Low mains voltage (200V)

[JamieP]

I recently moved to a new house and a few things - most notably fans running slow - don't seem to be working properly.

I got hold of a cheapo multimeter and I'm only reading ca. 200V. Any ideas?

[KhunBENQ]

Unfortunately you are not alone.

A mate not far from here has the same problem.

You would only have a cheap fix, if the voltage at the meter (outside) is good.

Then the wiring from the meter to your house or wiring in the house is very bad.

Unlikely.

Likely: the next transformer is far from your house and/or the wiring from the transformer is poor.

Follow the low voltage (230 V nominal) line from your pole to the transformer.

You would have to complain to PEA (electricity provider).

Can be become frustrating and/or expensive.

Is it a rented house?

Do you have a chance that neighbours let you do measurements?

Last resort: buy a big voltage regulator. Expensive!

[JamieP]

I did a quick check on the breaker box to check what was coming in.

Across the main breaker I got 213Vac.

And on a slightly different note, the grey wire that is connected to the fifth breaker is running an aircon (12,000 BTU), is it adequate for this? It looks a but thin to me?

Unfortunately it's not rented, bought it last month......

[IMHO]

200V isn't low enough to make things not run right.... that's still within +/-10% of spec.

213V is plenty.

Are you sure the meter you bought is measuring accurately?

Can you test the voltage both with no/light load and then again at high load (i.e. turn on the AC, hot water, microwave etc then test) so we have at least 2 points of reference?

Can you see any printing on the gray AC wire? if it's 2.5mm2 it's probably OK, so long as it's not a overly long run. If it's 1.5mm2 it's surely undersized though.

[KhunBENQ]

As IMHO writes, 213 V would be OK to the norm even in Europe.

You have to measure at the breaker box (input) with all consumers off.

Ideally switch the main breaker off and measure at the input.

And then go through one by one and try to measure as close to the device as possible.

Forget my idea to measure at the meter. Not feasible without calling/complaining at PEA.

Indeed this small grey wire looks quite weak.

[Crossy]

+1 ^^^ on the measurements, at 200V you shouldn't notice much loss of performance although your fan may run slow.

A 12,000 BTU aircon will pull about 6A when running, 1.5mm² cable would handle that without getting warm. That said there's a significant start-up surge which whilst it won't bother the cable it may cause enough volt drop on a long run to cause the aircon issues, 2.5mm² cable is the norm on all but the largest aircon units.

EDIT I also see no earth leakage protection, I would seriously consider installing a front end Safe-T-Cut RCBO particularly (but not only) if you have an electric water heater.

[JamieP]

I switched all the breakers off including the main one and I'm now only measuring 203V. After that I switched on both aircons in the house and a couple of fans so it was about as loaded as it could be. There was no discernable voltage drop.

The aircon wire is 2.5mm, so, that's one less worry at least. The cable run is probably 10-15m total.

[Crossy]

Have a look at the voltage at a time when the network is least loaded (say 3AM) and again at 7PM when the maximum domestic load comes on. A couple of times during the day if you're at home can't hurt. You need an idea of the worst case position.

If it's not varying much you could talk to PEA to change tap on the local transformer to up the voltage slightly.

[JamieP]

Is it worth asking the neighbours to see what they're getting? Would it prove anything worthwhile?

[Pib]

If that cheapo meter is an analog meter (i.e., scale with swinging needle type) recommend you buy/try a cheapo digital multimeter as they are just inherently more accurate. If it is a cheapo analog meter be sure the meter reads zero with no input....if not, the meter should have a mechanical zero adjustment on its meter panel....bottom, middle of the meter. If the meter zero is off , if it's a small meter, if maybe each meter division represents 20 volts then the meter zero being off can really degrade its accuracy....make it read significantly low or high of actual value. If it's digital meter, never mind about the meter zero thing except maybe for measuring resistance/ohms.

Usually items are spec'ed to work properly within a +/- 10% of nominal voltage (220V)...and many -15% to +10%. But a -15% voltage on some water pumps can make them run and run without being able to spin fast enough to build water pressure back up to their pressure cut off setting...my water pump is like that...right around 180V it struggles...but fortunately in my part of Bangkok it's not often I experience blackout or brownouts...I still experience them but fortunately not often and they are brief in duration.

[Crossy]

Is it worth asking the neighbours to see what they're getting? Would it prove anything worthwhile?

At this time I wouldn't bother unless you're on very good terms with them, you can guarantee they will think you're trying to pull some sort of fast one

[Pib]

Is it worth asking the neighbours to see what they're getting? Would it prove anything worthwhile?

Sure that would be helpful...at least it would help you confirm whether it's just "your" residence with the low voltage or all the residences around you.

[Crossy]

Hmmm, a difference of opinion Pib

I agree it could be useful.

I'm just concerned about the standard village paranoia, we still get it after nearly 3 years.

[JamieP]

It's a digital meter.

Maybe I'm just going to have to get the wife to go an talk to the PEA. That's going to be fun trying to cajole her into that.......

[Crossy]

Do make a log of the voltage at various times to give her some ammunition

[Pib]

Don't be surprised if neighbors in your area seem clueless about low voltage in the area because based on what electrical devices they use (and how much they use them) they may not be noticing any problems at all. Then others will say, yea they know there is low voltage sometimes but will also say what can they do? For some Thais to complain about about certain things it has to get really bad first. Hope you get your voltage up.

[KhunBENQ]

Is it worth asking the neighbours to see what they're getting? Would it prove anything worthwhile?

