Rcbo Selection

[TS79]

Here is a question.

If your main CU incomer breaker is 63A and you decide to have an overall RCBO to protect the downstream circuits (e.g. sockets, lights, aircons etc), then what size 30mA RCBO should you choose? IS there a rule or calculation that should be used?

Is it wise to assume the RCBO should be less than the main breaker? Does it really matter too much as the individual circuits have their own MCB's to protect them against over-current so a high rated RCBO would still be effective for an earth leakage fault?

In the case of SquareD, they have 16, 20, 32, 45, and 63A 30mA RCBO's.

[Crossy]

You could replace your incomer with a 63A / 30mA RCBO (provides overload and earth leakage protection), or add a 63A (or greater) / 30mA RCD (provides earth leakage only) between your incomer and the rest of your installation.

Since you're talking Square-D one assumes a plug-in type CU so you're limited to replacing the incomer or putting a Safe-T-Cut type unit in front of the lot in which case the 63A unit would be the one to choose.

[electau]

The main switch is a 63A MCB, it would be reccomended that you retain this and install a 63A/30mA RCBO between the load side of the MCB and the line side of the busbar for the final subcircuits. (The size of the consumers mains should be 10sqmm or 16sqmm.)

The 63A MCB determines the max demand of the electrical installation.

[Mike45]

You could replace your incomer with a 63A / 30mA RCBO (provides overload and earth leakage protection), or add a 63A (or greater) / 30mA RCD (provides earth leakage only) between your incomer and the rest of your installation.

Since you're talking Square-D one assumes a plug-in type CU so you're limited to replacing the incomer or putting a Safe-T-Cut type unit in front of the lot in which case the 63A unit would be the one to choose.

Crossy why is he limited to the 63A? Is it because they don't sell the individual plug-in type for each circuit for square D type?

[Crossy]

His current incomer is a 63A MCB, replace with an RCBO with the same over-current rating.

Square-D consumer units don't allow configuration to use a single RCD to protect all the ways, only option is a front end RCBO or individual RCBOs on each circuit.

Square-D are actually the only CU that I KNOW supply single width RCBOs in Thailand, 1500 baht a pop.

[Mike45]

His current incomer is a 63A MCB, replace with an RCBO with the same over-current rating.

Square-D consumer units don't allow configuration to use a single RCD to protect all the ways, only option is a front end RCBO or individual RCBOs on each circuit.

Square-D are actually the only CU that I KNOW supply single width RCBOs in Thailand, 1500 baht a pop.

Crossly

I'm sorry but I am not 100% sure of your meaning.

In your second paragraph are you saying that they don't allow single (individual circuit) RCD's but then in the third paragraph you say they do?

I'm also not sure what you mean by "front end" "protect always""incomer"

Sorry I'm an American and can't speak English LoL

Someone once said we were two people's separated by a common language.

[Mike45]

I saw this today at HomePro. What would you call it and where would you place it?

I didn't see any RCBO single breakers at HomePro I suspect I would have to look in a specialty outlet.

Thanks

Mike

[bankruatsteve]

That looks like the main CB to me. Home Pro definitely has single circuit RCBO's (they usually have a curly blue (?) wire to connect the neutral.

[Mike45]

That looks like the main CB to me. Home Pro definitely has single circuit RCBO's (they usually have a curly blue (?) wire to connect the neutral.

I just discovered that HomePro has an online catalog and I found the breakers just as you said with the blue curly wire.

PRODUCT AVAILABILITY QTY EACH TOTAL

CIRCUIT BREAKER 16A QO116VS6RCBO10 SQD

Article: 230653

Remove

In-Stock

฿1,635.00 ฿1,635.00

CIRCUIT BREAKER 20A QO120VS6RCBO10 SQD

Article: 230654

Remove

In-Stock

฿1,635.00 ฿1,635.00

[kyrre]

The homepro shop also have a lower price... I ordered a Square D 63A RCBO from directtoshop as they only had it in stock at Homepro chonburi and not pattaya. The price was THB 500 lower online than in the shop. I did the express delivery and it was at my door 2 days later.

[Mike45]

The homepro shop also have a lower price... I ordered a Square D 63A RCBO from directtoshop as they only had it in stock at Homepro chonburi and not pattaya. The price was THB 500 lower online than in the shop. I did the express delivery and it was at my door 2 days later.

That's good to know because as I said there weren't any in Ubon.

Thanks

[Mike45]

The homepro shop also have a lower price... I ordered a Square D 63A RCBO from directtoshop as they only had it in stock at Homepro chonburi and not pattaya. The price was THB 500 lower online than in the shop. I did the express delivery and it was at my door 2 days later.

Would that be the one they have listed as

BREAKERกันดูด/รั่ว QO263MBGX30T SQD

Funny thing is that when you look at the photo up close it says D45 on the switch.

Is this a 63 A RCBO that will fit into the Main Circuit Breaker location of the CU or is it designed to go into a separate box before the CU.

