Advice on proper circuit breakers

[Fruit Trader]

6 hours 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

Schneider TPN load centre kits make provision for a dual neutral bar each side of the main breaker linked with a rear strap. This would provide 24 neutral terminals at a x24 panel.

The earth bars fixings are located near to the panel sides.

 

There is also option to have plug in neutral bars where individual breaker neutrals are required.

[Mike R in CM]

On 8/4/2018 at 4:54 AM, bankruatsteve said:

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.

As per my previous reply (a different post) RCD's and RCBO's are useless unless you have a good solid earth (ground) installed. I installed three 2.4M copper rods spaced at one metre apart connected to each other with a 16mm sq. bare copper wire and back to the main breaker box with a 16mm sq. insulated copper cable. I also didn't bother installing RCBO's with the lighting circuits but came across a "borrowed" neutral in the maids accommodation so that had to be rewired to separate the lighting and socket neutrals.

[bankruatsteve]

2 minutes ago, Mike R in CM said:

As per my previous reply (a different post) RCD's and RCBO's are useless unless you have a good solid earth (ground) installed.

Sorry, but that is not correct.  "RCD" common now trip on imbalance between L and N over the rated current.  While a good solid earth is a must, it is not required for the RCD to work properly.

[Mike R in CM]

1 minute ago, bankruatsteve said:

Sorry, but that is not correct.  "RCD" common now trip on imbalance between L and N over the rated current.  While a good solid earth is a must, it is not required for the RCD to work properly.

Correct but I actually referring to RCBO's which are installed on individual circuits and hence provide the safety you require from frying yourself!

[Crossy]

Neither an RCD or an RCBO require a ground to function, they work just fine without.

 

That doesn't mean you can omit the ground on a Class-1 appliance but it does mean they work with Class-2 appliances (no ground).

 

SOME RCBOs have a "functional ground" which enables them to better detect N-E faults, but they are rare in Thailand.

[johng]

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

I think they reduced it to 50 units and only after 3 months consistently under 50..it caught a few poeple out who had their meters removed after the first month of non payment !

[Crossy]

Some light reading for those who want to know how and RCD/RCBO works.

 

rcd_handbook_dec_2010_49836.pdf

 

 

[DineshR]

@Crossy Thank you for that rcd handbook. Very informative. I have a much better understanding of the subject.

[unblocktheplanet]

We did have ground rod installed but all this sounds beyond the ken of our 20+ year local electrician. Might anyone recommend an electrician experienced with this in Udomsuk/Bangna? TIA! cjATtuDOTacDOTth, please; the TV notification system doesn't much work for me. (Not grounded enough?!?)

[DineshR]

Hello,

 

I was continuing to do some more research before having the discussion with the electrician and here is what I have found so far.

 

The main circuit breaker I have is the unit referenced with this link.

 

https://www.schneider-electric.com.my/en/product/EZC100N3100/circuit-breaker-easypact-ezc100n---tmd---100-a---3-poles-3d/?range=997-easypact&node=166393365-circuit-breaker

 

It only has overload and short circuit protection - and does not have the type of protection that an RCD provides.

 

Similar to the individual circuit breakers that are on my panel, I found this RCBO unit - https://www.schneider-electric.co.th/th/product/QO116C10RCBO30/qovs---earth-leakage-circuit-breaker---1p-%2B-ns---c-curve---16a---30ma/

 

which should be a good replacement for the existing circuit breakers on my panel. 

 

I would replace the 16A units (for all the plug points) with the 16A equivalent RCBO versions and the 32A units (for all the water heaters) with the 32A equivalent RCBO versions.

 

I would like to know if my understanding of the below is correct.

 

When installing the RCBO's,  it is essential that the live and neutral for each RCBO is distinct and separate for each RCBO ... meaning, that each RCBO must have their own live and neutral connections and they cannot be shared.

 

That said, each RCBO can support multiple plug points ... that is, multiple plug points can be controlled by a single RCBO.

 

An earth, or ground connection, is not required for the RCBO's though for each plug point, the ground plug must be grounded properly.

 

Is my understanding correct ?

 

Is there anything else I should be aware of when I discuss this with the electrician ?

 

Your advice will be much appreciated. Thank you.

[Crossy]

@DineshR Yup, I agree with Arjen, your plan sounds sound.

 

The single biggest issue you will have is that of borrowed / shared neutrals. Use of a lamp, battery and a long lead (and an assistant) can reduce the pain significantly.

 

Do the water heaters first, they will likely be (reasonably) hassle free and also pose the greatest hazard to your health.

[Fruit Trader]

2 hours ago, DineshR said:

Hello,

 

I was continuing to do some more research before having the discussion with the electrician and here is what I have found so far.

