Thread: Electric Voltage seems variable

Presently find that power is fine during the day but around 6pm the water pumps stop working and lights flicker have been told that if I install a voltage regulator it will boost the voltage so no more problem

Can anyone tell me if this is true and how it works and whether there is a different/better solution

A voltage regulator will only be good for momentary fluctuations, like one minute or less. Maybe you need a generator which kicks in a certain voltage level?

Originally Posted by donald36

Presently find that power is fine during the day but around 6pm the water pumps stop working and lights flicker have been told that if I install a voltage regulator it will boost the voltage so no more problem

Can anyone tell me if this is true and how it works and whether there is a different/better solution

You can get a 45 amp Voltage stabiliser for around 19,900 Baht that may well be enough for you, otherwise there are 70 and 100 amp ones that will get rather expensive. Places like Global house stock them.

Lights flickering while not nice aren't a big problem but low voltage will kill things that have a motor.

Unfortunately there is no such thing as something for nothing. If your supply voltage/current is dropping not a lot you can do. You might want to check the amp rating of your meter/supply. As stated could be you are downstream from hi wattage users. ( any factories etc nearby?)
If you can get any sense out of the PEA you might want to enquire...?

Originally Posted by crepitas

Unfortunately there is no such thing as something for nothing. If your supply voltage/current is dropping not a lot you can do. You might want to check the amp rating of your meter/supply. As stated could be you are downstream from hi wattage users. ( any factories etc nearby?)
If you can get any sense out of the PEA you might want to enquire...?

You are correct that you don't get something for nothing. But wrong about not being able to do something about it. The voltage stabiliser I mentioned will accept a lower (or higher) than normal voltage in and output a normal voltage out.

The price for the stabilisation from low to high is an increased power consumption, as an example the normal draw might be 10amps but when the voltage drops it might be 11 or 12 amps.

And for sure if you can get the PEA to do something then that is the best option.

Thank you Gentlemen, I am most grateful for your replies all of which are most helpful ,it seems that it will have to be fixed at source with the Electricity company as the voltage reductions are not temporary but for hours at a time
thank you once again

If anyone is interested… an electricity primer:


Electricity can be loosely analogous to water.


Where volts are flow rate and amps are volume, combine the two by multiplication and you have power (watts). Increasing flow rate per Woodworker will demand more volume ...there lies the problem if it is not available. A dead battery on a vehicle will often register +- 12volts but has not enough available amps to drive the starter.


Ergo if your supply has a two inch pipe and your neighbor has a four inch pipe then he will reduce your power.


Simple example: think what happens if you are in the shower and someone turns on a tap or flushes a toilet?

Trivia: The word ‘tap’ remains in common use to hook into electricity, cable TV and data because plumbers were the first artisans to be utilized.

Originally Posted by crepitas

If anyone is interested… an electricity primer:


Electricity can be loosely analogous to water.


Where volts are flow rate and amps are volume, combine the two by multiplication and you have power (watts). Increasing flow rate per Woodworker will demand more volume ...there lies the problem if it is not available. A dead battery on a vehicle will often register +- 12volts but has not enough available amps to drive the starter.


Ergo if your supply has a two inch pipe and your neighbor has a four inch pipe then he will reduce your power.


Simple example: think what happens if you are in the shower and someone turns on a tap or flushes a toilet?

Crepitas, agreed, you're 100% correct, but unfortunately sometimes it's like trying to explain that the earth is round to a flat earther who's got a friend named Google!

Simple example: think what happens to the lights if you have a 6kw shower heater and someone has a shower.

Voltage stabilisers do work, but you pay for them in increased electricity bills for as long as they're connected - even if there are no power fluctuations your bill will still go up and if the power varies your bill goes up accordingly. As you said, you don't get something for nothing, and if you're lucky the cheap ones are 80% efficient at best. At a VERY broad guess, you can expect your bill to go up by 20% if it's connected all the time, obviously depending on the degree of fluctuation.

Originally Posted by sometimewoodworker

The voltage stabilisers are effective for domestic use, if they weren't then they would be returned and places like Global, HomePro etc would stop selling them

So ..... you can tell if something works because otherwise nobody would be selling it?

Are you serious?

I am going to repeat myself and reiterate that these constant voltage devices are ultimately dealing with a symptom and not the disease. Ultimately the local supply is seriously under capacity for the load the community are all putting on it.

financial responsibility for electricity distribution in thailand seems to be split between the electricity companies and the local governments. you need to get the electricity company to acknowledge you have a problem, work out what needs to be done to fix it and work out whos supposed to pay for it.

