17th edition - cables and cable protection in domestic walls

[Paul Downham]

Hi all,

I have a question. 17th edition states my cables need to be at a depth of 50mm or protected by a metallic sheath. The only metallic sheath around is steel conduit, heavy and cumbersome for domestic use. Is there such a thing as metallic channel?

If not, what do you guys use? Seems to be difficult to find a lightweight metallic protector for cables.

Cheers all,

Paul

 

[Hawk81]

I think you will find most don't go for the metal conduit/capping. The use of a 30mA rcd does away with the need for this.

 

[Deleted member 26818]

There are cables that incorporate metalic sheaths, BS8436 cables more commonly known as flexishield.
Another option is to protect the cables with an RCD.

 

[Paul Downham]

Hi guys, I thought this metallic protection was required in addition to an RCD?

 

[malcolmsanford]

Reg 522.6.7 will tell you that if where you installation is not intended to be of use by a skilled or instructed person, normally domestic, and is installed in accordance of regulation 522.6.6 (v), but not complying with (i) (ii) (iii) or (iv) of that regulation then additional protection by 30mA RCD is required.

 

[Deleted member 26818]

No. There are 5 options.
1) Bury the cable at a depth greater than 50mm
2) use an earthed metallic sheath (this sheath does not offer mechanical protection, it just provides a fault path if the cable is penetrated by screws or nails)
3) use earthed conduit or trunking
4) provide mechanical protection sufficient to protect the cable from penetration by screws or nails
5) install the cables in safe zones and provide RCD protection.
If this is a circuit for socket-outlets, then you will probablly just want to use RCD protection for the whole circuit.
That way you are protecting both the cables and the socket-outlets at the same time.