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Generator Grounding (Earthing)

Dear Sir,
I have just brought an IG770 Kipor generator for use on the bank. My boat being Viking 28, is of GRP construction. I had to ask the company (Kipor)direct about what is required to earth it (Grounding). Before looking on the internet it is not so simple as to just stick a bit of metal into the ground. For starters using a thicker grounding rod does not reduce the resistance from rod to earth[when earthing a power station but may apply to a degree] . The length of the grounding rod is important and also what substrate you are sticking it into (gravely soil, sand, wet soil or dry, clay etc). It is impracticable to use a four foot rod as it may well bend or be impossible to pull out of the ground. If using more than one, they should be spaced not nearer than the length of each one's depth in the ground. An Ohms test should be done between the earth cable hence the thick cable required from the generator to the rod or rods. The mind boggles if you start to look deeper at the subject.
We are interested in our own generator set, so require the earth rod or rods for what our generators max power can produce, plus (at a guess) 30-40% to be on the safe side. My boat is of GRP construction.
Kipor told me to use as followed. [I can email the information from Kipor along with drawing if required].
Materials needed:
1. a copper wire(cross sectional area 2.5mm2)
2. a threaded copper rod(diameter 10mm, length 600mm)
3. an ohm meter
Operation steps:
1. Find the ground terminal on the panel
2. Twin the terminal with the copper wire
3. Twin the copper rod with the copper wire along the threads
4. Insert the cooper rod into the earth, the cooper shall not be above the earth for more than 150mm, a warning sign beside the cooper will be better
5. Measure the resistance between the terminal on the panel and the cooper rod, the resistance shall be lower than 4 Ohm, or, please use shorter copper wire
Not quite what you may have expected(??) 2.5mm2 but may be ok for max 770 Watts output!
Yours Sincerely
Gary Dean.
WW subscriber.
PS I have seen generators this year at WW boat show along the canal at Crick, without any grounding, quite big lumps too. They must be mad or stupid idiots.

Asked by: Gary  | 2.29pm, Tuesday 9 June

WW says:

The earth connection on a generator is an important safety feature that is often ignored. The earth connection of the boat electrics will be connected to the generator via the shore lead.
Earthing the generator in the manner described has several purposes: it stops the generator itself becoming highly charged with static electricity, and it prevents any stray earth current flowing to ground via the hull (not in this case with a GRP boat) or any metal parts such as steering gear or propeller. It also ensures that the RCD device which should be fitted to the boat electrics for safety protection, works correctly under fault conditions.
The earth connection specified is correct, and does not normally have any current flow; only if a major fault occurs.

Rupert Smedley  | 12.55PM, Wednesday 10 June

It doesn't help that some cheaper generators centre tap the earth connection, so that live and neutral are both 115V above ground, using the earth as a neutral return... Which usually triggers the "polarity error" lamp on many systems, so the earth return doesn't give proper protection (and hence missing from some cheaper units)

Mark Langley  | 8.04PM, Thursday 11 June

Readers say:

Just to add the total output is (KVA)0.77KV

Gary  | 2.42PM, Tuesday 9 June

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