Domestic Electricity Supply

[missismiggins]

Not sure if this is the best place to ask, but it is a bit general.

Anyone know what kind of current you could expect to get from your electric supply here?

My meter is rated at 15/45 Amp, which I "suppose" is 15Amp continuous and 45Amp peak???? Correct me if I am wrong.

The problem being is, the main breakers and safety cut outs are all rated at 60A. I use RCD and Safe-T-Cut together, these work fine no tripping etc.

The strange thing is Voltage drop, whenever you turn on a few appliances at the same time.

The main one being the electric shower unit, it runs on 3 settings - 3KW / 6KW / 10KW.

At the lowest setting (3KW) the voltage in the rest of the system drops to around 190 Volts, at 6KW it is down to about 175, which causes problems with computers crashing etc. and if the automatic pump comes on at the same time you cannot start a flourescent light.

I am curious to see if it is possible to get a higher rated electric meter or is 15/45 standard? because if 15A is the maximum rated continuous current then that is less than 4KW power for a whole house.

Even at 45 A the maximum is still just about 10KW.

Any ideas what may be causing the problem or is it just not enough electrical supply power (we live in a small rural village) only single phase supply, and only one pair of cables going through the village, my nearest transformer is about 750 metres from me. (I am using 750 V heavy aluminium cable from the meter to the house - around 200m long) it is almost the same diameter as the electric cables that are used by the power company, so that shouldn't be an issue, and also I am getting about 230V at the input to the cut outs, so it must be a load problem or a fault somewhere.

Thanks in advance for your advice.

[Crossy]

You'll get a better response in the DIY section where the sparkies hang out. MODS!

IIRC the 15/45 meter is 45A max (about 10kW) so your 60A breaker is correct.

You are however on a l-o-n-g feed, best bet is going to be an AVR (Automatic Voltage Regulator) to supply critical appliances (TV, aircon, freezer etc.). This will maintain the voltage at 220V even if the input falls to 170v or so, it does this by drawing more current from the line so obviously there could be a visous circle in operation here

What voltage do you have at your incoming breaker (at the fuse box in the house that is) with the shower on each setting? Will give us some idea of what is going on.

Edited April 1, 2008 by Crossy

[onzestan]

AFAIK you can apply for a more powerful meter, will cost you though.

cheers

onzestan

[Crossy]

AFAIK you can apply for a more powerful meter, will cost you though.

Whilst this is true, the major issue here is that the OP is on the end of nearly a kilometre of 220V feeder, a bigger meter won't help if the feeds aren't uprated by bringing the 22kV supply into the village (MONEY ).

[missismiggins]

You'll get a better response in the DIY section where the sparkies hang out. MODS!

IIRC the 15/45 meter is 45A max (about 10kW) so your 60A breaker is correct.

You are however on a l-o-n-g feed, best bet is going to be an AVR (Automatic Voltage Regulator) to supply critical appliances (TV, aircon, freezer etc.). This will maintain the voltage at 220V even if the input falls to 170v or so, it does this by drawing more current from the line so obviously there could be a visous circle in operation here

What voltage do you have at your incoming breaker (at the fuse box in the house that is) with the shower on each setting? Will give us some idea of what is going on.

Thanks for that advice Crossy, will post it there as you suggest.

As for the voltages, at the breaker side I get about 230 volts off , 190 volts at 3KW and 170 ish at 6KW - setting to 10KW doesn't seem to make any difference (sort of like it is already swamped - plus the water temperature at 6KW and 10KW seems the same)

Once again thanks!

[Crossy]

Thanks for that advice Crossy, will post it there as you suggest.

As for the voltages, at the breaker side I get about 230 volts off , 190 volts at 3KW and 170 ish at 6KW - setting to 10KW doesn't seem to make any difference (sort of like it is already swamped - plus the water temperature at 6KW and 10KW seems the same)

PM a mod who's online and ask them to move the thread rather than double posting (frowned upon).

[missismiggins]

AFAIK you can apply for a more powerful meter, will cost you though.

cheers

onzestan

Hi Onzestan,

interesting, do you have any info on a larger meter?

(the Kam Nan here reckons there isn't enough electric here, but I'm not convinced that is the case, i.e. when the temple has there do's here, they plug everything into the supply side of my meter (effectively stealing the electric) before my outlet side of the meter and those parties are burning way more than 10KW, so it is only after the meter that there seems to be a problem

Cheers

[jayenram]

When I connected up my house I had a 30/100A supply installed (expensive but I can't remember how much). The cable (armoured) to the house cost me Bht 12,000 for 50 m (year 2000).

