Domestic Electrical Wiring

[chownah]

Guess I could go with 35 square mm cable then.....did you find that the length of the run does not affect the cable size in relation to the temperature rise issue? I'm wondering about this because in my mind the temperature rise issue is not quite resolved yet....some things seem to indicate that the length is immaterial and some things seem to indicate the opposite so I'm trying to resolve these different ideas....so I'm just wondering if you had done the same analysis but the cable length was 10 metres would the temperature rise calculations be the same as for 200 metres?

Chowah

[elkangorito]

Guess I could go with 35 square mm cable then.....did you find that the length of the run does not affect the cable size in relation to the temperature rise issue? I'm wondering about this because in my mind the temperature rise issue is not quite resolved yet....some things seem to indicate that the length is immaterial and some things seem to indicate the opposite so I'm trying to resolve these different ideas....so I'm just wondering if you had done the same analysis but the cable length was 10 metres would the temperature rise calculations be the same as for 200 metres?

Chowah

It's all connected together. It's just that in some instances, one factor will be predominant. In your case & at the end of the day, volt drop is predominant.

Equation 1. Fault Current is the current squared multiplied by the time (in seconds) that this current can flow.

Equation 2. K squared multiplied by S squared, where K is a constant (determined by a table in the standard) & S is the cross sectional area (CSA) of the cable in square mm. Since the CSA of a cable can determine the voltage drop over a certain distance & the CSA will affect the outcome of Equation 2, both are linked.

So, by transposition, S = the square root of (I squared x t divided by K squared)

[chownah]

Guess I could go with 35 square mm cable then.....did you find that the length of the run does not affect the cable size in relation to the temperature rise issue? I'm wondering about this because in my mind the temperature rise issue is not quite resolved yet....some things seem to indicate that the length is immaterial and some things seem to indicate the opposite so I'm trying to resolve these different ideas....so I'm just wondering if you had done the same analysis but the cable length was 10 metres would the temperature rise calculations be the same as for 200 metres?

Chowah

It's all connected together. It's just that in some instances, one factor will be predominant. In your case & at the end of the day, volt drop is predominant.

Equation 1. Fault Current is the current squared multiplied by the time (in seconds) that this current can flow.

Equation 2. K squared multiplied by S squared, where K is a constant (determined by a table in the standard) & S is the cross sectional area (CSA) of the cable in square mm. Since the CSA of a cable can determine the voltage drop over a certain distance & the CSA will affect the outcome of Equation 2, both are linked.

So, by transposition, S = the square root of (I squared x t divided by K squared)

Very interesting, thanks for posting this. It seems that none of the inputs for the two equations above would change because of the length of the run with the possible exception of K which you get from a table. In Equation #1 the Fault Current is calculated using the current that can flow (is this 20 amps or is it the 6000amps?) which is the same for any length of cable run and the time which depends on the circuit breaker (I think) and does not change regardless of the length of the cable run. In Equation #2 we have I (I guess this is the Fault Current from Equation #1), t (I guess this is the same t in Equation #1), and K (which is found in a table). When you are looking in the table to find K what are the numbers you use to locate the appropriate value of K in the table?

Chownah

[elkangorito]

Guess I could go with 35 square mm cable then.....did you find that the length of the run does not affect the cable size in relation to the temperature rise issue? I'm wondering about this because in my mind the temperature rise issue is not quite resolved yet....some things seem to indicate that the length is immaterial and some things seem to indicate the opposite so I'm trying to resolve these different ideas....so I'm just wondering if you had done the same analysis but the cable length was 10 metres would the temperature rise calculations be the same as for 200 metres?

Chowah

It's all connected together. It's just that in some instances, one factor will be predominant. In your case & at the end of the day, volt drop is predominant.

Equation 1. Fault Current is the current squared multiplied by the time (in seconds) that this current can flow.

Equation 2. K squared multiplied by S squared, where K is a constant (determined by a table in the standard) & S is the cross sectional area (CSA) of the cable in square mm. Since the CSA of a cable can determine the voltage drop over a certain distance & the CSA will affect the outcome of Equation 2, both are linked.

