Circuit Breaker

[bonsaimax]

For the past five days, power at home cuts off regularly at about 9:00 pm and at least once again at around 10:00 pm. I always have to run back downstairs to switch the circuit breaker back on. I fear it would damage my PC so I bought a UPS for it today thinking that it would delay the shut down and give me time to exit all running programs, but it didn't. Is my assumption correct?

I suspect the problem to be in the Earth wire of the shower heater, so I disconnected the all the wires except for the Earth wire. Still we've had three power cuts already in the last 2 hours. I'm running out of ideas, and I'm definitely not knowledgeable with electrical stuff.

Any ideas??? Or maybe if any of you kind souls could refer me to a legit electrician--I know they are hard to come by here in LOS

Cheers!

[chownah]

If you believe that the load should not be high enough to trip the breaker....maybe the breaker is bad. It's a long shot but it is possible....and cheap and easy to try a new one.

Edit: Just had an idea. If you buy a cheap volt-ohm meter you can test your voltage around the time the breaker trips and see if the voltage is too low...it might be possible that a low line voltage could trip the breaker if you were near capacity and an electric motor started up when the voltage was too low....this too is a long shot.

Edited February 2, 2006 by chownah

[Guest endure]

For the past five days, power at home cuts off regularly at about 9:00 pm and at least once again at around 10:00 pm. I always have to run back downstairs to switch the circuit breaker back on. I fear it would damage my PC so I bought a UPS for it today thinking that it would delay the shut down and give me time to exit all running programs, but it didn't. Is my assumption correct?

Is the UPS battery charged up fully yet?

[lopburi3]

You ask for someone to recommend an electrician but don't say where you are.

If you just bought the UPS the battery probably did not have a full charge. Yes, it should give you time to shutdown everything if you only have the computer/monitor plugged into it.

Are you using an airconditioner? A refrigerator? They are the most common source of excess current draw. As said that is probably a low voltage time so if your main breaker is almost at capacity it could trip it. Breakers can become bad but it is not the most likely problem. Make very sure you do not remove any green wires from anything. Is your breaker a normal type or a GFI/ECCB ground fault type? What is the amperage rating? Is it your only breaker or is there a larger one that it is attached to? Does all your home go out or just a section? Anyone else having troubles about the same time?

[bonsaimax]

Disconnected most of the appliances last nightexcept for the fridge, water pump and A/C. Also disconnected the shower heater's earth wire, which I just realized there were two of. This is aside from the two other terminals for electricity. Still had 6 power cuts in 3 hours last night. I'm stumped as to why it happens at a particular time of night. Might it be the A/C compressor? Just a wild guess. I'm stumped!

If you buy a cheap volt-ohm meter you can test your voltage around the time the breaker trips and see if the voltage is too low

I could get a volt meter, but wouldnt know how to use it. How do I go about using it? What exactly should I be looking for? And is there a way of knowing if the two extra wires in the shower heater are Earth wire(s). Took a look around the house and couldn't find any wire physically stuck to the ground. But the phone line should have one shouldn't it?

Is the UPS battery charged up fully yet?

well of course! We don't expect the salesperson to know or tell us anything about it, should we? How would I know if the battery is fully charged? There doesn't seem to be any indicator light, except for the power LED.

Thanks for your replies.

[lopburi3]

Are you running anything else when this happens? Like dryer or dishwasher? Do you have any other heavy use of electric at this time? Is the airconditioner normally off during the day?

As for the two extra wires on water heater do you have grounded electric service (3 pin plugs)? If so one is probably the normal electric ground and the other a direct wire to ground (or should be). All you should need is the electric ground if it is good.

Telephone lightning box should have a wire to ground.

This time of night is normal low voltage time as everyone has there lights on/tv aircon and such. And that could cause a breaker to trip if you do not have much spare capacity.

[chownah]

A voltmeter has two probes. There is usually a selector switch on the meter....set it to a voltage range so that you can measure 220 volts. Go to any electrical outlet and put the probes into the two slots that a plug would use. Read the voltage on the scale.

