Solar inverter on dual RCD board

[bsr]

Hi

I have a modern (steel) dual RCD board. My solar inverter is on a dedicated circuit with a B20 MCB on one of the two RCD segments.

Am I right in thinking this is bad practice as it means the RCD tripping won't prevent current flow to the circuits fed by that RCD for the three second permitted shutdown time?

How important is it to resolve and what's the simplest way? I could move the solar circuit to before the first RCD but then it won't be on the busbar segments so I'll need some chunky tails to join to the first RCD. Do you use 25mm or is there something specific?

I have a third neutral bar in the CU.

Thanks

 

[Risteard]

Hi

I have a modern (steel) dual RCD board. My solar inverter is on a dedicated circuit with a B20 MCB on one of the two RCD segments.

Am I right in thinking this is bad practice as it means the RCD tripping won't prevent current flow to the circuits fed by that RCD for the three second permitted shutdown time?

How important is it to resolve and what's the simplest way? I could move the solar circuit to before the first RCD but then it won't be on the busbar segments so I'll need some chunky tails to join to the first RCD. Do you use 25mm or is there something specific?

I have a third neutral bar in the CU.

Thanks

It's not just bad practice - it's prohibited.

 

[ericmark]

Interesting, I have just posted about using an RCD and it has been pointed out they in the main are directional due to the electronics, so the solar inverter must feed the correct side of the RCD.

 

[Murdochcat]

It's not just bad practice - it's prohibited.

got a reg for that?

I agree with you 100% but lots of PV and ev installers think otherwise

 

[Murdochcat]

Interesting, I have just posted about using an RCD and it has been pointed out they in the main are directional due to the electronics, so the solar inverter must feed the correct side of the RCD.

not sure I agree with “correct side” statement

 

[Risteard]

got a reg for that?

I agree with you 100% but lots of PV and ev installers think otherwise

EV is easy - 722.531.3.101 requires that each EVSE be "protected individually by an RCD..." I'll have a look at the PV side and get back to you.

 

[bsr]

If you can find a reg then I can call back the company

Any advice on moving the MCB to the non load side as above?

 

[Murdochcat]

If you can find a reg then I can call back the company

Any advice on moving the MCB to the non load side as above?

If the pv is on a shared RCD , that side of the board will be unable to comply with the necessary disconnection times