RCBO found not connected

[bikerider]

Hi.

 

I am just another frustrated Falang who have build a house in Chiang Mai. Had had many issues, but the most surprising was recently when I had to install an additional air conditioning unit I found that some of RCBO in my distribution board (3Phase) had not been connected correctly and did not work/provide any safety. I have found that it is because the electrician had shared the neutral between different circuits. When the electrical system was designed it was with normal breakers, but during the construction I asked and paid to have RCBO's installed on all light, socket outlets, water heater circuits. 

I brought the issue to the builder but he have now said that it is normal and no problem to share neutral in thai electrical systems and the fault is kind of mine since I changed to install RCBO while the build was ongoing. I am mad on myself that I trusted the builder (from UK) and never checked that the trip function on the RCBO worked before I made final payment. My question is now what I can do about it? Is it according to electrical regulation rules allowed to share neutral on circuits like what they have done on breaker for light and breaker for socket outlets? Appreciate any help or advice

 

Soren

[johng]

Get the "builder from the UK" back to fix the "balls up"...if he won't fix it then threatened you'll go to the Labour department..because 99% sure he wouldn't want that to happen.

[bankruatsteve]

So, the RCBO cannot be switched on - just trips?  Or, was it just eliminated from your circuits?  It is NOT OK anywhere in the world to share neutral - so if they are saying that it is totally BS.  You could maybe take it to court.  But, TIT.

[bikerider]

21 minutes ago, bankruatsteve said:

So, the RCBO cannot be switched on - just trips?  Or, was it just eliminated from your circuits?  It is NOT OK anywhere in the world to share neutral - so if they are saying that it is totally BS.  You could maybe take it to court.  But, TIT.

The RCBO trip if connected correctly. They have thus not connected the RCBO to Neutral and the circuit Neutral wire was connected to Neutral bar and not to Neutral on RCBO. Anybody can give reference to where I find the Thailand electrical rules and regulation in English

[Crossy]

I've never seen the Thai regs ("Standard Electrical Installation for Thailand, 2013") in English, I doubt they exist. They almost certainly don't go to the level of saying it's ok to borrow neutrals, even the nanny UK regs BS7671 or Aussie AS3000 don't go to that level, it's just accepted as poor practice.

 

For your issue, the real fix is to rip it out and do it properly. The pragmatic approach is to determine which circuits borrow neutrals and then, if it's safe, put them all on one RCBO. Alternatively, put in a front end RCBO and have done with it.

If you distribution board is DIN mount then you could group circuits with shared neutrals on one RCD (keeping the individual breakers). 

[bikerider]

40 minutes ago, Crossy said:

I've never seen the Thai regs ("Standard Electrical Installation for Thailand, 2013") in English, I doubt they exist. They almost certainly don't go to the level of saying it's ok to borrow neutrals, even the nanny UK regs BS7671 or Aussie AS3000 don't go to that level, it's just accepted as poor practice.

 

For your issue, the real fix is to rip it out and do it properly. The pragmatic approach is to determine which circuits borrow neutrals and then, if it's safe, put them all on one RCBO. Alternatively, put in a front end RCBO and have done with it.

If you distribution board is DIN mount then you could group circuits with shared neutrals on one RCD (keeping the individual breakers). 

Good morning.

Really appreciate your reply. I really thought it would be written somewhere that it is illegally (not according to reg.) to borrow Neutral especially in a 3phase system where you then make a kind of connection between 2 phases out in somewhere in the system in case your common neutral is lost or removed for in the distribution board.

I know the real fix would be to rip out the wiring and do it again. Since the house was build a couple of years ago I am quite sure I will have to bear the cost of it all. The cost is just one thing but to have to maybe remove ceilings in a big 2 floor housing really gives me headache, but after all I want my system to be safe.

I have one main incomer panel and then 3 separate distribution boards. 1 DB for the main house, 1 DB for guest house - maid area - workshop, 1 DB for swimming pool and sprinkler system.

I think it is manageable to rectify the swimming pool DB since I found that only the pool lights have a shared neutral (light switch inside house with feed from house DB and Neutral found connected in swimming pool DB neutral bar. 

Guest house- Maid etc we have already cut holes in the ceilings in order to get access to junction boxes and I will thus request electrician to continue this work and have each circuit with RCBO.

