Electrical Help

[Forkinhades]

Just like to show the set up I have here, with an imported Crabtree box from the UK.

This has 2 main RCCB's inside, which both control 5 MCB's, so in the event of a fault only half of the circuits go off, and the house is wired so in any such event, that in every room a light or a socket will still work! (17th edition)

It has a main switch with another 3 MCBs that do not have RCCB protection, and these are used for my security cicuits such as Fire Alarms/Cameras etc etc.

You are very close to this set up, and with a little extra cost you can acheive this.

oh and that makes my 1000 post

[Negita43]

Thanks Fork in Hades for the pic

One question: Do I need to have a load also plugged in (as per some previous posts)

[Forkinhades]

Thanks Fork in Hades for the pic One question: Do I need to have a load also plugged in (as per some previous posts)

Yes you do need a load

You can plug the 'short' plug in first under no load - should be no trip

Then you plug in any device that will draw a current, and the rcd if configured correctly will trip

[Forkinhades]

^ ok sequence of test

turn off the DB by the RCD,

plug in the shorted plug

turn on DB - everyhting should be ok

then plug a device in that will draw a current >30 mA (6mA if you have set that low) anything will do really

If polarity is incorrect then the MCB for that circuit will trip (might be fighting with the RCD on what trips first) if so change connections.

Trust me this really does work if you have proper functioning RCD!!

[Negita43]

Hi all

Fork in Hades I will try the test tomorrow and let you know. Today busy watching Aircon instal and builder doing my waste pipework.

However one thing I took as a positive sign was this:

The builder being a Thai builder had a 20 meter extension cable made of very thin cable with a the plug (just the plug socket) sheathed in insulating tape - we were cutting plastic pipe and we had to change the blade on the grinder, the builder (being a Thai builder) used a nail to loosen the blade whilst still attached to the socket (which in turn was plugged into a socket in my house. When we came to restart the grinder NO POWER - I checked the main 100 amp breaker under the house - OK. I went up to the CU and the RCBO trip in Box 1 had tripped (the second one in the picture) but the main breaker (the first one in the picture)had not tripped>

I take this as good sign assuming that when he was buggering about with the grinder still attached to the extension he had briefly shorted something and tripped the RCBO

What do you think?

I'll still do the test tomorrow and let you all know

[Forkinhades]

had a few archas

but sounds good!!!

If the RCBO is tripping and not the main switch then hey it does seem to be working.

you can still do the test though,

[Forkinhades]

Hey you guys 'So many men so many opinions' Blaise Pascal I don't want you to fall out over a question I asked. And while you two argue about L- E N- E etc. and how to test please remember. All I want to know is: 1. From the info you have do you think the boxes are wired correctly? 2. Does the ON/OFF on the RCBO mean ON is Bypass and OFF is RCBO active (as Lopburi3 seems to confirm (thank you). 3. Finally as Crossy suddenly mentioned MEN, has he seen anything in the info I sent that suggests that is what I have. Thank you all for trying to help me

1. Yes I think they are correct. Check my post #13

2. See 1. "Turning to those same instructions, item 6 says that with the RCBO switch 'on' it is in 'direct' (bypass) mode so the correct position of

this switch is 'off'"

3. From the images you have posted MEN does NOT appear to be connected. Whether the supply is configured as MEN is unknown. As it is you're connected TT and fully RCD protected, i.e. safe

MEN connectiions on the consumer side does NOT comply with any (BS7671) regulations past or present (Domestic)

Would strongly suggest against it!

But hey TiT

Better still would like to see some pictures of a domestic install which has it here in LOS

[Forkinhades]

Just looked it up and there is a difference between a volt meter and a volt tester. A volt tester has a lower impedance to eliminate 'ghost voltages'. They now have dual impedance meters with high/low selections. I've always used standard multimeters where the impedance are normally no less than 1Mohm but more often 10Mohm. My error in not knowing the difference.