So, by transposition, S = the square root of (I squared x t divided by K squared)

Very interesting, thanks for posting this. It seems that none of the inputs for the two equations above would change because of the length of the run with the possible exception of K which you get from a table. In Equation #1 the Fault Current is calculated using the current that can flow (is this 20 amps or is it the 6000amps?) which is the same for any length of cable run and the time which depends on the circuit breaker (I think) and does not change regardless of the length of the cable run. In Equation #2 we have I (I guess this is the Fault Current from Equation #1), t (I guess this is the same t in Equation #1), and K (which is found in a table). When you are looking in the table to find K what are the numbers you use to locate the appropriate value of K in the table?

Chownah

Please bear in mind that this equation & finding 'K', is a very small portion of the total calculation.

Anyway, 'K' is based upon the type of cable insulation, the 'starting' temperature & the 'final' temperature of the cable (of which you have a choice. This is where you need to make an educated decision).

BTW, the cable size input would change as the length changes, therefore varying the outcome of cable size in the above final equation.

Edited January 28, 2007 by elkangorito

[Somtham]

Have a question regarding disconnecting a hot line. The previous owner of our house had an electrician splice into the main electrical cables that feed our house. This spliced in wire then runs to a workshop. I want to disconnect the cable at the splice which is covered with tape. If I wear rubber gloves to take off the tape and unwrap the splice how thick should the gloves be and what resistance of rubber to avoid current passing through them.

Thanks and rgds

[Crossy]

Have a question regarding disconnecting a hot line. The previous owner of our house had an electrician splice into the main electrical cables that feed our house. This spliced in wire then runs to a workshop. I want to disconnect the cable at the splice which is covered with tape. If I wear rubber gloves to take off the tape and unwrap the splice how thick should the gloves be and what resistance of rubber to avoid current passing through them.

You need proper electricians gauntlets, which are likely to cost as much as getting an electrician to disconnect the offending cable

Whilst regular rubber gloves are quite thick enough for handling 220V it only needs one strand of the cable to penetrate and you are history!

PLEASE do not attempt to remove this splice whilst the power is on. There should be a means of isolating the supply at or near the meter, open the breaker or pull the fuse.

[chownah]

Since I'm a farmer and not an electrician I can give advice in situations like this without the risk of ruining my reputation...what me? reputation? hah!

Cutting a power supply cable is really not much more dangerous than cutting a smaller wire from what I can gather. A small wire can kill you just as dead as a big one. 220V is 220V and it doesn't matter what size the wire is.......I'm telling you this to steady your nerves a bit....when handling live wire you need to have steady nerves. Have you ever watched a professional Thai crew work on the powerlines? Do they look nervous...no. They handle live wire every day...and live to talk about it.....usually.

First, I would not try to remove the spliced wire...I would just cut it off and then insulate it. I would probably just put a ton of good quality black tape on it but there are probably products on the market that would be better than the black tape...I might even research this a bit to find something better but if it is not available then black tape it is (assuming that the short wire stub that remains is out of reach of even basketball stars on steroids (aren't they all?).

So...now that you have the insulation scoped (sussed) out now you need a tool for cutting the cable....cable cutters...hack saw....hatchet....machette....many options. The important thing is that whichever one you choose be sure that it has an insulated handle (tools with two handles should have two insulated handles...and by "handle" I mean anyplace where you might want to grab the tool in your excitement). The nice thing about using professional grade cable cutters (like the linemen I mentioned above use) is that they will have insulated handles which top notch insulation which will do the job....that's what the pros use....and believe me that professionals DO cut hot lines without turning the power off...I know because I have seen it many many many times...and even more than that. If you want to use a tool but it has no insulated handles then you can insulate the handles with pvc pipe, water hose (dry water hose), or tons of black tape...or combinations of these.

So....now you've got your tape or other insulation to put on the stub of a wire that will remain and you've got your tool of choice prepared with adequately insulated handles....now to the gloves. Really there is no need for gloves if you've got insulated handles (and are coordinated enough to be able to reliably handle the tool by only touching the insulated part of the handle)...and gloves can make you clumsier...but if you want to wear gloves then I recommend those (usually) black gloves you can buy in various sizes and leather gloves in combination. First put a close fitting new pair of those thick rubber gloves on after first examining them to make sure that they are not defective and then over that use a good pair of new leather gloves...dry gloves....and if you want you could put another pair of rubber gloves....or two or three....I'd probably wear one pair of rubber gloves and nothing else (clothes of course...not nud_e) and consider it to be sort of ridiculous...but I'm a ridiculous kind of guy sometimes (just look at some of my posts) so oh well.....