From the photo its difficult to see if there is a plug in neutral bar on your breaker rail. It is unlikely your panel has the plug on neutral option but its best to ask your electrician to check as it makes a tidier installation.

 

If your panel has plug in neutral then you can use the Schneider RCBO without the pigtail neutral.

Edited August 6, 2018 by Fruit Trader

[DineshR]

Hello again,

 

1. Yes, I will do the water heaters first.

 

2. Just so that I completely understand what @Crossy meant by "Use of a lamp, battery and a long lead (and an assistant)" is to take a bulb, battery and a long wire that can reach all parts of the house from the panel and connect the wire bulb and battery in series - as shown below

 

X(neutral point on circuit breaker being checked) ------------ (one end of battery, say + ---------- the other end of battery, say -)---------bulb--------- long wire------------------- x(neutral point being checked on plug point or water heater)

 

If there is continuity between the 2 neutral points, then the bulb will light.

 

Is this the way you would check to make sure all the neutral points are properly wired ? And I assume, I would do this with the mains breaker turned off.

 

Please confirm.

 

3. I was looking at the pricing of these RCBO's (either 16A or 32A rated) and noticed that the ones with a 6A short circuit or breaking capacity are about 2190 while the ones with a 10 A short circuit capacity are 3560. Can I use the 6A short circuit capacity ones here ?

 

4. @Fruit Trader Is this - https://www.schneider-electric.co.th/th/product/QO116C06RCBO30/qovs---earth-leakage-circuit-breaker---1p-%2B-ns---c-curve---16a---30ma/?range=1095-square-d-qoe%2C-qovs%2C-qobvs&node=316394885-residual-current-devices - the unit that does not have the pigtail neutral ? Or is there another model ? Here is a pic of the back of the cover for my panel.

 

It says here that the QOVS-RCBO units are plug in compatible to this panel box. And in searching for QO-VS RCBO's is how I came across the unit I mention above.

 

Please advise. Thanks.

 

 

 

[Fruit Trader]

43 minutes ago, DineshR said:

It says here that the QOVS-RCBO units are plug in compatible to this panel box. And in searching for QO-VS RCBO's is how I came across the unit I mention above.

 

Please advise. Thanks.

 

Your panel does not have the plug on neutral code so you will need the RCBO with neutral pigtail.

Eg QO116C06RCBO30 - 6Ka breaking capacity

[DineshR]

@Fruit TraderThanks !

[Crossy]

9 hours ago, DineshR said:

If there is continuity between the 2 neutral points, then the bulb will light.

 

Is this the way you would check to make sure all the neutral points are properly wired ? And I assume, I would do this with the mains breaker turned off.

Pretty much.

Power off yes.

You must remove each neutral from the neutral bar to check if it goes to your heater / outlet etc. Once identified mark it with some tape and move on to the next circuit. It's not actually difficult just a bit time consuming.

 

[DineshR]

@Crossy .... Thank you for confirming the method and clarifying the need to remove each neutral from the neutral bar as they are checked.


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[Crossy]

8 hours ago, DineshR said:

@Crossy .... Thank you for confirming the method and clarifying the need to remove each neutral from the neutral bar as they are checked.

Just pull all of them (no need to put back until you're done), it's the work of a moment to ping down the lot to find the connected one (do check them all, it's not unknown for them to get linked somewhere).

 

[carlyai]

@DineshR Can I just offer a warning? You may be turning the power on and off, so it is important (in my eyes) that you get into the habit of checking with a meter or some other device that there is no power to the circuits you are testing. Don't just rely that you've turned the main breaker off. So if you're turning the power off then on off then on, it is possible to think it's off when on. Always double check.

When you leave the main breaker off and go somewhere testing or for a drink etc, lock the cabinet or secure it so no one can turn the power back on.

 

Sent from my SM-J700F using Tapatalk

 

 

 

 

[Artisi]

49 minutes ago, carlyai said:

@DineshR Can I just offer a warning? You may be turning the power on and off, so it is important (in my eyes) that you get into the habit of checking with a meter or some other device that there is no power to the circuits you are testing. Don't just rely that you've turned the main breaker off. So if you're turning the power off then on off then on, it is possible to think it's off when on. Always double check.

When you leave the main breaker off and go somewhere testing or for a drink etc, lock the cabinet or secure it so no one can turn the power back on.

 

Sent from my SM-J700F using Tapatalk

 

 

 

 

Very sound advice. 

[bankruatsteve]

15 hours ago, Crossy said:

Power off yes.

You must remove each neutral from the neutral bar to check if it goes to your heater / outlet etc. Once identified mark it with some tape and move on to the next circuit. It's not actually difficult just a bit time consuming.

