Domestic Electrical Wiring

[Crossy]

Hi Thaipaw, I'll try to address your issues

MEN (Multiple Earthed Neutral) or PME (Protective Multiple Earthing) are similar but not identical systems, both require a link between the incoming neutral and the ground bar in your consumer unit. With MEN expect each house to have a ground spike, with PME the earthing is provided by the utility and no ground spike is found at the house (this is the UK system).

The biggest danger if you connect a MEN link when one is not required is the potential hazard should the neutral become open between you and the transformer. In this event the neutral on the 'cold' side of the fault will rise to phase potential (via all the loads because there is no return path) and will attempt to ground out via your MEN link and ground spike (being the only path back to the transformer). Your ground spike stands no chance of sinking this current therefore all your 'grounded' metalwork will approach phase voltage, not a situation you want.

Therefore. You should never connect neutral and ground unless you KNOW that MEN/PME is implemented, better not to have the link at all.

The best test of live is a neon screwdriver (the type you put your finger on the end and it lights up on live), this will guarantee to find the live pole and since it requires only one connection cannot be fooled by the MEN link. Use your meter to check for correct wiring of your outlets (220V L-E, 220V L-N, 0V N-E).

The neutral will be grounded at the transformer by the supplier, do NOT make further connections to this ground, provide your own ground spike and ensure it is at least 2m from the transformer ground (for protection in the event of a lightning strike to the utility system).

Don't forget to install an ELCB/GFI/RCD/RCCB/Saf-T-Cut device for maximum safety

A low current lamp (neon) between live and an independent ground (the re-bar of your house will be sufficient as the current is tiny, a few microamps) and another between neutral and the same ground will give you an idea if an accidental L-N reversal has occured (the lit lamp should be the L one if the N lamp lights you have a problem). To be honest I wouldn't bother, but that's the way to do it.

Please feel free to ask for clarifications, if we save one person from a dangerous zap it's all been worthwhile

Edited May 25, 2008 by Crossy

[thaipaw]

Thanks Crossy,

That's clear and complete.

I forgot that I'd purchased a neon screwdriver for the purpose of distinguishing Line from Neutral a couple years ago when I was grounding my rented abode in Phnom Penh. At that time I ran a wire around the house to the clothes washer, water heaters, microwave, and computers.

But then while I was away on holiday, rain shorted a wire somewhere so the landlord (who lived up stairs) called an electrician. The first thing the electrician did was tear out ALL of the ground wire I'd installed. (He didn't understand it, so it must have been the cause of the problem..

I was suprised to find Safe-T-Cut in so many homes in Thailand. I've never seen anything like it in Cambodia or in the US (where GFCI is only installed in kitchens, bathrooms, basements, and outdoors). I want to buy something to take back with me, but I'd prefer something a bit more packable than a Safe-T-Cut.

My new home's wiring is currently being protected by a single 30-amp breaker (no aircon, hot water, TV, or cookers. Just a refrigerator, water pump, some laptops, fans, and lights). Would purchasing one of the devices referred to in Elkangorito's post suffice? Can you help me determine which would be most appropriate for my application? The "A Type" is only availabe in a 16 amp model. If I purchased, e.g. the 40amp "AC Type" DOMC47C4030C, then could I use that to cover the whole house?

Try this;

http://ecatalog.schneider-electric.com/

Go to;

"Products and Services" then,

"Offers per function" then,

"residential final distribution" then,

"Domae" then,

"MCB and busbars", then

"Domae RCBO residual current circuit breaker".

You should see a picture of a circuit breaker in the right hand window. In this window, click on "Technical documents".

You should purchase the "A Type" (not the "AC Type"). It should be rated at no more than 30mA & NOT be adjustable. You want a "Curve C" device.

This is a standard DIN type device, so it should fit into your consumer unit without any problems although it will use 2 pole spaces (36mm) in your consumer unit (the width of 2 circuit breakers).

BTW, it will not be cheap. Expect to pay at least 2500 Baht for a good RCBO. I think this one may be a bit more expensive. They should be orderable through most wholesalers who stock Square-D products.