So...now you've got your tape or other insulation to put on the stub and you've got you tool for cutting with insulated handles and you've got your gloves (also wear a stiff jacket and substantial long pants and shoes...real shoes...hat too I guess....basically cover up....dry clothes please) so now to proceed...you get your ladder (bamboo ladder...no aluminum)....oh wait....don't forget to disconnect the wire you are cutting and tie it up and be absolutely sure that it is not connected to anything and that no uninsulated parts of it can come in contact with the ground or anything else that is in contact with the ground (which is just about everything here on the planet).....ok....put up your ladder and take your time so you can climb up it and feel balanced and comfortable up there while working....then ascend the ladder. Check to see if there is alot of tension on any of the cables....you don't want any cables bouncing around or moving abruptly when a cable is cut. If there is alot of tension then relieve it...or beware of how the cables can move and take precautions.....then cut the bloody thing.

Disclaimer: Never take my advice....I'm an idiot and you could hurt yourself if you do what I have suggested. It actually is very bad advice and I'm sure that others will come on and tell you this. You could even die....which doesn't stop stuntmen but perhaps it should stop you.

Chownah

Edited January 31, 2007 by chownah

[elkangorito]

..............Disclaimer: Never take my advice....I'm an idiot and you could hurt yourself if you do what I have suggested. It actually is very bad advice and I'm sure that others will come on and tell you this. You could even die....which doesn't stop stuntmen but perhaps it should stop you.

Chownah

Actually, the so called Thai 'professionals' only work on live equipment because they have to. It is NEVER recommended to work on live equipment. Always look for ways to isolate the supply...and do not trust anything you think might be insulation. Unless the insulation is designed to be used for electrical purposes, don't use it.

Sorry Chownah, couldn't help myself.

[chownah]

..............Disclaimer: Never take my advice....I'm an idiot and you could hurt yourself if you do what I have suggested. It actually is very bad advice and I'm sure that others will come on and tell you this. You could even die....which doesn't stop stuntmen but perhaps it should stop you.

Chownah

Actually, the so called Thai 'professionals' only work on live equipment because they have to. It is NEVER recommended to work on live equipment. Always look for ways to isolate the supply...and do not trust anything you think might be insulation. Unless the insulation is designed to be used for electrical purposes, don't use it.

Sorry Chownah, couldn't help myself.

No problem. Did I ever tell you about the time my friend and I moved the live supply cables on his house from his old service entrance to his new one?.....well it was...........

Chownah

[Somtham]

Have a question regarding disconnecting a hot line. The previous owner of our house had an electrician splice into the main electrical cables that feed our house. This spliced in wire then runs to a workshop. I want to disconnect the cable at the splice which is covered with tape. If I wear rubber gloves to take off the tape and unwrap the splice how thick should the gloves be and what resistance of rubber to avoid current passing through them.

You need proper electricians gauntlets, which are likely to cost as much as getting an electrician to disconnect the offending cable

Whilst regular rubber gloves are quite thick enough for handling 220V it only needs one strand of the cable to penetrate and you are history!

PLEASE do not attempt to remove this splice whilst the power is on. There should be a means of isolating the supply at or near the meter, open the breaker or pull the fuse.

Thanks for the advice Crossy. Unfortunately there are no breakers or fuses from the supply pole to the meter (3 phase) to the house. The offending wire is spliced in front of the house off the main feed to the house, runs through the attic, out the back of the house, across the patio roof and to the workshop in back.

I asked the wife to call the guy at the electric company that installed the 3 phase meter and lines.

again, thanks.

[elkangorito]

Have a question regarding disconnecting a hot line. The previous owner of our house had an electrician splice into the main electrical cables that feed our house. This spliced in wire then runs to a workshop. I want to disconnect the cable at the splice which is covered with tape. If I wear rubber gloves to take off the tape and unwrap the splice how thick should the gloves be and what resistance of rubber to avoid current passing through them.

