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Thailand Electric Voltages


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Hello. I'm American and have an above-average understanding of electrical wiring. I'm comfortable installing new lights, sockets, breakers, etc.

 

We're building a new house (having it built) and I am checking the electrical wiring.

 

In America (110 volt system), if you check the neutral - ground connection, it should have minimal voltage,  0-1.5 volts maximum. Any more, and your neutral line is carrying too much voltage.

 

When I measure here, I'm getting 5 - 10 volts. It is not stable either, it bounces all over the place, sometimes spiking over 10 volts.

 

I don't know much about 220 volt systems. Does anyone know if my readings are normal?

 

Thanks.

 

20201106_094621.thumb.jpg.1147b69d929636cb361c03b539ef1e0a.jpg

 

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You probably have a TT system with a local earth rod, the neutral being earthed at the transformer only.   The N-E voltage will vary with load (IR volt drop on the neutral), in reality it's

Just a final follow-up on what happened.   Roughly 10 days ago the wife went down to PEA to apply for the final meter (switch the account). They said it would take about a week to process th

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35 minutes ago, Thomas72 said:

 

 

Hello. I'm American and have an above-average understanding of electrical wiring. I'm comfortable installing new lights, sockets, breakers, etc.

 

We're building a new house (having it built) and I am checking the electrical wiring.

 

In America (110 volt system), if you check the neutral - ground connection, it should have minimal voltage,  0-1.5 volts maximum. Any more, and your neutral line is carrying too much voltage.

 

When I measure here, I'm getting 5 - 10 volts. It is not stable either, it bounces all over the place, sometimes spiking over 10 volts.

 

I don't know much about 220 volt systems. Does anyone know if my readings are normal?

 

Thanks.

 

20201106_094621.thumb.jpg.1147b69d929636cb361c03b539ef1e0a.jpg

 

 

Ya want the Electrical forum, you will be moved. 

 

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I'm going with Crossy's hunch, that "You probably have a TT system with a local earth rod, the neutral being earthed at the transformer only."

 

Even though our local electrical grid in the village is MEN (Multiple Earth Neutral, neutral bonded to ground on every third power pole), local electricians never seem to make the N-E Bond also in the Consumer Unit (breaker box) where the differential would be cancelled out sooner, so with no local 'bond' your neutral will 'float' above earth-ground a bit more than usual.

 

My house has a local N-E bond in the box, but I still get about 1.24vac at the socket of the washing machine without any load. But then our house utilizes a combination of ufer and multiple earth-ground stakes around the house and outbuildings. And given that non of our neighbors have N-E bonding in their CUs I'm guessing we're getting a bit of earth-ground bleedover from their systems. 

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I wish I had found this forum sooner.

 

The house is a new construction. It should be completed in the next week. Today I was inspecting the electrical.. All the lights, switches, sockets, etc. when I came across these voltage readings.

 

The electrician installed a 3 meter earth rod right below the breaker box. They drilled through the slab. I never saw anything like that before.

 

The build is permitted, and extensive construction plans were drafted. I don't have a photo of the breaker box on me. I'll get one ASAP and post it.

 

Thank you so much.

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31 minutes ago, Thomas72 said:

The house is a new construction.

 

You will likely have a "construction supply" which is billed at 8 Baht per unit, to get a permanent supply you need to pass a (pretty cursory) inspection but the inspector will expect to see the MEN arrangement shown in my earlier post along with at least a front-end RCBO in the board.

 

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14 minutes ago, Thomas72 said:

I don't have a photo yet but I found the receipt and looked up the main breaker.

 

That's good an RCBO, one box checked.

 

The instructions for your Square-D / Schneider board should show the MEN connection, question is, did your sparks follow them? (if so I'd be expecting a much lower N-E voltage).

 

Sadly just looking at the meter can't tell us what tariff you're on.

 

Also, depending upon your inspector a 63A incomer on a 15/45 may attract a comment.

 

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Thanks Crossy, you're giving me invaluable information.

 

Tomorrow I am meeting the electrician at the job site. It's for a final review/inspection, and then he'll want payment.

 

I messaged him earlier today about the N-E readings.. He just said, "I'll be there tomorrow and everything will be fixed".

 

Will the PEA inspector want to physically see the earth rod? Like I said, it's below the breaker box, inside the house. The builder was wanting to tile over it today. Like I said, I never saw anything like this before:

 

20201102_093533.thumb.jpg.5e20b53364ca639bfa2c3c4a0ed809ae.jpg

 

1604656835791.thumb.jpg.bedb2ec13101c81eba791de47640bfdd.jpg

 

I have a picture of the breaker box now too:

 

20201102_093549.thumb.jpg.254c79e9730631a7bd945fae20f899dc.jpg

 

This picture was taken before the main was run to the meter (2 days ago).

 

 

 


 

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7 minutes ago, Thomas72 said:

Will the PEA inspector want to physically see the earth rod? Like I said, it's below the breaker box, inside the house. The builder was wanting to tile over it today. Like I said, I never saw anything like this before:

 

Is the rod connected using the recommended thermic weld or a clamp? If it's thermic take a photo, if a clamp NEVER bury it.

 

Our man looked at the top of the rod, checked that the main box had the correct routing of the neutral, moaned about my 63A incomer (replaced by a 50A for the re-check although he never came back, now back to 63A) and spent 30 mins gassing with Wifey.

 

We need to see how the real incoming wiring is routed, the inspector will be looking for it.

 

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22 minutes ago, Thomas72 said:

This picture was taken before the main was run to the meter (2 days ago).

 

I see a couple of worrying (not green) wires on the earth bar, I don't see a nice fat (>10mm2) wire going to the rod.

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