Multiple GFI relays

29 Nov 2005
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United Kingdom
So I live in a village, in Thailand and there is a garden with fish ponds and lights. The supply to the Dist. Bd for the pumps and lights is three phases and a neutral, no earth.

It’s three phase because in the past the load was much higher. In the Dist Bd the neutral bar is connected to the earth bar. The earth bar is connected to an earth rod sunk into the ground, I can see the connection.

It looks like an MEN system as the overhead supply transformer neutral is earthed and the neutral conductor is also earthed at every three electric poles, well a wire disappears into the ground from the neutral.

Now all the wiring to the lights and pumps is two core and no GFI relay anywhere, the pumps and the lights have metal casings. It is quality cable, two rubber sheaths.

I have already sunk into the ground an earth rod at each pump local junction box, so at least the pumps are now earthed (obviously the last bit of cable is three core), the pumps are the submersible type. Previously there wasn’t even a junction box, this is Typical Thai Electrics by the way. Here, out of interest the earth rods are at least two metres long. It is not really practical to either earth individually each light or to try and pull an earth lead to each.

It is possible to put all the circuits onto one phase, the Dist Bd is a ‘Square D’. Now when it rains here, it really rains and it is also very humid. So I am looking at fitting GFI relays to each individual circuit, not one for the lot. I don’t want everything to trip if one circuit gets a bit damp.

So my question is, am I likely to get nuisance trips when circuits are switched in and out, I will be fitting timers to each circuit. Am I likely to get less nuisance trips if all circuits are fed from one phase…..thanks
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I cannot answer your question about nuisance trips, but I would have thought your pumps & lights would be double insulated & not need earthing.
Thank you

So would I, but infact neither are. someone has already got a belt off one of the metal light casings, cause was a loose wire. So we are having a good look at everything.

I want to fit GFIs and quick, but think it will cause grief when it rains hard, maybe have to spread a lot of silicon around.

You won't believe the state of the average wiring in Thailand...anyone who knows how to use a screwdriver can call himself an electrician, in fact many do!
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Thank you

You won't believe the state of the average wiring in Thailand...
Yes I would I have seen it many times :D ( Phuket only). The distribution set ups can be appalling, but also seen some galvo conduit with singles done very expertly. As for the tripping after further thought I know of no reason why you should have problems with nuisance tripping, but I definately think your idea to seal everything with silicon is a good idea, to prevent corrosion if nothing else.