You need proper electricians gauntlets, which are likely to cost as much as getting an electrician to disconnect the offending cable

Whilst regular rubber gloves are quite thick enough for handling 220V it only needs one strand of the cable to penetrate and you are history!

PLEASE do not attempt to remove this splice whilst the power is on. There should be a means of isolating the supply at or near the meter, open the breaker or pull the fuse.

Thanks for the advice Crossy. Unfortunately there are no breakers or fuses from the supply pole to the meter (3 phase) to the house. The offending wire is spliced in front of the house off the main feed to the house, runs through the attic, out the back of the house, across the patio roof and to the workshop in back.

I asked the wife to call the guy at the electric company that installed the 3 phase meter and lines.

again, thanks.

The above situation is typical of many electrical installations in Thailand, which is dangerous.

The proper way is to ensure that ALL sub-circuits are fed from the load side of the main distribution board, through a dedicated circuit breaker. If this method is applied, all circuits throughout the installation can be isolated from one point (the main switch/circuit breaker) at the main distribution board.

[chownah]

In the US the meters can be pulled quite easily but there is a seal which is not suppposed to be broken so you have to call the elec company to come and do it for you so they can replace the security seal when you are done.

Chownah

[elkangorito]

It is mandatory in Australia that any installation must be able to be safely isolated from the supply, without risking personal injury.

[elkangorito]

It appears that some people have problems when it comes to sizing their electrical supply. See link below.

Electrical Panel

The size of incoming mains cables & the kilowatthour meter is easily calculated. Those with any questions can either PM me or ask here.

[Somtham]

Ah, I'm here another day to write another post.

The guy from the electric company stopped by last night on his way home from work. Took a look at the wires overhead and said "where's the ladder?" Grabbed some oridinary wire cutters (no gloves), up the ladder, snip snip finished. I handed him some electrical tape and he wrapped both wires and that was that. He went around to the back of the house. Up the ladder again and pulled the wires out through the back.

On his way back to the car I offered him B500 and he refused to take it, several times. This is not the first time this guy has come over for electrical work and refused payment.

rgds and thank you for your replies.

[chownah]

That guy is a total fool!!!! hahahahhaahhahahaha how very un-"professional" ahahhahahahahahaha

Chownah

[elkangorito]

Ah, I'm here another day to write another post.

The guy from the electric company stopped by last night on his way home from work. Took a look at the wires overhead and said "where's the ladder?" Grabbed some oridinary wire cutters (no gloves), up the ladder, snip snip finished. I handed him some electrical tape and he wrapped both wires and that was that. He went around to the back of the house. Up the ladder again and pulled the wires out through the back.

On his way back to the car I offered him B500 and he refused to take it, several times. This is not the first time this guy has come over for electrical work and refused payment.

rgds and thank you for your replies.

If he keeps this up, this may the last time anybody will see him.

"One flash & you're Ash!"

[chownah]

Some electricians say that if you wear dry rubber footwear and keep one hand in your back pocket all the time then you never have to worry about serious injury from handling house wiring!!

Personally I think that if a person knows their abilities then they can decide for themselves whether they should handle live wires...let's face it each individual is the one who make the final decision on this. Some people should not do it...if you can't remain calm and focused on what you are doing then you shouldn't do it. If someone look nervous while handling live wires then they shouldn't be doing it. On the other hand someone who is so casual about it that they don't maintain their focus shouldn't be doing it either.

But then I'm an idiot and any advice I have given here is clearly foolish advice and if you take this advice and then injure or kill yourself or someone else then you will have demostrated that you are even more foolish than the idiot who made this post.

Chownah

Edited February 1, 2007 by chownah

[Crossy]

Some electricians say that if you wear dry rubber footwear and keep one hand in your back pocket all the time then you never have to worry about serious injury from handling house wiring!!

Quite true, but the footware must be RUBBER and it must be DRY, in LOS dry could be somewhat difficult.

The 'one hand' adage is a very useful one that is tought to many 'lectricians (it was the second thing I learnt, after finding where the loo was), the idea is to avoid cross-body (through the heart) current which is considerably more lethal than down an arm and leg.

Like elkangorito posted, handling live kit is best avoided at all costs, if you can kill the juice, do so, before it kills you

Experiment at your own risk!!!

[Somtham]

Quite true, but the footware must be RUBBER and it must be DRY, in LOS dry could be somewhat difficult.

