bath earthing help

[mrjc]

Hi,
i've got a metal bath and i'm going to use an electric shower to provide the hot water (this is in Thailand, so there's no other system of hot water in the house). The bath will be mortared, but what should i do about earthing the bath? The pipes used here are plastic, so I can't earth the bath to the pipes. The electricity supply is a two wire system, live and neutral. The shower gets an earth from the masonary wall it's attached to. Would earthing the bath to the wall be sufficient?

 

[chrishutt]

The bath will be mortared

Do you mean bedded in mortar? I doubt if UK standards are applicable or appropriate to Thailand, so it's hard for us to comment.

 

[JPC]

i wouls suggest a wire from the bath to an earth rod that u will need to hammer in to the ground

like this one http://www.tlc-direct.co.uk/Products/TLER.html

nb ....dont hammer it thru the gas mains, electrics, foul waste, water mains, telephone wire or unexploded mines

 

[mrjc]

i wouls suggest a wire from the bath to an earth rod that u will need to hammer in to the ground

like this one http://www.tlc-direct.co.uk/Products/TLER.html

nb ....dont hammer it thru the gas mains, electrics, foul waste, water mains, telephone wire or unexploded mines

sounds like a good option. there's a metal bracket on either side of the tub. would you bolt on the wire to one of these brackets or mig weld it onto the underside of the bath?

 

[brumylad]

the principle of earthing things in a bathroom is called supplementary equi-potential bonding.

The idea is simply that if everything is electrically linked then should one metal part become live, then all the metal parts in the room will be at the same potential.

Hence a person will not recieve the bad shock that would result if they were to touch two metal parts at different electrical potentials simulateously.

 

[Biggles..]

Dont forget if your bathroom has a radiator that should be earthed as well.

 

[JohnD]

Don't weld anything onto your bath or the enamel will fall off! If it has brackets already fitted, use them with stainless steel nuts and bolts. If it is cast iron it will be very difficult to drill it without cracking.

If you earth the water pipes going up to the taps as well that should be pretty comprehensive. You can usually use the same length of copper earth wire to go round multiple clamps.

Of course this assumes that you have connected the CPC of all the circuits in the bathroom (light, heaters, maybe immersion and shaver socket) into the same earthing set, and that there is an equivalent of a UK MET near the meter where the incoming suppliers earth is bonded to incoming services. If your country has a different approach you need to know how it works there, and why.

 

[chrishutt]

Dont forget if your bathroom has a radiator that should be earthed as well.

In Thailand?

 

[Biggles..]

chris as you say, never assume: just because its nice doesn't mean they dont have heating.

 

[chrishutt]

Heating in Thailand! It's nearly on the equator! Even in the mountains in the far north of the country daytime temperatures rarely fall below 30C and nighttime temperatures rarely fall below 15C. I'm not making assumptions - it's just bleeding obvious.

 

[JohnD]

Better earth the air con ducts, then.

 

[mrjc]

thanks for all the tips guys.
the bath was mortared to the floor yesterday and i'll use a copper pipe in the ground connected to the exsisting brackets with bolts. The shower will also be earthed through the wall and it has it's own circuit breaker, so I think i'll be safe.
By the way, it does get cold here during the winter (Nov to Jan), especially in the evenings (if you come from England you'll think it's warm, but after living here five years you really feel the drop in temp.), but hardly anyone has heating in their home.