Sure that would be helpful...at least it would help you confirm whether it's just "your" residence with the low voltage or all the residences around you.

Not really related...

We sometimes have "outages" for a certain time (up to hours).

170 Volt!

All devices with switching power adapters (router, latop) work well.

Some LED bulbs still on. Other lamps (neon) can not be started.

Water pump on low rpm.

Fans on low rpm (dangerous, can overheat).

AND: sister in laws house (15 m away): everything OK.

Different transformer and/or different phase.

[Pib]

Is it worth asking the neighbours to see what they're getting? Would it prove anything worthwhile?

Sure that would be helpful...at least it would help you confirm whether it's just "your" residence with the low voltage or all the residences around you.

Not really related...

We sometimes have "outages" for a certain time (up to hours).

170 Volt!

All devices with switching power adapters (router, latop) work well.

Some LED bulbs still on. Other lamps (neon) can not be started.

Water pump on low rpm.

Fans on low rpm (dangerous, can overheat).

AND: sister in laws house (15 m away): everything OK.

Different transformer and/or different phase.

Probably everyone in Thailand has low voltage/brownout periods...I sure do but fortunately they are brief and infrequent in my part of Bangkok. But at least checking with his neighbors would confirm whether it's just something squirrelly with the OP's residence only...if I was a betting man it affecting others also.

Heck, if it was me and I could access the meters of my neighbors (which in my case I can easily do since the meters are on the poles on the soi) I would just go check the voltage entering/exiting the electric meter running to the residences....would avoid knocking on doors to ask....I don't think anyone would shoot a person for checking electric meter voltage for a few seconds (if they even noticed).

[JamieP]

Fans on low rpm (dangerous, can overheat).

Hmmmm,

Yes, I do have one fan in particular that's quite a big beast and that's the one thing that really shows the problem.

It does seem to run a bit hot as well.

[Mojomor]

As OP has a multimeter, he should also check the voltage between neutral and ground. It should be zero, but on one occasion many years ago, I read 40 volts.

The live should be 230 to ground, and between live and neutral. If you have a voltage on neutral, clearly the grounding system is close to non-existent.

[Crossy]

Apart from the fact that Thailand is nominally 220V Mojomor has a good point, anything over, say, 10V N-E indicates a possible issue.

As noted previously, 200V is within the +- 10% which most appliances are designed for so there is no specific hazard, certainly motors are not going to get hot enough to cause problems. That said, if it's constantly low it should be a relatively easy fix for PEA to swap the tapping on the transformer.

[IMHO]

Fans on low rpm (dangerous, can overheat).

Hmmmm,

Yes, I do have one fan in particular that's quite a big beast and that's the one thing that really shows the problem.

It does seem to run a bit hot as well.

Perhaps the problem is localized to the fan, or the outlet it's plugged into to?

What happens if you plug it into a different receptacle/circuit? still run slow?

Does the cable or plug for the fan get warm or hot?

Perhaps the fan is just dying?

[JamieP]

The fan is the same in different sockets in different parts of the house.

The fan could itself have a problem but it seems a bit too coincidental that it started running slow the first time it was used in this house.

[JamieP]

I'll check the Earth/neutral voltage later on and report back

[Pib]

The fan is the same in different sockets in different parts of the house.

The fan could itself have a problem but it seems a bit too coincidental that it started running slow the first time it was used in this house.

The fan's problem could be it's start/run capacitor or gummed up bearings....either can cause the fan to start up slower, run slower than normal, and hotter than normal. I've had both problems on two different floor fans...and a capacitor problem on a ceiling fan. The capacitors are usually around 1.5 to 2.5uf in size can be bought in a lot of places like Amorn Electronic stores for around Bt25...and sewing machine oil works good on the bearings...but a person needs to do a little bit of fan disassembly to oil the bearings/replace the capacitor....will need to use a soldering iron to properly replace the capacitor.

[Mojomor]

Last report from the OP was over a week ago. Strange the way people disappear. Hope he is okay.

Those of us who offer advice, would like feedback. It allows us to learn more and perhaps help someone else. Sort of the way the world goes around.

Just my 2 satangs worth. Thanks.

[Crossy]

Those of us who offer advice, would like feedback. It allows us to learn more and perhaps help someone else. Sort of the way the world goes around.

Agree, it does get irksome when advice is freely given and the receiver of the advice just vanishes with no indication whether everything is now ok, sadly it's the way forums are. There's also a forum bug which means notifications don't always get generated, so he may not have any indication that there's activity here.

Hopefully our OP will return so we can sort his issues, he was last active at 10pm yesterday, so he's not got zapped

[JamieP]

My apologies for not getting back so far,

I have had other things going on which I needed to sort out.

I'll check the earth-neutal voltage in the next couple of days and report back. Where is the best place to measure that? Are the green wires I can see earths (a possibly dangerous assumption) or is there a better place to check?

In the meantime, my wife has spoken to the PEA to come and check the supply but it will apparantly take at least a couple of weeks because there's a big list.

Does anyone know or have contact details for a competent electrician in the Khon Kaen city area.

I'll take the advice of getting a Safe-T cut but I obviously want it done properly. There's a few other little jobs I need doing as well.

Thanks again

Jamei

[JamieP]

Further update:

I got home a short time ago and after I turned on the WiFi on my phone I got a Line message from my wife saying the PEA would check the power at 4 pm.

I don't know if they have been or not but the power is now at 223V.

[JamieP]

Also, assuming I was checking it correctly there is no voltage between earth and neutral.