SAFE-T-CUT TRIPPING DAILY

[sometimewoodworker]

5 minutes ago, livram said:

A/C were cleaned middle March 500 Baht each. 18K BTU set at 27 other 2 12K set at 25. All A/C. All cool down to set temp but the 2 12K A/C compressor runs quite a bit because Thai family leaving doors or window open.

 

Last electric bill 1150 consumption and 5105 baht which was a new record for this house.

At that consumption, though a little high, unless you are compressing it into a short time per day, the meter should be able to easily supply enough power.

 

You say that you can shorten the supply cable from 60 to 30 meters. That will help. It will be even better if you can use the extra cable to double up on the cables from the meter to your house.

 

all the other advice needs following up 

 

[lopburi3]

We leave main house non ac - only have in bedrooms and only use when needed - but have 4 refrigerators (3 over 19CF) running 24 hours a day in non ac locations so that is a big user, along with water cooler/ice maker.

Suspect your very long wire run from meter to panel may well be an issue (and as said wires were often not replaced even when meters were).  Is there any real reason you could not feed from front (60 meters) if have to replace?  Do not believe mine are more than 30 meters (and panel is in rear of house).

[livram]

2 minutes ago, lopburi3 said:

We leave main house non ac - only have in bedrooms and only use when needed - but have 4 refrigerators (3 over 19CF) running 24 hours a day in non ac locations so that is a big user, along with water cooler/ice maker.

Suspect your very long wire run from meter to panel may well be an issue (and as said wires were often not replaced even when meters were).  Is there any real reason you could not feed from front (60 meters) if have to replace?  Do not believe mine are more than 30 meters (and panel is in rear of house).

No real issue to run cables from meter to front. If I need to go to bigger size cables that is what I will do.

[livram]

UPDATE: Apology for long post

This morning received Amp Clamp - 500 baht from Lazada. Also PEA came with a cherry picker truck and 5 men. Examined PEA meter and said too many lines on line 1 (5 meters on my pole) and moved my meter to line 2(???). After they left I checked elec again. Same as before, all 3 A/c run OK but when turn on 3500 KW shower heater, main breaker trips after heater and water pump run for 3 minutes.

 

Also while I waiting for Amp Clamp I measure voltage at power point plug with multi-meter and it was consistently 213-215 volts. Today after PEA said they moved the PEA meter I again measured voltage and now it seems to be consistent 235-237V.

 

Also last Sunday we had a real brownout for 2 hours, voltage dropped to 165V but the main breaker DID NOT TRIP. The A/C's ran but blew hot air and all the fans and LED lights stayed on. Two old style ceiling lights with ballast would not turn on.

 

The wiring coming from the 15/45 meter has Thai wring and I think the numbers are 2X5 600. I have bad eyes so that may be incorrect. It looks like a flat ribbon type cable that has 2 wires, it seems that you separate the wires by pulling them apart instead of cutting.

 

Finally I measured Amps at the PEA meter with all 3 A/c's on-14.48 Amps. I took the lid off the Safe-T-Cut and the wires are so packed in I could not get the Amp Clamp to fit around.

 

Can I measure everything from the PEA meter or do I need to separate wires and measure from the CU box?

 

[sometimewoodworker]

1 hour ago, livram said:

Also last Sunday we had a real brownout for 2 hours, voltage dropped to 165V but the main breaker DID NOT TRIP. The A/C's ran but blew hot air and all the fans and LED lights stayed on. Two old style ceiling lights with ballast would not turn on.

I would not expect the RCCB to trip in that situation.

 

My house supply will cut off at about 185V~195V to protect my equipment.

 

1 hour ago, livram said:

The wiring coming from the 15/45 meter has Thai wring and I think the numbers are 2X5 600. I have bad eyes so that may be incorrect. It looks like a flat ribbon type cable that has 2 wires, it seems that you separate the wires by pulling them apart instead of cutting.

Take a picture or 2 and post that. The cable maybe small.

 

You should measure the voltage both at the meter and at the house with a full load, and post the information.

 

[livram]

20 minutes ago, sometimewoodworker said:

I would not expect the RCCB to trip in that situation.

 

My house supply will cut off at about 185V~195V to protect my equipment.

