Where to buy cheap, off the shelf, 3 phase main breaker box (Bangkok)

[Monomial]

Brief history - I have been building a new house for the last 9 months, and I now feel my contractor is intentionally trying to stall the completion of my house so as to milk me for as much as he can get.

Question - I have been told it will take maybe a week to order a custom main breaker panel. Since I want the house finished before then, this is unacceptable. I am looking to buy something inexpensive that I can get the same day or following day at the worst. I made the contractor send me what he was saying he wanted to design "custom". This picture is attached below. Personally, I don't care what it looks like and whether it has integrated volt meters and ammeters or not.

Our incoming supply is 3 phase 30/100 per phase on 35mm copper cables. The contractor has specified a 150 amp main breaker, which then breaks out into 3 loads, and from there will go to individual residential panels on each of the 3 floors. I also require a 3 phase Safe-T Cut.

Can anyone recommend something that will not create a problem with the PEA, that is relatively inexpensive and that I can purchase off the shelf somewhere in the Bangkok area? This building site is in Rangsit.

Thank you for any advice. I am really at the end of my rope with this guy.

[Monomial]

More on this topic.

First, I went out and checked. The electric company has already installed the meter and a box with a 100A breaker at the front of my house, so there is no point in putting in a main breaker larger than 100A. Strike 1 for the contractor.

I then went over to Thai Watsadu and asked the clerk there if there was any problem just purchasing a Square D 12 way load center (QO3-100EZ12G/SN), loading it with an MCCB (EZC100H3100), and 3x 3 phase 50A breakers (QO350VSC6T). The clerk didn't seem to think there was any problem with that configuration and that the electric company shouldn't have an issue with it either.

Next I took my idea to the contractor. He first got angry and said he wouldn't take any responsibility for that. Then, after a while, he said that the cables I have coming into the house are 35mm, and all 4 plus the ground need to enter the box as a single bundle. This means a 2.5" hole is required for the PVC to attach to the box, and he didn't believe an off the shelf box had such a hole.

Question: Is there such a regulation like this, written or unwritten, in Thailand, and will there honestly be a size problem with an off the shelf load center? Those 35mm cables are pretty large.

The problem is I really don't trust this guy. He is a snake, and while I have a solid technical background, I have absolutely no knowledge of any arbitrary rules that the PEA may have. It is very difficult for me to effectively call him out when he has much more experience with this than I do.

Can anyone offer any advice?

[bankruatsteve]

100 amp is a LOT. I don't know but suspect the folks that need 3-phase for domestic are just hedging. No real reason otherwise. (OK - my opinion)

As for knock-outs, my recall is that Square-D boxes have some really large ones - so can't imagine that would be a problem.

If you don't like the PEA decision or your contractor, maybe you could be specific on your requirements and sure to get response from experts here.

[Monomial]

100 amp is a LOT. I don't know but suspect the folks that need 3-phase for domestic are just hedging. No real reason otherwise. (OK - my opinion)

As for knock-outs, my recall is that Square-D boxes have some really large ones - so can't imagine that would be a problem.

If you don't like the PEA decision or your contractor, maybe you could be specific on your requirements and sure to get response from experts here.

Thanks for the response. I really appreciate. My requirements are to make a simple design using parts I can buy at any hardware store to build a main breaker box. The electric company has already installed the 3 phase 30/100 meter outside my house along with a 100A 3 phase breaker at my gate. I have 4 large 35mm copper cables plus a big ground wire coming from this breaker through to my electrical room.

I need to follow the electrical plan which was submitted to the PEA which calls for load centers with 50A 3 phase power on each floor.

All I need is to design a main distribution box with 100A 3 phase power in, and 3x 50A 3 phase power out. The breakers themselves have to be able to accept the 35mm cable.

Is there any reason why the PEA would object to using a standard Square D load center for this?

My contractor is not happy I am asking this question and objecting to his overpriced custom solution. But my contractor is a lying snake, and I need to get my power connected in spite of him.

[bankruatsteve]

Well, I'm pretty sure requirements don't follow amps in/out. Try to be specific on the loads you will be looking at, for each floor it seems? If you have 3-phase, then you will want to be looking at load balance

Only your main breakers need to be able to handle 35mm2. The rest only need to handle the specific load requirement for the circuit.

Again, try to show exactly what your requirements are and I'm pretty sure you can get help from here.

.

[Monomial]

OK.

This is my design. It is cheaper than what the contractor is proposing, and uses all off the shelf components. The wire sizes and current ratings are the same.

The contractor's design was acceptable to the PEA, so there should not be any issues with specific circuits. Taken this as a given, is there any reason why the components I have chosen and the way I have laid them out can not be used as indicated?

[Satcommlee]

Tricky subject but I do get the feeling you are being oversold, but if you need to ask advice here then maybe it is best left to the contractor or get a second contractor, do not do a DIY job!

I'm not sure I would be giving advice on a forum either, even if I did know the answer.

Good luck with it all by the way.

[Crossy]

That is a BIG system!

Are you sure it's not a small factory you're building? We have our 3 bed plus large garden on a single-phase 15/45, the front end 50A incomer has never opened on over-current.

Anyway, what you propose should be fine, I suggest you are well oversized, but with no indication of the connected loads I can't comment further.

I don't like a single RCD/RCBO (Safe-T-Cut) on such a large system, one earth fault will take out all the house power (and be a nightmare to diagnose). Much better to provide distributed protection, say one RCD per floor.

Are you intending any 3-phase loads? If not why not simply have single-phase sub-mains? One phase per floor with a local RCD would likely do the trick without leading to massive phase imbalances.

[carlyai]

Listen to Crossy.

He helped me with my 3 phase to 3 single phase system with stabalisers moves rcds chsngeover switch gen set etc.etc.

Back from 3 months in aus. Regards to crossy.