Ceiling cable routing

[TJR]

When routing cables between joists in a ceiling, does the 50mm depth apply - i.e. where the cable hang down between the joists and rest on the plasterboard, this will be less than 50mm from the surface of the ceiling?

If it does, how do you route the cables in the voids, so they don't rest on the plasterboard without having to clip them along the joists - trying to avoid having to lift loads more floorboards!

I'm asking as I am starting my first fix soon - all notified to LBC etc...

 

[stephenf8542]

Is it RCD proteced?

 

[Spark123]

Not sure why RCD would make a difference?
I take it we are talking bog standard twin and earth? The cable needs to go at least 50mm from the top or bottom of the joist or it needs to have some sort of plate across the joist to stop a screw or nail hitting the cable.
You need to also be carefull where you drill the joist - //www.diynot.com/wiki/electrics:route
As for it laying on the plasterboard ceiling yes, that is fine.
Just don't go putting insulation over it all though!

 

[TJR]

Thanks for your replies - yes std. T&E. Will all be RCD protected - although this doesn't make a difference regarding safe zones does it as far as I am aware?

So its OK resting on the plasterboard - technically this is less than 50mm from the ceiling surface though isn't it? Although I suppose, if a nail or suchlike is put in from below the cables will move out of the way.

cheers.

 

[ban-all-sheds]

Moving out of the way of a nail or drill has always been my assumption.

If you want to be obsessive about it, you could always run short lengths of trunking between each joist, supported on mini-hangers..

 

[Chri5]

Not sure why RCD would make a difference?

Because RCD protection allows the cable to be less than 50mm from the surface, be that a wall or a ceiling?



BAS forgot to mention the earthing requiremnt for metal containment

 

[ban-all-sheds]

I was going to ask about that.

If you aren't relying on the trunking for earthed mechanical protection, and if the cables are DI, does the trunking qualify as an exposed conductive part?

 

[TJR]

Not sure why RCD would make a difference?

Because RCD protection allows the cable to be less than 50mm from the surface, be that a wall or a ceiling?

My understanding is that the cables still have to be in 'safe zones' though? Is the ceiling classes as a safe zone?

 

[Spark123]

Have a read of 522.6.5 which is for cables in a ceiling or floor.

Regulation 522.6.7 calls for RCD protection for cables concealed in a wall or partition where regulation 522.6.6 (v) apples.