Notwithstanding that, when one of the showers is turned on (and the water supply pump) I experience substantial voltage drop causing the UPS on the computer to click in and out virtually continuously.

Topic moved to "Do in yourself housing forum".

[Crossy]

Thanks for moving this jayenram

I'm wondering how much drop we're getting on the 200m of aluminium (it's not as good as copper) and we don't know the size used, can our OP either find out the cable size OR measure the voltage at the meter (the incoming end of the aluminium) with the shower on 3kW.

A quick-and-dirty calculation from the info given by the OP, ie 220V no load 190v at 3kW suggests a line resistance of about 3 ohms to the transformer.

Edited April 1, 2008 by Crossy

[missismiggins]

When I connected up my house I had a 30/100A supply installed (expensive but I can't remember how much). The cable (armoured) to the house cost me Bht 12,000 for 50 m (year 2000).

Notwithstanding that, when one of the showers is turned on (and the water supply pump) I experience substantial voltage drop causing the UPS on the computer to click in and out virtually continuously.

Topic moved to "Do in yourself housing forum".

Wow, not cheap!

There appears to be a new electric supply being put through the village soon, however it is still just a 2 cable system (no 3 phase) however there is a new transformer going to go up on a new pole about 50-60metres from me, and it is supplying power to a new road. If I get the meter moved from where it is now maybe I will get an improvment, the only worry is, no one else is connected yet, so I woul;d be the only one on there, if it goes down.....how long to wait to get the power back on is my worry.

Do you know what voltage is normally supplied on the 2 wire system prior to the transformer? I don't think it will be as high as 22KV but I may be wrong.

Regarding your meter, was this supplied by the electric company? or did you install it yourself?

They are a bit of a rip off! I had an irrigation pump running here originally 5/15A before the house was built and that cost me about 4K to put in. When the house was ready, the electrician told me that the 5/15 was fine for the house, I trusted him. Foolishly!

Later the electric company charged me 1K for burning the meter!

They then charged about 5K to replace with the 15/45 AND kept the old meter too!

They are on a good little earner!

Cheers for the help!

[missismiggins]

Thanks for moving this jayenram

I'm wondering how much drop we're getting on the 200m of aluminium (it's not as good as copper) and we don't know the size used.

Can I ask our OP to measure the voltage the the meter and at the fuse box in the house with the shower on 3kW.

Will do,

bear with me as I need to get someone to set the shower as it is about a kilometer to get to the meter as it is on the other side of a small river and I cannot get to it from my place directly (planning huh!)

[Crossy]

Better use the mobile phone too, don't want to run up the electric bill too much, or you could swim across the river

The incoming to the transformer is going to be around 10kV or 22kV. You will be much better off if you can get on the new transformer, you may not even need a new meter (do you really need a 10kW shower?).

Consider a solar pre-heater, we have a neighbour with 2m2 of solar, his water is too hot to shower with and all that heat is free (I like free) apart from the cost of the solar heater in the first place, DIY water heating is easy to arrange if you're on a budget.

Edited April 1, 2008 by Crossy

[missismiggins]

Better use the mobile phone to, don't want to run up the electric bill too much, or you could swim across the river

The incoming to the transformer is going to be around 10kV or 22kV. You will be much better off if you can get on the new transformer, you may not even need a new meter (do you really need a 10kW shower?) consider a solar pre-heater.

Lol,

no I don't need a 10KW shower, sorry, it's actually a "multipoint Panasonic thingy" supposed to supply hot water for everywhere, however we only need about 6KW in the winter.

The main problem is, even at 3KW if someone is having a shower then you cannot get the flourescent lights to fire, the microwave runs at a snails pace and the computer has a tendency to reboot!

I rechecked some measurements inside the house with all power off elsewhere and got the following - measured at the Safe-t-cut input,

3KW - 191V

6KW - 181V

10KW- 161V

I guess it seems to be trying to do the right thing as it appears do be roughly doubling the current each time as I presume this is 15A / 33A / 59A respectively, it's just this voltage drop that is the problem, I have three pumps that all use electric motors 2 outdoor 2" waterbore pumps and a domestic water pump for the house and I worry that the drop will ruin the motors, also the fridge motors etc.