[Crossy]

Yeah, the Saf-T-Cut is a rather big box, containing mainly air

If you want to replace your existing 30A breaker you should use an RCBO such as DOMCN7C3230C RCBO Domae 1P+N 32 A 30 mA AC Curve C 6000A as this incorporates the overload function as well as the earth leakage function.

These units clip onto a DIN rail in the housing, so depending upon your existing installation you may want to get a baby consumer unit or at least a box as well. Have a poke round in Homepro, they should have most of what you need

[Crossy]

I'm looking for three-way switches (IIRC the US call them 4 way).

I need to operate a light from THREE locations.

My local leccy shop look blank even when shown a diagram, Homepro have two way but not the three way intermediate switches

The electronics chaps would call them double-pole changeover, I can get a switch that will do the job in Amorn, but it really needs to be a regular light switch in form.

[Khonwan]

I'm looking for three-way switches (IIRC the US call them 4 way).

I need to operate a light from THREE locations.

My local leccy shop look blank even when shown a diagram, Homepro have two way but not the three way intermediate switches

The electronics chaps would call them double-pole changeover, I can get a switch that will do the job in Amorn, but it really needs to be a regular light switch in form.

I searched last year but couldn't find any - had to get my dad to post one from U.K.

Rgds

Khonwan

[david96]

I'm looking for three-way switches (IIRC the US call them 4 way).

I need to operate a light from THREE locations.

My local leccy shop look blank even when shown a diagram, Homepro have two way but not the three way intermediate switches

The electronics chaps would call them double-pole changeover, I can get a switch that will do the job in Amorn, but it really needs to be a regular light switch in form.

Connect the light as two way switching and connect an intermediate switch in the wiring at the third location.

[Crossy]

I'm looking for three-way switches (IIRC the US call them 4 way).

I need to operate a light from THREE locations.

My local leccy shop look blank even when shown a diagram, Homepro have two way but not the three way intermediate switches

The electronics chaps would call them double-pole changeover, I can get a switch that will do the job in Amorn, but it really needs to be a regular light switch in form.

Connect the light as two way switching and connect an intermediate switch in the wiring at the third location.

It's the intermediate switch (double-pole changeover) that I can't find.

I need to be able to fully control the light (off when it's on, on when it's off) from all locations. I'm quite sure they're available, just not in the places I've been in

[david96]

I'm looking for three-way switches (IIRC the US call them 4 way).

I need to operate a light from THREE locations.

My local leccy shop look blank even when shown a diagram, Homepro have two way but not the three way intermediate switches

The electronics chaps would call them double-pole changeover, I can get a switch that will do the job in Amorn, but it really needs to be a regular light switch in form.

Connect the light as two way switching and connect an intermediate switch in the wiring at the third location.

It's the intermediate switch (double-pole changeover) that I can't find.

I need to be able to fully control the light (off when it's on, on when it's off) from all locations. I'm quite sure they're available, just not in the places I've been in

Clipsal and HPM have them. Series 30 and 770 series. The intermediate switch has 4 terminals and the switching is 1 to 2

and 3 to 4 changing to 1 to 3 and 2 to 4. You could try the Clipsal agent in Bangkok. They are dearer than the standard mech switching C-1/C-2. (C is the common terminal). You use 2 standard 30 or 770 switches and 1 intermediate in all.

Edited May 30, 2008 by david96

[Crossy]

I'm looking for three-way switches (IIRC the US call them 4 way).

I need to operate a light from THREE locations.

My local leccy shop look blank even when shown a diagram, Homepro have two way but not the three way intermediate switches

The electronics chaps would call them double-pole changeover, I can get a switch that will do the job in Amorn, but it really needs to be a regular light switch in form.

Connect the light as two way switching and connect an intermediate switch in the wiring at the third location.

It's the intermediate switch (double-pole changeover) that I can't find.

I need to be able to fully control the light (off when it's on, on when it's off) from all locations. I'm quite sure they're available, just not in the places I've been in

Clipsal and HPM have them. Series 30 and 770 series. The intermediate switch has 4 terminals and the switching is 1 to 2

and 3 to 4 changing to 1 to 3 and 2 to 4. You could try the Clipsal agent in Bangkok. They are dearer than the standard mech switching C-1/C-2. (C is the common terminal). You use 2 standard 30 or 770 switches and 1 intermediate in all.

Cheers david. My local chap can order Clipsal so I'll see what he can do.

