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BANGKOK 19 July 2019 19:13
Yellowtail

Electrical Service

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The building we are in has a three-phase panel, but it is currently wired single phase.

 

The meter has four terminals, I think this is line and neutral in, and line and neutral out, is that correct?

 

There are four wires on the poles in front of the building, that would be three phases and a neutral, correct?

 

The three-phase wiring that went to our panel is still there, but it is stubbed-out at the meter.

 

To get three phase service, I should only have to have a new meter installed and reconfigure the wiring to and in the panel, correct?

 

I would like to start upgrading my aircon to three-phase.

 

Thanks

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Huh?  3-phase to 3 single phase distribution is common practice.  I don't understand most of your OP.  Aircons typically do not use 3-phase.

 

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You would also need the connections made to the other two phases on the supply more than likely.  It is not common in Thailand to use 3 phase for air conditioners domestically as most are splits for a single room which run on single phase as opposed to whole of building units in the US for example.

 

Cheers

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2 hours ago, bankruatsteve said:

Huh?  3-phase to 3 single phase distribution is common practice.  I don't understand most of your OP.  Aircons typically do not use 3-phase.

 

Thanks for the response. I want three phase sub-panels on each floor. I would like to start upgrading the AC and be able to run a compressor, a welder and a couple of other pieces of three-phase equipment. 

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1 hour ago, Litlos said:

You would also need the connections made to the other two phases on the supply more than likely.  It is not common in Thailand to use 3 phase for air conditioners domestically as most are splits for a single room which run on single phase as opposed to whole of building units in the US for example.

 

Cheers

I think I can have the MEA install a new meter and cut in the leads when they upgrade the service. I'm trying to figure out how big a deal it will be. Once I get it to the main panel I can install sub-panels as I need them, 

 

It is not common now, but I think three-phase is getting more and more common. The big cassette units are offered in three-phase which is what I want to start moving to.

 

Anyone recommend a decent electrician in Lat Krabang?  

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From what you describe it should be a simple task (famous last words) to remove the single-phase kit from the board and reinstate the 3-phase metering. A couple of photos of the relevant bits would help confirm this.

 

I would however caution about using 3-phase equipment generally unless it's absolutely necessary. The most common power failure mode in our area is loss of one phase (invariably the one we are using), you will need to protect your 3-phase appliances from this failure.

 

A 3-phase service may be necessary, but do you actually need 3-phase for your welder and other toys?

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1 hour ago, Crossy said:

From what you describe it should be a simple task (famous last words) to remove the single-phase kit from the board and reinstate the 3-phase metering. A couple of photos of the relevant bits would help confirm this.

 

I would however caution about using 3-phase equipment generally unless it's absolutely necessary. The most common power failure mode in our area is loss of one phase (invariably the one we are using), you will need to protect your 3-phase appliances from this failure.

 

A 3-phase service may be necessary, but do you actually need 3-phase for your welder and other toys?

The welder and compressor are three-phase, I could change the motor on the compressor, but the welder I'd have to replace. As much as I would use it, might be cheaper to replace than turn on...

 

We're in greater Bangkok and the power is good. The compressor has a starter that will/should protect it, not sure about the welder.

 

Would not the new airconditioners be protected? I think I want to run one 40K (bedroom floor)  and one 60K (living room floor) cassette AC units each about 12 hours a day. I'll get a couple of photos a little later.

 

Thanks 

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34 minutes ago, Yellowtail said:

Would not the new airconditioners be protected? I think I want to run one 40K (bedroom floor)  and one 60K (living room floor) cassette AC units each about 12 hours a day. I'll get a couple of photos a little later.

i side 100% with Crossy. moreover, 48k btu/h units are available in single phase plus using a "lonely" 60k btu/h unit proves that you did not consider an optimal spread of cooled air. another indication for my assumption is that you are planning "floor cooling" which is a futile attempt with one outlet and return air at the same location.

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2 hours ago, Naam said:

i side 100% with Crossy. moreover, 48k btu/h units are available in single phase plus using a "lonely" 60k btu/h unit proves that you did not consider an optimal spread of cooled air. another indication for my assumption is that you are planning "floor cooling" which is a futile attempt with one outlet and return air at the same location.

I understand I can get larger units in single-phase, I have a few of them now. I am in the process of replacing one with a new single-phase unit now. 

 

Switching to three-phase is a long term plan. You are correct, a single large cassette unit would not be ideal. Giving it some thought, a ductless multi-split system with cassette style FCUs and a single condenser on each floor would be much better.

 

I think three-phase will lower my peak usage and lower my operating costs.

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A few of us have incoming 3 phase.

For me the 3 phases are mostly used as 3 seperate phases. I have each phase taking some of my load. So I have the loads from lights, fans, pumps etc across the 3 phases. Each of the 3 aircons are on each one of the 3 phases.

If you spread the lights, power plugs etc across the 3 phases, then if one phase goes down, you still have lights and power.

I have two, 3 phase multi-point hotwater heaters. (They use 2 phases on low heat and the 3 on high heat). So you could still use 3 phase equipment as well as having 3 seperate phase supplies.

Also with 3 seperate phases you have more options and can switch an incoming phase around if that particular phase goes low at 5pm.

Sent from my SM-J700F using Tapatalk

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2 hours ago, carlyai said:

A few of us have incoming 3 phase.

For me the 3 phases are mostly used as 3 seperate phases. I have each phase taking some of my load. So I have the loads from lights, fans, pumps etc across the 3 phases. Each of the 3 aircons are on each one of the 3 phases.

If you spread the lights, power plugs etc across the 3 phases, then if one phase goes down, you still have lights and power.

I have two, 3 phase multi-point hotwater heaters. (They use 2 phases on low heat and the 3 on high heat). So you could still use 3 phase equipment as well as having 3 seperate phase supplies.

Also with 3 seperate phases you have more options and can switch an incoming phase around if that particular phase goes low at 5pm.

Sent from my SM-J700F using Tapatalk
 

 

As I understand it, the phases are always separate, so I'm not sure what you mean. 

 

Would I not want to balance the load across the three legs? 

 

As most of the power I use is AC, balancing the AC load using three-phase would provide the most bang for the baht...

 

Where'd you get the 3ph water heaters? I have a 50 gal single phase Rheem I brought from the US.

 

Any gas water heaters around? I wonder if LP would be cheaper heating water than electric...

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Posted (edited)
2 hours ago, Yellowtail said:

As I understand it, the phases are always separate, so I'm not sure what you mean. 

They can be a single 3 phase supply to your outlets or wired as 3 independent single phase supply's. The PEA requirement is that the load is roughly balanced across the 3 phases.

2 hours ago, Yellowtail said:

Any gas water heaters around? I wonder if LP would be cheaper heating water than electric...

Yes there are, yes it is

 

 

Edited by sometimewoodworker

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2 hours ago, Yellowtail said:

As most of the power I use is AC, balancing the AC load using three-phase would provide the most bang for the baht...

The original connection is much more expensive, so may be not.

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4 minutes ago, sometimewoodworker said:

They can be a single 3 phase supply to your outlets or wired as 3 independent single phase supply's. The PEA requirement is that the load is roughly balanced across the 3 phases.

Yes there are, yes it is

 

With three-phase I think can use one leg and a neutral for 230, two legs for 400 or three legs for 380.

 

I don't know that I can balance the load any better than using three-phase equipment. 

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