3 phase wiring

[tedel]

Hello,
i need advice with my house electricity wiring. My house has 3 phase, the solar inverter is the only device on 3 phase, everything else is single phase.
My current setup is Schneider Load Center with 21 Square D breakers, 7 on each phase.
https://www.se.com/th/en/product/QO3-100EZ24G%2FSN/square-d-classic-main-breaker-load-center---100a---surface-mounted---24-ways/
I would like to add more safety thru RCBO, but seems like i would have to replace all mcb with rcbo (21 x 900 thb).
Maybe i could split to 3 separate phase but i didnt find a junction box which could accommodate it all, would need like 1xMCCB + 3x rows , each for one phase.
Anyone experienced here to guide me which way to go? thanx for all advices

 

[Crossy]

You can add single-phase RCBOs to "critical" circuits (outdoor outlets, water heaters, bathroom outlets etc.), no need to replace ALL the MCBs. These just plug in to replace the MCB, you'll need to find the associated neutral for each circuit as the RCBO needs that connected too.

 

OR

 

You can add a front end RCBO of the Safe-T-Cut type which are available as 3-phase.

 

Personally I'd go with the individual RCBOs as a trip will only kill the one circuit rather than all your power and you can retain "unprotected" circuits for things like the freezer which you really want to stay on.

 

[tedel]

Thanx for quick answer. I already checked Safe-T-Cut, but it means additional box and dont have much space there. RCBO for square D are about 900thb each and i would need to replace like 15 of them with current wiring. Isnt split to 3 separate phase with one rcbo per phase better solution? maybe something like this x 3 LINK ?

[mahjongguy]

We have the Schneider Load Center set up for 3-phase, There are 14 breakers, 6 of which are RCBO. Three of those protect the three water heaters and any outlets near a sink. The other three protect outdoor devices and outlets, like the well pump, house pump, gate motor, etc. All as Crossy recommended.

 

I like the flexibility of this approach.

[bankruatsteve]

If you want another opinion... single RCBO is probably your easiest solution and not compromising safety.  You don't really need RCBO on lighting circuits, for example.  Inside power circuits that are properly grounded are not likely to ever require RCD protection.  Just the places Crossy mentioned should be fine.

[mahjongguy]

Just to mention, Lazada sells a clone RCBO for just 435 baht. Not sayin' I'd have 'em, 'cause I wouldn't.

 

https://www.lazada.co.th/products/rcbo-nano-16a-20a-32a-1pole-6ka-30ma-plug-on-kerry-i820926384-s1681664179.html?spm=a2o4m.pdp.recommendation_2.1.7b74391dOpWr0b&mp=1&scm=1007.16389.126158.0&clickTrackInfo=47c031cd-9e30-4f5a-bae1-0849b367646c__820926384__10100214__trigger2i__169977__1.0__0.97903776__0.0__0.58075565__0.016429998__0.97903776__0__8__PDPV2V__251__null__null__0__

[Crossy]

23 minutes ago, tedel said:

Isnt split to 3 separate phase with one rcbo per phase better solution? maybe something like this x 3 LINK ?

 

It's a lot more work to set up. If going from scratch then maybe, but you'll still need a 3-phase MCCB incomer and MCB for your solar.

 

For the cost of just 3 x those units you could get 12 genuine Schneider RCBOs or a whole box of the copy units.

 

 

[Metropolitian]

You can choose from either thinking about adding a STC box, which is not very big, which can be setup to protect one phase, but as you have a device that uses three phase I don't think it would be happy loosing one phase but not sure I wouldn't go for that solution in your setup without knowing if the inverter can work on two phases or not. ( @Crossy ? )

 

For your setup the best is, without 'trashing' a CB, to add three RCBO switches and connect the groups that you want to protect on this. (outlets, kitchen and/or outdoor pump..)

You have populated 21 gangs and the CU has room for 24.

 

[bankruatsteve]

14 minutes ago, Metropolitian said:

For your setup the best is, without 'trashing' a CB, to add three RCBO switches and connect the groups that you want to protect on this. (outlets, kitchen and/or outdoor pump..)

Not sure that can be done in a Square-D box.  (?)

