Electrical Problem

[tassini]

Hi, I hope you electrical buffs (Crossy, Electau.........) can help me with this problem. Started yesterday evening around 7pm, lights started flickering and going off and on sporadically, same thing with TV. It seems to me that we have a supply issue as when we turn on something that draws a lot of juice (A/C, water heater) other electrics such as TV and lights will shut down. Been in this house for a few years now and never had this problem before.

Any ideas? Although I am an Engineer (Civil) and have a good knowledge of electrical installations I just can't solve this at the moment!

Tas

[lopburi3]

It likely is low voltage - do you have an incandescent light you can view as this will become dimmer/brighter according to the voltage? Here is Bangkok that is normally a fuse blown on supply transformer so some customers have no electric and gets repaired quickly and those that continue to have electric drop to the 160 volt area so some lights keep working and some fail.

[Hssl]

I'm thinking voltage drop - got a multimeter ? Know how to use it?

[BuckarooBanzai]

The TV going off is a surprise as TVs always seem to be very forgiving of voltage fluctuations - but for the rest I have a similar problem whenever the guy down the road uses his welder which is quite often. My voltage drops can be 40 to 60 volts at times lasting for as long as the welding contact. Up down up down etc. I have put 300 volt analog meters at the various places around the house - Circuit breaker box - computer - etc. so I can keep an eye on it. If bad enough I have to shut down the air-con so the compressor doesn't stall. Pain in the arse.

[Crossy]

Sounds like low voltage to me too.

I'd power off any technology, the fridge and A/C until the problem goes away.

[genset]

Hi Tassini,

The brownout conditions you are experiencing are a common occurence in Thailand. They may occur naturally as the utility system is overloaded, storms or other system problems occur. Or they may be a deliberate act on behalf of the utility provider when they sense that problems are imminent and are often a preferred option to instituting rolling blackouts.

Crossy is of course correct to suggest you turn off any sensitive electronic devices which may operate intermitently, and any device which incorporates a motor which will draw more current as a result of the lower voltage, and may result in overheating and burnout .

Genset

Edited September 25, 2011 by genset

[Satcommlee]

I'd go with low voltage also, and agree there is no better way for a layman to detect this than with an old fashioned Light Bulb, you will see it dim.

I had similar problems in my last house, the only thing that would remain on though would be the television because that worked from 110 Volts to 240 Volts, everything else Air Con, Fluorescent lights died a death!

[electau]

Sustained low voltage eg voltages below the normal nominal voltage ranges to the consumers terminals or point of supply are usually caused by.

1. Fault conditions on tthe HV distribution network, eg. loss of one phase.

2. Poor voltage regulation at peak load periods. 1. Distribution network, or 2. LV distribution network.

Low voltage of short duration ( transient events) usually may be caused by the following.

1. Operation of auto circuit reclosers on a HV distribution network.

2. Switching on the HV network.

3. Intermittent heavy loads eg motor starting, welders etc.on the LV distribution system.

Reduction of voltage by system operators on an HV system is not carried out.System operators will shed load or load will be shed automatically by protective devices on the HV system

[Pushit]

Contact the MEA/PEA ask them to send an engineer to do something about this.

[BuckarooBanzai]

Contact the MEA/PEA ask them to send an engineer to do something about this.

Tried this route myself - was told for 100,000 baht they would put in a transformer for me - when I told them was on a single phase low voltage feed line with no HV available they said SOL.

In most developed countries electrical utilities must maintain tight control of the voltage variation but TIT. When I told them my voltage often dropped to 160 volts I was told 160 volts is plenty good enough.