On the other hand....it seems that you might be better off to find an electrician....just as you requested before.

[bonsaimax]

Is your breaker a normal type or a GFI/ECCB ground fault type? What is the amperage rating? Is it your only breaker or is there a larger one that it is attached to? Does all your home go out or just a section? Anyone else having troubles about the same time?

From what I see on the circuit breaker, it says RCCB 240V tripping current 10mA. This is the only breaker we have at home. It has about 10 switches on it, but only 5 are in use. It is only our home which is affected. All the rest of the neighbours' houses have their lights on.

The power cuts happen only during the night, which I think as mentioned, is when most of the appliances are in use.

Is the UPS battery charged up fully yet?

I'm not sure if it is fully charged yet, though I've left just the UPS plugged all day today.

Are you running anything else when this happens? Like dryer or dishwasher? Do you have any other heavy use of electric at this time? Is the airconditioner normally off during the day?

[/qote]

Most of the electrical appliances are on during the day as well, but most of the neighbours aren't home. Wonder if it matters.

As for the two extra wires on water heater do you have grounded electric service (3 pin plugs)? Telephone lightning box should have a wire to ground.

We do have 3 pin sockets, but I don't think the ground wire is connected. The phone box has a ground wire connected. I checked and it is embedded in the ground by just approx 70cm., without the metal bar.

This time of night is normal low voltage time as everyone has there lights on/tv aircon and such. And that could cause a breaker to trip if you do not have much spare capacity.

How will I know how much capacity it has? And if it is not enough, how do I increase it?

A voltmeter has two probes. There is usually a selector switch on the meter....set it to a voltage range so that you can measure 220 volts. Go to any electrical outlet and put the probes into the two slots that a plug would use. Read the voltage on the scale.

I might give it a try, though I must say that I really am not comfortable playing around with electricity.

Again, thanks all for your help.

[chownah]

Is your breaker a normal type or a GFI/ECCB ground fault type? What is the amperage rating? Is it your only breaker or is there a larger one that it is attached to? Does all your home go out or just a section? Anyone else having troubles about the same time?

From what I see on the circuit breaker, it says RCCB 240V tripping current 10mA. This is the only breaker we have at home. It has about 10 switches on it, but only 5 are in use. It is only our home which is affected. All the rest of the neighbours' houses have their lights on.

The power cuts happen only during the night, which I think as mentioned, is when most of the appliances are in use.

Is the UPS battery charged up fully yet?

I'm not sure if it is fully charged yet, though I've left just the UPS plugged all day today.

Are you running anything else when this happens? Like dryer or dishwasher? Do you have any other heavy use of electric at this time? Is the airconditioner normally off during the day?

[/qote]

Most of the electrical appliances are on during the day as well, but most of the neighbours aren't home. Wonder if it matters.

As for the two extra wires on water heater do you have grounded electric service (3 pin plugs)? Telephone lightning box should have a wire to ground.

We do have 3 pin sockets, but I don't think the ground wire is connected. The phone box has a ground wire connected. I checked and it is embedded in the ground by just approx 70cm., without the metal bar.

This time of night is normal low voltage time as everyone has there lights on/tv aircon and such. And that could cause a breaker to trip if you do not have much spare capacity.

How will I know how much capacity it has? And if it is not enough, how do I increase it?

A voltmeter has two probes. There is usually a selector switch on the meter....set it to a voltage range so that you can measure 220 volts. Go to any electrical outlet and put the probes into the two slots that a plug would use. Read the voltage on the scale.

I might give it a try, though I must say that I really am not comfortable playing around with electricity.

Again, thanks all for your help.

