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- 27 Jan 2008
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I am trying to get my head around multiple TN-C-S supplies where metalwork of some sort, connects the buildings, or supplies. What stops excessive current through the PEN conductor if the PEN of one supply is lost?
Or what stops excessive current through connecting metalwork, for example an air line.
Where I work there is a collection of buildings, not sure how many supplies, but at least four. At least 3 into one metal clad steel framed building. And due to that building having more supplies than required, the EV charging point and compressor are connected to that building, and there is a large pipe connecting it to the workshop, this passes the accommodation block under a steel bridge, and likely touches hand rails and fences, possibly also connects to the railway lines which run for 8 miles, and there are further buildings along the line also with their own supplies, at the half way point I know there is an aerial mast with a massive copper earth at base, and a large coax into the signal box where the repeater is, which goes under the track.
I see no chance of the buildings becoming live, and in the main the connecting metal work could take 100's of amps without a problem, but it is more down to what happens with a loss of PEN to the other PEN's? And I have seen no bonding cables between the air line and other metal, so the connection between the PEN's is unknown, it may be just the supply cable to the compressor.
Is there a RCM on the DNO supply to show imbalance or some monitoring of the PEN current?
Or what stops excessive current through connecting metalwork, for example an air line.
Where I work there is a collection of buildings, not sure how many supplies, but at least four. At least 3 into one metal clad steel framed building. And due to that building having more supplies than required, the EV charging point and compressor are connected to that building, and there is a large pipe connecting it to the workshop, this passes the accommodation block under a steel bridge, and likely touches hand rails and fences, possibly also connects to the railway lines which run for 8 miles, and there are further buildings along the line also with their own supplies, at the half way point I know there is an aerial mast with a massive copper earth at base, and a large coax into the signal box where the repeater is, which goes under the track.
I see no chance of the buildings becoming live, and in the main the connecting metal work could take 100's of amps without a problem, but it is more down to what happens with a loss of PEN to the other PEN's? And I have seen no bonding cables between the air line and other metal, so the connection between the PEN's is unknown, it may be just the supply cable to the compressor.
Is there a RCM on the DNO supply to show imbalance or some monitoring of the PEN current?