[fremmel]

I picked one up here in Udon. It's branded National on the front and Matsushita on the back. The part number on the back of the switch is WNG-5004-7. The invoice listed the brand as Panasonic and gave the same part number. It was kind of pricey at 380 baht where the 3 way switches, for 2 locations, (Panasonic WNG-5002) were only 57 baht. The clerk knew the switch as a 4 way switch and it was listed that way on the invoice. I checked it with my meter and it is a double pole change over switch.

[Crossy]

I picked one up here in Udon. It's branded National on the front and Matsushita on the back. The part number on the back of the switch is WNG-5004-7.

Thanks Fremmel, a search on the part number turned up this outfit in BKK http://www.electricprice.com/product.asp?sLang=EN looks useful

[david96]

Here's an interesting example from a friend near Buriram. His house has just been finished, and we went up there a few days ago for the house blessing and party.

He has been very careful to specify to the electrician that he wanted all sockets properly earthed, etc. When he came to check, the only snag was that the electrician told him that the builders had poured concrete over the earth rod, so it was no longer visible. Hmmmmm.

For the Isaan style party, the stage crew tapped directlt into the supply on the electrical pole outside his property, on the outlet from the meter. Whilst they were setting up, he went to have a shower and came back very quickly complaining that he had just had a shock from the shower tap. I went to check the circuit breaker box, and found that the box itself was live.

What had happened was that the stage crew had reversed live and neutral when reconnecting the wires to the meter, and inside the circuit box was a cable linking the neutral bus bar and the earth bus bar, hence every earted item becoming live. The earth connection to the ground rod did nothing to stop this. Very nasty.

He is now waiting for the electrician to return and check/correct.

The earth electrode should be exposed to the weather and not enclosed in concrete, you should have equipotential bonding,and the touch voltage should not exceed 50VAC under fault conditions. Polarity testing of the consumers mains must be carried out before connection to supply.The main earth conductor (min 4mm) copper does not carry fault current in any magnitude due to soil resistance (100-500 nominal)

Earth electrode should be a min of 1.2metres in the ground and a min of 12.7mm copper clad steel.

Ref AS3000.

The main earthing conductor bonds all PE and all exposed metalwork in the installation to the general mass of earth. The main earthing conductor must never be disconnected from the earth electrode.

(In my opinion the direct earthing (TT) system should be used where the polarity of supply can not be guaranteed. )

Edited May 31, 2008 by david96

[david96]

Maximum Demand in Mains and Submains in a Single Residence.

1. By calculation as in the table below.

2. Limitation. The maximum demand may be determined by the current of affixed setting circuit breaker, or by the load setting of an adjustable circuit breaker. The maximum demand of consumers mains may be determined by the sum of the current settings of the circuit breakers protecting the associated final subcircuit/s and any further submain/s.

Maximum demand in final subcircuits.

1 For single items of equipment, by assessment of the connected load or,

2 For multiple items of equipment, by limitation of the current rating a circuit breaker.

Notes.

Information derived from AS3000.

The maximum demand is the sum of the load groups where applicable. Eg A+B+D+E

A twin socket outlet shall be treated as a single point for the purposes of calculation.

Lighting, for calculation of the connected load, 60W for incandescent lamps, full connected load current for fluorescent and discharge lamps.

Single domestic electrical installation or individual living unit

Load Group

A Lighting 3A for 1 to20 points + 2 A for each additional 20 points or part thereof

B Socket outlets not exceeding 10A, permanently connected electrical equipment not exceeding 10A and not included in other load groups

10A for 1 to 20 points + 5A for each additional 20 points or part thereof

Where the electrical installation includes one or more 15A or 16A socket outlets other than socket outlets provided to supply electrical equipment set out in groups C,D,E,F, and G. add 10A

C Cooking appliances or socket outlets rated at more than 10A for the connection thereof.

50% connected load

D Airconditioning equipment or socket outlets rated at more than 10A for the connection thereof

75% connected load

E Instantaneous water heaters 33.3% connected load

F Storage water heaters Full connected load

G Motors Full connected load of 1st motor + 50% of the FL current of remainder

[longball53098]

I would be interested in getting a copy of this Wiring Standard or a condensed version. Is there a source here in LOS?

