How to wire a house using 3 phase

[pferdy62]

We are getting 3 phase power delivered to our property via our own dedicated transformer.  We want to rewire the house and other buildings so that we can use different appliances on different phases.  We have 4 air conditioners, 3 hot water units and the usual assortment of things you would find in a house.  The other buildings have a similar setup.

 

It seems to make sense to split the hot water units across each phase and to do something similar with the air conditioners.

 

But the big question is what sort of distribution unit do I need to achieve this?  It will have 3 phase power going in and then it needs to supply single phase circuit breakers that may each be connected to one of the three phases.  

 

We also want the system to be protected by an RCD.

 

Is this doable?

 

Thanks.

[RichCor]

You have a couple of choices.

 

If you're planning to branch the power to several outbuildings then you'll probably want to first bring the 3-phase power in from the meter to a common start point with it's own Mains Breaker and Distribution Breakers.

 

Then in each building you can choose to install either

3 independent single-phase distribution boards, or

1  three-phase distribution board

 

Which you choose will really depend on the number of breakered branch circuits you want to have in each building, and if you ever want to simply wire a three-phase appliance to triple-breaker (easily installed into a three-phase board).

 

There's really very little difference between a single-phase and a three-phase residential distribution board, except the three-phase board usually feeds each of the three phases to every third breaker in the line of breakers, (R, S, T, R, S, T, R, S, T, etc, etc.)  The electrician can then take the first three breakers and wire it to a three-phase appliance, or use the breakers independently to run as phase-dependent isolated circuits wired also to the Neutral bar.  

 

 

As for the RCD, you have just as many choices. It can be 'whole house' wired in front of the distribution board (single unit handling all three phases, or 3 unit handling each phase), or the rcd can be part of the distribution board breaker design, or only chosen branch circuit protection where the standard MCB (Miniature Circuit Breaker) is replaced by a RCBO (Residual Current Breaker-Overload device) providing RCD only for that circuit.

 

 

  

 

[pferdy62]

Thanks RichCor.  

 

We already have a control box going in that will split the 3 phase supply out to different buildings as you suggest.

 

For the houses, it sounds like the 3 phase distribution board is going to be a better choice for us.  I guess I need to head off to our local electrical shop and have a chat to the guy there about what he can get for us.

[carlyai]

Hello[mention=209146]pferdy62[/mention]

 

We used 3 phase and I have included a few pics. of our setup and some suggestions for the planning stage.

 

The first thing you need is an electrician that is farmiliar with 3 phase wiring. Many say they are, but they really don't know. I was fortunate that I found someone who wired up factories and knew a bit more than the average sparky.

 

This is how I did it. I'm not saying it is correct, but just to give you an idea how I did it.

 

The first pic. is the 3 phase coming in from the road (in the yellow pipe). There the neutral is tied to earth with an earth stake. It splits there, 3 phases underground to the house, 1 phase underground to the shed, branch to the bore and house pump out the back, and branch to driveway lights and other lights.

 

Second pic is where the 3 phases come into the house to a transfer switch, connecting mains or genset. Then the separate 3 phases + neutral go to 3 voltage stabalisers, then into the 3 phase main CU through a 3 phase Safety Cut. (probably in hindsight, use one per phase).

I put in 3 phase multipoint water heaters for kitchen and bathroom 2 and laundry and bathroom 1. (Do make sure you use someone for the water who knows how to join those green hot water pipes.)

 

Next you need to plan for a million power points and lights and switches. I used all low powered LED lights. Also aircon power feeds to each room, even if you don't plan on using them. Also TV, sound system speakers and internet.

 

Some pics of my power points, fans and lights.

 

Plan for your 3 phases extensions, like irrigation pump, pool pump, outside kitchen, and more you haven't thought of.

 

Split the phases up so you have power and lights on all phases, so if you lose 1 phase you still have lights and power on from the other phases.

 

I also split my pumps off before the SafetyCut, as read somewhere they can cause unwanted trips. The pumps are connected to float switches which switch the bore pump on to fill the tank and switch the house pump off if the tank runs empty.

 

 

 

 

 

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[carlyai]

These diagrams may come in handy.

The first on shows a 3 phase set up.

I know you already have wiring and buildings, but if your sparky hasn't done a wiring plan with the 3 phase, it helps to do one. I drew this up first, then went over everything with the sparky.


