Not enough power for air con

[Goanna]

Hi guys. I have had to come back to Australia to work yesterday, and so missed the installer who came to fit up our new 18 000 btu samsung split system aircon.

It trips a circuit breaker every time it is switched on. He claims that the house power is insufficient for the machine.

This is a new house, and has a working earth stake, and power board, so I'm thinking that he may have wired it to the light circuit or a nearby power gpo.

These aircons run at 7 to 8 amps, but maybe more at startup. I was thinking that surely if he ran the cable to the board on it's own 15 amp breaker, that this would be ok. There are no other aircons in the house. The power is the standard supply.

Any ideas?

[Bredbury Blue]

If nobody answers soon, search for member Crossy and pm him: he seems knowledgeable on all things sparky.

[Litlos]

The other option is he was a bit careless with his wiring and the live wire is touching the earth. Easy test is switch everything else in the house off and try again, thereafter a process of elimination. If it still trips the breaker when it is the sole load there is something wrong with the installation.

Cheers

[Farma]

I've experienced this in a house on the edge of a small village. Sometimes the aircon trips the CB and other times it doesn't.

The electrician said there was nothing he could do about it. He said it was power drop due to the house location.

[mcfish]

Try a new technition to back up the story. Like a doctor sounds like a second opinion is needed

[Goanna]

Thanks. I'm not home for another 3 weeks, but I've told the missus that this guy was wrong and to get someone else to have a look. She believes him, which is annoying, and wants to just leave it. But she will get the second opinion now.

I have run a welder from a power point no probs, albeit an inverter welder, which is why I think it should be enough. But thanks for the help.

[Crossy]

You pretty much have it in the OP.

What is the rating (Amps) of the breaker that is opening? Or is it an RCD (Safe-T-Cut)?

An 18,000 BTU A/C will draw about 8A when running, even the smallest 5/15 supply will handle that without flinching (you probably have a 15/45, you can check on the meter). I would put it on 2.5mm² cable and a 20A breaker.

An A/C is usually given its own circuit and breaker, but it's quite possible your installer has hooked it to an existing circuit.

[Goanna]

Thanks Crossy. I'm not home to check, but I just wanted confirmation that power would be enough. Wife has had a second opinion now, and he claims that the power is ok, but the power board is not. Never mind. They will sort it out, or not. If not, I can trouble shoot when home. Cheers all.

[Utley]

Depends on where you live. We live in the central provinces and have 2 air cons; 1 mid size and 1 small. We cannot run them both at the same time - not enough power. We've been to the government electrical company and they helped a little, but the bottom line is that adequate residential power supply is not a priority for them. Right across the road from us runs high power lines that feed the factories about 10 km away; but the residents along the road get squat.

[weedywhaoo]

Make sure that the cables in the safety box are tightened. If loose heat can develop and damage the breaker. Happened to my installation last year.

[Goanna]

Thank you all for your helpful replies. The bloody thing is now working. I don't know why, but possibly some sort of supply voltage drop at time of install.

ha. I can only hope it still works in three weeks. It was good to bounce the problem off you guys with more experience.

Thanks again. Saved by the fluctuation.

[SteveSamui6262]

You have or run a dedicated line from the circuit breaker box to the a/c unit. I think a 15 amp line sounds right. In the event your circuit breaker box, known by Thais as a "safety cut box" doesn't have the proper amp rated breaker switch, you will need to upgrade the box. It's also possible you may need to run a higher amp cable from the power pole to the house, which I had to do just to install a hot water heater at my girl's parents house in Isaan. Remember, it wasn't too long ago when this country was having frequent blackouts & brownouts. Good luck with your task.

[avocadowangnamkeouw]

A fuse/breaker for a separate circuit doesn't trip because of insufficient power, and it has usually a slower respond time than the safety breaker, so if your circuit breaker is too small, you would still be able to start the ac before the fuse trips.

What you describe looks like an 'earth leak', meaning that the amount of peak power you request from your system, does not flows away through the neutral phase, as it were consumed by the ac, but it finds its way outside the system, and it is detected by your safety breaker.