If so how much? I looked at the website where one can be purchased and it looks quite expensive at about 200AUD. Is that correct?

Why so much?

Can I get one here?

[Crossy]

I would be interested in getting a copy of this Wiring Standard or a condensed version. Is there a source here in LOS?

If so how much? I looked at the website where one can be purchased and it looks quite expensive at about 200AUD. Is that correct?

The 17th Edition of the IEE Wiring Regulations (the UK standard) is 55GBP (about 112AUD), you'll possibly be able to get it cheaper from ebay or Amazon (is there an Amazon Australia?).

These publications are expensive because of the limited circulation meaning the publication costs are amortised over a much smaller number of copies.

The ideal standard would of course be the Thai one but it's unlikely to be available in English, it is apparently based on the same sources as the IEE and Aus regs so wiring to AS3000 would be a good fit

EDIT This site http://www.etu.asn.au/members/shop.html has the hard cover version for 140AUD much more reasonable.

Edited June 9, 2008 by Crossy

[david96]

All Australian Standards are available from here including AS3000/2007. Also international standards are available from

this website.

http://www.saiglobal.com/shop/Script/search.asp

AS3018/2001 covers domestic installations up to 80A single phase and 50A multiphase and is available from above.

Edited June 9, 2008 by david96

[david96]

Practical Information for a Single Residential Electrical Installation.

Single phase 230V.Information based on AS3000. Guide only.

Voltage drop. Max 5% of supply voltage within an installation.

Voltage drop can be generally disregarded in residential installations for final subcircuits where route lengths of cable are less than 25 metres and the max demand is assessed at less than

50% of the current rating of the circuit breaker protecting the circuit. With 10A socket outlets connected across 2 or more circuits the max demand of the final subcircuit may be regarded as 10A.

Calculate the max demand of the consumers mains or use the current limitation method.

In practice the load (actual load in amps) is lower than that calculated. This allows for diversity.

Select the size of conductor in sq mm. Eg. 45A max demand select 10 sq mm (63A)

Select the size of conductor and protective device for final subcircuits, this will generally

in practice be:- TPS 2 core or 2 core and earth cable. Minimum size for a separate earth

conductor 2.5 sq mm (7/067)

Lighting and fans:- 1 sq mm or 1.5 sq mm (7/050) with a protective device rated at 10A or 16A dependant on current rating of cable chosen.

Power circuits including socket outlets, 2.5 sq mm (7/067) minimum with a protective device of 20A.

Cables run in free air as single circuits separated from each other and do not operate at

maximum current in temperatures not exceeding 40C continuously and not enclosed in thermal insulation. Separated means not bunched or enclosed with other cables along their route length.

If cables are enclosed in free air cables may be derated multiply current ratings below by 0.8.

Enclosed means enclosed over 50% of the cable route, eg in conduit.

Current ratings and protective device selection for 1 sq mm to 25 sq mm for cables used in single phase applications in air and unenclosed.

The unenclosed ratings may be applied to enclosed cables in ground.

Sq mm Protective device rating in Amps.

1.0 ------- 10

1.5 ------- 16

2.5 ------- 20

4.0 ------- 32

6.0-------- 40

10--------- 63

16-------- 80

25-------- 100

Socket outlets. Instal socket outlets across 2 or more circuits in an installation and protect with

30mA RCDs or RCBOs.

Main earth conductor and bonding conductor min 4 sq mm, earth electrode 12.7 copper clad steel 1.2M minimum.

Note. Copper (Cu) conductors specified thoughout.

Ambient temperature continuous not exceeding 45C.

________________________________________________

Edited June 9, 2008 by david96

[Crossy]

An interesting fact that has recently come to my notice is that Great British No-No, the power outlet in the bathroom.

As long as I can remember the only outlets allowed in bathrooms in the UK were the transformer isolated 'Shavers Only' units, in fact even these were banned from new installations for a short time.

Now, in a major turn-around the new IEE regs. (17th Edition, published in January 2008) actually permit regular power outlets in the bathroom. These must be RCD protected and at least 3m from the edge of the bath, shower or sink. Since most UK bathrooms don't have any dimension of >3m I see few outlets actually getting installed.