Let me add that you should set the selector switch on the volt meter so that you can measure 220 volt AC........not DC. House current is AC so you want to set the selector so that you have selected a range that can read 220 volts AC. Don't worry about when you put the probes into the slots in the sockets....nothing happens except the needle on the meter will move....there is no spark or flash or sound or anything....no need to worry. If you put the selector on a scale that is inappropriate (for instance if you put it on a scale to measure between zero and ten volts AC) then you might ruin the meter...but then again most meters made now are pretty rugged and even this blunder might do no harm....but why tempt fate? Also, if you go to buy a meter....a cheap one is good enough....I'd recommend not the cheapest one which usually has a very very small needle and scale...get one that is a bit bigger and easier to read....I would think that you should be able to get one for 500 baht or even less....I forget how much as its been awhile since I bought mine.

Edited February 3, 2006 by chownah

[lopburi3]

Ok you have ground fault protection (RCCB) and it is very sensitive (10ma) where most is 30ma so most likely that is what is causing the trips. Those switches below the breaker are probably also breakers if it is a normal circuit box. Each should be marked with an amperage also.

My first test would be not use air conditioner and see if still have trips - it you do it is not the airconditioner and most likely not low voltage.

So now you have to search for the fault. It could be an appliance (easy) or a wire in the wall (much harder) or it could be a chin chuk leaving his home in the wall switch and causing a slight short. Do you by any chance have an outside light on at this time? They are a common source of GFI type trips.

You need to isolate the problem and that may require turning off all the switches. Hopefully that will end the trips - if not something is not wired through the switches and you should have professional help. If you can find the switch that causes the trips you can pull everything from that until stops. If does not stop you will probably have to have someone check the wires on that circuit for low resistance/intermittent shorts.

It can be a real problem finding a cause - and 10ma trip means the slightest problem is going to cause a trip (but you are safe - so don't bypass).

If you have three hole outlets I suspect you do have a ground - be foolish to pay for the outlets if not use them. Most homes do not have the RCCB that you have so it appears your home was well wired.

[bonsaimax]

You need to isolate the problem and that may require turning off all the switches. Hopefully that will end the trips - if not something is not wired through the switches and you should have professional help.

This is what I've been trying to do for the past week or so. The air conditioner is on almost all day, and there are almost no power cuts during the day. It is a weekend today and most of our neighbours are home as well. I was expecting to have another outage this morning. Fortunately, none yet. But, I bet that between 9-12 tonight we will be hit with another 5 or 6 power cuts as we were last night.

I will do as you suggested and hope that our home is actually well-wired. But then again, I don't trust what these electricians do unless I see it with my own two eyes.

Thanks for all the suggestions, Lopburi.

[doctormann]

You may have a wiring fault.

I had a lot of problems with my earth leakage breaker tripping - it got so bad in the end that it was tripping out every few minutes. I got an electrician in to have a look and it turned out that I had a damaged underground conduit, coupled with damaged insulation on the actual wires - happened on installation I guess. Over a period of time water had seeped into the conduit and caused the problems. When he pulled the old wires out they were thoroughly knackered.

The guy is Pattaya based - he's German but speaks good English. If you would like his number please PM me.

DM

[bonsaimax]

Thanks doctormann. How I wish. But unfortunately, I'm in Bangkok.

[lopburi3]

Be very careful so you don't chase your tail. Door bells that use 220v are also a common problem with water getting into wire or lizards across switch. I have had poor tape over electric wires behind an outlet (where they had spliced another wire in). But if you can narrow it down to one of the five feed lines you have 80% of the job done.

[autonomous_unit]

... But if you can narrow it down to one of the five feed lines you have 80% of the job done.

And another 80% to go, the way these things usually work.

[highonthai]

Are you resetting your breaker correctly? Turn off then on again, don't just turn it back on.

A good tool to have is an Amprobe, you can check the actual draw of any circut by just clamping it

around and wire. Check to see if any circut is drawing more than the rated breaker or an abnormal amount, 15, 20, 30, amp etc. GFI's are nortorius for tripping with out cause.

Remember any motor will have a high startup draw and then will drop down to the normal amps.

With out being at your home home is impossible to trouble shoot your problem I would think....

Ex Sparkie by trade.

