Replacing Safe-T-Cut with individual RCBO Breakers

[MJCM]

We have in our old House one of these

 

 

And the individual breakers are the "normal" kind.

 

Can we replace the breakers with these (see link) and then set the Safe-T-Cut to DIRECT?

 

https://www.lazada.co.th/products/schneider-rcbo-1p-10a-40a-circuit-breaker-i962890702-s2049980012.html?

 

We have the Schneider Box (so the plug-on type should work)

 

Can send pictures tomorrow!

 

[Crossy]

Yup, no problem going to individual RCBOs on those "risky" circuits.

 

The hardest bit in an older house will be ensuring the relevant neutrals go to the correct RCBO, get it wrong and it won't stay "on".

 

[MJCM]

Thx DC.

 

That is a problem for the Sparky!.

 

We have a couple of those left from our new build and those will let the Sparky try to replace a couple and see how that goes.!

 

Will post some pictures of the whole setup tmrw!

[sometimewoodworker]

1 hour ago, MJCM said:

Thx DC.

 

That is a problem for the Sparky!.

 

We have a couple of those left from our new build and those will let the Sparky try to replace a couple and see how that goes.!

 

Will post some pictures of the whole setup tmrw!

Just a word of warning, we had a “Thai sparky” do most of the wiring.
 

They were totally incompetent when it came to tracing and eliminating a borrowed neutral. We had to (and did) find a real qualified electrician to come in and put the circuits into the correct configuration. It was something north of 20,000 

 

So don’t believe that your sparky actually understands and can sort out the situation if it happens, until proved that he really can.

[lopburi3]

Unless there is a specific reason (like some circuits not on RCBO) I would let sleeping dogs lie.  That one RCBO should provide good protection if tested occasionally and set at 30ma or below.  You start placing individual breakers and nobody is going to know how to fix, much less install.  In western countries they are the standard - here one RCBO is the standard and with missing earths - very much needed. 

Edited May 17, 2022 by lopburi3

[MJCM]

24 minutes ago, sometimewoodworker said:

 

So don’t believe that your sparky actually understands and can sort out the situation if it happens, until proved that he really can.

Thx, but our Sparky fortunately knows what he is doing he wired our whole new house all with individual RCBO breakers and was totally approved by the PEA after their inspection. And never an issue in almost 2 years now.

 

The only problem with him is that he likes the Lao Khao too much

Edited May 17, 2022 by MJCM

[MJCM]

13 minutes ago, lopburi3 said:

Unless there is a specific reason (like some circuits not on RCBO) I would let sleeping dogs lie. 

There is 1 good reason, once in a long while the Safe-T-Cut trips, and thus with the current setup the Whole house is in Darkness because the Safe-T-Cut cuts the power, with the individual RCBO's we know which one the problem lies with!

 

And then we tackle that problem!

 

Edit: Plus we have some spare ones from our current build so we don't have to buy new ones! If it doesn't work, we just put back the old ones ????

 

Edited May 17, 2022 by MJCM

[lopburi3]

4 minutes ago, MJCM said:

There is 1 good reason, once in a long while the Safe-T-Cut trips, and thus with the current setup the Whole house is in Darkness because the Safe-T-Cut cuts the power, with the individual RCBO's we know which one the problem lies with!

 

And then we tackle that problem!

 

 

Indeed makes trouble shooting easier but not sure that for most a change of operating system is justified - especially as most workers are not going to have a clue.  As for light have flashlights within reach as power fails much more often than have RCBO trip.  I am still using an original Safe-t-cut from 1978 but have several sub panels with own RCBO these days.  

[MJCM]

12 minutes ago, lopburi3 said:

Indeed makes trouble shooting easier but not sure that for most a change of operating system is justified - especially as most workers are not going to have a clue.

Fortunately our Sparky knows what he is doing.

 

12 minutes ago, lopburi3 said:

As for light have flashlights within reach as power fails much more often than have RCBO trip.

Let me tell you this, we live 20 kms from our old House, at 11pm one day we got a call, my wife's 68 year old uncle was on the phone (he was visiting and staying in our old house).

 

He - "No lights in House"

We - "Power Outage??"

He - "No, neighbor has light"

We (read I)  - "Ooh ... Safe-t-cut

We (for the next 25 min) - tried to explain how reset the Safe-T-Cut

We (After those 25 mins) gave up and we jumped in the car drove the 20km's reset the Safe-T-Cut and then drove back!

 

Since then we wanting to change the Safe-T-Cut for the individual ones. At least then either the AIrcon/Lights/Water Pump/Water heater keeps working ????

Edited May 17, 2022 by MJCM

[lopburi3]

5 minutes ago, MJCM said:

Fortunately our Sparky knows what he is doing.

 

Let me tell you this, we live 20 kms from our old House, at 11pm one day we got a call, my wife's 68 year old uncle was on the phone (he was visiting and staying in our old house).

 

He - "No lights in House"

We - "Power Outage??"

He - "No, neighbor has light"

We (read I)  - "Ooh ... Safe-t-cut

We (for the next 25 min) - tried to explain how reset the Safe-T-Cut

We (After those 25 mins) gave up and we jumped in the car drove the 20km's reset the Safe-T-Cut and then drove back!

Indeed pull down push up seems to be a hard concept for many of us (we just want to push up).  ????

[MJCM]

Chips, I am mistaken, the box with the Breakers is NOT Schneider but it's ABB!!

 

Does this mean we also have to change the Box?

 

[Crossy]

3 hours ago, MJCM said:

Does this mean we also have to change the Box?

 

No just use DIN mount RCBOs ???? 

 

Single width (same as an MCB) ones are available if you hunt them out.

