Temporary power generation

Following a local cut in supply, UK Power Networks installed a temporary generator (about half the size of a large container) at the local
substation. There were 5 identical orange cables (about 25 - 35 mm in diameter) running from the generator to the substation.
Why 5? I had assumed 4 were the 3 phases and neutral, but if that was the case, what was the other one for?
--

Jeff

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Jeff Layman wrote:

GROUND.
--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.
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On 14/02/2011 15:31, Michael A. Terrell wrote:

Thanks. Why isn't the steel armour of the live/neutral cables used for the ground?
--

Jeff

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Jeff Layman wrote:

It can't handle the full fault current.
--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.
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Singles can't have steel armour - unbalanced magnetic field inside. If they need a metalic sheath, it's a copper mesh, but those cables probably don't have any earthed sheath as they aren't expected to be used in location where that's needed. They'll just be double insulated single core flexes.
--
Andrew Gabriel
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On 14/02/2011 22:10, Andrew Gabriel wrote:

The generator (500kVA) was disconnected today. There were four 30mm diameter cables, but the fifth, which had been partially covered by the others, was in fact only 15mm. It was connected at one end by its ring to a clamp and 1200mm x 12mm earth rod.
--

Jeff

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