[longball53098]

I came across this small but informative book and purchased one from the local SE-ED bookstore. The cost was in the area of 250 baht.

This small wiring book is aimed at the Thai who wants to do things right and I think this book could help us all in our quest to get our home electrics done correctly. The pictures and associated explanations should help you get your Thai electrician on the same page as you.

I can't read Thai but from the pictures and charts it looks pretty good.

[Crossy]

I came across this small but informative book and purchased one from the local SE-ED bookstore. The cost was in the area of 250 baht.

This small wiring book is aimed at the Thai who wants to do things right and I think this book could help us all in our quest to get our home electrics done correctly. The pictures and associated explanations should help you get your Thai electrician on the same page as you.

I can't read Thai but from the pictures and charts it looks pretty good

Looks like a good find. Does it have an ISBN or similar reference number so I stand a chance of finding a copy?

I note that the outlets on the cover are mounted the 'wrong' way up. Conventional wisdom is to mount them with the ground at the top, in which case any conductive object (a knife for example) won't short live to neutral should it slip down the back of a plug

[longball53098]

Yes the outets are in our world upside down but I think the main part of the book looks pretty good.

ISBN 974 7751 67 4

Amarin Printing and Publishing Co Ltd

I went to the online website of SE-ED and found the book stock number and went to a store and ordered one. Could have mail ordered it though.

[Cuban]

I note that the outlets on the cover are mounted the 'wrong' way up.

I bet it was done this way so they look like smiley faces !

[jojothai]

The link between ground and neutral (the MEN link) is important for safe operation (and required by local regulations),

Hi Crossy, david96 and others

I have been looking at crossy's wiring website, it was very helpful thanks.

I am now finalizing the electrical system on a new house with my electrician and have a few queries. I note how helpful you have been to people in the past and would be grateful for advice.

I have a vertical cable race void left in the block work inside the house at the CU location which is about 400mmm wide and find it looks best to get two consumer units because I need about 24 circuits and a few spare.

So I would stack them vertically. The units I like best that will suit are the SENSE R3 which include the earth leakage breakers and surge protector.

For my queries, a diagram will help as follows

My Queries are

1. Where is it best to put the MEN? Direct to the main circuit breaker or split to the consumer units.

2. What size should the MEN link cable be if direct, or if split. Is it 4 mmsq

3. For the cables to the 2 consumer units from the MCB I assume we need to run them individually as the diagram shows since the CU has only 63A rating so I should not run cable to the first CU and then from the first CU to the second.

4. With the two SENSE R3 units they are 3+4+4+4 so I will only have 6 circuits without earth leakage protection but I will need 6 aircons + 3 other circuits. So I presume I can get the electrician to remove one of the Earth leakage breakers (RCBO unit) to provide another 4 circuits without protection. Have you any comment?

5. My original house drawings showed 125 A main breaker.

The electrician thinks 100A will be OK. Using the advice for load calculations I get 113A.

Lighting 7A, sockets 15A, Aircons 27A (6 units 36A total rating), Water Heaters 40A, oven& hob 24A

Any comment on 100 vs 125 please?

Does the 125 require a 3 phase supply? If so I will have to limit to 100A for single phase.

I am providing wiring for 6 A/c but will only install 4 units initially total rating 24A so the total load calculation reduces to 104A. I believe I am unlikely to fit the other 2 aircons.

6. The incoming supply point is about 50m from the house, 70 m in cable length from the CU. The cable will be connected from the top of the supply post through the air via a new post to a corner of the roof. What cable size should we use if the MCB is 125A or what size if 100A? The electrician says 2x 50mmsq should be OK but another electrician who quoted said 70mmsq. Do you think 50mmmsq is sufficient or not.

Also, what is the type of cable should be used?

Thanks for your help.

jojothai

[Crossy]

OK Jojo, you're going the right way

1. The MEN link MUST go to the incoming neutral, it is vital that it connects on the hot side of any earth-leakage devices for proper protection.

2. The MEN link itself should be the same size as the incoming active conductor, in your case the incoming is 50 or 70mm2, since that is likely too big to fit your ground bar use the biggest that will go in the holes available (you may want to drill out the hole a little to get a bigger wire in).

I would designate one of the ground bars as 'master' and hook the MEN and your ground stake to that one, link the 'slave' ground bar to the master again with the biggest cable that will fit.

