Earthing SWA at both ends

[atm84]

Ok so from this I have come to the conclusion that:

1. if the SWA is not used as a cpc and is classed as an exposed conductive part then earthing at one end is sufficient. Earthing at both ends is considered 'good practice'.

2. If the SWA is regarded as a CPC then earthing at one end, again should be sufficient, however by earthing at both ends you are ensuring the integrity is maintained and it will also help to lower the ZS for that circuit.

 

[Andy78]

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

Ah right sorry. One end is satisfactory for earthing only purposes, but make it the supply end. Both ends is better practice and improves the return path as Davesparks pointed out in post #3.

 

[Andy78]

Ok so from this I have come to the conclusion that:

1. if the SWA is not used as a cpc and is classed as an exposed conductive part then earthing at one end is sufficient. Earthing at both ends is considered 'good practice'.

2. If the SWA is regarded as a CPC then earthing at one end, again should be sufficient, however by earthing at both ends you are ensuring the integrity is maintained and it will also help to lower the ZS for that circuit.

No. If the cpc is not connected at one end then you have no cpc.

 

[7029 dave]

Supply end is the Norm, but if you do both ends, even better good practice IMO.

 

[Leesparkykent]

It also depends on what you are glanding into if you was only thinking of earthing the supply end. For example Some enclosures are provided with removable gland plates and in these circumstances the earth continuity relies on the gland plate fixing screws. In these circumstances I would use the banjo/earthing nut with a suitably sized CPC connected to the earth bar/terminal. Even though it's never done with conduit or MICC (unless using a pot with an earth lead) which also relies on these fixing screws for earth continuity. An alternative would be to drill the gland plate and bolt a CPC to it connected to the main earth bar.

 

[7029 dave]

Banjo/ fly lead yes, Never used to do that with metal clad, only ever used MICC earth tag pots when specked. Always run cpc's in metal conduit, just something I did.

 

[timbobelfast]

Both ends for me, well on a Hazardous Area site every gland has supplementary bonding connected fire alarm and all.

Also no shrouds as these have been found to hold water and glands start to corrode.

Most of the motors onsite are 3 core swa so no option but to use 16 or 25 mm from the tag to the frame.

 

[infinity]

Agree with one end of its not used as cpc, also if it's not a removable gland plate and it's into a metal DB then may not need to fly lead it. I think a good example may be if you have 20 odd SWA's going into the board it would get messy trying to fly lead every one, and probably make no difference if the enclosure is metallic and earthed.

 

[shanky887614]

Just a thought, can you get heatshrink gland shrouds ?

yes you can

 

[trev]

2. If the SWA is regarded as a CPC then earthing at one end, again should be sufficient, however by earthing at both ends you are ensuring the integrity is maintained and it will also help to lower the ZS for that circuit.

So it it's earthed at the circuit end only then where is the return path in the event of a fault?
If it's earthed at the supply end only then the same question applies.
Jesus!

 

[atm84]

So it it's earthed at the circuit end only then where is the return path in the event of a fault?
If it's earthed at the supply end only then the same question applies.
Jesus!

Sorry I obviously wasn't been clear. When I say it's only earthed at one end then I obviously mean it's done at the supply end.

 

[trev]

Right so if it's only earthed at the supply end then where is your fault path.
Draw a diagram if it'll help mate
It has to be earthed at both ends.

 

[timbobelfast]

Sorry I obviously wasn't been clear. When I say it's only earthed at one end then I obviously mean it's done at the supply end.

If cable is a 3 core I hope LOL. If two core then fly leads needed at both ends

 

[davesparks]

If cable is a 3 core I hope LOL. If two core then fly leads needed at both ends

Yes, but necessarily flyleads, it could just be glanded into a metal enclosure of some form with reliable metal to metal contact

 

[atm84]

Right so if it's only earthed at the supply end then where is your fault path.
Draw a diagram if it'll help mate
It has to be earthed at both ends.

Im saying that's only done when the swa is an exposed conductive part.

That was my OP. Should the swa be connected at both ends its an exposed conductive part?