 

As said, it is not a difficult process to identify a circuit with a "borrowed neutral".  The nightmare usually begins in attempt to find where the breach is and then fix it.  If you do find, your choice might be to just leave those circuits out of RCBO.  

[DineshR]

Hello,

 

Thank you all for the sound advice above. Thought I would provide a quick update.

 

Just went to the local supply shop and bought myself an RCBO. Picture below. I didn't understand an earlier comment by @Fruit Trader about a pigtail but you can clearly see it in the pic ... that is the neutral in. The good news here is that it's 1350 a pc (from an earlier estimate of 2190) for the 16A version.

 

It'll be about a week before I provide a final update after it's all done. But thank you so much for the quick education.

 

[bankruatsteve]

My suggestion is to just plug in the RCBO on the circuit(s) you want to protect and if there's no problem - then there's no problem.  Again, I wouldn't use on lighting circuits.  If it does trip (problem) there are ways to test as Crossy has given, I could give some alternative testing that I think is much easier if you want.  Just do one RCBO circuit at a time and you will be good.  Cheers.

[johng]

[mention=265452]DineshR[/mention] Can I just offer a warning? You may be turning the power on and off, so it is important (in my eyes) that you get into the habit of checking with a meter or some other device that there is no power to the circuits you are testing. Don't just rely that you've turned the main breaker off. So if you're turning the power off then on off then on, it is possible to think it's off when on. Always double check.
When you leave the main breaker off and go somewhere testing or for a drink etc, lock the cabinet or secure it so no one can turn the power back on.
 
Sent from my SM-J700F using Tapatalk
 
 
 
 

Sometimes if the polarity is wrong the switch is switching the "neutral" instead of the "live"...you think its off (light off or appliance doesn't work ) and safe but its not...so best to check...those neon screwdrivers are quick and easy.

[Litlos]

If you paid 1350 Baht it sounds like you are buying from Homepro.  I paid 1030 Baht each a couple of months ago from Watsadu, though they are available on Lazada for about 1150 Baht so the price may have gone up.  After you plug in the new circuit breaker the red wire goes to L, the associated white neutral is removed from the neutral bar and goes to N on the breaker, the blue lead then goes to the neutral bar where the white came from. Pretty straight forward as long as there is no sharing or borrowing of neutrals.  The guy that wired my house was ex PTT and there were shared neutrals that had to be fixed. 

 

I did 10 years O&G offshore in Thailand as a construction supervisor I&E, my main thing was double checking everything power related before power up, and do not believe the design engineers would get it correct either.

 

Cheers

 

[Artisi]

On 8/7/2018 at 7:30 PM, johng said:

On 8/7/2018 at 8:02 AM, carlyai said:

[mention=265452]DineshR[/mention] Can I just offer a warning? You may be turning the power on and off, so it is important (in my eyes) that you get into the habit of checking with a meter or some other device that there is no power to the circuits you are testing. Don't just rely that you've turned the main breaker off. So if you're turning the power off then on off then on, it is possible to think it's off when on. Always double check.
When you leave the main breaker off and go somewhere testing or for a drink etc, lock the cabinet or secure it so no one can turn the power back on.
 
Sent from my SM-J700F using Tapatalk
 
 
 
 

Sometimes if the polarity is wrong the switch is switching the "neutral" instead of the "live"...you think its off (light off or appliance doesn't work ) and safe but its not...so best to check...those neon screwdrivers are quick and easy.

Yep, test screwdriver on everything is my motto. 

[Crossy]

1 hour ago, Artisi said:

Yep, test screwdriver on everything is my motto.

A neon that does not light up does NOT mean the wire is dead. Check the neon first on a known live!

 

Too many have died when the <insert indicator type here> was faulty and showed dead when it wasn't.

 

Proving dead is a remarkably difficult thing to do.

[xtrnuno41]

for instance B16 A fuse including 30mA differential switch

 

 

[xtrnuno41]

1 minute ago, xtrnuno41 said:

for instance B16 A fuse including 30mA differential switch

 

 

I saw you had C20 A , but C is higher when detecting, b is better. Fuse for shortcut and dif switch for earthleakage detecting. 

[sometimewoodworker]

3 hours ago, xtrnuno41 said:

I saw you had C20 A , but C is higher when detecting, b is better. Fuse for shortcut and dif switch for earthleakage detecting. 

A little pedantic but it isn't fuse but a Circuit Breaker, a fuse is a wire that melts.

 

If a type B, C, D, K, or Z MCB is better or even if it should be used is dependent on the type of load it is used on and the earth fault loop impedance of the circuit, unfortunately it seems that few if any domestic electrical installers (most are not electricians) know how to check that, or even if they know how they do not check.

 

The difference between the various letters is the amounts of short term startup over current they will allow ranging from 2x to 20x the rated current