comercial board change

[bartkusal]

Hello everyone and HNY.

I need clarification on this:
I been asked to change the fuse board in commercial premises, it is a sub main SP board in a basement area. The earthing cable/cpc to board is the armor of SWA cable, all circuits to the accessories has the cpc via metal conduit. I had a look at the job and the only tests I could do is Zs. The readings where in the range of 0.40-0.50 ohms, so it seems that I have fairly good Ze and R1+R2 (still to be confirmed when the isolation can take place)

I know that for new installs, you cannot have the armor or conduit as the only means of cpc, but it is only the board change and all wiring methods complied with the regs when they were installed.

So, the question is:
· Do I have to pull a new earting cable/cpc up to the board and,
· Do I have to pull in the cpc for all wiring in the final circuits


As you can understand it is a significant difference in work and cost involved and I don’t want to do it if I don’t have to. The client is a very tight as usual these days.

Thanks and best regards: Al

 

[snowhead]

I know that for new installs, you cannot have the armor or conduit as the only means of cpc,

Do you have a reference to the regs for that??

 

[telectrix]

conduit is fine for earthing as long as your readings comly.

 

[bigbaddave]

Hello everyone and HNY.

I need clarification on this:
I been asked to change the fuse board in commercial premises, it is a sub main SP board in a basement area. The earthing cable/cpc to board is the armor of SWA cable, all circuits to the accessories has the cpc via metal conduit. I had a look at the job and the only tests I could do is Zs. The readings where in the range of 0.40-0.50 ohms, so it seems that I have fairly good Ze and R1+R2 (still to be confirmed when the isolation can take place)

I know that for new installs, you cannot have the armor or conduit as the only means of cpc, but it is only the board change and all wiring methods complied with the regs when they were installed.

So, the question is:
· Do I have to pull a new earting cable/cpc up to the board and,
· Do I have to pull in the cpc for all wiring in the final circuits


As you can understand it is a significant difference in work and cost involved and I don’t want to do it if I don’t have to. The client is a very tight as usual these days.

Thanks and best regards: Al

Since when.. If you have proved the results comply then crack on with the board change.. Simples

 

[Jonny66]

Agreed with above, nothing wrong with conduit as a cpc

 

[Engineer54]

I know that for new installs, you cannot have the armor or conduit as the only means of cpc,

​

You know nothing of the kind, as there is no such requirement!! Where pray tell us did you get this idea from??

 

[Jonny66]

The Electricians Forum??? :6:

 

[bartkusal]

Thanks everyone for the replies, obviously i got that wrong, i dont remember where did that came from, i did reed that somewhere, probably that was a guide or recomendation and not the regs.

I need to look in regs book more offen then.

thanks again everyone

 

[Sintra]

Hello everyone and HNY.

the only tests I could do is Zs. The readings where in the range of 0.40-0.50 ohms, so it seems that I have fairly good Ze and R1+R2 (still to be confirmed when the isolation can take place)

/QUOTE]

You could always do an R2 as it will give a better indication of the continuity of the containment system.

 

[martinh89]

I know that for new installs, you cannot have the armor or conduit as the only means of cpc,: Al

Im only a student but isnt that classed as a TN-S supply and you can use it for new installs ?

 

[Rampantchilli]

Reg 543.2.1
" a protective conductor may consist of .............
(vi) a metal covering, for example, the sheath, screen or armouring of a cable
(vii) a metal conduit,metallic cable management system...................."

 

[bartkusal]

Thanks everyone, but from post 8 I did realised my mistake, and all relevent regs been noted. .i think this thread can remain as history now. thanks again.

Al