Electricity Supply

[davoz45]

We built the lovely home a couple of years ago in sisaket, across the river from Kantararoom. We have had two power surges that have blown the lights to pieces, nearly starting fire, a surge protector didn't seem to work. Shutting off after the blowouts. The house is 5 of the High Voltage poles from a transformer, about 500m To 1 km. Along with a lot of neighbours wiring I am guessing that this is too far and we should get a transformer at the pole out the front of the house. I am not there at present and took pictures that's to google street view.

[brianinbangkok]

You want humming transformer in front of your house ?

I do not see how this would improve your situation.

I have never had a house that close to the transformer in Thailand.

Never had a problem like yours.

Nor do I think the neighbours wiring have much influence on your house.

Unless its a factory or so.

Invest in proper grounding and surge protection is the way I would go.

[Crossy]

Moving to the sparking forum for directed replies.

[davoz45]

checking on the map it looks to be 400m from house to transformer

[brianinbangkok]

Close enough davoz45, I have seen them blow up !

You should just ask them to check the one 400 meters from your home.

And the grounding in your home.

[davoz45]

Thanks Brian, I will invest in the best surge protector I can find. I thought having the transformer closer would giver a stronger supply as in being able to run machinery and air conditioning. Is there anything also I can do to improve the supply and or safety?

[brianinbangkok]

Hi Davoz45,

Every house (6) that I have lived in Thailand the grounding was not connected or bad.

Sockets have grounding pins but wires are going nowhere

My advice is check grounding at your house.

And have this installed

https://en.m.wikipedia.org/wiki/Residual-current_device

[Crossy]

Good advice above.

Thai electrical supplies tend to have one or more of the following issues:-

• No ground
• No earth leakage protection
• Persistent low voltage
• Persistent high voltage
• Lightning induced surges

1. Is easy enough to sort by bashing in a rod, but without 3-pin outlets and the correct wiring to them it doesn't have many advantages (but see 5)

2. Is also easy to sort (and helps mitigate 1.) by installing a front end RCBO or Safe-T-Cut.

3. (common) and 4. (rarer) can be sorted by using a device to cut the power when the supply goes out of range, like this http://www.ebay.com/itm/63A-230V-single-pole-reconnect-over-voltage-and-under-voltage-protective-device-/251986329175?hash=item3aab8e3e57 of course, with one of these you have no supply when the mains is out of range.



Or you can get an AVR (Automatic Voltage Regulator) which will regulate low or high voltage and keep your power on http://www.aliexpress.com/item/High-Accuracy-Ac-Automatic-Voltage-Regulator-model-SVC-8KVA-Single-phase-CE-passed-Servo-motor-type/490830610.html but are significantly more expensive in the larger sizes.



5. Needs a surge arrestor or MOV (Metal Oxide Varistor) like this http://www.ebay.com/itm/SPD-ADM5-20KA-1P-AC-220V-Surge-Protective-Device-Over-Voltage-Lightning-Arrester-/272217019128?hash=item3f616612f8 these devices need a good earth to be fully effective.

[westom]

checking on the map it looks to be 400m from house to transformer

Separate hearsay from the many and separate issues.

Distance from transformer is mostly about voltage found in household receptacles. A meter (or something equivalent that is plug-in) reads / monitors household voltage. Since Thailand should be 230 volts, then voltage should always remain between 210 and 250. That is what the central transformers is suppose to do - adjust voltages there so that voltage in the house remains relatively constant.

Voltage variations are also made obvious by incandescent bulbs. Those should not vary in intensity where major appliances power cycle. Voltage variation due to major appliances suggests a serious problem with household wiring.

If bulbs change intensity to 50%, then all electronics remain perfectly happy. That same voltage variation can be hard on motorized appliances (ie refrigerator, air conditioner).

Safety ground in a receptacle is to protect human life. An RCD was recommended to disconnect power during a fault - because safety ground was missing. RCD is superb protection of human life. And does nothing to protect appliances. RCD must be protected by a solution necessary to protect all household appliances (discussed below).

Earth ground has a different purposes. One critical functions is to make voltage transients (not related to those 210 and 250 numbers) irrelevant. No protector does protection. A protector is only as effective as its earth ground (which is not a receptacle safety ground). A properly earthed 'whole house' protector must be earthed at the service entrance - where all wires must be incoming. That connection to earth must be low impedance (ie less than 3 meters, no sharp bends, not inside metal conduit, etc).

A 'whole house' protector (for transients) means hundreds of thousands of joules harmlessly dissipate outside in what actually does the protection - that earthing electrode. That 'whole house' solution is even essential so that an RCD and plug-in protectors are not damaged (and cause a fire).

Safety ground and RCD are for human safety issues. Earth ground is for human safety and for transients that cause household appliance damage. Even a TV cable and phone must connect to earth ground before entering. Otherwise all appliance protection (and the effective 'whole house' protector) is compromised.

[KhunBENQ]

400 m from the transformer is not so unusual in Thailand.

Here on the countryside they have significantly more like 1 km although not for fully equipped houses but just a 3 inch well pump e.g.

Ours is about 250 m or so.

What exactly the outcome will be depends on the size/diameter of the low voltage cables.

And I don't know what they use here?

By theory it can be endless long if it is endless thick

When you use high power devices like water heater and AC then expect the voltage to go down but likely within the tolerance.

The meter will hopefully be close to your house, so that the losses ("heating the wire") are not on your bill.

Remember that you have to measure the voltage when all or the most powerful devices are running.

