The Importance Of Earth Wires

[JimGant]

Lop,

Your info is very helpful. But still a little confusion on my part....

My biggest worry is in the bathrooms over here. Yes, the on-demand wall-mounted water heater has an ELB trip, which I guess is the same as the ELCB you mention -- and GFI in the States(?). But the wall plugs have no GFI protection. So, Safe-t-Cuts for at least the bathrooms are in order (the rest of my house has wooden floors, so I'm not as worried with them -- plus I'm not usually dripping wet when standing on them.)

But do I need a Safe-t-Cut for the wall hot water heater with its own ELB? Is this really any added protection? Also, it sounds like grounding my hot water heater serves no required safety purpose as long as I have ELB/GFI, since this is what will trip milliseconds before any circuit breaker reacts. Currently, my hot water heaters aren't grounded. And to do so would require drilling through the walls, then running the ground down the outside wall. But if my recollection of Ohm's law is correct, this had better be a finger-sized cable, and not a thin green wire, or Mr. Zap will prefer me, not the thin green wire......

Anyhow, your rationale for having the whole house Safe-t-Cut equipped makes a whole lot of sense. But there are a lot of options out there -- and the following photo of a 'micro' Safe-t-Cut is illustrative, if only by the switch option of "direct," which disengages the Safe-t-Cut. And since I do plan to Safe-t-Cut the whole house, and I am away from the house quite a lot, this option is great, since I'm not worried about electrocuting anyone when I'm away, but am worried about a gecko turning off my refrigerator. The "direct" option fits the bill.

[lopburi3]

This in only a 20 amp breaker so can not be used for whole house - it is more aimed at upcountry use where the normal 60 amp or so size is overkill (not a good word).

Your heater should have a ground wire and a thin green wire the size of your normal power wires is all you need - it is not going to burn out before you trip the main breaker and it is still going to be a better path to ground than you no matter how large you are.

Another ELCB before the bath heater is added protection and well worthwhile as the built in unit is only going to work if the current makes it through and if it works - you could get a short before the ELCB and have the heater turned off but case alive so it is very important to ground this item.

[andy50]

an easier option might be to get/upgrade to, a breaker board, with individual rccd (residual current circuit breaker), to protect each outgoing circuit individually.

each circuit breaker has a built in rccd and test button.

by using these it eliminates the need for rccd devices all over the house ,

also you don't always need rccd protection on some circuits, (lighting/aircon/don't need it IMO)

and the freezer would be better off without it as well( in the case of nuisance tripping)in this case just use normal non-rccd trips in the breaker board,

always use 30ma rated rcd breakers for risky areas, or less- ie :(20ma) that way you probably wont be electrocuted to death,should somthing go wrong, as the circuit will disconnect before you are getting a shock for too long a time

(hopefully)!!dont forget to test them each 2 weeks by pressing the test button,that way you know they work,ive tested them in the past here in uk and some dont work at all and some dont work at the stated ma-rating!!

Edited February 28, 2005 by andy50

[ProThaiExpat]

Some personal experience in my home in Chiang Mai:

Mild electrical shock felt on washer/dryer units as well as dishwasher. Called the electician and he grounded each plug. Don't know how he did it but the plugs look much different after he finished. No residual mild shock ever encountered since. I think he used a ground wire of some type within the exisiting house wiring system.

Six months ago, complaints from my Thai that there was current felt in kitchen sink. I poo pohed it because I could not replicate the sensation.

Three months ago, complaints of "loose current" in shower which shares electric water heater with kitchen sink. I verified it and it was very strong. I do believe the water was a conduit as well as the shower fixture even though the water heater is located on the other side of the wall separating this shower from the kitchen and perhaps two meters away.

Called my new electician and he grounded both of my water heaters, neither are near the showers they serve. Seimens automatic three phase. Don't think they have an individual circuit breaker, but may have. He did run a ground wire from the kitchen water heater to the grounded switch for the dish washer, no doubt using the same ground wire.

