Advice on proper circuit breakers

[DineshR]

Hello,

 

I just read the news of the poor guy that was electrocuted recently in another forum and am a little worried re my electrical wiring in my home. I have posted the same in that other forum.

 

I would appreciate some guidance.

 

I have a similar circuit breaker box as Samuel Smith above (in the other forum) for all the individual circuits such as lighting, plug points, water heaters etc but the main breaker switch I think, has a test button as shown in the pictures below. Does this provide sufficient protection or should I have these RCD's (or should they be RCBO's) on each of the individual circuits ?

 

Also, I have 3 phase into the house but I notice I have only one main circuit breaker - does this make sense or should I be having 3 of these main circuit breakers ?

 

Please let me know if my setup is fine or if I will need to make some changes. Thanks in advance.

 

 

[bankruatsteve]

I 'googled' that Schneider main breaker and it appears to be 3-pole but not sure that's for 3 phase.  I also do not see any specification for RCD and, if so, you would need RCBO on the individual circuits you want to protect (I wouldn't bother with the lighting circuits myself).  Unfortunately, that will be problematic if neutrals have been "borrowed".

 

Do you just have one CU (breaker box)?  In any case, I suggest posting a photo with the cover off and wait till Crossy can comment.

[Crossy]

Yes, to be sure please post a photo with the lid off (care please).

 

Safe-T-Cut do make 3-phase units so you should be able to get one installed in front of your main breaker.

 

Or you could use individual RCBOs on circuits with safety hazards (water heaters, outdoor lighting etc.) but this would be a more expensive solution.

 

[DineshR]

Thank you all for the feedback so far.

 

I took a couple of photos (below) of the complete box but I am not brave enough to remove the screws and open the panel to see the wiring below. (Question here - if I switched off the main circuit breaker - single switch on the top of the panel box, would it be safe then to remove the screws and take a picture ?)

 

 For sure I have 3 phase, since I have a 3 phase meter outside the home and I remember the electrician asking me to request PEA to get me 3 phase since I have a large number of a/c's as well as an oven, washers and a dryer. I can see the 3 phase wires coming into the house from the pole outside (4 total thick wires).

 

Just as an aside, there is a red test button on the main breaker switch - does this mean it is an RCD -or RCB ?

 

Based on the feedback so far, I am assuming the following :

 

a. Best to install RCBO's on each of the circuits that need them - in this case, I would install it on those circuits that involve plug points, the oven, and the water heaters. Not essential on the a/c units or lighting.

or 

b. Replace the current main breaker switch with the 3 phase Safe-T-Cut switch.

 

If I were to do (a) - what RCBO would you recommend ? 

 

Thanks again for all the input.

 

Here are the new pics.

 

[bankruatsteve]

You should be safe to remove the top cover.  Turn the main breaker off if it makes you feel better but with that being in the same enclosure it's not going to make much difference.  Like Crossy said, individual circuit RCBO can get expensive.  I would just put on power point circuits.  The oven, refrigerator, freezer, AC, etc. really only need ground IMO.

 

It is curious to me that your main breaker has a test button - again the specs I looked at didn't show any RCD (that I could see) so not sure what is being tested.  I'm sure others will know.  Anyway... you really should try to get that cover off and post a photo.  It should just wiggle off after removing screws but don't force anything if not.

[1130bobs]

I was in the power industry for 20 years (selling PEA over 20 mil THB monthly - a big american company) making protection equipment for 11 Kv & higher voltages.    Also worked for a large low voltage manufacturer (110 - 600 VAC) making circuit breakers, switchboards & motor controls.  But I don't know the european terms RCD or RCBO. 