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[Crossy]

Number one task = Planning.

 

• What loads do you expect in each building? (big man-cave with machine tools - see what sometimewoodworker has installed)
• Does a building need 3-phase? (like big water pumps).
• Do need voltage stabilisers? (how far out in the sticks are you)
• Will you be installing a genset? (how far out in the sticks are you)
• Any plans for solar?

 

These things are easier to build in at the start rather than hack the system about later (I have this t-shirt).

 

Then design your system (we can help here, just ask).

 

Then tell your sparks what to do.

 

 

[carlyai]

Yes planning...this was not the end set up, but planning breakers and loads.
Memories, thanks again Crossy.

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[carlyai]

This is the Planning sign I like.


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[kamalabob2]

The OP should go in person with a trustworthy translator, to see a previous installation of 3 phase that any local electrician claims he has installed. The excellent photos and plans posted by Carlyai are a good heads up on what is entailed. A Schneider catalog might prove helpful, yet a licensed electrical contractor who has successfully accomplished this in your province or next province is worth consideration. I paid for my own 3 phase transformer and the plans submitted to the PEA  by a licensed private electrical contractor were very detailed. I do not own 3 phase water pumps, but there certainly are farms, rock quarries and hotels in Buriram with 3 phase Mitsubishi Super pumps and three phase electrical motors. I have visited Buriram residences with a Mitsubishi elevator and/or  Daikin central air conditioning which would also need 3 phase electrical installations. 

[RichCor]

As other's have correctly stated, knowing your present and future anticipated electrical loads and designing an electrical diagram or plan is the first step.

 

Remember that a circuit breaker is there primarily to protect the wiring from overheating. So when you design your electrical plan, large-wattage appliances usually get their own dedicated breaker and wire run; medium-wattage appliances can be grouped and share a breaker with a daisy-chain or star-pattern wire run; and smaller appliances, plug points and lighting similarly grouped to share breakers and a common wire run -- but all designed never to exceed the max carry capacity of the wire. 

 

And if this is a large house you may want to plan having sub-panels or junction boxes to cut down on multiple long wire runs.

 

The tricky part will be trying to balance the active loads across each of the three available phases.

But as Crossy stated, if you have questions or concerns, post them here. While some of use are sparky wannabes, there are a few certified (in not outright certifiable) folks here who can give educated and/or experienced advice.

 

 

3-phase Distribution Board example stolen from the Internet

[pferdy62]

To give everyone a bit more information on the scope of this project.  We have a lot of land that currently has one main house ( 4 air-con, 3 hot water), 3 guest bungalows (each has 1 air-con 1 hot water) and a factory that has three devices that can draw a lot of current when in use.  All of this is currently single phase.

 

We have just started building a 2 bedroom bungalow and plan to add about 40 to 80 more one bedroom units over the coming years as a retirement village.  There will also be various other buildings that will form a part of this project which will stretch the abilities of our local builders and architects.

 

In terms of location, we are about 10km from the centre of Lampang, so we are not in the sticks as such, but the PEA is extending the third phase high voltage wire down to us so that we can connect our own 160kVA transformer up to the grid.  At the moment, the whole street is powered from a single 30kVA transformer and we have regular brown outs and blackouts.  Normal voltages are often in the 200 to 210V range.  Whenever the sky goes dark and you hear thunder in the distance, someone kills the power to our area.

 

The house currently has a manual 5kVA generator that can be switched in to run the house without any air-con or water heaters.  In the event of a blackout all of the bungalows are without power at the moment.

 

Moving forward, we do plan to add a 3 phase generator, but this is going to be further down the track.  We will leave space for this next to the 3 phase distribution and control box that is about to be installed.

 

The house needs to be rewired to cater for 3 phase power and I want to be able to run the existing generator (single phase) to run one phase of the house in the event of a blackout.  I have been in the ceiling space and under the floor and I don't like what I saw in the way of wiring.  The house is currently wired backwards for lack of a better term.  The circuit breakers are wired to the neutral line and the circuits are still live even after you turn off a circuit breaker.  Any electrical work requires a total isolation of the electrical supply.  As you would expect it is a two wire system that should be upgraded at some point.

 

There has been a bit of talk about solar, but that's all so far.  