When everything is idle you will measure 220 to 230 or so even for a very long cable.

[westom]

When heavy loads exist, a transformer increases voltage so that household receptacle voltages remain constant.

Concern is not only for a voltage drop during heavy loads. Concern is also for high voltages when loads are near zero.

[Crossy]

When heavy loads exist, a transformer increases voltage so that household receptacle voltages remain constant.

Please explain how a fixed-ratio transformer (which most are in Thailand) achieves this, we're not talking automatic tap-changers or ferro-resonant CV transformers here. Technical terms are OK.

By the way, outside Bangkok (where it is indeed 230V) the supply is nominally 220V.

[westom]

Please explain how a fixed-ratio transformer (which most are in Thailand) achieves this, we're not talking automatic tap-changers or ferro-resonant CV transformers here. Technical terms are OK.

An adjustable transformer must always exist between the grid and local distribution. Otherwise a constant voltage range (ie 210 to 250) could not be maintained. Utilities may use these transformers to lower voltage by as much as 5% (in an emergency); an intentional brownout to reduce demand without shedding load.

Most common method is by transformers whose taps constantly change repeatedly throughout a day.

[Crossy]

Please explain how a fixed-ratio transformer (which most are in Thailand) achieves this, we're not talking automatic tap-changers or ferro-resonant CV transformers here. Technical terms are OK.

An adjustable transformer must always exist between the grid and local distribution. Otherwise a constant voltage range (ie 210 to 250) could not be maintained. Utilities may use these transformers to lower voltage by as much as 5% (in an emergency); an intentional brownout to reduce demand without shedding load.

Most common method is by transformers whose taps constantly change repeatedly throughout a day.

It's important to remember where we are, we are not in the US or Europe where local tap-changers are reasonably common.

The 25kV to 220V transformers in most villages are not adjustable, at least not automatically, they may have fixed taps which can be used to mitigate persistent low voltage (but then the off-load voltage may rise to unacceptable levels).

So any automatic regulation needs to happen at the area 115kV to 25kV transformer, rather too coarse an adjustment for maintaining voltage over local load surges. I'm not even sure that our 115 to 25 transformer is an automatic tap-changer.

Voltage varying up to > 240V and down to < 200V during a 24 hour period is a fact of life, local regulation is poor particularly as many village transformers are already at maximum load (or overloaded).

Today is a public holiday, at 1.15PM our incoming supply is 212V, I expect it to drop a little tonight when the lighting load comes on, but anyone who is going to use aircon probably has it on now (38C ambient), if I look again at 2AM I expect it to be up near 240V.

There's also a daytime load somewhere that pulls the supply down by 10-15V on a cycle of 5 minutes every 30 minutes or so, must be a factory of some kind (it's not doing it now).

All good fun, AVRs are growing in popularity here, with good reason.

Anyway, we've drifted off topic somewhat, anything that happens before the meter is largely outside our control. We need to do whatever we can to keep our end of the system in order and safe.

[westom]

Today is a public holiday, at 1.15PM our incoming supply is 212V, I expect it to drop a little tonight when the lighting load comes on, but anyone who is going to use aircon probably has it on now (38C ambient), if I look again at 2AM I expect it to be up near 240V.

Those numbers imply an adjustable transformer is working just fine. Those good voltage numbers imply no AVR is required.

Listed were solutions for the OP. However that last protector at http://www.ebay.com/itm/SPD-ADM5-20KA-1P-AC-220V-Surge-Protective-Device-Over-Voltage-Lightning-Arrester-/272217019128?hash=item3f616612f8 is undersized; only 20,000 amps. A minimal device to do what that is intended should be at least 50,000 amps. And ineffective if not connected low impedance (ie less than 3 meters) to earth ground (different from safety ground).

[Crossy]

Even an undersized MOV us better than no MOV but I agree, the bigger the better.

Ours is 60kA like this one:-

http://www.aliexpress.com/item/100KA-420v-2pole-1P-1N-100A-surge-arrester-SPD-lightning-arrester-surge-protective-device/32470929619.html

Got about 6m of 16mm² (distribution board is upstairs) down to a 3m driven rod.

We also have little 8kA MOV's L-N at each aircon and many light fittings (at only 10 Baht each no need to skimp) and plug in arrestors at each piece of technology to mop up the last of the surges.

[offset]

When I was suffering a big voltage drop down to 159 volts sometimes (my house is at the end of the line) I was told the only way was to run an extra cable from the transformer to my house and I am the sole user of this cable which although I did not think it would solve my problem I agreed to have it done at my cost it seems to have worked I now have a reasonable stable supply

I was always able to show the problem to the PEA electricians all I had to do was turn on my air con units and my ground water pump on and the voltage would drop and the water pump would cut out

[westom]

Even an undersized MOV us better than no MOV but I agree, the bigger the better.

Protector at the service entrance (ie 60,000 amp) is for a type of surge that typically causes damage. During each surge, it is as effective as the earth ground. Additional earth ground rods may make it more effective. Protection is compromised if a hardwire and low impedance (ie less than 3 meter) connection to the same rod is not to incoming satellite or TV cable wire, or to a protector for phone lines.

8000 amp protectors at appliances are for a completely different (and typically not destructive) transient. Those also must be protected by that properly earthed 60,000 amp protector. Otherwise those adjacent protectors have made appliance damage easier. Or in rare cases create a fire.

If damage happens to appliances or adjacent protectors, then an investigation begins with THE most critical item in that protection system: connection to and quality of the single point earth ground electrode.