The 'one hand' adage is a very useful one that is tought to many 'lectricians (it was the second thing I learnt, after finding where the loo was), the idea is to avoid cross-body (through the heart) current which is considerably more lethal than down an arm and leg.

Like elkangorito posted, handling live kit is best avoided at all costs, if you can kill the juice, do so, before it kills you

Experiment at your own risk!!!

I was taught stand on your right leg and work with your right hand. If there's a problem the current will flow down the right side of your body hopefully negating death :-( I even use this technique when turning light switches on and off in Thailand.

One of my projects this year is to rewire the 3 buildings on the property installing proper grounds, breaker panels, switches, EFI breakers where required, and outlets. One building is finished.

Hopefully I can continue to receive professional advice from you guys when I need it.

Thanks

Oh yeh, the electrician that didn't die last night was wearing a thick sole rubber shoe and standing on the roof tiles when he cut the wire.

[h90]

guys come on, thats basic knowlege:

take good shows with rubber bottom and you can work on a live wire without any problem, no matter where you do the other hand. It is like a bird on the wires outside.

The only reasons why you shouldn't do it:

thouch the wet wall nearby and you jump

if there is something turned on and the two sides are sepperated that you have two different levels in your hand, make you jump as well.

You oversee any other problem.

But if the electric can not flow thru you it is no problem, you can hang on the 380 kV cable as long as you are far away from anything else.

Quite true, but the footware must be RUBBER and it must be DRY, in LOS dry could be somewhat difficult.

The 'one hand' adage is a very useful one that is tought to many 'lectricians (it was the second thing I learnt, after finding where the loo was), the idea is to avoid cross-body (through the heart) current which is considerably more lethal than down an arm and leg.

Like elkangorito posted, handling live kit is best avoided at all costs, if you can kill the juice, do so, before it kills you

Experiment at your own risk!!!

I was taught stand on your right leg and work with your right hand. If there's a problem the current will flow down the right side of your body hopefully negating death :-( I even use this technique when turning light switches on and off in Thailand.

One of my projects this year is to rewire the 3 buildings on the property installing proper grounds, breaker panels, switches, EFI breakers where required, and outlets. One building is finished.

Hopefully I can continue to receive professional advice from you guys when I need it.

Thanks

Oh yeh, the electrician that didn't die last night was wearing a thick sole rubber shoe and standing on the roof tiles when he cut the wire.

[elkangorito]

Just got some info that may be useful.

One of my electrical colleagues here at the Technical College has informed me that if you need a kilowatt hour meter for an installation & it is your first electrical installation with the PEA/MEA & it is NOT a commercial or industrial installation, a kilowatt hour meter will be supplied free of charge but it is owned by the energy authority. So if it buggers up, they have to fix it at their expense.

If you own the meter & it buggers up, you are obliged to fix it at your expense.

So far, I'm assuming this info to be correct. If anybody else has any definitive info about this, post it please.

And please, no guessing.

[Khonwan]

Just got some info that may be useful.

One of my electrical colleagues here at the Technical College has informed me that if you need a kilowatt hour meter for an installation & it is your first electrical installation with the PEA/MEA & it is NOT a commercial or industrial installation, a kilowatt hour meter will be supplied free of charge but it is owned by the energy authority. So if it buggers up, they have to fix it at their expense.

If you own the meter & it buggers up, you are obliged to fix it at your expense.

So far, I'm assuming this info to be correct. If anybody else has any definitive info about this, post it please.

And please, no guessing.

My 3-phase meter blew apart during a lightning strike a few months ago - PEA replaced it for free.

[Crossy]

A dumb question.

If I should opt for 3-phase (we will be a big house on the end of a long feed) is it better to have a 3-phase meter or three single phase meters. ie which will give me the best (cheapest) billing options

The feed is already to the village, but the incoming 220x3 disappears off over the rice paddies and I don't see the main Tx.

[Khonwan]

A dumb question.

If I should opt for 3-phase (we will be a big house on the end of a long feed) is it better to have a 3-phase meter or three single phase meters. ie which will give me the best (cheapest) billing options

The feed is already to the village, but the incoming 220x3 disappears off over the rice paddies and I don't see the main Tx.

