

 

[HappyHippyDad]

Could you not just add an RCD?

 

[snowhead]

Is the cable visible for it's full length under the floor ?

 

[andyb]

Could you not just add an RCD?

I don't think that does it HHD, needs to be 50mm or mechanical protection or earthed conduit or etc etc.

 

[Iain123]

The inverter manufacturer SMA Sunny boy guidance says do not use an RCD with a tripping current of less than 100ma to prevent false tripping which the NAPIT tester will not accept (he wants a 30ma RCD.

The cable is fully visble for all of its run from airing cupboard and along landing.

I have not asked him yet to quote the reg he's failing it on.

 

[davesparks]

Since when has running a cable under floorboards/above a ceiling required RCD protection?
The 50mm reg is applied to cables buried in walls

 

[andyb]

The inverter manufacturer SMA Sunny boy guidance says do not use an RCD with a tripping current of less than 100ma to prevent false tripping which the NAPIT tester will not accept (he wants a 30ma RCD.

Is the cable installed in a wall then?

 

[Iain123]

Clipped direct to wall, not in wall and then under flooirboards

 

[andyb]

Since when has running a cable under floorboards/above a ceiling required RCD protection?

It doesn't.

The 50mm reg is applied to cables buried in walls

And cables below a floor Dave.

 

[andyb]

Clipped direct to wall, not in wall and then under flooirboards

Then I would say that you do not need an rcd, it sounds like the inverter manufacturer are saying that if you use an rcd then it should be 100ma. It doesn't sound to me that they are saying that they require one.

 

[davesparks]

And cables below a floor Dave.

Since when? There is no requirement for cables to be RCD protected purely due to be installed under a floor, regardless of whether they are 50mm deep or not!

If you think otherwise please do quote a regulation number to back this up.

 

[Iain123]

The inverter manufacturer says the inverter does not need an RCD, but if an RCD is used on the circuit it needs to be 100ma or greater.

 

[andyb]

Since when? There is no requirement for cables to be RCD protected purely due to be installed under a floor, regardless of whether they are 50mm deep or not!

If you think otherwise please do quote a regulation number to back this up.

Dave, could you please read my post again that you've taken my quote from.

You'll see that I'm agreeing with you that cables below the floor and above ceilings do not need rcd protection.

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