[lopburi3]

That's the chasing your tail part. Make up a flow chart and follow it. Or check if you can replace the main breaker with a 30ma unit. That should still provide safety and "might" last long term. If not you are not out that much. But if there is no main breaker before this one you do not want to replace it yourself with a live incoming mains so you are probably going to have to have somebody come anyhow.

Ammeter is great if you know what you are doing but for DIY it is not that safe. You have to use one wire, and that usually means inside a power panel, so for most of us with butterfingers it would not be recommended. Every time I have had a fault trip there has been a cause - it may take a long time to find however. I have used since they became available here in the mid 1970's. And still have the original Safe-T-Cut and it still works fine.

[bonsaimax]

I might have isolated the problem. We went out for the weekend and turned off the A/C main switch overnight. Coming back home this evening, found that there were no power cuts while we were gone. Would it be safe to assume that it is the A/C which causes the outages?

I had a problem with the garden lights and door bell causing a short circuit last year. Had three electricians come over to check it out. After a week and 3,000 baht, I ended up having to disconnect all outdoor wiring because none of them were competent enough to resolve the problem.

Thanks all. I'll take all your suggestions into consideration

[lopburi3]

That is probably it and the reason that most electricians try to avoid using RCCB for the air conditioner lines. You may want to have a direct run for that with a normal breaker/switch next to unit. Make very sure that they run ground wire (probably already have) and that outside compressor is also attached to ground. If you do not have any protection prior to your RCCB I would also install a breaker (non RCCB) there to protect the line from passing full meter current.

If you know a decent air conditioner man perhaps it would be a good time to service and perhaps that would be enough to fix the problem.

[bonsaimax]

lopburi, you are probably right. used the A/C again last night,and as expected, the power tripped. the A/C must be the culprit.

cheers!

Is the UPS battery charged up fully yet?

How do we know if the UPS is fully charged yet. It stays on for just a few seconds before shutting down. How long is the PC supposed to stay on? 5 sec. is just not enough time to shut everything down.

[lopburi3]

lopburi, you are probably right. used the A/C again last night,and as expected, the power tripped. the A/C must be the culprit.

cheers!

Is the UPS battery charged up fully yet?

How do we know if the UPS is fully charged yet. It stays on for just a few seconds before shutting down. How long is the PC supposed to stay on? 5 sec. is just not enough time to shut everything down.

If you have had it plugged in for a day the UPS should provide at least 10-20 minutes of power to allow a complete save of material and shutdown process. If you are only getting a few seconds, and do not have more than a computer/monitor plugged into it, it is defective. Are you sure you are plugged into the right outputs? Sometimes they have filtered but non UPS outlets on the back.

[chownah]

It seems that the AC is causing the porblem. Have you determined if it is tripping the breaker becasue of a ground fault problem or because it is drawing too much current?

Edited February 6, 2006 by chownah

[bonsaimax]

I also remember that before I disconnected the water heater, after switching the power back on, the shower heater turns on by itself.

This looks like as chownah suggested, a ground fault problem too.

[lopburi3]

This is going to be a novel soon. What kind of water heater do you have? The normal single or multi point instantaneous type can not turn on without water flow (unless seriously defective). Do you have a storage tank type system? For the tank type it would probably be normal to heat back to preset temperature after a power failure.

[Rinrada]

Think that I am going to have to pack an Earth Loop Impedance Tester on my next visit....what do they say "Old Sparks never Die they end up working double bubble in Chiang Mai"....

This is part of the earthing/grounding regs under UK /EU -IEE standards but having worked to US and Japanese National Wiring Codes... its all pretty similar...

Bit of Info...

Earth Electrode Resistance Testing..

There are two methods of carrying out this test.

(1) using a proprietary tester, and

(2) using an earth loop impedance tester.

(1) the proprietary tester.

The test unit has three connections. The first is attached to the electrode under test, the second to an auxiliary potential electrode or ‘spike’, and the third to an auxiliary current electrode.

The meters utilise an ohms scale and will typically have the following settings to choose from.

