Which RCCB should I use?

[AlainSanchez]

I live in Cuba. In my house I have two 120V lines an a neutral. I also have a ground instalation not binded to the neutral. Some parts of the house are wired with L1 and others with L2. There are some outlets that uses both lines as some equipment (AC for example) needs 220V.

Given that instalation, what RCCB should I use? One 2P? Two 1P + N? One 3P + N and use only connections for 2 of the poles letting one not connected?

Many Thnx!!!

 

[Avo Mk8]

I live in Cuba. In my house I have two 120V lines an a neutral. I also have a ground instalation not binded to the neutral. Some parts of the house are wired with L1 and others with L2. There are some outlets that uses both lines as some equipment (AC for example) needs 220V.

Given that instalation, what RCCB should I use? One 2P? Two 1P + N? One 3P + N and use only connections for 2 of the poles letting one not connected?

Many Thnx!!!

I think the simple answer is that all the circuits that provide equipment with 220V need to go onto a 2 pole RCCB (or a 2 pole RCCB for each of those circuits), all the circuits on L1 on one (or more) single pole RCCB, and those on L2 onto another (or more) RCCB.
Using one 2P on the whole lot will mean any L1 or L2 load will trip it.
Using 2 separate 1P + N will mean any 220V load will trip either or both.
I'm not sure what a 3P + N would do, but with unbalanced phases may trip - or not? - anyone else comment?

 

[brianmoooore]

I'm not sure what a 3P + N would do, but with unbalanced phases may trip - or not? - anyone else comment?

3P+N RCCB (RCD) works normally on a 2P+N supply, as long as you make sure that the unused phase is not the one that supplies the test button. I've used them many times on 230-0-230 supplies, which are common in my area.

 

[AlainSanchez]

I think the simple answer is that all the circuits that provide equipment with 220V need to go onto a 2 pole RCCB (or a 2 pole RCCB for each of those circuits), all the circuits on L1 on one (or more) single pole RCCB, and those on L2 onto another (or more) RCCB.
Using one 2P on the whole lot will mean any L1 or L2 load will trip it.
Using 2 separate 1P + N will mean any 220V load will trip either or both.
I'm not sure what a 3P + N would do, but with unbalanced phases may trip - or not? - anyone else comment?

I think I should have explained a little better. Here in Cuba is pretty odd to have a subpanel with subcircuits for each room. The usual setup (like the one I have) is Metter -> Two 1P 50 AMPS MBCs (one for each phase). From the MBCs, two 6 gauge wires plus the neutral and ground (AWG 8) goes around the house and they are tapped at each outlet (with phase 1 or 2 or both deppending on what you want). Thats also de case with lights, half of the house is wired with L1 and the other with L2. This is totally not compliant with any norm, but this is Cuba remember, it is what it is.

So, as normally the loads will never be perfectly balanced between the phases, I guess using a 1P + N for each phase will not work? Is that right?

Thats why I think 3P + N (using just 2P) is the adecuate solution as the sum of the current at the RCCB input should be the same at the output. I'm just gueesing here.

The problem with that last variant is that if something happens anywhere, the whole house will be turned off. I would prefer to segregate the protection of L1 and L2 so that a leakage in a L1 outlet lets say only disconnects L1.

 

[Avo Mk8]

So, as normally the loads will never be perfectly balanced between the phases, I guess using a 1P + N for each phase will not work? Is that right?

Thats why I think 3P + N (using just 2P) is the adecuate solution as the sum of the current at the RCCB input should be the same at the output. I'm just gueesing here.

The problem with that last variant is that if something happens anywhere, the whole house will be turned off. I would prefer to segregate the protection of L1 and L2 so that a leakage in a L1 outlet lets say only disconnects L1.

Thanks for the explanation of how the power is distributed. I did wonder if it might be "different"!
To answer your question above - yes!

As you know, residual current devices work by looking for a small difference in current flowing in L and N. Typically 30mA here, the maximum current considered 'non-lethal' if you get a shock, but trip at lower than that - other ratings available.
The problem you have is that if you put one in L1 and use a combined neutral, the moment any load is switched on using L2, the neutral current will be different than line current for the L1 breaker. The thing will trip on any L2 loads.
If the distribution round the house had separate neutrals for L1 and L2 you wouldn't have the problem, but I don't see how you can protect L1 and L2 with separate residual current devices as long as you have a common neutral.
The only solution is a 2 phase or 3 phase RCCB (RCD) as per Brian's post previously, but I see the disadvantage that everything goes off!
You could protect individual outlets with residual current sockets as per GFCI's in the USA?

 

[AlainSanchez]

Thanks for the explanation of how the power is distributed. I did wonder if it might be "different"!
To answer your question above - yes!

As you know, residual current devices work by looking for a small difference in current flowing in L and N. Typically 30mA here, the maximum current considered 'non-lethal' if you get a shock, but trip at lower than that - other ratings available.
The problem you have is that if you put one in L1 and use a combined neutral, the moment any load is switched on using L2, the neutral current will be different than line current for the L1 breaker. The thing will trip on any L2 loads.
If the distribution round the house had separate neutrals for L1 and L2 you wouldn't have the problem, but I don't see how you can protect L1 and L2 with separate residual current devices as long as you have a common neutral.
The only solution is a 2 phase or 3 phase RCCB (RCD) as per Brian's post previously, but I see the disadvantage that everything goes off!
You could protect individual outlets with residual current sockets as per GFCI's in the USA?

I could do a lot of things better I guess, the only (and monumental) problem here is money. A decent RCD can easily cost more than 2 times my monthly income, so I have not a lot of options here. But I totally agree, a second Neutral line arround the house is definitely the best solution.

Thanks for your help!!!!