Apologies if this has been asked, a search did not come up with anything.

I recently had PEA upgrade my service here in San Kamphaeng from 5/15 to 15/45 hoping to solve my low voltage problem when AC and water heaters ran simultaneously, but no joy. My UPS shows anywhere from 205V to 218V nominal, turning on a couple of AC units drops it below 200, add in a water heater and it drops much lower.
I measured the voltage at the meter (about 100 meters from the house) and saw no significant difference, when 3 aircon units were switched on it dropped 2V at the meter and 15V at the UPS in the house.
I am thinking about an AVR - would this solve my issue? I'm not averse to changing out the wire from the pole to a larger gauge.

It's the local transformer - too many users/households pulling juice. Changing your meter just allowed you to pull more Amps from a oversubscribed transformer. 

 

I had the same issue for years. Had to complain/ask PEA to upgrade our local transformer - explaining that the original unit was designed for the house load count at the original time of install - approx 1999 (yes, my local area did not get AC power until right before the new millennium. Even afterwords, no one had refrigerators, just a few lights and a TV.

 

Now everyone pulls much more power - but the low voltage issue has improved since the transformer was upgraded.

 

Have the Misses call PEA.

18 hours ago, Lysdexic said:

I measured the voltage at the meter (about 100 meters from the house) and saw no significant difference, when 3 aircon units were switched on it dropped 2V at the meter and 15V at the UPS in the house.

 

So, you have a potential problem between the meter and the house.

 

For consistency measure your voltage at the incoming terminals of your distribution board.

 

What size are the A/C units you are using?

 

What size is the cable to the house, it should be marked in mm². Is it copper or aluminium?

 

For 100m on a 15/45 you'd be looking at 35mm² copper or 50mm² aluminium.

 

Can you also measure the voltage between a known ground (stick a screwdriver in the lawn, not your ground rod) and both L and N with and without the load.

 

EDIT What is the voltage at the meter with no load?

Cheapest option would probably be to replace the incoming cable, but that requires the voltage to the meter to be good and stable.

 

There's also my AVR thread pinned at the top of the forum.

 

 

Have an electrician coming tomorrow, likely looking at replacing the existing aluminum cable with copper.

2 hours ago, Lysdexic said:

Have an electrician coming tomorrow, likely looking at replacing the existing aluminum cable with copper.

 

Check the size they intend using, too small and you may not see a significant improvement.

 

What size is the Al you have now?

 

On 5/27/2021 at 2:12 PM, Crossy said:

 

Check the size they intend using, too small and you may not see a significant improvement.

 

What size is the Al you have now?

 

Crossy is right. I have friends whose wire is way undersized, and their voltage drop is terrible. (Doesn't drop too much at the meter. But is often 140 volts or below at their property, 1000 meters from the meter.)

 

So what did the electrician tell you? And what did you decide/do?

If the electrician only has undersized cable he can as a temporary measure run a second set of cables in parallel with the existing cables.

Note this is only a suggestion for a temporary fix. I do not recommend this as a permanent solution.