swa submain query

[james beckford]

I have been asked to install a db in a wooden outbuilding, the building has been erected on the base of an old garage.

There is an old 2 core SWA cable running from the main DB in the house underground coming up in the building

I have tested out all the cables and continuity and insulation all fine, the house is tncs.

My question is this, can i use the armour as the earth back to the main DB ? i fitted the board on and connected in a socket and Zs and trip times all good, well within limits or do i need to replace the old cable with a 3 core ?

ps i have disconnected everything pending solving this problem.

client wasnt too happy when i said that i would prefer to dig out cable, said another sparks had told him it would be fine,

Thanks in advance for the usual helpful answers

 

[micknew]

No unless its damaged.

 

[james beckford]

Mick,

sorry brain bit slow tonight, are you saying that it is okay to use armour as the earth ?

James

 

[Midwest]

Someone will be able to tell you, but you will need to provide more information. Cable size, length, load or what the new db is going to supply. Then adiabatic equation, but don't ask me!

 

[james beckford]

cable size 4mm2

lenght 10M

2 double sockets and 1 flourescent light

checked all my calcs for votage drop etc etc and was well in.

I was concerned as sub main comes out of non rcd board so was planning on putting powerbreaker adjacent to board

any comments ?

 

[D Skelton]

Do you own a copy of BS 7671? If so, what does it say regarding the use of armour as a CPC?

 

[GLENNSPARK]

Mick,

sorry brain bit slow tonight, are you saying that it is okay to use armour as the earth ?

James

if i gave you a length of 3 core SWA for a 3 phase motor.....would you think it was OK?

or lets say you came across an existing install (single phase) with both live conductors running through a steel conduit...what would you think about it?

i expect answers to both please.

 

[micknew]

Mick,

sorry brain bit slow tonight, are you saying that it is okay to use armour as the earth ?

James

What do you think its there for (apart from protection)?
Just realised that you're obviously not a sparks, Bit slow tonight.

 

[shocking_eg]

**** sake !! what a stupid question ! :banghead:

 

[GLENNSPARK]

What do you think its there for (apart from protection)?
Just realised that you're obviously not a sparks, Bit slow tonight.

thats enough now Mick...
he`s to work it out see...

 

[james beckford]

d skelton,

its out in the van, i shall go and fettch forthwith.

Glenn,

if i was installing from new i would have put 3 core in but cable already in situ from old building that waqs knocked down, wouldnt use conduit for earth as requires someone to connect it right but armour should be continuos.

Mick,

always taught that armour there in case jonny jcb driver puts bucket through it,

I appear to have asked the wrong question tonight, just trying to avoid going half a mile to garage to get 17th out leaving kids in bed

 

[GLENNSPARK]

.........

 

[GLENNSPARK]

d skelton,

its out in the van, i shall go and fettch forthwith.

Glenn,

if i was installing from new i would have put 3 core in but cable already in situ from old building that waqs knocked down, wouldnt use conduit for earth as requires someone to connect it right but armour should be continuos.

Mick,

always taught that armour there in case jonny jcb driver puts bucket through it,

I appear to have asked the wrong question tonight, just trying to avoid going half a mile to garage to get 17th out leaving kids in bed

is this a true statement James?...

 

[shocking_eg]

"always taught that armour there in case jonny jcb driver puts bucket through it"

:crazy:

 

[D Skelton]

So is the BGB in the van or the garage???