Fluke

yes voltage tester, not meter

Look here http://docs-europe.electrocomponents.com/webdocs/0551/0900766b8055122f.pdf

[Crossy]

MEN connectiions on the consumer side does NOT comply with any (BS7671) regulations past or present (Domestic)

Would strongly suggest against it!

Thailand does not use BS7671! It uses a Thai Industrial Standard "Electrical installation standards for Thailand 2545" (มาตรฐานการติดตั้งทางไฟฟ้าสำหรับประเทศไทย พ.ศ. 2545) ISBN 974-7197-59-1 which costs a whole 300 Baht IIRC. Obviously this is in Thai, closest English language standard would be AS3000 which places the N-E link in the CU.

The PEA (and I assume MEA) specified arrangements for MEN are very similar to the US NEC. This is a Thai installation drawing, note that the incoming neutral is linked via the ground bar which is effectively the MEN link.

Also see the CKY installation instructions below.

The left hand diagram shows the same routing via the ground bar (the right hand diagram is for an un-grounded TT installation).

This is not an arrangement I like as it makes MEN disconnection for testing difficult, but it's the required setup for all new installations (along with a front end 30mA RCD), not that any domestic sparks actually takes any notice.

If you can get a copy of the PEA document 'groundwire.pdf' http://www.pea.co.th/pdf/groundwire.pdf it again shows the same information.

NOTE it seems that the PEA download site is down at present I do have a copy, but not on this PC.

[Negita43]

Just took a Thai 3 pin plug connected neutral and earth plugged, into socket immediate RCBO and circuit MCB trip. Main MCB unaffected. What do you think about that??

[Crossy]

The circuit MCB tripping suggests an overload/short.

Maybe your outlet is mis-wired, did you verify the outlet is correct?

Are you certain you linked N and E (not copying Forky's photo which is a UK plug).

[Negita43]

oK because I am trying to finish my house quick and am very busy fitting the kitchen - this is what I did

I had an old thai cable with a moulded plug from a failed appliance I taped up the red wire and taped together the black and the white to create the short (It is possible there was alraedy a load on the circuit from my house alarm (the sparks has failed to label all the circuits so I'm just trying to fathom out which is which by trial and error

I am not familiar with Thai wiring colours for plugs so maybe I connected the wrong two cables!!!

[Crossy]

PLEASE do not do any more 'trial and error'.

Electricity is not something to mess with, the next error could be your last. Randomly shorting two wires and then plugging into a live outlet is a recipe for something nasty.

By the way, Thai cable code is Black - Live, White - Neutral, Green (or seemingly red) - Earth.

EDIT This is exactly the reason I suggested using a lamp. In this case the lamp would have illuminated, nothing else.

[bankruatsteve]

Yah. But what I find shocking (ahem) is why not trust the TEST button? That's what it's for: to test the RCD. If that trips the breaker, there is no more testing needed. If it doesn't trip the breaker is when you use the lamp wired L-E to test if the RCD is bad.

[Tywais]

-

Randomly shorting two wires and then plugging into a live outlet is a recipe for something nasty.

EDIT This is exactly the reason I suggested using a lamp. In this case the lamp would have illuminated, nothing else.

That also makes me nervous using the term 'short' for testing. Pretty much any appliance, including a filament lamp, will have more than low enough resistance to verify tripping. I work with industrial grade systems where an incorrect short would mean 400 Amps and a meltdown.

[Forkinhades]

MEN connectiions on the consumer side does NOT comply with any (BS7671) regulations past or present (Domestic)

Would strongly suggest against it!

Thailand does not use BS7671! It uses a Thai Industrial Standard "Electrical installation standards for Thailand 2545" (มาตรฐานการติดตั้งทางไฟฟ้าสำหรับประเทศไทย พ.ศ. 2545) ISBN 974-7197-59-1 which costs a whole 300 Baht IIRC. Obviously this is in Thai, closest English language standard would be AS3000 which places the N-E link in the CU.

