Serious Electricity Supply Problem - Advice/direction Urgently Needed Please

[gdhm]

Panic not, our supply is normally 241V (in the condo). No issues with reduced life of lamps (all CFs or electronic ballasts for the ring fluorescents) etc. AV and PCs are on UPSs with built-in AVRs so 220V all the time for them. I know it's counter-intuitive, but a slight over-voltage is much less harmful than a chronic under-voltage for most equipment.

The supply can only get lower as more homes are built so make hay whilst the power is good.

240V is only 9% high, perhaps some of our less fortunate members could use some of your spare volts

EDIT You do not appear to have any RCDs (unless you have a separate Safe-T-Cut unit), as others note it would be wise to add some sort of earth leakage protection, if your board is not full you could reasonably easily convert it to a split-service board, see here:- http://www.crossy.co.uk/wiring/Consumer.html

Hi Crossy,

Thanks again for your advice and for the reassurance.

No we do not have a separate Safe-T-Cut and I assume the ground wiring to a 2mtre copper rod is not safe enough. Wish to be safer anyway.

I do not think the split unit in your diagram is now practical as the house building electrician has not wired allowing for easy isolating any unprotected circuits (maybe oven, water heaters, heated shower units and aircons which I asked him to place on separate breakers. However any other items one would normally plug into a conventional power outlet socket could not be isolated. Consequently, items like freezer and fridges water pump, pond pump, washing machine are plugged into the normal outlet circuit and we cannot separate sockets. House alarm system is almost certainly connected to a lighting or outlet socket circuit.

Do air cons, water pumps, kettle water heaters, showers heaters, PIRS 150W lamps, trigger nuisance trips as well as freezers. As we have all these. Is triggering likely and if so if this amount of items were isolated wouldn't it be somewhat self defeating or is outlet and lighting sockets that are the main concerns for RCD?

I have just looked at the roadside meter. Interestingly whilst the PEA told us we had to have higher rated cable (we have 30mm form meter to house they only have 25mm into the metre. (No idea if our electrician was over cautious or what).

Any concerns here for me in your opinion Crossy?

I would agree with you that we do not have any RCD(s) fitted). Maybe explains when recently I stupidly cut though an extension cable and there was a big bang where I cut BUT no breakers tripped off. I must admit I was disconcerted about that. We do have a 2 metre Ground copper rod earthed to the consumer units.

I note on your plan you suggest that some appliances may nuisance trigger. such as a freezer) and we do have a freezer. I suspect will be too complicated impossible to isolate the plug sockets for one or 2 items around the house.

Would it therefore be considered best to buy one of the safe-t-cut boxes where one can adjust the sensitivity or would you feel the freezer etc may nuisance trigger to a higher level than is safe to set the insensitivity to?.

If you feel one of these boxes is appropriate what Amp rating should I select to be suitable for covering BOTH both consumer units?.

I assume it is OK being in line between the mains cable into the house and BEFORE the 2 consumer units Main breakers.

Would it matter if the wires out of the Safe-T-Cut go to EACH of the 2 consumer units instead of one unit feeding the other? (only ask as I do not know how the units have been wired and if either method is OK, then I will leave it to the electrician which method is easiest)

If you feel a combined MB/RCD is probably OK and I do nto need to get a Safe-T-Cut unit is it OK to fit two (i.e.one MB/RCD to each of my 2 consumer unit (I have no idea if the electrician split the cables into each the consumer Units or ran one from the other and the multiple cabling area above has been boxed and semi permanently boxed/plastered in).

Needless to say if there is only one safe method I will follow the course of action you advise.

Forgive me for asking you so many questions Crossy. I have 100% faith in you and your advice, but not in my local electricians. I have had a load of rubbish (sometimes dangerous) from 3 to date (even I knew they were advising me incorrectly. I am sure there are many excellent electricians in Thailand who are pretty expert in their profession, but I will not risk me guessing one form the other.

Oh final question based on your comments:

"The supply can only get lower as more homes are built so make hay whilst the power is good."

Looking for trouble down the line what would be the next upgrade route. A more powerful transformer up the road (the one that feeds us has 250 on the front (photos earlier in this thread) or the need of an extra transformer closer to our soi?