The lights are a damned nuisance but once they are on they generally stay on, however, you certainly know when someone is taking a shower with the standard lamps - it is like in the movies when they switch on the electric chair and all goes dim a buzzes! LOl

I'll get back to you with the meter voltages when the other half gets back later.

Cheers for the help!

[Crossy]

Hmmm, you have a lot of stuff.

Yes, constant low voltage will fry the motors

Whilst waiting for the other half, make a list of everything that uses electricity along with its power rating ([k]Watts or [k]VA), we may as well do this properly and actually calculate some demand figures

[jayenram]

When I connected up my house I had a 30/100A supply installed (expensive but I can't remember how much). The cable (armoured) to the house cost me Bht 12,000 for 50 m (year 2000).

Notwithstanding that, when one of the showers is turned on (and the water supply pump) I experience substantial voltage drop causing the UPS on the computer to click in and out virtually continuously.

Topic moved to "Do in yourself housing forum".

Wow, not cheap!

Regarding your meter, was this supplied by the electric company? or did you install it yourself?

I'm still racking my brain to try and remember the installation cost. I have the receipt somewhere but it's with 3,000 others and I never got around to filing them in any kind of order (being all in Thai doesn't help). However, I'll hazzard a guess that the connection fee was over Bht 10,000.00 but the meter was included.

[missismiggins]

Hmmm, you have a lot of stuff.

Yes, constant low voltage will fry the motors

Whilst waiting for the other half, make a list of everything that uses electricity along with its power rating ([k]Watts or [k]VA), we may as well do this properly and actually calculate some demand figures

Now some figures...WOW!

Okay,

been through the main items, I haven't included things like mobile phone chargers etc. as

they are pretty insignificant.

The main items listed are the ones that COULD possibly be on AT THE SAME TIME.

The remainder are just used now and again, and would be unlikel;y to be on with everything

else.

TV 150

DVD 15

MICROWAVE 800

PUMP Sprinkler 2530

PUMP Bore 2645

PUMP Home 300

SEWING MACHINE 460

WASHING 500

FRIDGE 500

FRIDGE 350

FREEZER 85

MULTIPOINT @3KW 3000 / 6kW / 10kW

11335 total.(a) / 14335 (6KW) / 18335 (10kW)

The reasons the three pumps can all be on is one is a 2hp automatic bore hole that supplys

tanks for the house water, the second is a 2hp bore hole that supplies sprinkler systems for

the trees, and the third is the "on demand" home pump that moves water from the tanks around

the house.

There are additional things that could be on but less likely

Lighting 1330

Toaster 860

Rice cooker 450

Blender 300

Shower 4500

Vacuum 1300

Water Boiler 1800

Iron 1200

Amplifier 500

Computer 400

TV/Video 400

13040 total (

The rest of the stuff I use could be things like power tools etc. but these again would

probably not be used at the same time as everything else and make up a total of about 5KW,

but I could only operate one at a time anyway and the heaviest is about 2000W.

So I guess I need at least 12kw / 50 A or so available on a daily basis (however I am not

using anywhere near that power as my bills are around 2000 month.) but there is likely to be

points during the day that it peaks, and could even be higher.

Boy it gets frightening when you start to look at it like this.....It may be I am in for

another repair bill for the meter as it is certainly possible I break the 50 Ampere mark on

a daily basis LOL!

And I checked the cable best I could from the meter, there is no rating or ID on it but it

is approximately 1cm diameter, and is made up (if I remember) of 9 strand solid aluminium.

What actually happens in a case like this, say I use 12KW at any point in time which would

(at normal voltage of 230V be about 52 Amps. ) but with the voltage drop to the level of 167

volts I measured with the 10K on, would I in fact be using nearer 72Amps???? i.e do the

appliances still consume the Wattage and guzzle additional current or, do they actually get

starved????

Interesting stuff this!!

OK, last check - checked the meter side of the circuit (I can only get the probes into the

output side not the input) but at the meter with no load there is 231Volts, with the 3KW

load it drops to 215V, plus, the cable going from the main supply to the meter is about half

the diameter of the cable I am using FROM the meter!!!

So I appear to lose about 16V at the meter and 24V over the cable, about.08V/M (which I

think is pretty much OK?).

What to do next methinks!