 

https://www.lazada.co.th/products/bticino-g8613ac20-rcbo-20-din-i2762765443-s10038793508.html

 

 

[MJCM]

Thx @Crossy

 

Just for my understanding.

 

What about these? Same same?

 

https://www.lazada.co.th/products/abb-1p-10a-40a-circuit-breaker-rcbo-dse201-10a-40a-1p-i3588545798-s13405885006.html?

Edited May 18, 2022 by MJCM

[Crossy]

There may be cheaper ones than the BtiCino ones, also note that the Bti ones have a "functional earth" lead, it's supposed to help discriminate when you have a N-E fault.

 

[MJCM]

I found one but that price can't be right

 

189 THB

 

https://www.lazada.co.th/products/18mm-230v-5060hz-rcbo-1pn-6ka-residual-current-differential-automatic-circuit-breaker-with-over-current-leakage-protection-i3130440359-s11650400634.html?

Edited May 18, 2022 by MJCM

[Crossy]

Wow, that is very cheap. Tomzn stuff is generally very good, I wonder if it's real.

 

I think Tomzn have an official Lazada store, have a look there for the same item.

 

[Dante99]

On 5/17/2022 at 9:28 AM, Crossy said:

The hardest bit in an older house will be ensuring the relevant neutrals go to the correct RCBO

Just talked with our electrical guy and he said he could not change to RCBO because he did not which neutrals went with with the ones we wanted to change.

 

So seems we need a different guy who can figure it out.  Please tell me what he will need to do to identify the correct neutrals if it is not too lengthy to explain.  I expect he will need to get in the attic and look at the wiring, do some testing? will he need a partner at the breaker box too?

 

Thanks very much.

[sometimewoodworker]

1 hour ago, Dante99 said:

Just talked with our electrical guy and he said he could not change to RCBO because he did not which neutrals went with with the ones we wanted to change.

 

So seems we need a different guy who can figure it out.  Please tell me what he will need to do to identify the correct neutrals if it is not too lengthy to explain.  I expect he will need to get in the attic and look at the wiring, do some testing? will he need a partner at the breaker box too?

 

Thanks very much.

What you need is an actual electrician, you don’t have one. 
 

what you now need is an actual plan. 
It is quite likely that you can wire a whole house RCBO for little more than the cost of the RCBO

It maybe less expensive to run new circuits for devices that you want protected by individual RCBOs.

 

It is most likely that the electrician will not be able to tell you what is needed until he takes a look at the job.

 

It is certainly possible that stripping out the old wiring and doing an actual new wire job could be cheaper that trying to solve the problem.

 

When we were accepting our new house the cost for the builder to eliminate the borrowed neutral was around ฿20,000, if I would be liable for that cost I could well have decided to use a single RCBO and ignore the problem, as it was the builder who did not contract with an electrician I insisted that he fix the problem.

[Crossy]

11 hours ago, Dante99 said:

So seems we need a different guy who can figure it out.  Please tell me what he will need to do to identify the correct neutrals if it is not too lengthy to explain.  I expect he will need to get in the attic and look at the wiring, do some testing? will he need a partner at the breaker box too?

 

OK, any half decent sparks would know, but anyway, a potted guide.

 

You will need:-

• A multimeter (or at least a battery and test lamp)
• A long wire that will reach from your breaker board to the appliance/outlet you want to protect.

What to do:-

• Mains OFF
• Connect your long lead to the neutral at the appliance.
• Disconnect all the neutrals at the breaker board.
• Identify which neutral has continuity with your long lead.

Repeat as necessary for each neutral you want to identify.

• Put the neutrals in the correct RCBOs
• Reconnect the other neutrals and the neutral tails from the RCBO to the neutral bar
• Turn OFF all the breakers.
• Turn ON the mains
• Turn on your RCBOs (with luck they'll stay on)
• Turn on the other breakers one at a time - hopefully the RCBOs will stay on (see below if they don't)

If turning on a breaker trips an RCBO there is a shared neutral, the easiest fix is to move the other circuit to the RCBO too. Finding the share is, er, fun.

[Dante99]

Crossy,

 

Thank you for the very clear explanation.

 

One more dummy question.  If a shared neutral is found and I move the other circuit to the RCBO do I need to use a RCBO with a higher amp rating.  Example the two circuits are on 20 amp breakers, should I use a larger breaker like 32 amps for the combined circuits or is sticking with the 20 satisfactory?

 

 

[sometimewoodworker]

24 minutes ago, Dante99 said:

Crossy,

 

Thank you for the very clear explanation.

 

One more dummy question.  If a shared neutral is found and I move the other circuit to the RCBO do I need to use a RCBO with a higher amp rating.  Example the two circuits are on 20 amp breakers, should I use a larger breaker like 32 amps for the combined circuits or is sticking with the 20 satisfactory?

 

 

A combination of circuits will have a higher amp rating protection than a single. However the individual circuits should still have their own individual MCBs/RCBOs.

 

FWIW @Crossy seems to have some very interesting, and possibly masochistic or sadistic, definitions of fun

Edited August 15, 2022 by sometimewoodworker

[Crossy]

26 minutes ago, Dante99 said:

Crossy,

 

Thank you for the very clear explanation.

 

One more dummy question.  If a shared neutral is found and I move the other circuit to the RCBO do I need to use a RCBO with a higher amp rating.  Example the two circuits are on 20 amp breakers, should I use a larger breaker like 32 amps for the combined circuits or is sticking with the 20 satisfactory?

 

Sadly, you have to stick with the 20A rating as it has to protect the cable. If you still need the full rating of both circuits you will have to find where the circuits join, split them then run a new neutral for the now isolated circuit.

[Dante99]

OK all clear.  Again many thanks.