No problems with current leakage since.

Knowing what I know now, I am terrified by the chances I took when I saw wires coming down through a ceiling and to the water heater located just inches above the shower head in a shower in a condo I rented.

My neighbor swears by gas water heaters, which he has always used. Cheaper and no electrical danger.

Edited March 1, 2005 by ProThaiExpat

[Jai Dee]

Knowing what I know now, I am terrified by the chances I took when I saw wires coming down through a ceiling and to the water heater located just inches above the shower head in a shower in a condo I rented.

I just starting to build a house now.

All the water heaters are going to be located behind doors under the benches in the vanity units in each bathroom, with copper piping for the hot water from the heater to the bath/showers.

And after reading all the posts here, I think I'll install a whole-of-house Safe-T-Cut.

Good idea na?

[lopburi3]

The RCCD idea for sub panels is good but they are normally set up with one RCCD and a few normal breakers on a bus bar rather than one RCCD for each circuit (at least that is the type sold under the Clipsal name). They can also be set up with only part of the bar being protected by the RCCD if you do not want to do the air conditioner or overhead lights (can see no reason not to do lights as they are not likely to be a cause of nuisance trips). As for freezer I would buy a small Safe-t-Cut as shown above with a bypass mode rather than not use protection.

Gas water heater may be justified on the mountains of Loei during the winter but remember that they need good vents or you are likely to be the next victim of carbon monoxide. Never operate in an enclosed area. And you have added the danger of another gas tank. Here in Bangkok they are so overpowered that I had to block 3 of the four burners in the National units I used to have just to keep the water from scalding me at the low setting during most of the year. Not recommended.

If you are building I would go with panels and/or sub panels protected with RCCB units as this makes it much easier to locate and/or bypass if you have trouble. For DIY or upgrade the one unit type Safe-T-Cut would be more useful. Just remember that if it trips and the person is lazy they may just bypass with the Safe-T-Cut and you then have no protection. They can not do that easily with the panel type RCCB.

Edited March 1, 2005 by lopburi3

[frequentatore]

Re. earthing rod:

If you ground the water heater or the washing machine, is that absolutely necessary to have a breaker installed just before those appliances? Can you rely only on the breakers from the main electrical panel? (I have 20A breakers for each floor. Air cond. have their own breaker on the panel)

Thanks.

[lopburi3]

Re. earthing rod:

If you ground the water heater or the washing machine, is that absolutely necessary to have a breaker installed just before those appliances? Can you rely only on the breakers from the main electrical panel? (I have 20A breakers for each floor. Air cond. have their own breaker on the panel)

Thanks.

<{POST_SNAPBACK}>

Breakers at the main panel are all that are needed but you need to be sure that there are breakers installed for specific runs (often they will just attach to main breaker and that is too big for safety). Most Thai are trained to turn everything off when not in use (including unplug everything) so these breakers are more like an on/off switch. As the cost is low can see no reason not to have them - but if for heater make sure it is installed outside of the bathroom. In an emergency, when everything else failed, they could be handy to cut the power fast.

[frequentatore]

Thanks. That's the second thread dealing with water heaters these last few months. This week, I finally disconnected mine... I really have to ground it...

My mother-in-law got really scared six months ago; she received a shock and burned her hand as it got stuck on the shower head; her unit had a small leak inside. That (National brand) water heater leaked a first time a few years ago when it was still under warranty... My wife has heard many stories about people getting shocked from a water heater.

Before getting a new one, she called the electricity company; they sent her mother some electricians to install a 2-meter earthing rod...

[jonik]

Ok the expert has arriwed.

Looking at the electric lines and instalations in thailand don't seen to safe. But earthing your condoe is the most important thing you can do.I guess there is not to many earthwires in the ground, so using the waterpipe is a good idea but make sure it goes all the way down into the earth.You can measure this.