This can take a painful period of time and things only happen for those who shout loadist... hence the need to work as a community... mob handed. Better to start this process sooner or later.

another option to consider, if you have the medium voltage 11k line running on the top of your electricity polls, it might be worth finding out if you can install your own single phase 11kv transformer. No idea about costs.... but it lets you buy your way out of the crap supply problems you are having and go into full blown I'm alright jack mode

Originally Posted by hazz

I am going to repeat myself and reiterate that these constant voltage devices are ultimately dealing with a symptom and not the disease. Ultimately the local supply is seriously under capacity for the load the community are all putting on it.

financial responsibility for electricity distribution in thailand seems to be split between the electricity companies and the local governments. you need to get the electricity company to acknowledge you have a problem, work out what needs to be done to fix it and work out whos supposed to pay for it.

This can take a painful period of time and things only happen for those who shout loadist... hence the need to work as a community... mob handed. Better to start this process sooner or later.

another option to consider, if you have the medium voltage 11k line running on the top of your electricity polls, it might be worth finding out if you can install your own single phase 11kv transformer. No idea about costs.... but it lets you buy your way out of the crap supply problems you are having and go into full blown I'm alright jack mode

All good points.

If I get a cold I treat the symptoms as I don't enjoy suffering.
If I get into the same position as the OP then I would treat the symptoms as for me the cost (20,000 ~30,000) would be acceptable while trying (but not too hard) to solve the disease, as again I don't enjoy suffering and unlike a cold the term of the disease is long and the outcome is unpredictable.
So would I then be in a (half?) blown I'm alright jack mode

Originally Posted by sometimewoodworker

Originally Posted by JohnG

Originally Posted by crepitas

If anyone is interested… an electricity primer:


Electricity can be loosely analogous to water.


Where volts are flow rate and amps are volume, combine the two by multiplication and you have power (watts). Increasing flow rate per Woodworker will demand more volume ...there lies the problem if it is not available. A dead battery on a vehicle will often register +- 12volts but has not enough available amps to drive the starter.


Ergo if your supply has a two inch pipe and your neighbor has a four inch pipe then he will reduce your power.


Simple example: think what happens if you are in the shower and someone turns on a tap or flushes a toilet?

Crepitas, agreed, you're 100% correct, but unfortunately sometimes it's like trying to explain that the earth is round to a flat earther who's got a friend named Google!

Simple example: think what happens to the lights if you have a 6kw shower heater and someone has a shower.

Voltage stabilisers do work, but you pay for them in increased electricity bills for as long as they're connected - even if there are no power fluctuations your bill will still go up and if the power varies your bill goes up accordingly. As you said, you don't get something for nothing, and if you're lucky the cheap ones are 80% efficient at best. At a VERY broad guess, you can expect your bill to go up by 20% if it's connected all the time, obviously depending on the degree of fluctuation.

Originally Posted by sometimewoodworker

The voltage stabilisers are effective for domestic use, if they weren't then they would be returned and places like Global, HomePro etc would stop selling them

So ..... you can tell if something works because otherwise nobody would be selling it?

Are you serious?

I see that you have gone from giving inappropriate information and advice about water having disclaimed any proficient as a plumber you are progressing to spreading FUD on another subject. I guess,in time, you will disclaim any proficient as an electrician or electrical engineer as well?

Modern (not cheap, built down to a price) voltage stabilisers are running at around 95% efficiency. (Fact 1)
Modern (not cheap, built down to a price) voltage stabilisers operate a pass-through mode when within a user specified range of voltages thus consuming virtually no power at those times. They also have a programmable operation time and outside that time also operate a pass-through mode (Facts 2&3)

Qed: unless you buy down to a price, if there are no fluctuations your bill doesn't change (refuted claim1)

There are longtime members of another forum who have had the same situation as the OP who have purchased voltage stabilisers from reputable suppliers (mostly from Global due to stock availability) who now no longer have the problem (refuted snark1) and others who have also bought based on the reports who are also happy with the purchase. One member has found that the stabiliser functioned down to 130volts.

Now as you seem to inhabit an alternative reality with regard to physics (return snark) it may be that in your world when products get retuned because they don't work shops keep on selling them with no regard to profit margins and customer satisfaction, however in this real world if enough get returned as not working they stop selling them. Despite claims by some people to the contrary reputable shops have a return policy in Thailand.