When it comes to the house I have 23 circuits in the DB (not DIN mounted). 11 of these have RCBO and here I found 2 have not been connected correctly. It would really be difficult to sort this mess out since even the AC units which each have their own CB have found to have their neutral shared with something else. is it possible to find a RCCB that could be installed upstream of this DB or do I have to install the  "Thai version - Safe-T cut".

 

The hardest thing of it all is that I blame myself for not having tested all the breakers before I took over the house - but again I feel that the builder blames me for ordering the RCBO install after the house build was well progressed and thus don't want to take responsibility for the shared Neutral as this is just the Thai way of doing things - doings things wrongly because you can get away with it. The electrical company who the builder hired for the work is no longer in existing (owner retired) and the builder have then sent another electrical guy to check the system and after had a meeting with builder and they kind of agreed that this is the Thai way and everything is working at it should if I just install the normal CB on all circuits which was original design. I really cant accept this - but how do I progress to prove my case?

[Crossy]

You obviously have a good idea of how it should be done. The quickest and easiest fix would be to put a 3-phase Safe-T-Cut in front of everything. Of course that means that "one-out, all-out" applies, you likely don't want that.

 

If there's only a couple of circuits borrowing neutrals you can likely bang both circuits on one RCBO and be safe. I admit that's what I would do rather than ripping out ceilings.

 

Our problem wasn't borrowed neutrals but one sparky (we used up six in the end) thought it was a good idea to link N and E in some outlets (despite having correctly run 3 wires back to the board). This led to random tripping of our RCDs (we have split boards rather than individual RCBOs), took me a while to work that one out. There is also a live link between two outlet circuits which I can't find so both circuits are on one breaker, luckily it's bedrooms not the kitchen. 

[Maybole]

I am just completing a house, The (Thai) electrician seems to have done a good job. I have never heard of a "shared neutral" before. Expert, please explain exactly what this is, I want to check my system.

[Crossy]

1 hour ago, Maybole said:

I have never heard of a "shared neutral" before. Expert, please explain exactly what this is, I want to check my system.

When I get a few mins I'll do a diagram (a Google search, unusually, came up empty).

 

Basically every circuit (breaker => switch => load => neutral return to board) should have it's own "neutral return to board".

 

A "borrowed" or "shared" neutral is when two (or more) circuits share a common neutral back to the board.

 

This, of course, works just fine, most of the time and is perfectly safe, nobody is going to die (just yet).

 

But there are a number of issues.

 

Firstly, overload. Consider we have two 15A loads on separate circuits, each wired in 2.5mm² cable (20A) and on a 20A breaker. If we share the neutral return to the board it will be carrying both return currents i.e. 15+15 = 30A rather more than the cable rating of 20A. Enter possible conflagration, or at least a smell of hot plastic ?

 

Secondly, electric shock to the maintenance chap. Same as above with a shared neutral. Our maintenance man turns off the breaker for one side, the load goes off. He then disconnects the neutral in order to do something BUT that neutral is still connected via the second load and breaker and becomes live. He touches it and dies!! ? ? 

 

A quick way to check if you may have borrowed neutrals is to count the number of live wires leaving your distribution board and compare it with the number of neutral wires returning to it. If they are the same you're likely just fine. Fewer neutrals than lives indicates that you have a possible borrowed neutral.

 

 

[Crossy]

Quite a good Youtube video here:-

 

 

[Maybole]

Many Thanks Crossy. I presume that two neutral wires sharing a common connection point on the neutral bar in the distribution box does not constitute s "shared neutral". I have seen that.

[Crossy]

12 hours ago, Maybole said:

Many Thanks Crossy. I presume that two neutral wires sharing a common connection point on the neutral bar in the distribution box does not constitute s "shared neutral". I have seen that.

That's fine, it's the wires back from the load to the neutral bar that shouldn't be shared.

[Litlos]

I had this issue with the house wiring with a UK Expat builder as well.  I bit the bullet and paid 8000Baht for the original "electrician" to come in and rectify.