[tedel]

@Metropolitian The solar inverter need all 3 phases to work
@Crossy MCCB i can use the one from sqare d load center; what i dont like about the schneider is that they have this plug on system which is fine if u use their mcb, but once u need for example pv export power meter its all din, so need separate box. I have a separate pv DC box with din rails but didnt want to mix ac with dc inside one box. Thats why i was thinking rework it all, AC box with din rails. Another thing is I was checking schneider square QO rcbo's they seems to be type AC only; i have a lot of electronic at home and type A would be much better for that ; or am i wrong ? I will make tomorrow my current electric diagram maybe it will help us better understand; thanx for help

 

[Metropolitian]

6 hours ago, bankruatsteve said:

Not sure that can be done in a Square-D box.  (?)

Yes it can, with this:

 

 

And as I understood in the post from the OP is that he has a 24 gangs load center and using 21 Square D breakers.

Which then I assume that he still have 3 free slots.

Of course he can have more of those RCBO's but then that would mean he has to take out a CB to make room.

[Metropolitian]

3 hours ago, tedel said:

@Metropolitian The solar inverter need all 3 phases to work
@Crossy MCCB i can use the one from sqare d load center; what i dont like about the schneider is that they have this plug on system which is fine if u use their mcb, but once u need for example pv export power meter its all din, so need separate box. I have a separate pv DC box with din rails but didnt want to mix ac with dc inside one box. Thats why i was thinking rework it all, AC box with din rails. Another thing is I was checking schneider square QO rcbo's they seems to be type AC only; i have a lot of electronic at home and type A would be much better for that ; or am i wrong ? I will make tomorrow my current electric diagram maybe it will help us better understand; thanx for help

Maybe move the dc part to near the panels and use the dc box as ac box.

 

If you are using surge arresters, it's better if they are close to the panels.  If the distance between the panels and the inverter exceeds the 10 meter then it would be better to use surge arresters at both ends of the line.

 

I have here 3 CU's grouped together. One is for the AC side of the inverter (And a few other MCBs for that side of the room) and the others are for the mancave and the rest of the house.

The DC side I mounted inside a enclosure a DC breaker and two surge arresters and on the front an DC voltmeter.

 

Old picture from the moment of installation:

 

[Crossy]

@tedel What do you actually want to achieve? Improve the safety of those "risky" circuits like water heaters etc. or something else.

 

Future plans for gensets, surge suppression, phase protection, AVRs  etc etc?

 

I would always go DIN but if you already have plug-in then why rip it out unless it's old and dodgy or you have future plans.

 

[bankruatsteve]

13 hours ago, Metropolitian said:

add three RCBO switches and connect the groups that you want to protect on this.

How would existing groups (circuits) be connected to an added RCBO in a Square-D box?

[tedel]

12 hours ago, Metropolitian said:

Yes it can, with this:

 

 

And as I understood in the post from the OP is that he has a 24 gangs load center and using 21 Square D breakers.

Which then I assume that he still have 3 free slots.

Of course he can have more of those RCBO's but then that would mean he has to take out a CB to make room.

yes i have 21 square d breakers and still 3 free slots. If i understand correctly this rcbo 1 pole is for replacing the CB, i dont need to add more circuits, just protect the ones i already have.

 

@Crossy i want to achieve maximum safety. I made a simple electric diagram how its now.

Got some questions:

1. Is it ok that the consumer unit does not pass the MCCB?

2. Seems like the best solution really is to keep the square D and replace the RCBO on some circuits as you all suggested. I found 6kV and 10kV versions, which would u recommend ?

thank you

 

[carlyai]

8 hours ago, Crossy said:

@tedel What do you actually want to achieve? Improve the safety of those "risky" circuits like water heaters etc. or something else.

 

Future plans for gensets, surge suppression, phase protection, AVRs  etc etc?

 

I would always go DIN but if you already have plug-in then why rip it out unless it's old and dodgy or you have future plans.

 

I think that's the question.

I think this is being over thought.

So the things against a SafetyCut brand 3 phase RCBO is: 1. there's limited room to enclose it in a box and 2. you lose power to your freezer if the beast trips.

Solution 1. Don't enclose it in a box. It doesn't need enclosing in a box.

2. If you are there all the time the beast tripping is not a problem. If you go away, get someone to check daily.

We have one and that's what we do. 

If it does trip then you can isolate the circuit with the breaker panel then reset the SafetyCut.

Ours does trip on close lightning strikes. A good feature.

In 5 years we've had about 3 trips. Nearly all lightning and one a stupid Falang.