Pea & Subbies Make For An Interesting Day

[petercsea]

Nearly there. There is a need to upgrade the meter from 5/15Amps to something larger.

Some of the items installed:

3 air-cons total power consumption: 4.8KW. Two of these may be used at the one time. Rarely would there be three on at the same time.

2 shower heaters: 3.8 KW each. Both could be in service at the same time

Hot water kettle: 0.6 KW. Left on for the day hours

Fridge: 75 Watts.

Then all the things that are occasionally used. Washing machine, Iron, computers etc., intermittent water pump

Currently only turning on one heavy consumer at a time. I compiled a list for the PEA's advice. Their answer was that there was no need to upgrade as no-one else in the nearby moobaans had anything different. They then walked around the outside of the house for their assessment (hot water heaters don't matter obviously) and agreed to upgrade: 15/45 Amps. With a lot of encouragement I got them to agree to provide a 30/90 Amp meter.

With the upgrade there is a need for higher supply rating cable which they suggested was 25 mm copper at 145 baht per meter; 50 meters to and from the pole to the house. My surprise prompted them into a second recommendation: 50 sq mm aluminium at 35 baht per meter. OK but what is the rating of that cable? Blank! Quick check showed that it was likely to be alright so went with that.

It may have taken them approx two hours to install the cable and fit it to the consumer box breaker. In that process they had to re-pull a couple of the cables in the box because of the width of the supply cable. Their re-wiring of the consumer box was a surprise to me. Neutrals (not the supply neutral) were connected to the earth bar and one or two earths were connected to the neutral bar. I queried it and was given the answer that it didn't matter because of the link from the earth bar to the neutral bar? I couldn't argue but decided not to touch anything until I had repositioned the wires.

Looking at the aluminium cable recommendations in general it states that a diameter of a curve bent in the cable should be at least 8 times the radius of the cable. I think they got it down to 3 times. Stressed cable?

Time for the test. Power on! First air-con on – The inside unit sprang into action but the compressor just hammered its little contacts continuously. He turned the air off with the controller and went to check the breaker itself. Wham! The chassis of the consumer box bit him so detection of live areas needed to be investigated. He was standing barefoot on an aluminium ladder and working from first principles, he grounded himself by touching the wall before checking his neon tester! The chassis was live for sure. The main CB was switched off and he then inspected the earth-neutral link, the earth cable, followed by the switch on the wall connected to the air-con. There was a short in the switch, which he corrected and then went through the process of turning it all back on. The air-con sprang to life and the chassis was at ground. Switched the second air-con on and it too sprang safely to life.

Back he went outside to check the meter and called urgently to have a look. The meter was flying around. This led him to check the earth stake but what ever he did he was happy that there was nothing out of the ordinary. Just stunned that the meter was moving so fast. I explained that was why I never turned on two air-cons at the same time. He said with a smile that an upgraded meter was needed!

Off to the PEA office to pay for the new meter prior to installation. The officer there said that a new meter wasn't needed. He took the money.

I have since re-connected the earths and neutrals to their corresponding connection bars. Waiting for the meter and the overall inspection. In this area it seems that you only need an earth system if you have a meter greater than the default supplied (5/15 Amps). So…………. it's big meters that can harm you in Thailand!

[Crossy]

Sounds pretty scary to me. How incompetents (for that's what they are) as these can be employed by MEA/PEA is beyond me, they evidently have no understanding of what they're doing.

Do you have an ELCB? If you do please check that the MEN (Ground - Neutral) link is connected to the incoming neutral on the inlet side of the ELCB. Connecting it to the output side of the ELCB will remove a significant degree of the protection provided by this device.

[petercsea]

Sounds pretty scary to me. How incompetents (for that's what they are) as these can be employed by MEA/PEA is beyond me, they evidently have no understanding of what they're doing.

Do you have an ELCB? If you do please check that the MEN (Ground - Neutral) link is connected to the incoming neutral on the inlet side of the ELCB. Connecting it to the output side of the ELCB will remove a significant degree of the protection provided by this device.

Thanks for the response Crossy,

I don't have ELCB protection like Safe T Cut, on the power line or the air-cons. Have RCBO's on the three ring mains and ELCB's on the 2 hot waters, have just re-checked those now and they're installed correctly. I presume installing them on the air-cons (and the light circuits) would be your recommendation? Think I'm asking the obvious there

It really did freak me and I must admit I feel a bit annoyed with them,. Feeling quite unsure about the installation competency for the new meter and it isn't even here yet, let alone the pre-payment, which is scary enough

[Crossy]

I don't have ELCB protection like Safe T Cut, on the power line or the air-cons. Have RCBO's on the three ring mains and ELCB's on the 2 hot waters, have just re-checked those now and they're installed correctly. I presume installing them on the air-cons (and the light circuits) would be your recommendation?