So this is what I think is your problem:

Or your own ac connection to the 'neutral' phase is not well (not tight enough), but more likely there is a bad neutral connection to or within the grid section of your neighborhood ( the top blank wire outside). This happens a lot in Thailand and the boys from the Electric Authority usually understand if you tell them 'Neutral mai dee'.

To check if this is the problem, you can do the following: turn on all your fan's, tea-makers, television sets and an old fashion light-bulb and set your shower boiler at max.

Then ask the missus to to open the shower\hot water tab and you will see the light bulb shine less bright if the shower boiler starts to consume power if this is your problem,

good luck

[impagencies]

did you install an additional circuit breaker?

[ozyjon]

When i built a house to give away to the outlaws because i

would never live in it, the time came to put the meter in and

connect the power to the house.

At the power company office (i have slight memory loss on this)

but i think they asked if we wanted cheaper 10 amp or 16 amp

meter,, maybe this could be the problem, worth a look.

[Crossy]

Thank you all for your helpful replies. The bloody thing is now working. I don't know why, but possibly some sort of supply voltage drop at time of install.

ha. I can only hope it still works in three weeks. It was good to bounce the problem off you guys with more experience.

Thanks again. Saved by the fluctuation.

It's worth coming back with some photos of the board and breakers once you get to Thailand.

It is quite possible that, if you have a Sate-T-Cut, someone has discovered that it works with the sensitivity set to 'Bypass' or 'Direct' which turns off the 'Safe' part (earth leakage detector).

[timsims]

I live up in Ubon the power into our house is only 100 volts not 240 every thing still works fine
except the coldness of the unit but still OK
your problem is that there is a dead short in your wires or the unit is wired wrong or unit no good

[Tonawatchee]

I have the same problem. At certain periods during the night, my voltage will fluctuate between 170-210 vac. If you have a volt meter, measure before you turn the unit on. Continual tripping on start up indicates a short somewhere.

[Crossy]

For those with voltage fluctuations or constant low voltage, have a forum search for AVR or automatic voltage regulators, not cheap but they can prevent a lot of heartache.

[mfd101]

I've experienced this in a house on the edge of a small village. Sometimes the aircon trips the CB and other times it doesn't.

The electrician said there was nothing he could do about it. He said it was power drop due to the house location.

I had a similar problem when we decided (belatedly) to install a/c in our 2-year-old house down the end of a dirt road at the end of the world. We had to pay for extra or heavier electricity cables for the last 20 or so metres with nice new concrete power poles to enhance the scenery. Can't remember the technical details nor the cost but it didn't break the bank & works fine (1 large unit, one smallish).

[bwpage3]

The problem is the meter on the pole outside of your house. Traditionally these are only 5 amp meters in Thaialand. The electric company has to change this to a 15 amp meter. There is a cost to upgrade the meter to 15 amps. The local electric company can sort this out easy. The issue is your current 5 amp meter is limiting the current entering the house to 5 amps.

[Crossy]

The problem is the meter on the pole outside of your house. Traditionally these are only 5 amp meters in Thaialand. The electric company has to change this to a 15 amp meter. There is a cost to upgrade the meter to 15 amps. The local electric company can sort this out easy. The issue is your current 5 amp meter is limiting the current entering the house to 5 amps.

Actually a 5/15 will provide 15A +++ and easily run a medium sized aircon (but not much else). They are usually fused at 20A (if there's a fuse at all).

Meters are incredibly robust withstanding a 100% overload without blinking (but losing some accuracy).

[Farmer1956]

Is it tripping the dedicated breaker for your Air-con? Are there any other appliances on this circuit?

You may be getting an increased start up current that may take out the breaker.

What make of breaker is it? There are different types of breaker that are produced to service different

load systems. In the UK we mainly use type "B" and type "C" breakers, type "C" are set up to deal with the start

up current by delaying the tripping of the device so that the start up current can dissipate and not take the breaker

out on start up.

Have a look on the breaker it may say something like B16 (16amp type , try replacing it with a type "C" (C16)

or maybe step up to a 20amp breaker, provided the cable is big enough this may solve the problem.

[jacko45k]

On the face of it it does sound like the electrician doesn't know what he is doing.

I presume the house has a proper supply, to it 30, 50 or 100 amps all of which is of course sufficient to run that AC.

