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  1. #1
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    Rewiring existing Thai home - to earth/ground

    Sorry if this a duplicate, I recall something about this but a search turned up just bits. Question is how difficult is it to ground the house? Can a grounding rod simply be planted in the ground near the house and attached to the mains somehow? Or does it require a complete rewiring job?
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  2. #2
    euston has flown

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    Its not that hard, you simply have to add a green earth wire of the correct size and lay it down next to the existing twin wire. the primary issue is cosmetic, assuming that you live in a traditional house with all the wiring nailed on the the wall.

    For new wires you can get twin+earth in thailand, but is not that widely available and you have to buy 100M at a time, as I put the wire in conduit when I put new wire down I use twin wire plus a separate earth as its easier to get and cheaper.

    Its a project I have been working on at home, Ive got the sockets, wetish areas and showers all earthed, leaving the indoor lighting cuicuts as a future project. I would say its a good thing for you to do, even if you just limit the work to the bathroom shower.

    The critical thing to make sure you do is to have an RDC cuicuit breaker to any cable runs that have an earth (there's no harm using them on runs without earths too). This will trip if there is a earth leakage, and if that leakage just happens to go through you it will limit the effects to a jump and a surprised look.

    As for how you earth, that depends upon how the electricity is supplied to your house. It could be:

    an earth rod in the ground,
    an earth rod thats bound to the neutral within the breaker box
    no earthing rod, just earth/neutral bonding

    The local electricity office should be able to help you out with the correct arrangement. at out place we have just an earth rod, which we are told by these people is fine... though I am not convinced.

    If you are interested I can send you some books covering UK wiring regs, best of luck with the project. BTW remember I am not a qualified electrician and I promise I am not trying to kill you

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    You need to drive an 8' brass rod in the ground leaving just enough above ground to clamp the wire to. Depending on how many amps you have coming to your house determins the size wire you need. Mine is 15 amp, so I ran an O wire also to the pole. So, I am double grounded. Grounding the switch box will only ground the house. To ground switches and outlets in the house, you need to pull a wire to each one.
    A Thai says you just need to drive the rod 3 or 4 feet. It's not easy and they are too lazy to do it right. That is why many here die of electrocution. Better to be safe than sorry. I wired mine according to the US electrical codes. Never had a problem.

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    Inside your load center there should be a brass neutral strip with an array of set-screws that the neutral wires are attached to. Another brass strip with a set screw should be mounted to the plastic frame within the load center. Run a wire from the existing neutral strip to the new ground strip. Run wire from the ground strip to a copper rod driven into the ground.

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    Thailand Expat terry57's Avatar
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    The smart money is on getting a qualified reliable electrician to do the Job.

    Don't start pissing around if you don't know what your doing.

    I'm sure DrAndy could give you the heads up on reliable electricians.

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    ^ wot he said.

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    Yes, thanks for all the info. It does seem a bit too much for me to try to do myself. I have two electrical main lines from the Soi to the house - so not sure how many Amps that adds up to.

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    ^You will have to instruct the electrician as to what you want because many Thai electricians are clueless about proper grounding.

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    also once (if u use) your earth rod is in the ground there is no guarantee it will conduct enough , different soils, depths etc .
    must be tested itself, independent of the house wires !!

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    The two main causes of electricution are - reverse polarity and incorrect earthing. You can wire lighting points etc, without much risk of fcuking up big time, but get the switchboard, mains and earthing done by a good electrician, please.

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    Most Thai houses only have the 2 pin power outlets so there are not earth wires run.
    By having a good reliable earth bond and RCD (known as earth leakage circuit breaker) on each circuit you can provide reasonable protection.
    You can buy bronze or copper jacketed steel earthing rods at most big hardware stores.
    Drive the rod into the ground at least 1.5m, 2m is better leave at least 200mm above the ground. Run a earthing wire 6mm2 minimum size between your main board and the earth rod. Clamp the earth wire to the rod as high as possible to avoid any corrosion problems. At the main board connect the earth wire to the neutral bar and a link between that connection and any existing earth connections. Most new houses have steel framing in the roof it is not a bad idea to also run a 6mm2 earthing wire between the frame and the main board earth connection.
    Good luck

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    Quote Originally Posted by Tom Sawyer
    Can a grounding rod simply be planted in the ground near the house and attached to the mains somehow? Or does it require a complete rewiring job?
    You put in the grounding rod then run that to the consumer unit. That would not be much use by itself though - you then need to run an earth wire to each outlet and change the sockets to three pin versions. Lighting does not need to be earthed.
    Quote Originally Posted by Tom Sawyer
    I have two electrical main lines from the Soi to the house
    really? one of those is probably feeding the neighbourhood! unless you just mean two seperate wires

    you have one meter then two mains wires from that to the house, anything else is suspicious
    I have reported your post

  13. #13
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    ^^^I doubt that incorrect earthing is a major cause of electrocution in thailand, on the grounds that there's not enough premises wired with earths for this to be the case, that us unless you count electrocutions caused by mains wiring faults that would have been rended harmless if an earth had been installed.