3. Yes wire it like that.

4. Yup you can remove one of the RCBO / ELCB / RCD units and get some more unprotected circuits in.

5. The biggest single phase supply available is 45/100 (100A max) and this is not available in all areas, you may need to look at 3-phase. Check with your supply authority before wiring up your consumer units.

6. At 100A 50mm2 cable 70m long will drop about 3% of supply, assuming your supply is not already low (and your 100A is not going to pull it low) that would be OK. BUT if your supply is already marginal the use of 70mm2 may be advisable. Both would assume COPPER, aluminium (aluminum) would require bigger cable.

I would look very carefully at 3-phase if it's available on the poles. You immediately divide the currents by 3 at the expense of more complex wiring of your consumer units.

Don't get 3-phase aircons, just balance them between the phases then if you lose a phase (quite common) you just lose one unit rather than all of them.

Edited September 10, 2008 by Crossy

[jojothai]

OK Jojo, you're going the right way

Thanks crossy

1. So if I understand right it is best to connect from the "master" ground directly to the 100A MCB neutral outlet.

2. Understood

I would designate one of the ground bars as 'master' and hook the MEN and your ground stake to that one, link the 'slave' ground bar to the master again with the biggest cable that will fit.

Yes Understood.

3. OK.

4. OK

5. The biggest single phase supply available is 45/100 (100A max) and this is not available in all areas, you may need to look at 3-phase. Check with your supply authority before wiring up your consumer units.

The 100A seems to be what the electrician was getting at and it fits with what you say then 100A is the max for single phase. I will check with him so he confirms we can get the 100A MAX. I understood it is available and although we are out in the country, there are some big houses not far away.

I will ask about 3 phase but I dont think I can get so readily. I am sure the electrician will tell me straight away if it is no way.

On the overhead electricity line can you explain what I see for a 3 phase line compared to single phase. More cables obviously. Do you perhaps have a photo?

6. The existing supply is already on a branch from the main power line at the main road a distance of about 110 meters, so there will already be some voltage drop. So I may well be pushing it expecting 100A to be OK with the 50sqmm. The electrician is fairly local so I will have to get his opinion to help judge from what is in the existing line.

Agree with what you say if it is marginal I better go to 70. I know 70 is more expensive than 50, but no good putting in 50 and then finding a problem.

Cable in copper understood, but in terms of the cable surround / insulation is there any need for a particular type when this goes above ground 50m to the supply pole? I may have to buy the cable in Bangkok if the local price in Prachuab KhiriKhan is not competitive enough. and I need to be sure on the Type designation.

]

Again thanks for your help.

jojo

[Crossy]

1. Yup, you've got it

Connect to the switched side of the main breaker, then if you pull that one it will isolate all your wiring from the rest of the planet. Before you power up for the first time ensure that live really is live and neutral really is neutral (use your handy-dandy neon screwdriver), it's not unknown for them to get crossed on the incoming and that will result in a hazard in a MEN system

5. If the poles have 4 wires (3 phases plus neutral) then there is 3-phase available, there is sometimes a fifth (ground) wire up there too.

6. 110m is a pretty long run at 220V I would suspect that things are marginal now before you bolt on your massive (by local standards) load

The specification of the overheads is outside my experience so you need to contact your electrician as to the exact types permitted in Thailand. Some info here that may be relevant http://www.tlc-direct.co.uk/Book/7.13.1.htm

Edited September 10, 2008 by Crossy

[longball53098]

OK Jojo, you're going the right way

Thanks crossy

1. So if I understand right it is best to connect from the "master" ground directly to the 100A MCB neutral outlet.

2. Understood

I would designate one of the ground bars as 'master' and hook the MEN and your ground stake to that one, link the 'slave' ground bar to the master again with the biggest cable that will fit.

Yes Understood.

3. OK.

4. OK

5. The biggest single phase supply available is 45/100 (100A max) and this is not available in all areas, you may need to look at 3-phase. Check with your supply authority before wiring up your consumer units.

The 100A seems to be what the electrician was getting at and it fits with what you say then 100A is the max for single phase. I will check with him so he confirms we can get the 100A MAX. I understood it is available and although we are out in the country, there are some big houses not far away.