 

I do not want a single RCBO on the mains tripping the whole house as an ant has gone into the wrong place, particularly as I work away from home a lot and the wife does not like the lights going out for no good reason.  The PEA guy who insisted on the Safe-T-Cut as was a house for Falang was quite miffed that it had been removed.  I asked him for the reg on installing said unit and the answer was for your safety.  I explained the benefit of individual RCBO's and he did not understand the difference between RCBO and ELCB, a little more baffling and he went on his way.

 

The other bad thing about shared neutrals is if you lose the neutral you have 380v across your appliance.  Even the yanks have said no more on the shared neutrals a number of years ago, I have that reference around here somewhere, looks like 2011 update to NEC may be it.

[Crossy]

RCD's (front end or otherwise) have been a requirement in Thailand for quite some years, but, like proper grounding and 3-pin outlets, the requirement has been generally ignored ("Thai electric not same farang electric").

 

Sadly many "professionals" still don't understand how this stuff works, particularly when individual RCBOs are installed.

 

We have a split board with RCDs on the water heaters and indoor outlets with separate RCBOs for outside power (10mA on the pool pump) and outside lighting. The freezer, inside lighting and aircon don't have any earth leakage protection.

 

[Litlos]

I have one board as we do not suffer from many power outages, so no back up generator.  I have just installed individual RCBO's as is more convenient in case of a circuit having leakage and not taking down the whole house.  I planned for this from day one by declining the offered Btchino switchboard as I have this long standing suspicion of Italian electrics, and the individual circuit RCBO's for the board were double slot.  Went with a Square D/Schneider board which has single slot RCBO's.  For the cost of a 3 phase Safe-T-Cut I have individual RCBO breakers which also do not have the override option, so the wife's nephew cannot "fix it" while I am away.

 

I actually had the UK expat builder explaining to me and others on Monday night at the local watering hole that Thai electrics are different.  There is no 415v like in the UK, there is only 230v.  Ok well I thought that Thailand was a nominal 220V which gives us 380v for 3 phase.  Would not have it.  I offered him to come around home and I will show with a meter, no I already know.  Sounds like the laws of physics do not apply in Thailand....

 

I actually have to do a technical presentation at least once a year at work, is one of their training initiatives.  So I am actually on the lookout for a video or similar showing the benefits of RCBO's etc.  The fun part for me will be I will push the "Safe at work, Safe at home" which is an existing company initiative and try and get the company to subsidise RCBO  installations at the homes of the nationals. So if anyone can point me at a decent presentation I can utilise I will be grateful.

 

Cheers

 

 

[Wirejerker]

I've never seen the Thai regs ("Standard Electrical Installation for Thailand, 2013") in English, I doubt they exist. They almost certainly don't go to the level of saying it's ok to borrow neutrals, even the nanny UK regs BS7671 or Aussie AS3000 don't go to that level, it's just accepted as poor practice.
 
For your issue, the real fix is to rip it out and do it properly. The pragmatic approach is to determine which circuits borrow neutrals and then, if it's safe, put them all on one RCBO. Alternatively, put in a front end RCBO and have done with it.

If you distribution board is DIN mount then you could group circuits with shared neutrals on one RCD (keeping the individual breakers). 

Curiosity got the better of me about shared neutrals in AS3000 and yes they allow it but there is a few things you must do
1 All circuit breakers or isolation switches must be linked so all actives are isolated
2 The neutral conductor must be clearly marked and the actives identified
3 the neutral cannot be looped in switches,lights,power points or appliances.
It’s a lot simpler to run a neutral for each active and be done with it


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[Litlos]

I found the reference in NEC 2011,  remarkably similar in intent to AS3000 when you follow all the other paragraphs:

"200.4 Neutral Conductors. Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code."

 

I think the practice was banned earlier in NFPA rules which is what oil and gas tends to follow.

 

Basically just poor practice and the only saving is a few meters of wire.

 

Cheers

[bikerider]

Hi

 Since it was me who started this tread I would like to give an update on how it is going.

Just completed the rectification of all the wiring. All 30 circuits in my 3 switchbords now got fully functional RCBO’s.

The housebuilder found a new electrician and covered half of the cost. Now I just wait for the ceiling guys and painters to come and repair about 20 access holes in the ceilings. I decided to go the way wth individual RCBO’s on each circuit since It was they way it should have been even though it is not required on light circuits inside the house.

thanks for all comments and helpful info.??