    Using a qualified electrician is the obvious and correct decision. But the fly in the ointment is that decent electricians are hard to find in thailand and when they are found their employers are keep to hold onto them, they have no problem getting well paid long term work in factories and building sites; why would these people give up that to do small contracts in houses lasting days/weeks? And the answer is they don't.

    If you hire a domestic electrician and you get the best that you can find, you will probably get someone who can tidily install your wiring, but probably has little experience of either three pin plugs and the importance of wiring up the live and neutral correctly, or even an understanding of the concepts behind earthing.

    Now if you are planning to just earth the shower, there is little that can go wrong and it would make the biggest dent to the dangers you face. all you need is an earth wire between the earthing rod and a shower, and RCD thats located far enough from the bathroom that you must leave it to each the breaker. Hard to get wrong but FIL's sparky though that wrapping the earth round a screw in the wall was good enough.

    If you start earthing your wall sockets it gets a bit more complicated as chang yai is suggesting. if you get a mains fault, which then gets earthed, every earthed surface in your house is now connected to the earth. If the earth wiring in your house is not cable at any point of draining that current away, the voltage on these surfaces will build up potentially to lethal levels. It could be argued that a badly installed earth is worse than non at all.

    This is why installing RCD's is essential when you install the earth, where a 30mA leakage to earth will cause the mains to trip in less than 30ms; good enough to keep you alive if that earth leakage is though you and enough to stop a significant explosion if its a dead short. It will also help protect you from the effects of having an earthing rod of insufficient conductivity... an easy situation to get into, which is why most modern mains supplies are designed with neutral/earth bonding.

    in the same way that if you get a house built you need to learn the basics of concrete and house building so that you can recognise when the builder is doing something dangerous and stupid. Wether you do it yourself or hire an electrician you need to learn and understand the principles of earthing and how it needs to be done; so that you can recognise that the jobs been done right.

    For example andy is right, the earth rod should go to your breaker board (assuming that you actually have one) and all of your earths should radiate from there, with one earth wire for each mains twin cable. The reason for doing this is to avoid earth loops, which can cause mains hum on audio equipment, random malfunctions of electrical equipment and potentially dangerous voltages to build up between different earthed surfaces. If you follow the regs, you kind of don't need to know that because the regs are designed to stop you doing anything that would cause it.

    Another thing you should consider along with your earth installation, is to compare the maximum current capacity of your wires and compaire that to the rating on the breaker they are connected to. The breaker should not have a higher trip current than the current capacity of the thinnest wire it is protecting.

    if you have a 16A breaker protecting say three 2.5mmsq wires, thats good. but if it were protecting three 2.5mmsq wire and one 1mmsq wire, then if you get a short in the 1mmsq wire, the breaker may well not trip quickly enough to stop the cable overheating and starting an electrical fire.

    it seems quite common practice in thailand to use a breaker that rated for the expected maxmium current that all the wires might draw. so its quite comma to find a 32A fuse being used to protect five or six 2.5mmsq cables each with a capacity of carrying 16A. Its why they have so many electrical fires in thailand.

    to summarise if you want a safe electrical installation in your house, you need to familiarise yourself with the electrical regs for thailand or your home country and ensure that your chaps installation complies with it. because the chances of you hiring an electrician with a knowledge of thai regs and an interest in complying with them is at best minimal.

  14. #14
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    Quote Originally Posted by ralphlsasser View Post
    A Thai says you just need to drive the rod 3 or 4 feet. It's not easy and they are too lazy to do it right.
    It is the easiest part, to put the ground rod into the ground. Sure you have to select the right location but a std grounding rod is 12mm so it will fit in the chuck of a standard 1/2" drill. Put the drill on hammer and the ground rod simply disappears into the ground.