Cheers

[Crossy]

OK more quick and dirty calcs.

AT THE METER

Off load 230V

3kW (14A) 215V [15V drop from 230V]

If we extrapolate to the maximum rating of your meter (45A or about 10kW which also happens to be somewhere near your guestimated maximum load) then you'll be dropping about 48V, already down to 182V and we've not even started considering your 200m run to the house

Replacing your meter with a 'bigger' one won't help unless of course the supply to the meter is uprated. Basically, you're buggered. The village supply just isn't up to a load anything like you're hoping to add

You should seriously investigate getting put on that new transformer, this will solve 99% of your issues at one swoop, whilst at it consider getting the bigger supply meter.

Meanwhile, get used to cold showers and hot rooms Get an AVR (NOT a UPS although you may want to add one as well if you also suffer from power outages) for the computer, that will keep the voltage the PC sees at 220V whilst you're having a shower (there's a thread in the computer forum "coping with low voltage mains" that discusses AVRs). You could also add an AVR to the lighting and fridge circuits although if you're going for the new transformer it's probably not worth it now.

EDIT AVR thread is here http://www.thaivisa.com/forum/index.php?showtopic=162728

Edited April 1, 2008 by Crossy

[missismiggins]

OK more quick and dirty calcs.

AT THE METER

Off load 230V

3kW (14A) 215V [15V drop from 230V]

If we extrapolate to the maximum rating of your meter (45A or about 10kW which also happens to be somewhere near your guestimated maximum load) then you'll be dropping about 48V, already down to 182V and we've not even started considering your 200m run to the house

Replacing your meter with a 'bigger' one won't help unless of course the supply to the meter is uprated. Basically, you're buggered. The village supply just isn't up to a load anything like you're hoping to add

You should seriously investigate getting put on that new transformer, this will solve 99% of your issues at one swoop, whilst at it consider getting the bigger supply meter.

Meanwhile, get used to cold showers and hot rooms Get an AVR (NOT a UPS although you may want to add one as well if you also suffer from power outages) for the computer, that will keep the voltage the PC sees at 220V whilst you're having a shower (there's a thread in the computer forum "coping with low voltage mains" that discusses AVRs). You could also add an AVR to the lighting and fridge circuits although if you're going for the new transformer it's probably not worth it now.

EDIT AVR thread is here http://www.thaivisa.com/forum/index.php?showtopic=162728

Many many thanks!

you seem to have hit the nail on the head! I Am BUGGERED

A few things you might be able to help me with though...

1: I am using a Fluke 87 III and if I measure max/min etc. it appears that if someone uses more power in the village, my voltage fluctuates..I suppose this is symptom of not having enough juice? it varies (no load from 227-237V with nothing connected - i.e. if Mr. Sat puts on his shower 1km from me I drop 10V....?)

2: The current consumption...i.e. will an appliance consume its requird wattage regardless of the voltage - i.e if a kettle is rated 1000w will it take 1000w regardless of the voltage?, in other words if the voltage drops will it simply eat more amps?

3: I would imagine that if I suffer from this voltage drop my consumption of electric becomes innefficient, am I wasting electric due to heat?

4: Could I improve things by putting the 200m cable underground? rather than on poles?

5: What do you reckon on the cable - 0.08v/m is this reasonable drop or should I look to copper?

6: The small diameter cable provided by the electricity company, approx. 1/2 cm diameter...is it worth having this changed?

Thanks for your help today, it really has been appreciated, and I have had my eyes opened too...back in the UK we tend to just forget about these issues, everything seems to workk just fine, here, it is getting the balance right!

Cheers

PS We are like something out of the land that time forgot..the whole village (despite being a "tambon" doesn't even have a telephone...hence I use my mobile as a modem,,,3G..don't hold your breath

[Beardog]

Isn't 15/45 to low for your needs. We put in 30/45 for our house that does not even have an ac. We could have gotten away with a 15 amp service but put in a 30 in case we get air(don't need it-house stays very cool) & a hot water shower also doubtful as it would be wasteful to heat hot water. Your village wouldn't allow you to get a bigger service from the start? Or do you need to upgrade the transformer first? Buy the way if you are planning on running a lot of #25 copper for a 30 amp breaker for a long distance- break out your wallet. OUCH!!!!!