I will ask about 3 phase but I dont think I can get so readily. I am sure the electrician will tell me straight away if it is no way.

On the overhead electricity line can you explain what I see for a 3 phase line compared to single phase. More cables obviously. Do you perhaps have a photo?

6. The existing supply is already on a branch from the main power line at the main road a distance of about 110 meters, so there will already be some voltage drop. So I may well be pushing it expecting 100A to be OK with the 50sqmm. The electrician is fairly local so I will have to get his opinion to help judge from what is in the existing line.

Agree with what you say if it is marginal I better go to 70. I know 70 is more expensive than 50, but no good putting in 50 and then finding a problem.

Cable in copper understood, but in terms of the cable surround / insulation is there any need for a particular type when this goes above ground 50m to the supply pole? I may have to buy the cable in Bangkok if the local price in Prachuab KhiriKhan is not competitive enough. and I need to be sure on the Type designation.

]

Again thanks for your help.

jojo

Here is what 3 phase in my housing project looks like:

You can see 4 lines at the top of the pole attached to the insulators.

The top most cable is the ground/neutral and the 3 below are the 3 phases, A, B and C

So in my village if I wanted to apply for three phase I imagine I could as it is available outside my door.

In this case you can see some cables attached to the top neutral and some cables attached to the supply lines. On this pole there are three houses and 3 meters 15(45) single phase connected. So I see 3 cables connected to the top neutral and 1 cable to each of the 3 phases for the 3 house meters and this balances the load on all three lines.

Edited September 11, 2008 by longball53098

[jojothai]

1. Yup, you've got it

Connect to the switched side of the main breaker, then if you pull that one it will isolate all your wiring from the rest of the planet. Before you power up for the first time ensure that live really is live and neutral really is neutral (use your handy-dandy neon screwdriver), it's not unknown for them to get crossed on the incoming and that will result in a hazard in a MEN system

5. If the poles have 4 wires (3 phases plus neutral) then there is 3-phase available, there is sometimes a fifth (ground) wire up there too.

6. 110m is a pretty long run at 220V I would suspect that things are marginal now before you bolt on your massive (by local standards) load

The specification of the overheads is outside my experience so you need to contact your electrician as to the exact types permitted in Thailand. Some info here that may be relevant http://www.tlc-direct.co.uk/Book/7.13.1.htm

Hi Crossy

Understood and very good of you to post the photo. It does help to see what we are talking about.

I read the previous discussions about the danger with the MEN link if it is connected the other way round.

Very scary to think that could happen. Judging by some of the electrics I see here it is very possible.

I will be going down to Prachuab and expect to finalize details with my electrician in the next few days.

Very grateful for your advice thanks

jojo

[longball53098]

1. Yup, you've got it

Connect to the switched side of the main breaker, then if you pull that one it will isolate all your wiring from the rest of the planet. Before you power up for the first time ensure that live really is live and neutral really is neutral (use your handy-dandy neon screwdriver), it's not unknown for them to get crossed on the incoming and that will result in a hazard in a MEN system

5. If the poles have 4 wires (3 phases plus neutral) then there is 3-phase available, there is sometimes a fifth (ground) wire up there too.

6. 110m is a pretty long run at 220V I would suspect that things are marginal now before you bolt on your massive (by local standards) load

The specification of the overheads is outside my experience so you need to contact your electrician as to the exact types permitted in Thailand. Some info here that may be relevant http://www.tlc-direct.co.uk/Book/7.13.1.htm

Hi Crossy

Understood and very good of you to post the photo. It does help to see what we are talking about.

I read the previous discussions about the danger with the MEN link if it is connected the other way round.

Very scary to think that could happen. Judging by some of the electrics I see here it is very possible.

I will be going down to Prachuab and expect to finalize details with my electrician in the next few days.

Very grateful for your advice thanks

jojo

jojo,,

Crossy did not post the photo. I did.

Thanks anyway

longball

[jojothai]

jojo,,

Crossy did not post the photo. I did.

Thanks anyway

longball

Hi Longball

My apologies, as I was writing a reply I scanned down and saw it and added the comment.

It was very good of you to post the picture so quickly. It helps a lot for me to see it now just before I leave for the province.

best regards

jojo