    Better to put the grounding rod in a wet spot , near a dripping garden tap? etc..and if you live in a veery dry place you'll need more than one grounding rod.
    Better to think inside the pub, than outside the box?
    I apologize if any offence was caused. unless it was intended.
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  15. #15
    euston has flown

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    ^If you live in Bangkok, you can push a 5ft 1/2" earth into the ground by hand in about 10 seconds. are any other capital cities built on a full blow marsh?

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    Quote Originally Posted by DrAndy View Post

    really? one of those is probably feeding the neighbourhood! unless you just mean two seperate wires

    you have one meter then two mains wires from that to the house, anything else is suspicious
    Yes that's what I have - one meter and two wires.

  17. #17
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    ^^in rural areas Ive seen quite a bit of that theft you are discribing andy, never seen it in the cities though.

    If its a modern install, tom, you might find that one wire is black and insulated and that the other is naked metal. I believe they do it make obvious to everyone involved which wire is the neutral(earth) and which is the 'hot' wire.

    If you look at the meter you it will tell you what your rating is. probably 15A(45A); we for various reasons we have 50A(150A) which is just a little scary given we are less than 30-40M away from the 2MW transformer that supplies us. I am genuinely concerned that our main trip thats rated for safely breaking 7500A short, might not be up to the job.

  18. #18
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    I realize it is difficult to get a good sparky in thailand. Maybe an opportunity for me as a consultant/trainer. I have a electrical contracting business in Australia, I employ over 40 sparks, training has always been a big part of that business, probably put 50 guys through an apprenticeship. Even after 4 years of tech school and thousands of hours of on the job training, one the most difficult things for apprentices to grasp is the concept of earthing. Direct earthing, multiple earthed neutral earthing, neutral bonding, voltage drop etc.

    I guess the important thing tho is that until there is a fault (eg. Washing machine with motor shorted to earth) the system will operate fine even if it is not earthed correctly and/or has the polarity reversed.

    So, if the washing machine is shorted to earth and the earth wires and earth stakes you have installed diligently are not connected properly to the neutral at the switchboard then the protective fuse or circuit breaker won't operate, leaving the frame of the washing machine live for electiction. Note that in this situation a fault at the premises next door could have a similar result.

    Also an RCD does not detect current in the earth wire, it monitors the current flowing down the active wire, through the appliance, and back up the neutral wire. If the difference is more than 30 millamps then the RCD will trip. Heart fibrillation can occur at around 30 milliamps.

  19. #19
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    Finding an electrician out here in the boonies is impossible and we not only needed the house wired, but a small factory. Ended up using the power company's own guys on their days off. Not as cheap as the village idiot, but every thing done neatly and properly. Jim

  20. #20
    euston has flown

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    ^there could be a lot to be said for that, given the many varied ways these chaps will have to kill themselves in their primary job.... the fact they are still alive suggests they might have some inkling as to what they are doing

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    Quote Originally Posted by hazz View Post
    ^there could be a lot to be said for that, given the many varied ways these chaps will have to kill themselves in their primary job.... the fact they are still alive suggests they might have some inkling as to what they are doing
    As the factory has a 32 KW transformer on site think we would have run out of village handymen pretty fast. Jim

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    ^Thats nothing. we have a 2MW supplying us ... ok mainly supplying the warehouse behind us that sells and tests (and occasionally blows up) electricity transmission equipment.

    but you are right, you would prbably have taken out quite a few village sparkies.... but think how many lifes you would have saved in the process.

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    When this place was built I specified the panels, grounds, etc and made sure it was correct. As we have 3 phase, I may have over-killed a bit. 3 ground rods for neutral, 3 ground rods for for ground, 2 ground rods for steel sub structure. All wiring from Square D 100A 3 phase panels 1 st, 1 2nd floor, all power comes in via a safety cut 80A master breaker. When lightning hit power lines about 50M from our house, safety cut tripped, 3 power strips (with MOV's) smoked, 3 UPS tripped offline, 2 fuses in AC units blown. No other damage. Down the road some Refrigerators trashed and a few tv's smoked
    Meanwhile the main sub about 4KM away blew up. Bought a couple new MOV power strips (feeding USP and sensitive equipment) and ran the generator some for a couple days. Generator is now in garage that has 2 ground rods for generator and 2 for steel substructure, while electric in garage 2 phases fed from house with ground wired as well into small safety type breaker panels as well. Generator connects to 1 totally separate receptacle in house via a 3 wire cable behind a safety breaker.
    I've seen far too many dead folks from this power here and lack of grounding.

  24. #24
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    you will probably trip over one of those rods and die

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