 

 3 phase service means PEA has provided you power from all 3 phases on their 11,000 volt supply line.  Each one is 440 volts above neutral - which is at 0 or ground voltage.  A 3 pole main breaker, as you have, is correct for 3 phase service.  If your house was normal size & not a mansion or shop,  you would get normal 'single phase' residential service, you would get only 2 phases in, and only have a 2 pole main breaker. Yes its technically 2 phase, but nobody calls it that.  PEA would never provide metered service with only 1 phase (& neutral) except maybe for those tiny homes receiving 'free power' because their usage is under 150 KW hours monthly.  You will use more than this with your house vacant with just security systems, water pumps, refrigerators & other normal constant loads.  All normal breakers (& fuses) protect the system & avoid house fires by shutting down for either a slow overload where too much power is being drawn for the house circuit wire size (plug in a toaster to all your kitchen outlets).  Unless poorly designed, you should be able to use all A/C at once as they are on separate circuits & properly sized.  Which is cheaper - more circuits from the main box or bigger $$ wires.  EE that signed your building permit should have this right.  Breakers also trip instantly - under 1 second ( as opposed to a few seconds for overloads) when a short circuit tries to draw all the power that PEA has available at your main box.  Neither will help with people protection (electrocution) or sensitive loads (computers).

 

Edited August 4, 2018 by 1130bobs

[Crossy]

The big beastie is just an MCCB (no earth leakage protection), in this case the "Test" button isn't a good indicator (exception proves rule?).

 

https://www.schneider-electric.com/en/product-range/997-easypact-ezc/

 

[Crossy]

6 minutes ago, 1130bobs said:

I was in the power industry for 20 years (selling PEA over 20 mil THB monthly - a big american company) making protection equipment for 11 Kv & higher voltages.    Also worked for a large low voltage manufacturer (110 - 600 VAC) making circuit breakers, switchboards & motor controls.  But I don't know the european terms RCD or RCBO. 

 

RCD is "most of the world" for GFI, the RCBO adds overload protection to the earth leakage function.

 

Thailand is (mostly) 3-phase 4-wire with 220V phase-neutral (not 440V, it's 380V phase-phase). Single phase supplies are one phase and the neutral.

 

[bankruatsteve]

5 minutes ago, Crossy said:

 

RCD is most of the world for GFI, the RCBO adds overload protection.

 

Thailand is (mostly) 3-phase 4-wire with 220V phase-neutral (not 440V, it's 380V phase-phase). Single phase supplies are one phase and a neutral.

 

So, with the main breaker being 3 pole, is the neutral just not switched?  And, is it common to have all 3 phases on the same overload switch?  Just curious.

Edited August 4, 2018 by bankruatsteve

[Crossy]

8 minutes ago, bankruatsteve said:

So, with the main breaker being 3 pole, is the neutral just not switched?  And, is it common to have all 3 phases on the same overload switch?  Just curious.

Yes, neutral isn't switched usually.

 

You CAN get 4-pole main breakers with a special neutral pole that opens last and closes first, this is to prevent you having the phases connected with no neutral which is a recipe for disaster if the load isn't perfectly balanced (voltages go all over the place, worst case is P-N of ->380V, your TV won't like that).

 

There's nothing to stop you having 3 MCBs and treating it like three single-phase installations, many do but retain the big 3 pole incomer as a single point of isolation.

 

[topt]

@Crossy I have a very similar board to the OP except it is a Square D VisiSafe Load centre.

Should I be adding a Safe T Cut to this as per your comments in the thread re the unfortunate gardener?

Quote

Partly. They are definitely an easy retrofit and when talking to a Thai sparks he will (almost) certainly understand "Safe-T-Cut".

Trouble is there is not much space to fit in the "cupboard"

Any other issues visible in the pic?

 

[billmichael]

If you are uncomfortable with your electric service just pay the money and have a qualified electrician come out and re-inspect your installation to make sure it it correct.  There are probably lots of intelligent people in this forum trying to be helpful but you will be so much better off with someone who can actually be there at your home to have a "look and see".  Let the electrician know of your concerns and ask all the questions you want.  If you do not already know much about electrical systems I would NOT take the cover off as there are lethal voltages in there.  Where I work we put "Death On Contact" stickers in such cabinets.  Anyway, good luck with your concerns.

[Crossy]

3 hours ago, billmichael said:

Anyway, good luck with your concerns.

Have you ever located a qualified sparks in Thailand other than on mega-projects or in O&G?

 

Sadly, they really don't exist in the domestic market, particularly up-country.