If you have felt 115 volts trough your body you know why.That is what you get from 1 phase and down to earth.If you touch bought phases you'll get about 230 volts.In the shower you most likely to get 115. And since you are standing in water its not a good idea to try this.You most likely to die or end up in a hospital.

The expert has spoken

[andy50]

in the uk we have one phase and one neutral or ground(same thing,the earth is connected to the neutral)

if you touch the phase you get 240 volt shock if you touch the neutral you feel nothing ,i think the same goes for thailand too---also i thoght that the water pipes under the ground in thailand were made of plastic? and therefore cannot be used as an electrical earth

Edited March 5, 2005 by andy50

[lopburi3]

Ok the expert has arriwed.

Looking at the electric lines and instalations in thailand don't seen to safe. But earthing your condoe is the most important thing you can do.I guess there is not to many earthwires in the ground, so using the waterpipe is a good idea but make sure it goes all the way down into the earth.You can measure this.

If you have felt 115 volts trough your body you know why.That is what you get from 1 phase and down to earth.If you touch bought phases you'll get about 230 volts.In the shower you most likely to get 115. And since you are standing in water its not a good idea to try this.You most likely to die or end up in a hospital.

The expert has spoken

<{POST_SNAPBACK}>

I am sure an expert like yourself would know we do not normally use 115 volts here. As water pipes are plastic they do not make good ground rods. Not standing in water with a live electric line in your hands is, however, good advise.

[eriksen]

What a great thread, and thank you all for the input... I always was jumpy over here in my 4 yo house... Back in AU u have to have these safety devices fitted.. Anyways, further to this topic, does anyone know:

1/ Earth/Ground - In the outlets (GPO), how does one check that all the earths go back to the board? No use looking in the outlet as even if it has a cable on the earth it could go anywhere.... I have a 3 bed house and the board only has 3 earths in it so I am highly doubtful....

2/ Safetycut - yes a great thing, went to homepro and they had the 6 unit box for 3950 THB, Vut, with various fixed amps,

this is surely not ideal as one would want to have the amps rating you want for the 6 circuits right? So then i was looking for an empty box one could fill up yourself like a CB box, but the staff were then trying to sell me CB's so I left.

What is the solution? I have 3 Phase so am thinking to reroute the circuits from before they enter the CB's , to the safeTcut

than back to the CB's..... Main circuits I want to cover are : Hot water, Kitchen outlets bathroom outlets..

Any ideas?

http://www.safe-t-cut.com/eng/index.php?name=product

[transam]

in the uk we have one phase and one neutral or ground(same thing,the earth is connected to the neutral)

if you touch the phase you get 240 volt shock if you touch the neutral you feel nothing ,i think the same goes for thailand too---also i thoght that the water pipes under the ground in thailand were made of plastic? and therefore cannot be used as an electrical earth

In UK it has 2 cores, L & N and a separate earth. Mains and service cable have lead or alloy sheath and most have steel armour. The sheath and armour are used for the earth. Every underground joint, the sheath and armour are bridged with a tinned copper strap to continue the earth.

Unless it's all changed.

[Crossy]

What is the solution? I have 3 Phase so am thinking to reroute the circuits from before they enter the CB's , to the safeTcut

than back to the CB's..... Main circuits I want to cover are : Hot water, Kitchen outlets bathroom outlets..

Any ideas?

http://www.safe-t-cu...hp?name=product

The easy route is to get one of the 3-phase Safe-T-Cut units and have the shop install it (yes, it goes in front of your DB). It will then protect all circuits.

[Crossy]

In UK it has 2 cores, L & N and a separate earth. Mains and service cable have lead or alloy sheath and most have steel armour. The sheath and armour are used for the earth. Every underground joint, the sheath and armour are bridged with a tinned copper strap to continue the earth.

Unless it's all changed.

Much of the UK has changed from TN-S to TN-C-S due to the armouring of old cables degrading and going high resistance. It's cheaper than digging up the cable.