"240V is only 9% high, perhaps some of our less fortunate members could use some of your spare volts"

Yes. I think it will not last too long as plots of land in our soi and enxt to su is being bought up by individuals and built on. Ours is a sought after Muang area only 1km (by roiad) .6kjm as the crow flies) from the Beautiful and popular lake in Khon Kaen.

Strangely first night after upgrade the volts fell to around 212V with 2 air cons on BUT second night (last night) was 222V. Either they made adjustments (not that I am aware of or the voltage is very susceptible to whether a few items are running or not). The water heaters individually hammer the volts. The 6Kw cause a massive drop whilst on. Just tested a moment ago 235V instantly becomes 217V with the 6Kw water heater on. I have no understanding why 6Kw (actually only 80% of max heating level ) can knock out about 18V.

Seems to me the system has very little (or no spare capacity even with 3 phase). Just a swell it peaks at 235V and not 220V.

I assume in the UK there is so much capacity in city areas that whole streets could be added without such drops or am I very mistaken!

So I will enjoy it whilst it lasts

Thanks and Kind regards

Dave

[elkangorito]

Whilst awaiting Crossy's reply, my comments in orange.

No we do not have a separate Safe-T-Cut and I assume the ground wiring to a 2mtre copper rod is not safe enough. Wish to be safer anyway.

The "primary protection" is earthing (to an earth electrode/ground rod). RCD's are "secondary protection". I assume you have an "earthed" system.

Do air cons, water pumps, kettle water heaters, showers heaters, PIRS 150W lamps, trigger nuisance trips as well as freezers. As we have all these. Is triggering likely and if so if this amount of items were isolated wouldn't it be somewhat self defeating or is outlet and lighting sockets that are the main concerns for RCD?

I have underlined the items likely to have residual earth leakage (can cause nuisamce tripping). Earth leakage on this type of equipment gets worse as the equipment ages. New equipment is not a problem.

I have just looked at the roadside meter. Interestingly whilst the PEA told us we had to have higher rated cable (we have 30mm form meter to house they only have 25mm into the metre. (No idea if our electrician was over cautious or what).

This could be due to voltage drop concerns. Don't worry about it. BTW, the cable will be 35mm².

Any concerns here for me in your opinion Crossy?

I would agree with you that we do not have any RCD(s) fitted). Maybe explains when recently I stupidly cut though an extension cable and there was a big bang where I cut BUT no breakers tripped off. I must admit I was disconcerted about that. We do have a 2 metre Ground copper rod earthed to the consumer units.

This sounds like you have a problem. Under such circumstances, a circuit breaker should have tripped.

I note on your plan you suggest that some appliances may nuisance trigger. such as a freezer) and we do have a freezer. I suspect will be too complicated impossible to isolate the plug sockets for one or 2 items around the house.

Would it therefore be considered best to buy one of the safe-t-cut boxes where one can adjust the sensitivity or would you feel the freezer etc may nuisance trigger to a higher level than is safe to set the insensitivity to?.

Please DO NOT USE adjustable RCD's. They can be set to the "off" position or a position greater than 30mA. In either case, this can be lethal.

RCD's should be 30mA maximum for general use. For extra protection, 10mA RCD's are used. The 10mA RCD's are ideal for bathroom socket outlets.

If you feel one of these boxes is appropriate what Amp rating should I select to be suitable for covering BOTH both consumer units?.

I assume it is OK being in line between the mains cable into the house and BEFORE the 2 consumer units Main breakers.

Having a 30mA RCD protecting your whole installation will surely give you nuisance trips.

As an example, the new Australian Wiring Rules do not recommend such a practice for this very reason. The new rules also state;

1] that no more than 3 circuits may be placed onto any RCD.

2] that all socket outlets must be protected by an RCD (there are special exclusions to this rule).

Would it matter if the wires out of the Safe-T-Cut go to EACH of the 2 consumer units instead of one unit feeding the other? (only ask as I do not know how the units have been wired and if either method is OK, then I will leave it to the electrician which method is easiest)

Don't do this (see above).

If you feel a combined MB/RCD is probably OK and I do nto need to get a Safe-T-Cut unit is it OK to fit two (i.e.one MB/RCD to each of my 2 consumer unit (I have no idea if the electrician split the cables into each the consumer Units or ran one from the other and the multiple cabling area above has been boxed and semi permanently boxed/plastered in).

I'm not sure I understand what you are trying to say. A Safe-T-Cut is an RCD. When I say RCD, I mean a combination RCD/CB.