The PEA (and I assume MEA) specified arrangements for MEN are very similar to the US NEC. This is a Thai installation drawing, note that the incoming neutral is linked via the ground bar which is effectively the MEN link.

E-01.jpg

Also see the CKY installation instructions below.

manual CKY2.jpg

The left hand diagram shows the same routing via the ground bar (the right hand diagram is for an un-grounded TT installation).

This is not an arrangement I like as it makes MEN disconnection for testing difficult, but it's the required setup for all new installations (along with a front end 30mA RCD), not that any domestic sparks actually takes any notice.

If you can get a copy of the PEA document 'groundwire.pdf' http://www.pea.co.th/pdf/groundwire.pdf it again shows the same information.

NOTE it seems that the PEA download site is down at present I do have a copy, but not on this PC.

Thanks Crossy interesting

[Forkinhades]

Yah. But what I find shocking (ahem) is why not trust the TEST button? That's what it's for: to test the RCD. If that trips the breaker, there is no more testing needed. If it doesn't trip the breaker is when you use the lamp wired L-E to test if the RCD is bad.

He has tried it, it does not work

[Forkinhades]

-

Randomly shorting two wires and then plugging into a live outlet is a recipe for something nasty.

EDIT This is exactly the reason I suggested using a lamp. In this case the lamp would have illuminated, nothing else.

That also makes me nervous using the term 'short' for testing. Pretty much any appliance, including a filament lamp, will have more than low enough resistance to verify tripping. I work with industrial grade systems where an incorrect short would mean 400 Amps and a meltdown.

we are talking domestic with rcbo and mcb's in circuit, not hrc fuses

[Forkinhades]

MEN connectiions on the consumer side does NOT comply with any (BS7671) regulations past or present (Domestic)

Would strongly suggest against it!

Thailand does not use BS7671! It uses a Thai Industrial Standard "Electrical installation standards for Thailand 2545" (มาตรฐานการติดตั้งทางไฟฟ้าสำหรับประเทศไทย พ.ศ. 2545) ISBN 974-7197-59-1 which costs a whole 300 Baht IIRC. Obviously this is in Thai, closest English language standard would be AS3000 which places the N-E link in the CU.

The PEA (and I assume MEA) specified arrangements for MEN are very similar to the US NEC. This is a Thai installation drawing, note that the incoming neutral is linked via the ground bar which is effectively the MEN link.

E-01.jpg

Also see the CKY installation instructions below.

manual CKY2.jpg

The left hand diagram shows the same routing via the ground bar (the right hand diagram is for an un-grounded TT installation).

This is not an arrangement I like as it makes MEN disconnection for testing difficult, but it's the required setup for all new installations (along with a front end 30mA RCD), not that any domestic sparks actually takes any notice.

If you can get a copy of the PEA document 'groundwire.pdf' http://www.pea.co.th/pdf/groundwire.pdf it again shows the same information.

NOTE it seems that the PEA download site is down at present I do have a copy, but not on this PC.

Ref : E-01.jpg : This is basicslly the same as a UK tn-cs system, it has 2 neutral bars one for the incomer, and one for the DB (which is not linked to earth) but the in uk the men connection is done at the service head.

I have never seen it done all within one enclosure, so if anybody has a picture of this type of set up, I would very much like to see it.

I have seen the 3 phase set up, but I am more interested in the domestic single phase set up

Edited April 7, 2013 by Forkinhades

[Crossy]

Randomly shorting two wires and then plugging into a live outlet is a recipe for something nasty.

EDIT This is exactly the reason I suggested using a lamp. In this case the lamp would have illuminated, nothing else.

That also makes me nervous using the term 'short' for testing. Pretty much any appliance, including a filament lamp, will have more than low enough resistance to verify tripping. I work with industrial grade systems where an incorrect short would mean 400 Amps and a meltdown.

we are talking domestic with rcbo and mcb's in circuit, not hrc fuses

But those RCBOs and MCBs are in an installation that has not been properly tested by our standards (it's had at best a 'bang' test), potentially has reverse polarity outlets and is not protected by a service fuse. It could also (by your suggestion) contain fake components which do not function as expected or at all (fake MCBs have even been found in UK trade outlets, scary).

