SWA termination

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davetheglitz

Electrician
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Mar 18, 2008
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Location
Saltash, Cornwall
More basic advice please - need to check if my gut feelings are right!

SWA from house to garage. 3 core SWA at house board, 2 core at garage. Presume there is a joint somewhere. Plan to re-use a plastic 2 way RCD CU in the garage.

I have been told to dress the cable so that a few cores of the SWA will reach the earth bar in the CU (sleeved of course) and trim and insulate the others off. I don't think this is right as I can't rely on the earth being continuous - not knowing how the joint was made.

I'd have thought that either

a) a terminal box with a gland and banjo should be used or

B) all of the sheathes should be connected together (could group in three braids) and either put directly onto the earth bar.

Am I being pedantic or is my gut feel right?

Would the split off a few SWA method be acceptable if there was no join in the cable?

Thanks

Dave

 
Dave

Firstly is there any chance you can use an adaptable box to terminate the swa outside the house and use appropriate t+e to the board.It would be a much better job

3 core down to 2 :( i would do continuity checks to find out whats been joined and mark them up.

would be ideal to find the joint of course

 
Hi TP - I appreciate your point regarding the adaptable box - but unfortunately it is not my job - I was just drafted in to help out - so I'm restricted in what I can do.

I like the idea of a continuity check - but cant se how it would work. If the SWA sheathes were touching you would get continuity - so couldn't readily differentiate the connected and touching strands - that's why I suggested connecting all of them at the garage CU.

Cheers

Dave

 
So then you either have a redundant core at the cu or the sheath has been jointed to it at the joint (where ever that is)

is that right

 
Hi TS - yes I was attemping to finish off someone elses work - but under the instruction of the senior electrician who advised me of the method he wanted me to use. I didn't get to see the CU at the house - only going on what I was told.

Why do I keep calling you TP - sorry about that!

 
I have been told to dress the cable so that a few cores of the SWA will reach the earth bar in the CU (sleeved of course) and trim and insulate the others off. I don't think this is right as I can't rely on the earth being continuous - not knowing how the joint was made. I'd have thought that either

a) a terminal box with a gland and banjo should be used or

B) all of the sheathes should be connected together (could group in three braids) and either put directly onto the earth bar.
Yes, all of the armour should be used. Any cutting away will reduce the CSA of the armour and, therefore, the CSA of the CPC.

Well done on being a member! (Hurr, hurr, hurr! He said 'member')

 
Evenin` all.

I would agree with using all the swa strands - I`ve glanded & banjo`d of a pvc box previously; with no ill effects.

I hate to raise the issue, but query earth exporting.

As far as the unknown 3-2 joint is concerned; a continuity check SHOULD give you a good idea of the connection strength; under these circumstances, I would use 1 or 2 of the live cores to determine the length of the cable.

HTH

 
Hi Kme - oh the dreaded exporting of earths!

In this case there are no services in the garage and it's only 30 ft away - so as such exporting isn't a problem. more importantly it's not my job - so I don't have to sign for it (what a responsible sparky!)

I appreciate the SHOULD - but as then joint would be at one point of the cable I'm not sure a meter would be sensitive enough to pick it up.

Thanks for the banjo tip - in this case it's one of those detachable cover CU's so it's a bit of a no go. I've heard some people use piranha nuts - has anyone used them?

Dave

 
Piranha nuts. One of the better ideas. :x

I love `em. Only one spaniel needed now. "stuff it in & wind it up" - "job`s a good `un". :D

Agree with your point r.e. carlsberg earth - no signee, no caree:^O:^O

 
if your not signing it, and the guy that is told you to be a rough un then just do as he says and cut the armour down till it fits.!

I would do a cont check tho, just to confirm length of cable and cont of earth, and to double check the polarity.!!!

B)

 
Piranha nuts

I bought one the other week, But haven't got round to fitting it. :(

 
Dave - How long have you been an Electrician, Mate?

Do you specialise in Domestic, Industrial or Commercial?

 
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