Needless to say if there is only one safe method I will follow the course of action you advise.

Forgive me for asking you so many questions Crossy. I have 100% faith in you and your advice, but not in my local electricians. I have had a load of rubbish (sometimes dangerous) from 3 to date (even I knew they were advising me incorrectly. I am sure there are many excellent electricians in Thailand who are pretty expert in their profession, but I will not risk me guessing one form the other.

Oh final question based on your comments:

"The supply can only get lower as more homes are built so make hay whilst the power is good."

Looking for trouble down the line what would be the next upgrade route. A more powerful transformer up the road (the one that feeds us has 250 on the front (photos earlier in this thread) or the need of an extra transformer closer to our soi?

The Electricity Distributor (PEA/MEA) is responsible for this. There are many things to consider before they upgrade anything. It may not be as simple as installing a bigger transformer or installing an additional transformer.

Also, don't be tricked into paying for the cost of any upgrades. They are obligated to supply you with a reliable electricity supply.

Since you say that your distribution transformer is 250kVA, I hope that the circuit breakers in your consumer unit are 6kA minimum (although 5kA should be ok).

"240V is only 9% high, perhaps some of our less fortunate members could use some of your spare volts"

Yes. I think it will not last too long as plots of land in our soi and enxt to su is being bought up by individuals and built on. Ours is a sought after Muang area only 1km (by roiad) .6kjm as the crow flies) from the Beautiful and popular lake in Khon Kaen.

Strangely first night after upgrade the volts fell to around 212V with 2 air cons on BUT second night (last night) was 222V. Either they made adjustments (not that I am aware of or the voltage is very susceptible to whether a few items are running or not). The water heaters individually hammer the volts. The 6Kw cause a massive drop whilst on. Just tested a moment ago 235V instantly becomes 217V with the 6Kw water heater on. I have no understanding why 6Kw (actually only 80% of max heating level ) can knock out about 18V.

Seems to me the system has very little (or no spare capacity even with 3 phase). Just a swell it peaks at 235V and not 220V.

I assume in the UK there is so much capacity in city areas that whole streets could be added without such drops or am I very mistaken!

So I will enjoy it whilst it lasts

Thanks and Kind regards

Dave

The voltages you indicate are ok. Your supply voltages are within the limits.

[jerrymartin]

my wife built a 30 room apartment development in Kabinburi 4 years ago , she had to have a transformer installed for 3 phase 220v and about 50m of cable and 2 poles from the highway...total cost 280,000 baht

[david96]

gdhm,

The heaters, 6Kw and 8kw, they would have a load of about 27Amps and 36 amps. Are they instantaneous

type?

Most storage waterheaters have ratings of 140Litre/1800watts and 270L/ 3600watts.

Solar types are 270L with an optional booster element. You can instal HWS on a time switch if you like to operate at night.

Off peak waterheating is not available in Thailand.

[gdhm]

Thanks all

Gee elkangorito wonderful info.

Yes I have my system grounded to a 2metre copper rod

"Cutting through the flex without tripping the breaker".

If I have a problem I cannot think what it is.

I tested the socket I used Neutral and Live are the correctly wired and the Ground is operational. The breaker on the circuit also works when deliberately triggered.

The lowest Circuit Breaker rating I have in either of my two consumer is 16A. I instructed the electrician to use breakers appropriate to the cable use/thicknesses

Thanks for correcting with 35mm2. Some people never learn I recall Crossy corrected many months ago when I forgot and made the same error )

From what you seem to be saying fitting an RCD is likely to be very problematic. Clearly if I was to use a safe-T-Cut adjustable box It should be positioned well above reaching height (which I could do). Then any switching off would be a deliberate act.

The water heaters and shower units have their own ELCB's already. I consider these (especially the shower units) by far the most dangerous items in need of secondary RCD protection.

===

David96. The water heaters are instantaneous (just large higher powered shower heater units.

====

Jerrymartin, Wow that seems very high for Thailand. I thought others elsewhere had quoted closer to 100,000 Baht but my memory is probably in error.

Thanks all

Dave

[Crossy]

Whilst awaiting Crossy's reply, my comments in orange.

Gawd elk, my eyes are buggered reading that

Anyway, agree 100% with what was said.