 

There's supposed to be a licencing scheme in place as of last year, but I've never met a licenced sparks, or for that matter, a contractor who knows about the scheme.

[Crossy]

10 hours ago, topt said:

Any other issues visible in the pic?

You have two choices like our OP.

1. Fit a 3-phase Safe-T-Cut device up front.
2. All individual RCBOs on circuits that need protection (water heaters, outside lighting, outlets).

I see a potential issue with option 2. You seem to have a lot less neutral (white) wires than you do live wires (from breakers). This suggests the there are neutrals "borrowed" or shared amongst several circuits. Whilst not an immediate hazard this is poor practice and will make installing RCBOs, er, interesting.

 

[carlyai]

My setup is similar, but Thai electricians don't or didn't like to install protection against someone coming in contact with the active and neutral wires. We installed the 3 phase SafetyCut after the main wiring had been done, hence the add-on appearance of the SafetyCut. Might not look to pretty, but it works, as I'm sure some of my Thai farmer workers are thankful for.

If you have the space probably better to install 3 separate SafteyCuts, because when it trips, it disconnects the 3 phases and the problem is usually only associated with 1 phase.

It was at this stage of my electrical installation that Crossy got angry with me. Never heard him writing angry before.[emoji21]



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[Crossy]

18 minutes ago, carlyai said:

If you have the space probably better to install 3 separate SafteyCuts, because when it trips, it disconnects the 3 phases and the problem is usually only associated with 1 phase.

Unfortunately, with a 3-phase panel you can't ?

 

Choice is a big one up front or individual RCBOs.

 

[Crossy]

4 minutes ago, Arjen said:

It shows that even super hero's like Crossy are finally human....

Rest assured, I wear my underpants on the inside.

[DineshR]

Apologies for the delayed reply. Had to find someone who could open the box for me to take some pics.

 

Here they are. If neatness counts for anything, I think the electrician did a pretty good job. And I can see the main circuit breaker is a 3 phase breaker with the 3 humongous wires leading into it and per Crosby's earlier comments, it looks like each circuit has it's own dedicated earth line(white wire). Please correct me if my observations are incorrect.

 

Please advise if RCBO's are advised on the appropriate circuits. This is what I am inclined to do if necessary as opposed to the single large breaker up front as I think it would lead to a cleaner installation and cause trips only on the circuit affected and not impact the rest of the house. A more costly option I understand.

 

[bankruatsteve]

Neat it is.  My assumption is that the white wires are all neutral.  (?)  If so, I don't see any ground (but then I'm not the best at seeing things).  Do you have 3 prong (grounded) outlets?  Maybe try to confirm what your ground situation is.  

 

For Crossy:  how can you tell how the phases are distributed?

[longball53098]

We have to assume the sparky only bought white wire and used it for the earth wires also as the earth bus bar has wires connected . This would be hard to keep track of what wires are what at the socket and device ends me thinks. I would wonder how many shared neutrals there are as there are about 32 circuits but only about 12 wires on the neutral bus

[bankruatsteve]

2 minutes ago, longball53098 said:

We have to assume the sparky only bought white wire and used it for the earth wires also as the earth bus bar has wires connected . This would be hard to keep track of what wires are what at the socket and device ends me thinks. I would wonder how many shared neutrals there are as there are about 32 circuits but only about 12 wires on the neutral bus

That's why I thought both bars are neutral.  It's the only way to make things add up.  If your count is correct, it is probably futile to put in RCBO on the individual circuits.

[Crossy]

Task A is to decide which circuits need RCBOs, I suggest as a starting point doing the water heaters. These have a fair to middling chance of not sharing neutrals. 

Task B, determine which neutral goes with the relevant live. A 12V lamp, battery, a long lead and an assistant are your friends.

 

It's also worth verifying that those leads on the earth bar (left side bar) are actually earths and not neutrals from somewhere.

 

[carlyai]

@DineshR

My electrician had installed factories, so I was extremely lucky to find him.
Regardless of that he had never installed RCBO's or SafetyCuts and he installed the wires incorrectly and it kept tripping. I rewired it with the help of this forum.