I'm not sure if PEA would provide three single-phase meters but were they to do so it should work out slightly cheaper in my opinion. A normal single-ph meter connected to the village costs 40.90 baht per month (plus VAT) standing charge whereas my 3-phase meter costs 228.17 baht per month (plus VAT) standing charge. Please note, however, my supply is via my own (PEA supplied) 50KVA 3-ph transformer. I pay the same unit charge as the villagers though.

I was going to say that the small saving might not be worth it should this preclude you from using 3-ph but, on second thoughts, I can't see why you cannot still hook up a 3-ph appliance. You're the sparky (I believe; I'm not): am I correct? If I am, 3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band.

[robint]

Its true, every apprentice tizzy is taught the one hand in pocket rule (and many other things)

sure rubber boots will protec you (so will a rubber mat if you are working at a bench)

think twice when you try to use two hands

be careful where you put your other hand.

aluminium ladders must have big rubber feet (but i hate using these, wooden is far safer)

I recommend you include the knuckle scrape test as well. just scrape your (dry) knuckles on any bare supposedly live wires you might be playing with, if any danger you will get a small prickle. A neon screw driver is always handy but be sure you have tested on a known live circuit first as they have been known to fail

survey your work area for wetness, dangerous objets (in case you fall)

its all built in to a tizzy's training, and he gets his ass kicked if he doesnt follow the rules

its easy for layment to think they know what they are doing. even i as a retired professional can still get caught out by the LOS f***k factor. It doesnt do to copy the shortcuts shown by local electricians,

let them fry themselves not you

[elkangorito]

A dumb question.

If I should opt for 3-phase (we will be a big house on the end of a long feed) is it better to have a 3-phase meter or three single phase meters. ie which will give me the best (cheapest) billing options

The feed is already to the village, but the incoming 220x3 disappears off over the rice paddies and I don't see the main Tx.

I'm not sure if PEA would provide three single-phase meters but were they to do so it should work out slightly cheaper in my opinion. A normal single-ph meter connected to the village costs 40.90 baht per month (plus VAT) standing charge whereas my 3-phase meter costs 228.17 baht per month (plus VAT) standing charge. Please note, however, my supply is via my own (PEA supplied) 50KVA 3-ph transformer. I pay the same unit charge as the villagers though.

I was going to say that the small saving might not be worth it should this preclude you from using 3-ph but, on second thoughts, I can't see why you cannot still hook up a 3-ph appliance. You're the sparky (I believe; I'm not): am I correct? If I am, 3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band.

Good & interesting info.

But I don't think any energy authority will let you get away with "3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band". I think the individual meter totals will be added to determine which price bracket you're in.

On the other hand, using one KWH meter to measure the power consumed by a 3 phase supply is not as accurate as having one meter per phase. I would reckon that the energy authority would make sure that any meter inaccuracy would be in their favour, which would steer me toward getting one KWH meter per phase.

[Khonwan]

A dumb question.

If I should opt for 3-phase (we will be a big house on the end of a long feed) is it better to have a 3-phase meter or three single phase meters. ie which will give me the best (cheapest) billing options

The feed is already to the village, but the incoming 220x3 disappears off over the rice paddies and I don't see the main Tx.

I'm not sure if PEA would provide three single-phase meters but were they to do so it should work out slightly cheaper in my opinion. A normal single-ph meter connected to the village costs 40.90 baht per month (plus VAT) standing charge whereas my 3-phase meter costs 228.17 baht per month (plus VAT) standing charge. Please note, however, my supply is via my own (PEA supplied) 50KVA 3-ph transformer. I pay the same unit charge as the villagers though.

I was going to say that the small saving might not be worth it should this preclude you from using 3-ph but, on second thoughts, I can't see why you cannot still hook up a 3-ph appliance. You're the sparky (I believe; I'm not): am I correct? If I am, 3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band.

Good & interesting info.

But I don't think any energy authority will let you get away with "3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band". I think the individual meter totals will be added to determine which price bracket you're in.

On the other hand, using one KWH meter to measure the power consumed by a 3 phase supply is not as accurate as having one meter per phase. I would reckon that the energy authority would make sure that any meter inaccuracy would be in their favour, which would steer me toward getting one KWH meter per phase.

