Cpc

[Frosty69]

Hi people I can't open the sticky PDF file about using swa armor as cpc. Is there a calc? I'll give you a few details of the job.
25m length
6mm 2core swa (buried)
Fed from 60898, B40
Feeds garage db containing a 32a ring main and 6a lighting circuit all rcd protected. 3x dbl sockets and 6x50watt fluorescent lights.
Basically how do I work out that the armor is ok to use as cpc?
Thanks

 

[Electricalserv]

Always use armour and 3rd core. That's my preference anyway

 

[sparks_114]

See 543.1 BS7671 I am trying to refresh my memory before I can give a direct answer.

 

[Frosty69]

Electricalserv I would usually do it that way if I was installing but it's already in under a new path. I'll check regs out tomoz as there in van as I've worked it out before just can't remember

 

[topquark]

Opens OK for me. Here's an image of it:
View attachment 5944

 

[sparks_114]

Can't get any mathematical symbols to appear here. Anyhow, I believe it to be the equation in 542.1.3. Where it is not desired to calculate then refer to table 54.7.

 

[telectrix]

sparks114, i believe you refer to 543.1.3, the adiabatic equation.

 

[Sparky Ninja]

You need to provide a little more info, with regard to earthing system and Ze values if you have it?