 

Take a picture or 2 and post that. The cable maybe small.

 

You should measure the voltage both at the meter and at the house with a full load, and post the information.

 

Here is a picture of the meter and the cable(blurry). Taking measurements at the house is a problem. I have a amp clamp but there is not enough room between wires to get the clamp in. I think I will have to get someone to separate the wires first. I am 75 and being sweaty on a ladder makes me a little nervous. 

 

To take a measurement at the PEA meter do I just clamp around one of the separated cables? 

[sometimewoodworker]

2 hours ago, livram said:

Here is a picture of the meter and the cable(blurry). Taking measurements at the house is a problem. I have a amp clamp but there is not enough room between wires to get the clamp in. I think I will have to get someone to separate the wires first. I am 75 and being sweaty on a ladder makes me a little nervous. 

 

To take a measurement at the PEA meter do I just clamp around one of the separated cables? 

The top picture is too blurry to get any information. But the cables look as if they may not be your problem.

 

You need a voltage reading at the meter not an amp reading, to get a voltage reading you need to stick probes on to the cables where they enter the PEA meter using your multimeter, and into a socket in the house. However an amp reading at the meter may also give useful information and yes, you clamp round a single cable 

 

It seems quite  likely that your Safety-T-Cut that is tripping needs replacing, but to be sure we need a picture showing the cables (from the meter to your house) so we can read the printing on them and the voltage readings at the PEA meter and in your house when you gave everything (that doesn’t trip) turned on.

Your supply should easily be able to support 3X as much as you are using.

 

of course you should also check to see that the load you are switching on is not a faulty appliance.

 

[livram]

7 minutes ago, sometimewoodworker said:

The top picture is too blurry to get any information. But the cables look as if they may not be your problem.

 

You need a voltage reading at the meter not an amp reading, to get a voltage reading you need to stick probes on to the cables where they enter the PEA meter using your multimeter, and into a socket in the house.

 

It seems quite  likely that your Safety-T-Cut that is tripping needs replacing, but to be sure we need a picture showing the cables (from the meter to your house) so we can read the printing on them and the voltage readings at the PEA meter and in your house when you gave everything (that doesn’t trip) turned on.

Your supply should easily be able to support 3X as much as you are using.

 

of course you should also check to see that the load you are switching on is not a faulty appliance.

 

I checked the voltage in the house with a multimeter after PEA workmen relocated the PEA meter from Line 1 (??) to Line 2 (??) today. The voltage was a consistent 234-235 volts up from the previous voltage readings of 213-215. I tested the voltage in the house by a plug receptacle using a multimeter.

 

Tomorrow will try to get a clear picture of meter cables. It looked like the numbers on the cable were 2X5 600, but will recheck.

 

If I remembe correctly the Safe-T-Cut CU is only 2 or 3 years old.

 

To

[sometimewoodworker]

4 minutes ago, livram said:

I checked the voltage in the house with a multimeter after PEA workmen relocated the PEA meter from Line 1 (??) to Line 2 (??) today. The voltage was a consistent 234-235 volts up from the previous voltage readings of 213-215. I tested the voltage in the house by a plug receptacle using a multimeter.

 

Tomorrow will try to get a clear picture of meter cables. It looked like the numbers on the cable were 2X5 600, but will recheck.

 

If I remembe correctly the Safe-T-Cut CU is only 2 or 3 years old.

 

To

Did you have everything switched on when you took the reading, it can make a big difference?

 

and there are more numbers on the cable.

 

just because it’s not old doesn’t stop it going bad.

[livram]

2 minutes ago, sometimewoodworker said:

Did you have everything switched on when you took the reading, it can make a big difference?

 

and there are more numbers on the cable.

 

just because it’s not old doesn’t stop it going bad.

I don't remember, will check voltage tomorrow with everything ON.

 

Will get more numbers off of the cable.

 

Thanks for your help.

[sometimewoodworker]

54 minutes ago, livram said:

I don't remember, will check voltage tomorrow with everything ON.

 

Will get more numbers off of the cable.

 

Thanks for your help.