As a minimum I would RCD any outlets that are likely to power equipment to be used out-doors (that would mean all downstairs outlets) and outlets in wet rooms as well as outdoor lights. This would be the requirement of the IEE Regulations 16th Edition (the UK regs), the new 17th Edition goes WAY over the top on the need for RCDs

If you can't re-arrange your consumer unit, you can either:-

Replace the relevant MCBs with RCBOs, these are the same width as a single MCB but contain the RCD function too.

OR

Use outlets with built-in RCDs, I HAVE seen these in an online catalogue for one of the Thai manufacturers (Haco maybe) but never actually spotted one in the wild.

EDIT Here we go Haco W8416VRCD-10MA and W8416VRCD-30MA, find them on the Haco website http://www.hacothailand.com/ all you have to do now is find somewhere that stocks (or can get) them

[kamalabob2]

Jerry Martin perhaps paid a fair price. It is not JUST a 3 phase transformer, there should be many additional parts installed up near the transformer by a qualified electrical contractor to deliver proper electrical supply. After reading GDHM troubles with obtaining safe, steady electricity I count my blessings we had two good electrical contractors "up Country".

[lopburi3]

I totally disagree that RCB installation is problematic. I have used since they became available here (1977) and consider the few extra trips (which found bad equipment or circuits) a price well worth paying. They can save your life.

The showers have an ELB but it is after the electric connection in the unit so they need a unit upstream also (in case they are not grounded or it fails). Make sure all such units do have a good ground.

[elkangorito]

I think Crossy meant that the use of RCD's with old equipment is problematic. I'm sure that he doesn't feel that RCD's are in any way a problem.

Edited September 28, 2009 by elkangorito

[Crossy]

I think Crossy meant that the use of RCD's with old equipment is problematic. I'm sure that he doesn't feel that RCD's are in any way a problem.

The issue I have with RCDing all circuits is that nuisance trips do still happen, and if it's your freezer that goes off whilst you're away........ let's just say it brings new meaning to 'opening a can of worms'

There are lots of problems in the UK with people upgrading to 17th Edition (all circuits RCD'd) with older appliances that have been just fine for years taking out the trip on leakage, owners are NOT happy 'it was ok until you came and installed that new box'

Provided you have a properly grounded system the attitude from the UK 16th Edition was perfect

[elkangorito]

I agree Crossy. AS/NZS 3000:2007 insists that everything be RCD protected (there are some exceptions). I think "common sense" should prevail in that if earth leakage protection be used for MACHINES only, 100mA would suffice (fire protection). If this is the case, each piece of equipment protected by a 100mA RCD needs to be on a dedicated circuit. Also, such equipment MUST be properly earthed.

The only problem that I can see is if somebody decides to unplug the freezer (protected by a 100mA RCD & decides to use the outlet for some other reason (e.g. using a high pressure water blaster on the kitchen tiles). In this case, the user has no earth leakage protection.

Perhaps the outlet could be labelled or be a different colour to indicate this lack of protection? Of course, the other solution is to permanently connect the equipment to the installation wiring, thereby eliminating the GPO.

Edited September 28, 2009 by elkangorito

[gdhm]

I totally disagree that RCB installation is problematic. I have used since they became available here (1977) and consider the few extra trips (which found bad equipment or circuits) a price well worth paying. They can save your life.

The showers have an ELB but it is after the electric connection in the unit so they need a unit upstream also (in case they are not grounded or it fails). Make sure all such units do have a good ground.

The water heaters and shower units are definitely grounded.

[gdhm]

Thanks one and all.

Most helpful

Dave

[mikejphuket]

have been thru this post and seen cable size referred to many times but can't see how to calculate. I am running 90 m. of underground 3 phase cable from the pole to MDB. Max load is calculated as 130 amps. What size of cable (NYY) do I need? Thanks in advance.

[Crossy]

have been thru this post and seen cable size referred to many times but can't see how to calculate. I am running 90 m. of underground 3 phase cable from the pole to MDB. Max load is calculated as 130 amps. What size of cable (NYY) do I need? Thanks in advance.

Is that 130A total or per phase?

[mikejphuket]

have been thru this post and seen cable size referred to many times but can't see how to calculate. I am running 90 m. of underground 3 phase cable from the pole to MDB. Max load is calculated as 130 amps. What size of cable (NYY) do I need? Thanks in advance.

Is that 130A total or per phase?

130 A total