Single or three phase electric?

[bobby2]

Having a small house built 2 beds 2 bathrooms.My question is the electrician is saying I need3 phase ,but I have already bought fuse box and had mains run under the new gov road from pole to house. The electrician says cannot do this with 3 phase. I will have 2x 4.5  shower heaters and 2 AC at about 11000 btu. Along with the usual bits is fridge etc.

Would a single phase be enough and what size meter should I try and get?

Many thanks.

[jastheace]

never seen domestic a/c or showers running on 440v. his concern is possibly total power load, if yr not more than 200m from decent overhead supply, then single is fine imo

[Crossy]

A 15/45 single-phase meter will be more than adequate for the load you are planning.

 

But running under the government road may be an issue (even for single-phase), did you check if permission was required get the relevant permissions?

 

Have you already run the cable under the road? What size / type of cable and ducting have you used? How deep is it buried?

 

Talk to your local PEA / MEA office, but I suspect they will be wanting a pole on your side of the road and an aerial road crossing.

 

 

 

[jastheace]

4 minutes ago, Crossy said:

A 15/45 single-phase meter will be more than adequate for the load you are planning.

 

But running under the government road may be an issue (even for single-phase), did you check if permission was required get the relevant permissions?

 

Have you already run the cable under the road? What type of cable and ducting have you used? How deep is it buried?

 

Talk to your local PEA / MEA office, but I suspect they will be wanting a pole on your side of the road and an aerial road crossing.

 

 

 

also I don't like to use a local earth for the neutral, prefer it comes of the last transformer, so that 3 phase plus neutral, sound a bit overkill for domestic

[Crossy]

7 minutes ago, jastheace said:

also I don't like to use a local earth for the neutral, prefer it comes of the last transformer, so that 3 phase plus neutral, sound a bit overkill for domestic

 

I'm not sure where you got the idea that the local ground is used as neutral, the neutral and ground are connected in your box but that's part of the TNC-S with MEN that is used here, there is always a solid metallic neutral back to the transformer.

 

Thailand is 3-phase 4-wire (3-phase plus neutral), single phase supplies are taken from one phase and the neutral.

 

I strongly suggest you talk to your supply authority before doing any more work.

 

This should be a simple single-phase hook up.

[jastheace]

9 minutes ago, Crossy said:

 

I'm not sure where you got the idea that the local ground is used as neutral, the neutral and ground are connected in your box but that's part of the TNC-S with MEN that is used here, there is always a solid metallic neutral back to the transformer.

 

Thailand is 3-phase 4-wire (3-phase plus neutral), single phase supplies are taken from one phase and the neutral.

 

I strongly suggest you talk to your supply authority before doing any more work.

 

This should be a simple single-phase hook up.

agree, totally agree, won't go into what I wrote, but to sum it up, I agree 

[Crossy]

8 minutes ago, jastheace said:

agree, totally agree, won't go into what I wrote, but to sum it up, I agree 

 

I got you confused with our OP. Must be a sign of age ????

 

Many don't like to see the N-E connection it frightens them. They don't realise that back home (for me the UK) N and E are very often linked (TNC-S supply) but you don't see the link as it's hidden in the sealed service head.

 

[jastheace]

8 minutes ago, Crossy said:

 

I got you confused with our OP. Must be a sign of age ????

 

Many don't like to see the N-E connection it frightens them. They don't realise that back home (for me the UK) N and E are very often linked (TNC-S supply) but you don't see the link as it's hidden in the sealed service head.

 

and agree again. ( not the age thing though, I don't know you) but seems you know yr stuff so hope the op takes note. I've had to use earth as a neutral at socket on occasions to prove machines work but neutrals missing, never left it connected, just to 'prove', then proper sparky gets the fun job. but yeah.... nice one

[tjo o tjim]

Crossy is spot-on as always; the only time you “need”3-phase power is if you have larger motors (over 5hp).  But, it is an odd comment from the electrician, so my guess is something is being lost in translation.  

[trd]

Speaking of earth, there is no earth in most houses as you know. When I get around to building my house should I make my own local earth with a copper rod in the ground and connect it to a three pin system?

[Crossy]

5 minutes ago, trd said:

Speaking of earth, there is no earth in most houses as you know. When I get around to building my house should I make my own local earth with a copper rod in the ground and connect it to a three pin system?

 

Absolutely! You won't get a permanent meter if you don't these days.

 

All new builds over the last 3 years or so should have rods, 3-pin outlets and RCBO protection.

 

Check this pinned thread:-