LSF Cable within a care home

[mags1972]

Hi

Just been handed the Spec for a care home that is to be rewired. The Spec from the architect basically asks for LSF cable throughout with all cable drops to be installed in High Impact PVC conduit.
My questions are;

1. Does the High impact PVC conduit count as mechanical protection hence doing away with the need for RCD protection at the fuse board for lighting circuits etc?
2. Does the LSF cable have to be installed in PVC conduit within stud walls with thermal insulation or can it be installed as standard thermoplastic twin & earth?

Cheers Guys

 

[pennywise]

High impact PVC conduit still needs RCD protection. The LSF in the walls in insulation would have thought it would be Ok but might reduce your current carrying capacity if its in direct contact with the insulation.

 

[mags1972]

High impact PVC conduit still needs RCD protection. The LSF in the walls in insulation would have thought it would be Ok but might reduce your current carrying capacity if its in direct contact.

Thanks Pennywisw. According to CEF they say their manufacturers say it will withstand a nail hence no RCD required, I'm not quite convinced, thought about using BS 8436 cable for switch drops to save customer money on RCBO's, works out he'll be saving about £50-£80

 

[pennywise]

I always use PVC conduit for everything domestic and commercial with RCD's . I believe the the reason you are allowed no RCD protection if using metallic conduit is not because it will just stop a nail it's because you will make contact with something earthed before you hit a live conductor and so trip the breaker. If it were PVC you could potentially put a nail through the conduit and only hit the live conductor which wouldn't trip the breaker out. Sorry if that doesn't make much sense I'm not the best at describing stuff. As for RCBO's spash out ;-)

 

[Guest123]

According to CEF they say their manufacturers say it will withstand a nail hence no RCD required

Ask for that in writing from them and then see what they say. Would they go to court on it???

To negate the need for RCD protection to the cables in walls, it would need to be "earthed metallic conduit"