We also have an inexperienced DIY enthusiast with only a basic knowledge of electricity who wishes to ensure the safety of himself and his family. He has no sophisticated equipment and neither the budget nor knowledge to acquire and use it anyway.

Our aim should be to assist him to check his setup using readily available bits and pieces in a manner which will not subject himself or his installation to damage even if it is miswired.

I still don't understand your objection to the use of a 220V 15W tungsten lamp, it would work for your N-E test too since its resistance when cold is a few ohms and has the advantage that, should volts be present because of a miswire, it will simply light up.

[Forkinhades]

Randomly shorting two wires and then plugging into a live outlet is a recipe for something nasty.

EDIT This is exactly the reason I suggested using a lamp. In this case the lamp would have illuminated, nothing else.

That also makes me nervous using the term 'short' for testing. Pretty much any appliance, including a filament lamp, will have more than low enough resistance to verify tripping. I work with industrial grade systems where an incorrect short would mean 400 Amps and a meltdown.

we are talking domestic with rcbo and mcb's in circuit, not hrc fuses

But those RCBOs and MCBs are in an installation that has not been properly tested by our standards (it's had at best a 'bang' test), potentially has reverse polarity outlets and is not protected by a service fuse. It could also (by your suggestion) contain fake components which do not function as expected or at all (fake MCBs have even been found in UK trade outlets, scary).

We also have an inexperienced DIY enthusiast with only a basic knowledge of electricity who wishes to ensure the safety of himself and his family. He has no sophisticated equipment and neither the budget nor knowledge to acquire and use it anyway.

Our aim should be to assist him to check his setup using readily available bits and pieces in a manner which will not subject himself or his installation to damage even if it is miswired.

I still don't understand your objection to the use of a 220V 15W tungsten lamp, it would work for your N-E test too since its resistance when cold is a few ohms and has the advantage that, should volts be present because of a miswire, it will simply light up.

Yeah agreed, I sometimes forget about the laymen here.

From my college days one lecturer told the 'class' about something similar that you suggest with L-E lamp, and gave an example of the lamps exploding, and how this type of set up got banned in the 70s, but hey that was a long time ago for me! (1984!) and cannot remember the exact details.

I am going to see if I can source a voltage tester here in LOS, and if the impedance is low enough to trip the rcbos.

[Forkinhades]

A little expensive http://th.element14.com/benning/050260/voltage-tester-ac-dc-duspol-1000/dp/1817166

[Crossy]

Hi Forky

Laymen and DIY are the bane of the UK sparking community, check out the IET forums http://www.theiet.org/forums/forum/categories.cfm?catid=205 for some of the horror stories. Here it's the other way round with the DIY'er often doing a better job than the 'professionals'.

You sure it wasn't a 3-lamp synchroscope he was talking about?

Either connection could do nasty things (lamps going pop) if one generator was running in reverse.

Our Uni. Machines and Control lecturer (Mr [Fray Bentos] Bentley) used to show off the lab's IT connected 3-phase by grabbing a live phase and not dying.

If he found a wiring error during his check before we applied power he would rip out all the terminals so we had to start again, a very good lesson to make one check and check again. There was a lab experiment that required the use of two un-grounded scopes which had their frames connected to different phases, a small note at the bottom of the lab sheet suggested that touching both scopes at the same time was not a smart move. As far as I remember nobody got fried by than one but I bet it's not on the list today.

[bankruatsteve]

Yah. But what I find shocking (ahem) is why not trust the TEST button? That's what it's for: to test the RCD. If that trips the breaker, there is no more testing needed. If it doesn't trip the breaker is when you use the lamp wired L-E to test if the RCD is bad.