I notice it doesn't have one of those blue wires attached to it

I'm also confused because I believe Crossey said above that they don't make a 63A main RCBO.

[eraymos]

If it's any help, his is my Square D 63A RCBO that fit into the Main Circuit Breaker location of the CU

[Crossy]

I'm also confused because I believe Crossey said above that they don't make a 63A main RCBO.

I'm confused because I don't recall saying that

Thanks for the picture eraymos, that's the beast for a whole house job

[Mike45]

His current incomer is a 63A MCB, replace with an RCBO with the same over-current rating.

Square-D consumer units don't allow configuration to use a single RCD to protect all the ways, only option is a front end RCBO or individual RCBOs on each circuit.

Square-D are actually the only CU that I KNOW supply single width RCBOs in Thailand, 1500 baht a pop.

Crossey

Sorry I didn't mean to put words in your mouth.

It was my understanding of what you said that apparently was incorrect.

When you were referring to "protect all the ways" I thought you meant the Main Circuit Breaker.

I also took your "front end RCBO" to mean placed before the CU.

As I said in an earlier post I didn't understand the terminology.

From your info and others contributions I believe I have made a decision how to go forward. Use a Schneider Square D box with a Main Circuit Breaker RCBO of 63A.

Does anyone see any problems with that?

Thanks for all the help so far.

Mike

[Mike45]

If it's any help, his is my Square D 63A RCBO that fit into the Main Circuit Breaker location of the CU

Thanks eraymos

A picture says a thousand words.

[Crossy]

His current incomer is a 63A MCB, replace with an RCBO with the same over-current rating.

Square-D consumer units don't allow configuration to use a single RCD to protect all the ways, only option is a front end RCBO or individual RCBOs on each circuit.

Square-D are actually the only CU that I KNOW supply single width RCBOs in Thailand, 1500 baht a pop.

Crossey

Sorry I didn't mean to put words in your mouth.

It was my understanding of what you said that apparently was incorrect.

When you were referring to "protect all the ways" I thought you meant the Main Circuit Breaker.

I also took your "front end RCBO" to mean placed before the CU.

As I said in an earlier post I didn't understand the terminology.

From your info and others contributions I believe I have made a decision how to go forward. Use a Schneider Square D box with a Main Circuit Breaker RCBO of 63A.

Does anyone see any problems with that?

Thanks for all the help so far.

Mike

No problem Mike I probably wasn't being as clear as I should, an RCD is not the same as an RCBO.

Yes, your RCBO solution is effective and simple to implement.

[Mike45]

That looks like the main CB to me. Home Pro definitely has single circuit RCBO's (they usually have a curly blue (?) wire to connect the neutral.

After all I've learned I went back to my previous post that had the picture of the 63A breaker. It has a yellow button that is labeled "regular test" and the side says " residual current CB with integral over protection" it also does not have a sticker that says "test monthly".

A little clarification please.

Is that a regular MB as previously thought or the one I have decided to use as the RCBO MCB?

[bankruatsteve]

Can't seem to make the "Quote" work. ??

Anyway... yes, that's a Square-D RCBO main breaker: 63a overcurrent and 30ma fault protection. The yellow button is to test the RCD and will cause the breaker to open. I suspect "Regular Test" is the Thai way to say "Test Regularly".

[Mike45]

Great so that means that my builders electrician can find all the breakers I need locally.

One more question.

Since my CU is going to be above the refrigerator in my kitchen I wanted to choose a better looking CU Box.

I noticed that Schneider does have two different types. One square gray metal and the other a sleeker white.

Am I correct that everything that I want to do can be done with the white box?

Thanks

[bankruatsteve]

Yup. The number of MCB slots will determine the maximum number of individually protected circuits you have. And again, the breakers must be for the Square-D box as other brands/types will not fit.

[Mike45]

Thanks to all that have contributed and to the OP for allowing me to ask follow-up questions to his.

[doglover]

If it's any help, his is my Square D 63A RCBO that fit into the Main Circuit Breaker location of the CU

june 2012 (9).JPG

........hey wait a minute! How come my CU only has 4 ground wires and his CU has enough ground wires to wire a house?

Since my CU is going to be above the refrigerator in my kitchen I wanted to choose a better looking CU Box.

Lol. Only in Thailand.

[doglover]

Great so that means that my builders electrician can find all the breakers I need locally. One more question. Since my CU is going to be above the refrigerator in my kitchen I wanted to choose a better looking CU Box. I noticed that Schneider does have two different types. One square gray metal and the other a sleeker white. ImageUploadedByThaivisa Connect Thailand1361502018.407627.jpg Am I correct that everything that I want to do can be done with the white box? Thanks

Make sure you purchase a CU that has a few more breaker slots than you require. At some point in the future you may need the space.

*My last post wasn't a jab at you Mike45. Just poking fun at your electrician*