 

Finding a suitably qualified electrician may prove difficult.  The last set of electricians we hired to run some 16mm cables to another supply box for our factory used green wire for both live and neutral.  I guess that was the only colour he had on the day. 

[RichCor]

5 hours ago, pferdy62 said:

The house is currently wired backwards for lack of a better term.  The circuit breakers are wired to the neutral line and the circuits are still live even after you turn off a circuit breaker.  Any electrical work requires a total isolation of the electrical supply.

 

While it's really up to you as to what you want to do, initially you could just swap the incomer lines LIVE <--> NEUTRAL and have the current distribution board function as intended.  Though I'd still do testing on each circuit to make sure they're implemented correctly (verify that all light switches connect to the now LIVE leg, and power points with earth-ground service are properly wired).  

 

If the house wiring is decent you could keep what you want, as your expected new 3-phase service will primarily be implemented as single-phase usage -- where you'll connect to any one of the three available phases (and the common neutral).

 

 

5 hours ago, pferdy62 said:

The house currently has a manual 5kVA generator that can be switched in to run the house without any air-con or water heaters.  In the event of a blackout all of the bungalows are without power at the moment.

 

Moving forward, we do plan to add a 3 phase generator, but this is going to be further down the track.  We will leave space for this next to the 3 phase distribution and control box that is about to be installed.

 

The house needs to be rewired to cater for 3 phase power and I want to be able to run the existing generator (single phase) to run one phase of the house in the event of a blackout.

 

Back to 'planning', you'll probably want your 3-phase distribution center to be large enough to make room for add-in items down the road ...like a Automatic Transfer Switch for a 3-phase generator, and possibly hosting large-capacity Automatic Voltage Regulators if your new 3-phase service still dips down on load. Possibly even Power Inverters for a Field of Solar Panels. 

[carlyai]

Sounds nice. Love to take a look at the retirement place when you're building.

 

You have probably thought of this already, but I think you may need a Town Planner or someone with these skills. And a consultant for the power. Maybe I'm speaking out of turn here, but this forum moderator would seem a good choice for a consultant.

 

You will need to plan the pumps etc for the sewerage, rise and fall if the plumbing etc. Also where you are going to place that noisy generator and the storage facilities for the diesel.

 

That's why I think you need a town planner to integrate everything.

 

Anyway, sure you've thought about that. [emoji3]

 

EDIT

 

I don't know much about the cost etc. but a solar grid tie system may be cost effective for power supply in the long run.

 

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[pferdy62]

Carlyaia.  I have already given a lot of thought to the various services that need to be supplied, namely water in, electricity, telephone lines (for ADSL), grey water, black water, storm water drains, roads, trees and space usage.  I want the electrity to be an underground service to keep the area looking nice.  There will be IP cameras on street light poles to keep an eye on things and each apartment will be wired to a common network to allow for the installation of IP intercoms, help buttons and cameras for people who need them.  There are probably a myriad of things I have not even considered yet, and your comments about a town planner are spot on.  But before we engage this person, I want to have a pretty good idea of what I think can be done and then get the town planner to confirm this.

 

While this is moving a little off topic, I have been considering the construction of a small scale sewerage treatment plant for the facility rather than using the traditional septic tanks for each building.  Our common area used for meals and things will have a floor area of around 600m2 and we have left space for a reasonable sized pool to be installed in a later stage.  The entire facility will be constructed as wheelchair friendly, so there will be no steps and buildings will comply with the requirements for people with mobility and other issues.  We are also considering having a small medical facility where a local doctor can visit as needed to make sure everyone is doing well and is keeping on their meds.  We have also planned for on-site nursing/assistance and security.  Most importantly, we will get a license to sell alcohol so that everyone can relax at night in the common areas.

 

Getting back on topic, solar is probably a good idea and we will do more research into this.  We are going to have a lot of roof area available so we could get a lot of energy during the day.  I wonder what the storage options are if we want to use this energy at night.  One thing that we are going to look at is solar hot water to reduce the need to rely on the electric hot water units as their current draw is quite high.

 

 

[carlyai]

Last thing from me as you need experts, but, also off topic, also have a think about an aquaponics set up for the retirees. You could grow all your fish, prawns and fresh veggies for food.