Actually what you've got sounds pretty OK. Pretty much what we're doing, although we're having a split-service consumer unit (ELCB half way down) and the added complexity of a genset changeover.

I wouldn't put the lights on ELCB (at least not all of them) for safety reasons, we don't want the lights to go out in an emergency.

Same for the fridge and freezer, nuisance trips can be a nightmare, you may discover new life in the fridge when you come back off vacation.

Up to you whether you do the aircons, if the outdoor units are grounded and out of reach I wouldn't bother myself.

[soundman]

I have often wondered about these meter ratings.

My house has a 5(15) meter. We regurarly run three to four times that power through it.

3 aircons, 2 x elec water heaters, two kettles, three tv's, microwave etc. Quite often all on at the same time and the meter is spinning so fast you can't see the graduations on the wheel.

Hasn't blown up or burnt out in over a year.

Anybody have any thoughts on the real maximum current conditions of these meters?

Soundman.

[petercsea]

I have often wondered about these meter ratings.

My house has a 5(15) meter. We regurarly run three to four times that power through it.

3 aircons, 2 x elec water heaters, two kettles, three tv's, microwave etc. Quite often all on at the same time and the meter is spinning so fast you can't see the graduations on the wheel.

Hasn't blown up or burnt out in over a year.

Anybody have any thoughts on the real maximum current conditions of these meters?

Soundman.

Hi Soundman,

Obviously a high tolerance. You're more adventurous than me.

I found the manufacturers web-site and their internet domain is up for sale. Also sent off an email to the manager but the delivery failed.

Their address and details:

ORIENTAL ELECTRIC INDUSTRY COMPANY LIMITED

Manager : prawit

Address : BANGCHAN INDUSTRIAL ESTATE, NO. 111 MOO 4, SERITHAI RD., T. KANNAYAO BANGKOK 10230 THAILAND

Telephone : 662-5171326,662-9199873

Fax :

Web Site : http://www.oeic.com

E-mail Address : [email protected]

[longball53098]

I have often wondered about these meter ratings.

My house has a 5(15) meter. We regurarly run three to four times that power through it.

3 aircons, 2 x elec water heaters, two kettles, three tv's, microwave etc. Quite often all on at the same time and the meter is spinning so fast you can't see the graduations on the wheel.

Hasn't blown up or burnt out in over a year.

Anybody have any thoughts on the real maximum current conditions of these meters?

Soundman.

Hi Soundman,

Obviously a high tolerance. You're more adventurous than me.

I found the manufacturers web-site and their internet domain is up for sale. Also sent off an email to the manager but the delivery failed.

Their address and details:

ORIENTAL ELECTRIC INDUSTRY COMPANY LIMITED

Manager : prawit

Address : BANGCHAN INDUSTRIAL ESTATE, NO. 111 MOO 4, SERITHAI RD., T. KANNAYAO BANGKOK 10230 THAILAND

Telephone : 662-5171326,662-9199873

Fax :

Web Site : http://www.oeic.com

E-mail Address : [email protected]

See this pdf of a spec on the Mitsu brand Watt-hour meters that I see around many moo bans.

Helps understand the 5(15) designation I hope

MF220_05A015_33E.pdf

[soundman]

See this pdf of a spec on the Mitsu brand Watt-hour meters that I see around many moo bans.

Helps understand the 5(15) designation I hope

MF220_05A015_33E.pdf

Thanx for that spec.

Exact model we have.

The spec. rates the unit I(max) at 15 amps. That is about what a 18000 BTU air unit draws.

We regurarely draw 3 or more times I(max) continuously for hours on end and the unit hasn't burn't out or malfunctioned.

Hence my question above.

[longball53098]

My guess as to why the meter never burns out is maybe Mitsu builds in a very high tolerance for overload? Possible this meter or series of meters is designed for countries like Thailand where they know that an overcurrent is more the norm than other more developed countries?

All I know is I had a similar issue in my last moo ban with the next sized meter and I know like you the meter was being overtaxed current wise,,,,,,,,,the dial spinning like crazy but it never burned out or smoked in any way.

I like you want to know how a meter that carries a specific rating can handle all this overcurrent-------------->>>>any electrical engineers know how to explain this?

[david96]

I have often wondered about these meter ratings.

My house has a 5(15) meter. We regurarly run three to four times that power through it.

3 aircons, 2 x elec water heaters, two kettles, three tv's, microwave etc. Quite often all on at the same time and the meter is spinning so fast you can't see the graduations on the wheel.

Hasn't blown up or burnt out in over a year.

Anybody have any thoughts on the real maximum current conditions of these meters?

Soundman.

I can only state from experience in Australia the standard watthour meter is now single phase 10/80Amp @400rpm of the disc at 10amps.

Calibration is at 10amps and max continuous current is 80 amps. Service fuse 100amp HRC. Min service size (aerials) to consumers mains termination is 6 sq mm HD copper parallel twin single insulated cable.

