Earthing SWA at both ends

[atm84]

Is it a requirement of BS 7671 to Earth SWA cable at both ends when using an integral conductor as a cpc. I don't think it is and can't find a reg which states that it is but wondering if someone could help clarify.

I was once told it was good practice to earth at both ends when using an integral cpc in case the armouring and cpc had a difference in potential and both were touched simultaneously during an earth fault prior to the disconnection device operating.

Any thoughts?

 

[Andy78]

It is definitely good practice yes.
If the SWA is the CPC then obviously a good connection at both ends is essential. If the SWA is not the CPC it is still an exposed conductive part and must be earthed. This can be achieved by earthing at one end, usually the supply end. I always earth at both ends regardless.

 

[davesparks]

If earthing at one end it should be the supply end of the cable as far as I know.
Earthing at both ends is not necessary, but it will help lower Zs.

 

[Leesparkykent]

It is definitely good practice yes.
If the SWA is the CPC then obviously a good connection at both ends is essential. If the SWA is not the CPC it is still an exposed conductive part and must be earthed. This can be achieved by earthing at one end, usually the supply end. I always earth at both ends regardless.

Is it?

 

[Andy78]

Is it?

It is as I was taught. Any exposed metal part that forms part of the wiring system.

 

[Leesparkykent]

It is as I was taught. Any exposed metal part that forms part of the wiring system.

The steel is covered by an over sheath of insulation so is not exposed. The SWA glands are an exposed conductive part until covered by the shroud.

 

[Pete999]

It is as I was taught. Any exposed metal part that forms part of the wiring system.

But it's already earthed at one end isn't it????

 

[Andy78]

But it's already earthed at one end isn't it????

It is in my world, but the OP asked if it needs earthing at all, at either end.

 

[Andy78]

The steel is covered by an over sheath of insulation so is not exposed. The SWA glands are an exposed conductive part until covered by the shroud.

This was always a point of mine whilst learning. My mentoring electricians and lecturers always maintained that the shroud was not sufficient to be relied upon to guarantee the gland would never be exposed, and that the gland, and by extension the armouring, were to be considered exposed conductive parts.

Possibly just a twisting of regulations and definitions to ensure best practice, but it's the way I was shown.

 

[Leesparkykent]

This was always a point of mine whilst learning. My mentoring electricians and lecturers always maintained that the shroud was not sufficient to be relied upon to guarantee the gland would never be exposed, and that the gland, and by extension the armouring, were to be considered exposed conductive parts.

Possibly just a twisting of regulations and definitions to ensure best practice, but it's the way I was shown.

A cable tie top and bottom of the shroud (doesn't look professional though) lol.


EDITED -Leesparkykent - you know the rules in the main forum for swearing, no matter how you spell it to try get around the software detection it is still not allowed, Ive altered it for you .

Darkwood.

 

[Andy78]

A cable tie top and bottom of the shroud (doesn't look professional though) lol.

I prefer a bit of tape if the gland is baggy, which is quite often with some gland packs now. Black PVC or sometimes SA tape if it's needed.

 

[Andy78]

Just a thought, can you get heatshrink gland shrouds ?

 

[Leesparkykent]

Just a thought, can you get heatshrink gland shrouds ?

I think Raychem make heatshrink swa shrouds.

 

[Leesparkykent]

EDITED[/COLOR] -Leesparkykent - you know the rules in the main forum for swearing, no matter how you spell it to try get around the software detection it is still not allowed, Ive altered it for you .

Darkwood.

Oops! :ban:Lol

 

[atm84]

It is in my world, but the OP asked if it needs earthing at all, at either end.

No I meant does it need earthing at both ends or is one end satisfactory.