My AC units are wired to dedicated 30 amp breakers, and the main (incomer) one is 100 amp.

Starting current can be substantially higher than rated running current and sometimes a breaker is particularly sensitive to short duration high loads.

(If it has both electromechanical and thermal elements)

Presuming it is not a residual current CB that is tripping ( that is something else) I would suggest a higher rating (you do not say what rating he is actually using). Of course staying well below the rating of the cabling from the distribution board to the AC unit.

Obviously there are tests that can be done, starting the unit without the compressor on... fan only mode to see if it stays on, most likely it is the starting current of the compressor/ outdoor unit fan causing the trip.

Hopefully the guy has run dedicated wiring and utilised a dedicated CB for the AC unit, if it did not already exist.

[Khon Kaen Dave]

I don't know about here,but when we used to fit electric showers,where there had not been one previously,We had to use the correct size wiring.Depending upon the shower.It had to have its own devoted circuit breaker, i think it was 32amp.When we changed from boards to consumer units,there were often a couple of 'Spares' for this very purpose.But as i say,that was a few years ago.Shower fitting may different now.Maybe Air con is a different situation.

Anyway,i hope it helps.

[Jing Joe]

I have the same problem. At certain periods during the night, my voltage will fluctuate between 170-210 vac. If you have a volt meter, measure before you turn the unit on. Continual tripping on start up indicates a short somewhere.

Don't agree 100% about continual tripping is from a short. Lower voltage maybe as below.. Anyway Goanna's troubles are over and the advice still flows in. All with good hearts eh.

Tona- Your 170v could be described as "brown outs" as opposed to complete "black outs" and as such your suggestion for Goanna about measuring before turning on could be more important for you to measure before, and best maybe NOT turn the unit on.

Reasons;- The motor/compressor might run too much slower, resulting in a heavier current and burn out the motor. (and currents that may or may not overload the switchboard circuit breaker.) This "lower voltage yet heavier current" sounds contradictory but it often happens here in Oz and people battle with the power supply companies or Insurance companies.

BTW did someone mention a shower heater? I've got a (Thai ??) "Sharp" brand unit and its heater is rated at 3400 watts at 220 volts which could potentially draw 3700 watts on 240V here in Oz. That's 15 amps and needs own circuit. Interestingly I've measured power levels of about 800 watts if the temp control is set at practical levels so max power may never be needed.

[IMHO]

For those with voltage fluctuations or constant low voltage, have a forum search for AVR or automatic voltage regulators, not cheap but they can prevent a lot of heartache.

Yep. Our mains voltage fluctuates between 170V and 190V under load - our 100A voltage stabilizer allows us to run 159,000 BTU of aircon at a stable 220V - but at ~12,500 watts power usage, we don't turn them all on at the same time very often

For a little over 30K Baht, it was by far the best & cheapest solution.

[Naam]

I live up in Ubon the power into our house is only 100 volts not 240 every thing still works fine

except the coldness of the unit but still OK

your problem is that there is a dead short in your wires or the unit is wired wrong or unit no good

your problem is that you have no idea concerning the voltage that's fed to your house

[Goanna]

Hi guys. Finally able to update this bloody thing.

The air con was indeed wired to the closest GPO. It made a mess of the wall, because they could have just gone straight up to the ceiling.

Also, some friend of a friend have wired the outside kitchen and GPO's, to a single f'ing power point. So I don't know who to blame.

Luckily, when the sparky came, he took the cover off the power board, and I see that there is no earthing. My missus said she saw them put in the earth stake, which is now under the outside tiles.

So, No earths, ok. I bought a multimeter, and checked the shower water heaters, and they are both earthed. I don't know yet if to roof steel, or earth rod, but done.

[Goanna]

Sorry this is a bit haphazard. Pic of powerboard. The sparky cost 600 baht incl offsider and some materials. Worth nothing, because he sorted the kitchen wiring, but forgot to connect it to the power.

Aircon works but. I don't want him back. I have bought a RCBO to install, but neglected the mounting, so will have that done soon. And typical thai wiring, lights are starting to fail here and there, so looking for a better sparky.

Anyway, I think I am on top of it now, so thanks for the help. Cheers.