Please help me understand Thai house electricals...

[David48]

Try touching one of those 22KV HV lines! By your theory you should be perfectly safe.

I mentioned earlier, that I don't have a lot of domestic wiring experience ... but something I know a lot about is the transmission side as I worked for the 'electric company'.

Again, from Australian experience ...

The really big mothers of lines are 275,000 volts.

The slightly smaller ones are 110,000 v

The sub-regional distribution is 33,000v

What you see Kris in the burbs when they have 3 wires on the upper side is 11,000V for the 3 wire and 240 v for the distribution to the house.

Jack ... I'm coming to your statement.

One of the things to get your head around is the concept of 'Potential Difference'

Because electricity is a sine curve and the '3 phase' curves are out of phase by 120^o ... there is a potential difference between the phases of (in Australia) of 415 volts. ... in Thailand, that difference would be maybe 380 or 390 volts.

So it's the potential difference that is important.

I used to work with a group of 'live lineys' ... they would work from a specially insulated 'Cherry Picker' and work with live 11,000 lines ...

Their vehicle was specially designed to insulate them for the 'ground' .. thus they had no potential difference.

Same when you are sitting in a car and a power line (say 33,000 or 11,000) volts drops on the metal body.

You can sit in the car and not get 'zapped' ... but open the door, place your foot on the ground and your hand on the car's metal body ... it's bye bye boozo.

It's all about potential difference.

[wpcoe]

If you can get the Square-D device I mentioned earlier it should be a straight swap.

Your man will have to disconnect at the meter so make sure he puts it back the right way round (mark the wires with tape).

I'm currently away from the condo, so the electric upgrade is on hold for a week. I feel that I have a handle on the concept now, though, thanks to many posters in this and other threads.

When I first moved in to the condo (nine years ago,) if I had all three air cons running and took a shower, sometimes when the water heater would kick in, the power for the condo would turn off. I would dry myself off, go to the closet down the hall and reset the circuit breaker for my unit.

IIRC (and please don't crucify me if I don't...) There was a 30amp breaker in the closet, even though my CU had a 45-amp main switch. I was told to go to the PEA office and upgrade my system to 45-amp, which I did, but was told I still needed to change the breaker switch in the closet down the hall to 45-amp.

I never got around to doing that , so will the 45-amp switch being pulled from my CU and replaced by a 45-amp ECLB, be the appropriate thing to install in that closet down the hall with all the condo CBs? They have now put a hefty lock on that closet door. I've just been mindful about not running all three air cons when I shower.

[Muhendis]

Jackflash

"My recollections was it was more an issue of AC v/s DC.

DC causes your muscles to freeze, while AC causes them to vibrate.

With luck you'll be thrown clear with AC."

Thrown clear? That is the main cause of injury and death. DC will possibly kill you because you can't let go. AC will kill you as a result of letting go (especially from a high place).

[jackflash]

> AC will kill you as a result of letting go (especially from a high place).

Yeah sure, it's better for the current to continue and slowly cook you, that for the circuit to be interrupted.....

I think I'll give up posting here. There are just to many idiots.

[Crossy]

I never got around to doing that , so will the 45-amp switch being pulled from my CU and replaced by a 45-amp ECLB, be the appropriate thing to install in that closet down the hall with all the condo CBs? They have now put a hefty lock on that closet door. I've just been mindful about not running all three air cons when I shower.

If the MCB from your CU will fit the slot available in the closet then it will be much better than the current 30A unit.

BUT

With similar MCBs in series you can never guarantee which will open first in the event of an overload. If the 45A unit won't fit in the closet then get a 63A unit to go in there, it's only got to protect the cable against short-circuit current as overload will be handled by the 45A RCBO you're going to install in the CU.

In the event of a dead short you still can't guarantee which will open first, but an overload will open the breaker you can get to

[wpcoe]

Ah, I hadn't thought of that. I should probably just get a >45a breaker of the appropriate size for the closet down the corridor. That way the one in my condo unit CU *should* be the one to "pop," and I can reset it without pestering the building maintenance staff. With my luck I would somehow trip the other CB in the middle of the night and be without power until they showed up for work the next morning.

[OMGImInPattaya]

You can do your own earthing with a ground spike and just run a wire back to the appliance. Ie. washing machine attach the earth wire to the machines cabinet earth wire. You don't need an earth wire for lighting.

Gee that's a bit of a backyarder style. Not quite what I'm looking for.

Agree this is not correct. The ground wire from the washing machine should go back to the ground bar in the main circuit board. All the ground wires in the house go back to this board and then one properly sized wire is run from the ground board to the earth spike.

[wpcoe]

The Schneider / Square-D device you need is QO245MBGX30 - 2 pole 45A/30mA plug-in RCBO, Thai Interelectric have these catalogued at 4,800 Baht. Ouch!

Not sure how current this catalogue is mind http://www.thai-inte...residential.pdf (Page 18), print that page and take it with you.

This is the easiest solution as you simply replace the incoming 45A breaker with this device.

Just came home from HomePro in Hua Hin. They had a QO245BGX30T ... same model number as you recommended, but with a T at the end. Being excessively anal at this point, I didn't buy it. I asked the seemingly knowledgeable sales guy, via their English-speaking interpreter, what the difference might be between his T model and the non-T model on the page I printed from the thai-interelectric .pdf file. He kept saying (through the interpreter) that it was a new model. I asked the difference between the old and new models. No difference. (Hmmm. Then why a new model?) I asked if maybe the T stood for Thailand, and it was a Thai model, but then realized the non-T version was being sold by a Thai company.

Finally, I took the device from the box and read what it said. Whereas the thai-interelectric .pdf page said "240/415 Volts," this switch said "220/240V." I'm 99% sure that that's okay, since I would hopefully not have 240-415V coming through. Maybe variances up to 250v or 260v, but surely not even 300v?

Then, as I was walking away, I noticed the price for the T model: B3015 -- less than 2/3 the price of the non-T version. For that price difference, do you think there would be any other difference between the T and non-T versions other than the voltage range it tolerates?

As said, I'm 99% sure the QO245BGX30T for B3015 will do the trick safely, but with an abundance of caution I'm asking for confirmation.

[Crossy]

Can't be absolutely certain of the differences (I can't find a datasheet for the 'T' version), but I'll bet it's just fine

Make sure you keep your Homepro receipt and the packing, just in case there is an issue installing the beast.