I have small, unfinished set up, but if you're interested in something Aquaponics contact Robert at Aquaponics Thailand.
He's building some large scale systems and you could use solar water pumps etc.
Sorry again for off topic and have great success. [emoji3]

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[DGS1244]

Are you talking about a Thai 3 phase or a European 3 Phase. I have a Thai 3 phase which is three separate 220v supplies coming from the street to the distribution panel. A European system is 360 volt total and would very careful wiring. I have seen fires started by someone connecting two floors of a building, which were on separate phases, resulting in serious risk to persons from electric shock apart from the fire situation.

[Crossy]

I think we have to assume we are talking about 3-phase, 4-wire, 220V L-N, 380V L-L. This is pretty much the same as the UK and Oz.

 

There are a few places in Thailand still using 3-phase, 3-wire, 220V L-L but these are now few and far between.

 

The nice thing about 3-phase, 4-wire is that it can be treated as if it is 3 single-phase supplies if you have no 3-phase appliances.

 

 

[DGS1244]

3 minutes ago, Crossy said:

I think we have to assume we are talking about 3-phase, 4-wire, 220V L-N, 380V L-L. This is pretty much the same as the UK and Oz.

 

There are a few places in Thailand still using 3-phase, 3-wire, 220V L-L but these are now few and far between.

 

The nice thing about 3-phase, 4-wire is that it can be treated as if it is 3 single-phase supplies if you have no 3-phase appliances.

 

 

I agree but you have to know what you are doing, in the past had to rewire places where so called electricians messed it up. In UK now there are very strict rules in domestic premises having 3 phase, almost impossible to get approval.

[wombat]

finding a sparkie that knows what earth is for would be a good start

 

[Can samui]

My 2 bahts worth.
It is absolutely essential that there is only one power feed per building, anything else will get someone killed.
My recommendation;
One 3 phase incoming feed from government supply with panel, wire and main breaker sized to amp feed from municipality.
Sub feeds either single or three phase fed from main panel to satellite panels.
Ground fault breaker protecting main panel.
Ground rod driven deep enough to ensure permanent continuity to earth.
Proper wire color coding, seen to many installations here with all the same colored wire......scary.
Not sure they actually certify trades here so you get what you get. Best advice is to find a falang electrician, retired or bored, and pay him in beer to quality control the work. As long as he does no physical work he will not contravene work laws.
Best of luck.


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[Crossy]

It's worth noting that our OP isn't just doing a home, it's a workshop, house, resort and common facilities with its own 160 kVA transformer, around 250A per phase.

 

I would suggest a 250A MCCB at the incoming supply (in a locked shed) with individually HRC fused (yes, BS88 fuses) protecting sub-mains to the properties, maybe - house, workshop, cabins (2 circuits). Good, solid, neutral earthing wherever possible throughout, make it all TN-C-S with MEN (PME for us Brits).

 

Distribution in underground SWA so no need for earth leakage protection of the feeder.

 

Then treat each building as a separate installation, TN-C-S with a MEN link and RCD(s) in each main board.

 

For the cabins an outside cabinet with an MCB (say 30A) and a meter, worth metering even if you don't intend charging for power to monitor for those "greedy" guests.

 

EDIT Whilst the ground is dug up I would run a 3x2.5mm2 "control" cable with each sub-main. That would allow you to turn off aircon and water heating when the genset is running, everyone gets "basic" power without requiring a prohibitively expensive genset.

 

[carlyai]

Yes well spoken diplomatically that man. I was tempted to chime in before, and say that this is a professional project, and why oh why, would you want a retired falang when there are really capable Thais out there?
I taught 60 young Thai kids in the diploma in Electronics and diploma in Computing, and went on programming courses with Thais; there are very very capable Thai people around.

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[Crossy]

12 minutes ago, carlyai said:

there are very very capable Thai people around.

Indeed there are and they're worth significant rates. For a project this size the real professionals are available.

 

It's worth talking to the local PEA chaps, many will moonlight for cash, most are competent. There's a reason our power poles are stamped "PEA" (we have a receipt from PEA for stupidly small money) and were installed by chaps in PEA fatigues using a PEA marked truck

 

[Autonuaq]

By Thai law electricians have to be qualified and the government did run several programs to get them certified.

 

Electricity is the patient silent killer.

 

To get the most out of all you need to have a good installation well balanced.

 

3 phase gives you a very good option to balance the power in all buildings on your premises.

 

Now you have a chance to split the 3 phase inside each building and when well designed you will have electricity ever where or close by when a phase fails.

