3 Core SWA earthing
- Thread starter Benway
- Start date
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It doesn't need a link from the armour to the earth terminal on the socket if thats what you mean, but it wouldn't do any harm to fit one.
And none of what you are talking about is cross bonding. That is something completely different which serves an entirely different function.
And none of what you are talking about is cross bonding. That is something completely different which serves an entirely different function.
It doesn't really matter about cross connecting the armour to the cpc core at every accessory but it needs to be earthed at source (or elsewhere) and be continuous to ensure of earthed mechanical protection.
Of course using the armour and seperate core in parallel will keep the earth fault loop impedance low.
Of course using the armour and seperate core in parallel will keep the earth fault loop impedance low.
I would link the sheaths to the main earth connection at this point, in case someone removes the earth connection from the sheath somewhere else. It does happen, when someone replaces a metal box for a plastic one, for example.
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I would use belt and bracer's unless good reason to not link for example clean and dirty earths.
I was very surprised as to the blame when things have gone wrong. A friend wired up a container and used the SWA as the earth. The container was it seems in the way, so a foreman moved it with a crane, without first having it disconnected. It was only being moved a few feet. The cable was pulled out of the gland, and some one got a shock. My friend was suspended, and then demoted for not ensuring this could not happen. Personally I would have blamed the foreman for trying to move the container while still connected to supply. But HSE said he was not skilled in that area, and it was understandable, but the electrician was skilled, and should have arranged it so if something like that happens, the automatic disconnection device will trip. So the earth wire should be longer than the line wire. Also clamps should have been used as well as the cable gland.
So in view of that case I would link then if the cable gets snagged the gland will be earthed, even after the SWA is dragged out of it, so it will open the MCB and fail safe.
I was very surprised as to the blame when things have gone wrong. A friend wired up a container and used the SWA as the earth. The container was it seems in the way, so a foreman moved it with a crane, without first having it disconnected. It was only being moved a few feet. The cable was pulled out of the gland, and some one got a shock. My friend was suspended, and then demoted for not ensuring this could not happen. Personally I would have blamed the foreman for trying to move the container while still connected to supply. But HSE said he was not skilled in that area, and it was understandable, but the electrician was skilled, and should have arranged it so if something like that happens, the automatic disconnection device will trip. So the earth wire should be longer than the line wire. Also clamps should have been used as well as the cable gland.
So in view of that case I would link then if the cable gets snagged the gland will be earthed, even after the SWA is dragged out of it, so it will open the MCB and fail safe.
Surely the foreman should have arranged for a skilled electrician to disconnect the supply?
How can HSE think it acceptable to move a container with a live electrical supply with a crane?
Though it's often said, a real case of Health and Safety gone mad.
How can HSE think it acceptable to move a container with a live electrical supply with a crane?
Though it's often said, a real case of Health and Safety gone mad.
AFAIK the armour generally is considered an acceptable CPC on its own.
P
Paul_C
So anyone installing electrical wiring is now supposed to take into account somebody else doing something stupid?
Is it any wonder that people now consider "Health & Safety" officials to be completely mad?
It appears from what has been posted the the earthing to the container was dependent on the gland. Since the gland is also the mechanical strain relief ( or clamp ) for the mechanical fixing of the cable it will be the first part that fails if there is ( excessive ) tension applied to the cable. Only after the strain relief and earth connection has failed will the live and neutral conductors come under strain.
If possible I allways bond the banjos at both ends
In situation of a moveable container, vehicle or machine powered by a fixed cable ( not by a snatchable plug and socket ) I would consider providing a means to automatically remove power from the cable at source if the cable became detached.
duplicate post removed
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