He has tried it, it does not work

See post #46. The TEST button tripped the breaker. He just didn't think it was the right breaker. Again, if the RCD test button trips the breaker, there is NO NEED for further testing for that.

[Negita43]

Thanks you guys - I am an electricity layman and I appreciate all your practical help that takes account of my Laymaness!!!

So what do I do

I can assure you that as far as I can ascertain every outlet is correctly wired.

How can I say this well

1. I told the sparks that it was imperative that he followed the correct colour wiring procedures.

2. I bought an extension plug (4 sockets) from homepro and it has two lights on it red and green if the red one lights the plug (as far as I can ascertain has reversed polarity in the green one lights all OK if both light NO Earth I'm pretty sure that this crude tester works because he wired one socket the wrong way and the light showed red I told him to rewire it and he did and the light showed green. I have tested every socket with this lead and they all showed green. So I am reasonably confident there is not reversed neutral live in the system.

All I want to do is to check that he has not bypassed the RCBO and to be honest after yesterdays trip and todays test (which I accept was dangerous - but isn't that why we have RCD's RCBO's etc) I think it is working.

If you have any other suggestions as to what I can do please let me know (and unless you instruct me otherwise I will when I have time between fitting the bathrooms and kitchens and curtains redo the trip test (but I have do be honest i don't understand how a lamp plugged in at the same time will give us more info).

Once again everybody thank you for your help - you are all invited to the housewarming - NO PUN INTENDED

[Forkinhades]

DONT use short cable, put a load across neutral and earth.

Or non lamp load across live and earth.

[bankruatsteve]

Negita - it's good you have the questions and want to do things correctly. I hope this thread has helped you for that. You still seem to wonder why you need to check the RCD with the lamp. You don't. Your main CU has a front end (main breaker) protected by RCD. The 2nd box does not. So, all the circuits (each MCB) in your main box are RCD protected. And, they are still protected even if the receptacle polarity is not correct. The TEST button will prove the RCD is working for all of those circuits.

[Forkinhades]

This thread has highlighted the importance of getting your electrics tested correctly with the right equipment, and in a safe manner.

Given the fact that the PEA/MEA in their wisdom decide not to protect their cables at the meter, any short method is a not advisable, and I regret offering that information. Who knows how far upstream this fault could have gone? wonder what they have in place to stop large fault currents above 10kA? Perhaps they realise that this is not going to happen with the poor earth on a TT system (any comments crossy?)

When I tender in the UK, I tender at 40 minutes a circuit. So if you just wanted your RCBO tested it would not take that long, and the cost would not be that high, but then I suppose you have the difficulty of finding a thai engineer capable of doing the job, and with the right test equipment.

Be Safe!

best regards to all

Edited April 8, 2013 by Forkinhades

[Crossy]

+1 ^^^

As to PEA/MEA protection of their distribution equipment, there do appear to be over-current devices on the village transformer, I've not looked closely and I'm not there to take photos right now, TBH I'm not even sure if they are on the LV or HV side.

I suspect that in the event of a solid L-N (or L-E on a MEN system) short on the feed side of your incomer the weak point will be the meter which will self-destruct in a fairly explosive manner, but at least it will disconnect the power.

A L-E fault on a TT will pull up the touch voltage to bitey levels, even a really good rod will likely not open a 63A incomer (which is of course why the UK require front end RCDs on all TT installations). Make sure your incoming supply is nowhere near anything grounded which it could short to.

[Forkinhades]

^ Just to expand on that comment

If your Prospective Short Circuit Current (PSCC) is greater than 10kA then when a L-N short circuit occurs, your MCB's will not be able to handle the current that flows, so in effect jumping over the MCB. Thus making the MCB ineffective.

Which would then possibly blow your meter off the wall! or keep going upstream where it would cause even more damage! This maybe a contributing factor of why we get so many power cuts here un LOS.

This value needs to be measured!

wiki link http://en.wikipedia.org/wiki/Prospective_short_circuit_current