Ohms -Ohms x 10 ohms x100

Choosing which scale to use requires experience of electrode testing although it should be noted, that damage to the meter will not occur if the wrong scale is used. The usual approach, therefore, is to start on the ohms’ scale and progress up, if and when full-scale deflection occurs.

The positioning of the auxiliary electrodes is critical to the test and positioning is dependant upon the length of the electrode under test. The current electrode is placed at a distance ten times the test electrodes length and the potential electrode is placed in a direct line midway between the two. At this point a reading is taken and noted.

Two further readings are now taken.

The first with the potential electrode placed 10% nearer the current electrode and the second, with the potential electrode placed 10% nearer the electrode under test ( from its original position ).

diagrams available..

NB)

the installation should be isolated and main earth at the electrode disconnected for the duration of the test

Interpreting the Results

The average of the three readings is taken as the electrodes resistance as long as all three readings are within 5% of one another.

If they exceed 5% the test must be repeated with the distance of test and auxiliary electrodes increased.

Electrodes that exceed a test value of 200W are prone to being unstable and a value of 20W is often quoted as being the maximum allowable value.

This comes from ohm’s law, where an installation relying on an electrode is provided with supplementary protection by a 30mA RCD.

50V divided by 0.03A = 1666W ( maximum touch voltage is 50V )

...more..examples...

with thanks to Blackburn College...

http://www.rsc-northwest.ac.uk/Curriculum/..._resistance.htm

[bonsaimax]

What kind of water heater do you have? The normal single or multi point instantaneous type can not turn on without water flow (unless seriously defective). Do you have a storage tank type system?

I have the normal single type (Turbora) which wont turn on without water flow. And yes I do have a storage tank.

An "electrician" came over today while I was at work, and of course said that everything's ok now. Just replaced a faulty wire somewhere. No problem!

As I am typing this on my laptop, the power has tripped for the 4th time tonight (expecting another 2 or 3 more). I've also given up on the UPS as I smelled something burning earlier. So no desktop PC until everything's sorted out.

It's really frustrating and am at the verge of burning the house down.

Just a few more questions if I may:

1) How do I locate the ground wire?

2) Is it possible to connect a new ground wire to the circuit breaker if I couldn't locate it?

3) Where in the circuit breaker is it connected.

Took a look inside the circuit breaker and was expecting to see red, green, wires. But NO! All black wires only.

[Rinrada]

Thailand uses US wiring codes (plus a mixture of others)...Black is the Positive Conductor,White - Negative/Neutral and Ground /Earth is or should be any combination of Green/Yellow.....as said ...should be but......

[lopburi3]

First rule. Carry a screwdriver type tester to check for live wires. Never trust the color code here.

From what you wrote you have an RCCB with a 10ma trip (but you did not mention the amperage size of the breaker). That I would assume is in a metal or plastic box and feeds the 5 switches you mentioned (which I believe are breakers and should also have amperage ratings). Inside that box when you take the cover off should be two sets of screw terminals. One for the neutral and one for grounds. The hot wires will be on the main bus and attach to the switches. The neutral and ground terminals may have a connection or may not. If you can not determine which wire goes to the ground stake you can detach all and then test with a meter between any hot wire until it reads 220 volts. That wire is going to a ground. But you may also have wires connected together instead of on terminals so it can become rather complex if not a good installation.

Another thing you can do is check outlets with the meter. From hot to neutral should be 220v and from hot to ground should also be 220v if properly wired and grounded. Meters that can serve this purpose are only a couple hundred baht at Lotus. And it is worthwhile checking after even a good electrician does work to make sure all grounds still work.

[bonsaimax]

From what you wrote you have an RCCB with a 10ma trip (but you did not mention the amperage size of the breaker). That I would assume is in a metal or plastic box and feeds the 5 switches you mentioned (which I believe are breakers and should also have amperage ratings).

The details I mentioned earlier was what was on the label of the box. I didn't see anything that shows the amperage size.

Meters that can serve this purpose are only a couple hundred baht at Lotus. And it is worthwhile checking after even a good electrician does work to make sure all grounds still work.

I think I will have to get one soon as it has become a necessity for me.