[Crossy]

1: I am using a Fluke 87 III and if I measure max/min etc. it appears that if someone uses more power in the village, my voltage fluctuates..I suppose this is symptom of not having enough juice? it varies (no load from 227-237V with nothing connected - i.e. if Mr. Sat puts on his shower 1km from me I drop 10V....?)

2: The current consumption...i.e. will an appliance consume its requird wattage regardless of the voltage - i.e if a kettle is rated 1000w will it take 1000w regardless of the voltage?, in other words if the voltage drops will it simply eat more amps?

3: I would imagine that if I suffer from this voltage drop my consumption of electric becomes innefficient, am I wasting electric due to heat?

4: Could I improve things by putting the 200m cable underground? rather than on poles?

5: What do you reckon on the cable - 0.08v/m is this reasonable drop or should I look to copper?

6: The small diameter cable provided by the electricity company, approx. 1/2 cm diameter...is it worth having this changed?

OK, some answers

1. Volt drops on loading are a fact of life on any system, that said the voltage is supposed to remain within tolerance even at the maximum load. Mr Sat taking a shower should not put you outside the 10% tolerance even if you're also taking a shower.
   
2. A kettle is a resistive load, the current is directly proportional to the voltage, lower voltage=lower current draw and lower power so it takes longer to boil. Motors on the other hand, can do some really weird things when under volted, they tend to be constant power and draw more amps at lower voltages, but get outside their specified input range and they can get very upset
   
3. You're only 'wasting' power in cables that are on your side of the meter, anything the other side is PEA's problem.
   
4. NO!
   
5. You need to take account of the current too, usually volt drop calculations are in mV/A/m (milliVolts per Amp per Metre). You're getting .08/14 = 5.7mV/A/m which is roughly equivalent to 6mm2 copper (I don't have the Aluminium figures to hand). 6mm2 copper would be rated at about 45A so you're pretty near the limit there too. Changing to 16mm2 copper would get yo down to 2.4 mV/A/m (and an 85A load) but a 200m run is not going to be cheap and it won't help with the drop the other side of the meter. Also those big pumps are going to draw around 4 times their rated current on start, you need to take account of that when sizing the cable (16mm2 WILL be too small).
   
6. It's a very long run (750m you reckon) so yes changing the cable would help, do YOU want to pay for it? That said I expect that the 'small' cable is only the dropper, the wire up on the poles is going to be much bigger (well it SHOULD be much bigger). I'll bet the transformer is on its limit too (bigger one will need paying for). Far better and cheaper to get on the closer supply.
   

Talk to the local supply people about getting a 30/100 meter (I think this is the biggest single phase meter available, may be wrong), show them the voltages, point at the new transformer (there is zero point getting the bigger meter on the supply feeder you have now). They are often very helpful although whatever solution they propose it's not going to be cheap

Edited April 2, 2008 by Crossy

[Khonwan]

Crossy,

As you know, I'm not an electrician but I do have a fair bit of experience (unfortunately) of voltage drop. How about this as a suggestion for the OP:

I presume his phase cable is 50mm²; regardless, I suggest he could improve his situation by piggybacking another 50mm² to his phase (live) cable. So much the better if he does this from the transformer (with his local PEA's agreement and assistance) in addition to the 200m run between meter and home. I reckon this would cost him around Bt20,000 for 1,000m 50mm² cable.

I am, of course, ignoring the possibility of PEA installing a new transformer closer to his home at their cost.

Rgds

Khonwan

[Crossy]

I presume his phase cable is 50mm²; regardless, I suggest he could improve his situation by piggybacking another 50mm² to his phase (live) cable. So much the better if he does this from the transformer (with his local PEA's agreement and assistance) in addition to the 200m run between meter and home. I reckon this would cost him around Bt20,000 for 1,000m 50mm² cable.

It would certainly improve matters, exactly how much is difficult to quantify without knowing the current cable size (probably 50mm2) and how much load over and above the OP's draw is actually being supplied.

It really needs a proper survey and supply upgrade to be performed by PEA. As a last resort if the connection to the 'new' tranformer doesn't come off, gotta be better than nothing. Even replacing just his 200m run with 50mm2 copper will improve things (slightly).

The killers are those two bl00dy great pumps and the blast-furnace water heater everything else could be worked-around with the judicious application of AVRs.

Edited April 2, 2008 by Crossy

[Beardog]

Yes those pumps & the water boiler are hungryyyyyyyyyy!

I am glad I got small consumption rates!