 

A good electrician know how to make a plan that fully uses you premisses and building and as well split the load balanced over three phase.

 

By a good design a rewired installation is also prepared on future expansion.

[Crossy]

1 hour ago, Crossy said:

It's worth noting that our OP isn't just doing a home, it's a workshop, house, resort and common facilities with its own 160 kVA transformer, around 250A per phase.

 

I would suggest a 250A MCCB at the incoming supply (in a locked shed) with individually HRC fused (yes, BS88 fuses) protecting sub-mains to the properties, maybe - house, workshop, cabins (2 circuits). Good, solid, neutral earthing wherever possible throughout, make it all TN-C-S with MEN (PME for us Brits).

 

Distribution in underground SWA so no need for earth leakage protection of the feeder.

 

Then treat each building as a separate installation, TN-C-S with a MEN link and RCD(s) in each main board.

 

For the cabins an outside cabinet with an MCB (say 30A) and a meter, worth metering even if you don't intend charging for power to monitor for those "greedy" guests.

 

EDIT Whilst the ground is dug up I would run a 3x2.5mm2 "control" cable with each sub-main. That would allow you to turn off aircon and water heating when the genset is running, everyone gets "basic" power without requiring a prohibitively expensive genset.

 

 

By the way, whilst we always appreciate sensible comments, if you have to ask what the abbreviations mean ...

 

[pferdy62]

Okay, to give a little more feedback.  We are talking about a 4 wire 220V L-N setup.  The high voltage will come in from the street where it will be reduced in our 160kVA transformer.  There is a city meter at this point I think which is how they will calculate what to bill us.

 

From there, the 4 wires feed into a control cabinet which will allow us to monitor line voltages and current for each phase.  The power is then split 4 ways, one for each of our projects and each supply has its own 3 phase power meter and master circuit breaker.  This unit has been approved by EGAT and PEA, so everything should be okay on that front.

 

Each building will have its own 3 phase distribution board sized for its expected power consumption. 

 

Getting a ground rod in deep enough is going to be a challenge as our ground is very rocky, but our electrician is insisting on a 3 metre ground rod.  I’ll enjoy watching how he gets that into the ground, but it is an encouraging sign.

 

When talking about wiring up our new building, I have told them (our electricians) what I would like to achieve in terms of cabling and after a couple of translation issues, we are all in agreement now.  They knew all about 3 phase colour coding of wires and when I showed them a wire nut, they knew exactly what it was for.  They appear to have a good understanding of the Thai standards and would not accept my ideas that they deemed to be illegal.  This was the big translation problem that took a bit of effort to resolve.

 

We have been doing walkthroughs with the electricians to look at everything electrical in each building and are working on the power distribution based on expected demands at various times of the day.  They stuck their head into the ceiling of the main house which was built over 20 years ago and their assessment was the same as mine, “it’s a mess”.  We are also discussing the pros and cons of having a master RCD or using circuit breakers with built in RCDs to protect circuits that really need it.

 

As for being a retired farang, I’m here to work, not to sit around having an easy time.  :)

 

There is lots of good feedback coming in.  Please keep giving me your ideas.  Thanks.

[Crossy]

@pferdy62 for future reference it would be interesting to know which of your ideas your sparks deemed "illegal".

[jacko45k]

Quote

The first thing you need is an electrician that is farmiliar with 3 phase wiring

It is a good point as I bet there are a few out there who do not!

[maxpower]

5 hours ago, Crossy said:

@pferdy62 for future reference it would be interesting to know which of your ideas your sparks deemed "illegal".

I would also like to hear the illegal ideas along with the Thai code that makes them so.

 

These are my favorites (only for fun nothing personal)

 

1. They knew about 3 phase color coding
2. I showed them a wire nut, they knew exactly what it was for
3. Our electrician is insisting on a 3 metre ground rod
4. They stuck their heads in ceiling and agreed it was a mess
5. We are also discussing the pros and cons of having a master RCD
6. This unit has been approved by EGAT and PEA

[RichCor]

6 hours ago, Crossy said:

@pferdy62 for future reference it would be interesting to know which of your ideas your sparks deemed "illegal".

I think it was the initial misinterpretation the Thai sparks were balking at.

But it would be interesting to know, if that was ever said, what they thought he was asking them to do.