Don’t forget to check at the meter as well as in the house 

 

and with the cable a picture is often better than copying down what is printed on it

[Metropolitian]

It looks like the OP has the STC CU as in the picture.

In this module the STC safety module and the main breakers are connected.

So my thought for a solution would be one of the two options, both with an extra 5 gangs CU.

 

Option 1:

Tap the incoming wires at the STC to a 2nd CU,  50amp 'main' breaker and 3 x 20amp single breakers.

Connect all the 3 A/C to those breakers.

 

Option 2:

The main wires going into the new CU, which then has a 63Amp main breaker.

Three extra single breakers for the A/C and connected to the STC 10-gangs CU.

 

 

Option 2 has my preference as the setup then has one true main breaker.

Option 1 if the incoming wires are coming trough the wall and can't be pulled.

 

 

 

Make sure the A/C are grounded, very much the case for the outdoor unit.

 

 

[Janner1]

It sound as though you are over loading your amp draw down when everything is turned on and if you have a fridge it will trip everything when it clicks on every time to maintain it’s temperature.

you need to rewire your power supply through a larger amp trip switch or better still put items onto separate trips in a larger consumer unit.

[sometimewoodworker]

4 hours ago, Janner1 said:

It sound as though you are over loading your amp draw down when everything is turned on and if you have a fridge it will trip everything when it clicks on every time to maintain it’s temperature.

you need to rewire your power supply through a larger amp trip switch or better still put items onto separate trips in a larger consumer unit.

With a 15/45 meter and a 50A RCBO 3 AC units and a few fans should not be getting anywhere near pulling maximum power. The overload trip will probably need to be around 70A with that unit. To get an instant trip when adding something like the water heater the power draw will have to be over or around 50A before adding in the heater.

 

So more information before jumping to the conclusion that @livram is maxing out the supply is a good idea.

[Crossy]

OK, I suggest making these measurements:-

 

Main Breaker OFF

Voltage at the incoming breaker =

Main Breaker ON

Load that does NOT cause a trip.

Voltage at main breaker = 

Voltage at the meter =

Supply current (measure where convenient at the meter is OK) = 

Load that DOES cause a trip.

Supply current = 

Voltage at main breaker = 

Voltage at the meter =

 

You may need help (and a couple of mobile phones) to take the measurements before the breaker trips.

 

It does look awfully like your breaker is going off early, but there are other faults which could have the same symptoms which we can discuss when we have some results.

 

Please can you post a photo of the Safe-T-Cut unit with the lid off so we can see how it's wired.

 

[livram]

1 hour ago, Crossy said:

OK, I suggest making these measurements:-

 

Main Breaker OFF

Voltage at the incoming breaker =

Main Breaker ON

Load that does NOT cause a trip.

Voltage at main breaker = 

Voltage at the meter =

Supply current (measure where convenient at the meter is OK) = 

Load that DOES cause a trip.

Supply current = 

Voltage at main breaker = 

Voltage at the meter =

 

You may need help (and a couple of mobile phones) to take the measurements before the breaker trips.

 

It does look awfully like your breaker is going off early, but there are other faults which could have the same symptoms which we can discuss when we have some results.

 

Please can you post a photo of the Safe-T-Cut unit with the lid off so we can see how it's wired.

 

I need to get a helper to start taking measurements. But here are the photos of the CU with the cover off. You can see that the cables are really crammed in and the reason the Amp Clamp hasn't been used. Also I took the cover off of the cable conduit leading from the ceiling into the CU. Some of the cables look really worn and also packed in.

 

Also all of our cables come thru the ceiling and down into the CU.

[Crossy]

OK 63A incoming breaker, no way that should be opening on overload with what you have connected. We can confirm once you've made some measurements.

 

No grounds, but that's an issue for another day.

 

A question, is it ANY additional load with causes a trip (kettle etc) or just the water heater?

 

Does the RCBO switch move into the red section? What's the label on the red bit? (some units have a "bypass" or "off" position)

 

[livram]

1 minute ago, Crossy said:

OK 63A incoming breaker, no way that should be opening on overload with what you have connected. We can confirm once you've made some measurements.

 

No grounds, but that's an issue for another day.

 

A question, is it ANY additional load with causes a trip (kettle etc) or just the water heater?