Of course as I said if the voltage stabiliser is doing its job and your supply is varying your electricity bill will increase. edit as the information is incorrect the current drawn increases if the voltage decreases, but it won't affect your bill as the meter is a true Watt-Hour meter (it uses voltage, current and power-factor to determine your consumption) big stabilisers with a variable transformer (variac) are very efficient, up in the high 90's, the smaller magneto-resonant type are less so and at low loads can get very lossy. So if you got a MR type it would affect the bill

Also your repair or replacement costs will also drop, things with motors will burn out with low voltage, other items also have drastically shorter life spans.

I was hoping to avoid this, as your attitude has already led to your having numerous abusive posts removed on the Udonmap forum and an open warning that the thread on your shed may be closed as a result.

I do not claim to be a qualified plumber or electrician and I have never pretended to be. Are You?

Your claims:

Modern (not cheap, built down to a price) voltage stabilisers are running at around 95% efficiency. (Fact 1)

True - BUT THE ONE YOU RECOMMEND IS NOT ONE OF THEM!!! That particular stabiliser claims 92% maximum efficiency. If you believe the claims made by cheap products made in China, up to you.

Qed: unless you buy down to a price, if there are no fluctuations your bill doesn't change (refuted claim1)

19,900 baht IS down to a price! You can hardly get much more "down"! Even the Chinese copies of American stabilisers (labelled as "American Designed") cost 30,000 baht and more. A good American or German stabiliser, as @hazz correctly said, will cost 100 -150,000 baht - these will do what you claim. Your piece of Chinese junk (or the piece of Chinese junk you know nothing about but simply Googled info about from another forum) won't.

big stabilisers with a variable transformer (variac) are very efficient, up in the high 90's, the smaller magneto-resonant type are less so and at low loads can get very lossy. So if you got a MR type it would affect the bill

True again - those with variacs are, but they're also very expensive, again as @hazz said, and for under 20,000 baht you get a cheap bit of Chinese junk. Although you're careful not to say so directly, you're suggesting that "19,900" baht gets you a "big stabiliser" that is "very efficient" when it doesn't. That's a con, plain and simple.


it may be that in your world when products get retuned because they don't work shops keep on selling them with no regard to profit margins and customer satisfaction, however in this real world if enough get returned as not working they stop selling them.

Just arrived, have you?

5555..no wonder the OP has gone into hiding..

A domestic brown out is hardly life threatening?

Less than 500 baht would buy a few buckets for water, a hello kitty ladle and a big packet of candles methinks.

Lots of subsequent posts for which I am grateful but please clarify one thing --earlier I was advised that voltage regulators only work for a short time and that if the voltage reduction is for hours then they would be of no benefit

Sigh: Do not waste your money on perceived magic bullets mate, if you really need power in times of a brown out or outage your best solution is a +- 2KW generator. (Saw a 5kw unit in Homepro for less than 30k baht.)
You do not need anything fancy; just plug it in to an auxiliary socket off domestic side of your main breaker or safety cut. … Switch off main breaker. A light or buzzer on supply side will tell you when power is back to normal.

My bad: You should be aware that your main breaker isolates live side of supply only. Therefore neutral is still ground/earth so it may behoove you to install a breaker for the neutral. Generator power output floats i.e. no polarity per se.

^^^ You should also be aware that voltage regulators also isolate and the output floats. …ergo no protection from ground or safety cut.

Originally Posted by crepitas

You do not need anything fancy; just plug it in to an auxiliary socket off domestic side of your main breaker or safety cut. … Switch off main breaker. A light or buzzer on supply side will tell you when power is back to normal.

I would use a three way knife switch upstream of the main breaker. Center connected to the house. Top to PEA and the bottom to the generator or vice versa. . That way you can never have both on together and still keep the breakers etc.

Originally Posted by crepitas

My bad: You should be aware that your main breaker isolates live side of supply only. Therefore neutral is still ground/earth so it may behoove you to install a breaker for the neutral. Generator power output floats i.e. no polarity per se.

If you main breaker is only working on the live side of your supply then whoever did your install broke the PEA rules and you should immediately change it to the required 2 pole breaker.

The requirement for any new install is that the main breaker MUST be a 2 pole breaker, after that one, most of the subsequent ones are single pole except for an RCD. You may be able to use an RCD as your main breaker, but a good general guide is to exclude refrigerators and freezers from an RCD as you want them on all the time. There is a debate over which circuits should be excluded.

My knife switch circuit cuts and joins both live and neutral. But yes maybe not a great idea to have shower while the gen. is running just in case, as GFI will not work!