It is for exactly this reason (PEA's loss of revenue) that I believe it probably would not be possible to have three single-ph metres installed at the one location. Were PEA to allow it, I can't see how their accounting systems (which are fully automated from my experience) could do anything but allow the relevant price bands to apply. Rather than mucking around with individually tailored billing systems, it makes more sense for them just to refuse to install 3 such meters.

[elkangorito]

A dumb question.

If I should opt for 3-phase (we will be a big house on the end of a long feed) is it better to have a 3-phase meter or three single phase meters. ie which will give me the best (cheapest) billing options

The feed is already to the village, but the incoming 220x3 disappears off over the rice paddies and I don't see the main Tx.

I'm not sure if PEA would provide three single-phase meters but were they to do so it should work out slightly cheaper in my opinion. A normal single-ph meter connected to the village costs 40.90 baht per month (plus VAT) standing charge whereas my 3-phase meter costs 228.17 baht per month (plus VAT) standing charge. Please note, however, my supply is via my own (PEA supplied) 50KVA 3-ph transformer. I pay the same unit charge as the villagers though.

I was going to say that the small saving might not be worth it should this preclude you from using 3-ph but, on second thoughts, I can't see why you cannot still hook up a 3-ph appliance. You're the sparky (I believe; I'm not): am I correct? If I am, 3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band.

Good & interesting info.

But I don't think any energy authority will let you get away with "3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band". I think the individual meter totals will be added to determine which price bracket you're in.

On the other hand, using one KWH meter to measure the power consumed by a 3 phase supply is not as accurate as having one meter per phase. I would reckon that the energy authority would make sure that any meter inaccuracy would be in their favour, which would steer me toward getting one KWH meter per phase.

It is for exactly this reason (PEA's loss of revenue) that I believe it probably would not be possible to have three single-ph metres installed at the one location. Were PEA to allow it, I can't see how their accounting systems (which are fully automated from my experience) could do anything but allow the relevant price bands to apply. Rather than mucking around with individually tailored billing systems, it makes more sense for them just to refuse to install 3 such meters.

Three single meters are available if you wish to buy them. Also, industry does not use one 3 phase KWH meter. They (the PEA/MEA) may not refuse such requests if one is willing to pay for the KWH meters.

[Khonwan]

A dumb question.

If I should opt for 3-phase (we will be a big house on the end of a long feed) is it better to have a 3-phase meter or three single phase meters. ie which will give me the best (cheapest) billing options

The feed is already to the village, but the incoming 220x3 disappears off over the rice paddies and I don't see the main Tx.

I'm not sure if PEA would provide three single-phase meters but were they to do so it should work out slightly cheaper in my opinion. A normal single-ph meter connected to the village costs 40.90 baht per month (plus VAT) standing charge whereas my 3-phase meter costs 228.17 baht per month (plus VAT) standing charge. Please note, however, my supply is via my own (PEA supplied) 50KVA 3-ph transformer. I pay the same unit charge as the villagers though.

I was going to say that the small saving might not be worth it should this preclude you from using 3-ph but, on second thoughts, I can't see why you cannot still hook up a 3-ph appliance. You're the sparky (I believe; I'm not): am I correct? If I am, 3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band.

Good & interesting info.

But I don't think any energy authority will let you get away with "3 single-ph meters may also save you a further bit extra since each meter may record an amount of units that puts you in a lower charge band". I think the individual meter totals will be added to determine which price bracket you're in.

On the other hand, using one KWH meter to measure the power consumed by a 3 phase supply is not as accurate as having one meter per phase. I would reckon that the energy authority would make sure that any meter inaccuracy would be in their favour, which would steer me toward getting one KWH meter per phase.

It is for exactly this reason (PEA's loss of revenue) that I believe it probably would not be possible to have three single-ph metres installed at the one location. Were PEA to allow it, I can't see how their accounting systems (which are fully automated from my experience) could do anything but allow the relevant price bands to apply. Rather than mucking around with individually tailored billing systems, it makes more sense for them just to refuse to install 3 such meters.

Three single meters are available if you wish to buy them. Also, industry does not use one 3 phase KWH meter. They (the PEA/MEA) may not refuse such requests if one is willing to pay for the KWH meters.

Interesting - I wish I had known that before buying my 3-ph meter.