 

When the water heater comes on the water pump also kicks in. But to answer your question the main breaker has tripped with 3 a/c on and the Microwave is turn on. Usually when the hot water trips it takes 2 or 3 minutes before the CU trips but when the 3 A/C's are on the microwave will trip immediately., or it doesn't trip at all.

[Crossy]

Does the RCBO switch move into the red section? What's the label on the red bit? (some units have a "bypass" or "off" position)

 

Have you ever verified that supply polarity is correct? (L really is L)

[lopburi3]

Not sure if you are comfortable using screwdriver but I would make sure those holding main wires are tight.  Can have real issues if they start to loosen.  One hand operation to do but if any vision issues or doubt pay a sparkie to check (he could then check all of them at same time).  

[livram]

8 minutes ago, Crossy said:

Does the RCBO switch move into the red section? What's the label on the red bit? (some units have a "bypass" or "off" position)

 

Have you ever verified that supply polarity is correct? (L really is L)

The RCBO does NOT move into the Red section. There is no label on the red bit. It is set to 20 mAmp. It looks like it has an OFF position. Last week the PEA sparky was here and my daughter said he pulled out the RCBO dial unit and cleaned it off but no improvement.

 

 I am not sure about polarity. 

[sometimewoodworker]

29 minutes ago, lopburi3 said:

Not sure if you are comfortable using screwdriver but I would make sure those holding main wires are tight.  Can have real issues if they start to loosen.  One hand operation to do but if any vision issues or doubt pay a sparkie to check (he could then check all of them at same time).  

One hand job is important.

 

Keep one hand in your pocket when using a protected (insulation round the shaft) screwdriver around connections that may be live.

 

the bottom one is mostly OK, the top is bad (possibly kill you or make loud sparking noises, bad) if you mess up.

[livram]

11 minutes ago, lopburi3 said:

Not sure if you are comfortable using screwdriver but I would make sure those holding main wires are tight.  Can have real issues if they start to loosen.  One hand operation to do but if any vision issues or doubt pay a sparkie to check (he could then check all of them at same time).  

Sparky to be here Monday, I will have him check. Right now just trying to get measurements and narrow down possibilities.

[Crossy]

Do you have a neon screwdriver (mains tester)? Easy to check the polarity if you do. It will light on whichever terminal is actually live.

[sometimewoodworker]

2 minutes ago, livram said:

The RCBO does NOT move into the Red section. There is no label on the red bit. It is set to 20 mAmp. It looks like it has an OFF position. Last week the PEA sparky was here and my daughter said he pulled out the RCBO dial unit and cleaned it off but no improvement.

 

 I am not sure about polarity. 

Have you used the test button recently (it should be done several times a year)

[lopburi3]

4 minutes ago, livram said:

The RCBO does NOT move into the Red section. There is no label on the red bit. It is set to 20 mAmp. It looks like it has an OFF position. Last week the PEA sparky was here and my daughter said he pulled out the RCBO dial unit and cleaned it off but no improvement.

 

 I am not sure about polarity. 

Actually if PEA pulled dial off they likely did check main screw connection tightness.  But have new person double check.

[sometimewoodworker]

Interesting point, but probably nothing to do with the situation (unless it’s the pump that always causes the trip), that is the first “B” class MCB that I’ve seen in Thailand 

[livram]

4 minutes ago, Crossy said:

Do you have a neon screwdriver (mains tester)? Easy to check the polarity if you do. It will light on whichever terminal is actually live.

I have mains tester I carry when doing any electrical work but I will have PEA guy check and tighten incoming wires if needed. I would not even be sure that the wires were in the right hole.

 

Also have recently used RCBO tester and if worked fine.

[Crossy]

Just use your tester on any breaker connection, it should indicate 220V or light up.

 

Also check that it does NOT light on the neutral bar (at the top of the box).

 

[livram]

3 minutes ago, Crossy said:

Just use your tester on any breaker connection, it should indicate 220V or light up.

 

Also check that it does NOT light on the neutral bar (at the top of the box).

 

I have cheap tester and as soon as it gets to within 6 inches of any breaker wire it lights up. But it DOES NOT light up at any part of the neutral bar.