My point being, get an electrician to install the RCBO's/SafteyCuts who has installed them before, not just says he has or hasn't installed them. It will work incorrectly installed but will trip now and again, so you don't want to add a problem.

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[DineshR]

Thank you all for the valuable feedback. I will now go find an electrician that's installed RCBO's before and get all the water heaters as well as all plug point circuit breakers (a total of 8 replaced with RCBO's. Also, will verify where the earth points are.

 

To an earlier question, all my plug points are 3 prong - but I don't know if I have true earth on those - which I will need to verify.

 

Once that has been completed, I will post a final summary here as well as post pics for completeness.

 

Thanks again.

[bankruatsteve]

1 hour ago, DineshR said:

Thank you all for the valuable feedback. I will now go find an electrician that's installed RCBO's before and get all the water heaters as well as all plug point circuit breakers (a total of 8 replaced with RCBO's. Also, will verify where the earth points are.

 

To an earlier question, all my plug points are 3 prong - but I don't know if I have true earth on those - which I will need to verify.

 

Once that has been completed, I will post a final summary here as well as post pics for completeness.

 

Thanks again.

Sounds like a good plan.  As mentioned before, the potential issue you will have is from "borrowed neutral".  Those are usually found in the lighting circuits so maybe you will be lucky.  Changing a breaker to RCBO is simple.  Finding a borrowed neutral can be EXTREMELY challenging and, if you don't have easy access to the wire runs, may be impossible.  Good luck.

[topt]

4 hours ago, Crossy said:

You have two choices like our OP.

1. Fit a 3-phase Safe-T-Cut device up front.
2. All individual RCBOs on circuits that need protection (water heaters, outside lighting, outlets).

I see a potential issue with option 2. You seem to have a lot less neutral (white) wires than you do live wires (from breakers). This suggests the there are neutrals "borrowed" or shared amongst several circuits. Whilst not an immediate hazard this is poor practice and will make installing RCBOs, er, interesting.

 

Thanks Crossy. 

Do you think it will be possible to fit a Safe-T-Cut or similar device in the space to the side of the cream box above the MCB (presume this is something to do with the incoming main cables)?

If not then thus could also be a bit of an issue.

 

The next task would be finding someone "capable" of installing it properly..............

 

[Crossy]

You can get an idea of the size of a 3-phase unit from Carlyai's photos in post #18, I reckon it would fit.

 

You need to confirm what's in the box, you may be able to just remove it when the Safe-T-Cut goes in.

 

As to installation, YMMV but I suggest starting with one of the big-box places like HomePro, they usually offer an installation service and (in our experience) are pretty reasonable.

 

[Artisi]

6 hours ago, Crossy said:

Rest assured, I wear my underpants on the inside.

We are pleased to hear that. 

[sometimewoodworker]

11 hours ago, billmichael said:

If you are uncomfortable with your electric service just pay the money and have a qualified electrician come out and re-inspect your installation

It would be wonderful if it was that easy. Qualified electricians are extremely difficult to find for most domestic installations. 

 

They exist, we have just had one sort the dogs dinner left by the builders people, but it took us a couple of months to find him.

[sometimewoodworker]

22 hours ago, 1130bobs said:

3 phase service means PEA has provided you power from all 3 phases on their 11,000 volt supply line.  Each one is 440 volts above neutral - which is at 0 or ground voltage.  A 3 pole main breaker, as you have, is correct for 3 phase service.  If your house was normal size & not a mansion or shop,  you would get normal 'single phase' residential service, you would get only 2 phases in, and only have a 2 pole main breaker. Yes its technically 2 phase, but nobody calls it that.  PEA would never provide metered service with only 1 phase (& neutral) except maybe for those tiny homes receiving 'free power' because their usage is under 150 KW hours monthl

Humm it seems that your experience is totally US and not relevant in Thailand or most of the rest of the world. Phases are usually 220~240v above neutral never 440v.

 

The US is the only country I know of that supplies twin phase (2x110v permitting an easy 220v supply), everywhere else uses single phase (1 of the three). Thailand certainly uses a single phase and neutral supply. 

 

 

Also the free power power limit is under 90 units per month.