5/20 meters where installed were phased out and replaced with 10/40 and 10/60 meters over 40 years ago.

Disc speed is on the meter nameplate. A 5/20 meter will carry 40 amps with no problems but the accuracy of the meter may be affected.

[david96]

Nearly there. There is a need to upgrade the meter from 5/15Amps to something larger.

Some of the items installed:

3 air-cons total power consumption: 4.8KW. Two of these may be used at the one time. Rarely would there be three on at the same time.

2 shower heaters: 3.8 KW each. Both could be in service at the same time

Hot water kettle: 0.6 KW. Left on for the day hours

Fridge: 75 Watts.

Then all the things that are occasionally used. Washing machine, Iron, computers etc., intermittent water pump

Currently only turning on one heavy consumer at a time. I compiled a list for the PEA's advice. Their answer was that there was no need to upgrade as no-one else in the nearby moobaans had anything different. They then walked around the outside of the house for their assessment (hot water heaters don't matter obviously) and agreed to upgrade: 15/45 Amps. With a lot of encouragement I got them to agree to provide a 30/90 Amp meter.

With the upgrade there is a need for higher supply rating cable which they suggested was 25 mm copper at 145 baht per meter; 50 meters to and from the pole to the house. My surprise prompted them into a second recommendation: 50 sq mm aluminium at 35 baht per meter. OK but what is the rating of that cable? Blank! Quick check showed that it was likely to be alright so went with that.

It may have taken them approx two hours to install the cable and fit it to the consumer box breaker. In that process they had to re-pull a couple of the cables in the box because of the width of the supply cable. Their re-wiring of the consumer box was a surprise to me. Neutrals (not the supply neutral) were connected to the earth bar and one or two earths were connected to the neutral bar. I queried it and was given the answer that it didn't matter because of the link from the earth bar to the neutral bar? I couldn't argue but decided not to touch anything until I had repositioned the wires.

Looking at the aluminium cable recommendations in general it states that a diameter of a curve bent in the cable should be at least 8 times the radius of the cable. I think they got it down to 3 times. Stressed cable?

Time for the test. Power on! First air-con on – The inside unit sprang into action but the compressor just hammered its little contacts continuously. He turned the air off with the controller and went to check the breaker itself. Wham! The chassis of the consumer box bit him so detection of live areas needed to be investigated. He was standing barefoot on an aluminium ladder and working from first principles, he grounded himself by touching the wall before checking his neon tester! The chassis was live for sure. The main CB was switched off and he then inspected the earth-neutral link, the earth cable, followed by the switch on the wall connected to the air-con. There was a short in the switch, which he corrected and then went through the process of turning it all back on. The air-con sprang to life and the chassis was at ground. Switched the second air-con on and it too sprang safely to life.

Back he went outside to check the meter and called urgently to have a look. The meter was flying around. This led him to check the earth stake but what ever he did he was happy that there was nothing out of the ordinary. Just stunned that the meter was moving so fast. I explained that was why I never turned on two air-cons at the same time. He said with a smile that an upgraded meter was needed!

Off to the PEA office to pay for the new meter prior to installation. The officer there said that a new meter wasn't needed. He took the money.

I have since re-connected the earths and neutrals to their corresponding connection bars. Waiting for the meter and the overall inspection. In this area it seems that you only need an earth system if you have a meter greater than the default supplied (5/15 Amps). So…………. it's big meters that can harm you in Thailand!

Doing a max demand assessment of the above loading using AS/NZ3000 for a domestic residence single phase connection one arrives at a figure of approx 40amps. Consumers mains would be 10 sqmm copper which has a 63 amp rating unenclosed, the service fuse would be 100amps HRC. Meter would be 10/40 amps min.

Ref AS3000 /2007 page 350 table C1. Current ratings page 370 table C5.

Note Aluminimum cables have a reduced current rating compared with copper.

An installation must be tested before connection to supply and the polarity of supply tested. The persons carrying out the work were not compentent.

[david96]

RPM @10 amps should read revolutions per Kwh, eg 400 revs per Kwh.

[Crossy]

RPM @10 amps should read revolutions per Kwh, eg 400 revs per Kwh.

Some may call me pedantic, but it's kWh (the case is important).

OK, I'm pedantic

[longball53098]

RPM @10 amps should read revolutions per Kwh, eg 400 revs per Kwh.

Some may call me pedantic, but it's kWh (the case is important).

OK, I'm pedantic

Heres a view of a couple of Mitsu watt hour meters.

They only spec in revs per Kwh

[soundman]

RPM @10 amps should read revolutions per Kwh, eg 400 revs per Kwh.

Some may call me pedantic, but it's kWh (the case is important).

OK, I'm pedantic

Heres a view of a couple of Mitsu watt hour meters.

They only spec in revs per Kwh

Looks like kWh to me.