Solar and splitting tails

[Raptor0014]

Evening all.

I have a question as I can’t get my head around something with solar PV

I’m going to be working on a new build in a couple of weeks as the contractors have installed the electrical installation incorrectly as per the customer request when buying and are now refusing to correct. There’s been some ongoing discussion between the owner and the builder but each are arguing from different points of view. So I’ve been asked to go in and sort it.

The problem is regarding the feed to a garage supply.

At the moment the garage is fed from a 50A MCB on one side of a split load board. Which then runs in 10mm SWA to a garage board where they have put a 32A MCB for the EV charge point

However under Amdt 2 and 722.531.3.101 this is not compliant as EV Charge Points have to be on their own dedicated DP RCD protection, with no other circuits, if it’s not built into the unit itself. The unit I’ll be installing doesn’t have inbuilt 30mA protection. I know they will be working to Amdt 1 as that will likely be the house design spec. But they have put a SPD board in (which is not necessarily a requirement under Amdt 1 if the CRLS doesn’t deem it so) so they’re kind of working to it in areas where they want and not in others.

So my options are

1. Create a non-RCD way in the board and feed the garage. Then install a RCBO board in the garage. Thus giving the EVCP its own dedicated protection. But I am not sure if this is possible until I remove the cover as it’s a BG board and if RCD one shares its neutral with the main incoming neutral bar then it may have to be option 2 anyway. Or get DIY Dave creative with Wago’s.

2. Split the tails, install a small 2 way enclosure and a 50A DP MCB and then a RCBO board in the garage.

However the customer wants to get proper solar PV and Battery Storage (there is a paltry 3 panels on the roof to ‘tick a box’ from the build).

So, as I don’t fully understand how solar works. If I go with option 2 and split the tails, so as not to use up one of the two remaining spare ways in the board. Will this mean the garage doesn’t benefit from the PV and Battery storage?

If that’s not the case and it will can someone explain to me how with split tails the garage would benefit from the PV & BS if they’re installed in the main board? As I can’t work out how the CT clamp would see the garage load unless they install it on the tails from the meter itself. But still then unsure how it would feed the garage as they would only be linked via the Henley block.

If I’m being dumb be gentle. I’m working 7 days a week at the moment and just can’t work out how the solar and PV would work with split tails.

Thanks

Carl.

 

[kropaske]

You will be OK with option 1 as BG dual rcd have 3 neutral bars - 1 main and 1 for each rcd.
PV is connected parallel to the supply, so it does not matter where its connected, whole install will benefit from it. Just need to remember that the CT clamp needs to go on the tails just before or after meter so it can read correctly all the loads.

 

[Raptor0014]

You will be OK with option 1 as BG dual rcd have 3 neutral bars - 1 main and 1 for each rcd.
PV is connected parallel to the supply, so it does not matter where its connected, whole install will benefit from it. Just need to remember that the CT clamp needs to go on the tails just before or after meter so it can read correctly all the loads.

Thank you.

I still cant get my head around how the PV would supply the garage if it’s fed into the main board and the tails were split.

 

[Gavin John Hyde]

However under Amdt 2 and 722.531.3.101 this is not compliant as EV Charge Points have to be on their own dedicated DP RCD protection, with no other circuits,
I have asked about this and discussed with ECA tech chairman, NICEIC assessor and NICEIC tech helpline and 1 other person involved in writing the regulation.
Its poorly worded but there is no issue with a type A DP RCD having say a socket circuit , some lights and an ev charger as long as the rcd is sufficient Amp rating for the circuits. you cant however have 2 ev chargers protected by 1 RCD so on a split load board with 2 Type A RCDS you would be able to run 1 off each.

With all this renewable stuff going in, I would fit a zappi that way the submain to garage assuming all is good doenst need RCD protection (note myenergi recommend a type a rcd/rcbo still) so could fit a type a rcbo in garage and then you can Most BG boards have 3 Neutral bars so place garage on an MCB and then ingarage you can fit whatever you need to allow for the battery/inverter etc.

The benefit of the zappi is you can use the harvi and hardwired ct clamps so garage wont overload submain but also the property as a hole. Have a read of the zappi instruction manual and the ct clamp pages. all is explained well. You will in my view need load management depending on battery size as some batteries charger at 40A from grid if ac coupled which given small size of pv explained above i assume might be considered. so coupled with an ev charger you are talking 72A+. circuit design is key here but it can be done.

 

[Raptor0014]

However under Amdt 2 and 722.531.3.101 this is not compliant as EV Charge Points have to be on their own dedicated DP RCD protection, with no other circuits,
I have asked about this and discussed with ECA tech chairman, NICEIC assessor and NICEIC tech helpline and 1 other person involved in writing the regulation.
Its poorly worded but there is no issue with a type A DP RCD having say a socket circuit , some lights and an ev charger as long as the rcd is sufficient Amp rating for the circuits. you cant however have 2 ev chargers protected by 1 RCD so on a split load board with 2 Type A RCDS you would be able to run 1 off each.

With all this renewable stuff going in, I would fit a zappi that way the submain to garage assuming all is good doenst need RCD protection (note myenergi recommend a type a rcd/rcbo still) so could fit a type a rcbo in garage and then you can Most BG boards have 3 Neutral bars so place garage on an MCB and then ingarage you can fit whatever you need to allow for the battery/inverter etc.

The benefit of the zappi is you can use the harvi and hardwired ct clamps so garage wont overload submain but also the property as a hole. Have a read of the zappi instruction manual and the ct clamp pages. all is explained well. You will in my view need load management depending on battery size as some batteries charger at 40A from grid if ac coupled which given small size of pv explained above i assume might be considered. so coupled with an ev charger you are talking 72A+. circuit design is key here but it can be done.

I have also had the same conversations. And had similar responses.

However see if you can get one of them to give it to you in writing. I’ll guarantee they won’t.

The technical manager of the ECA also argues against. I’ve banged my head against a brick wall over it. But no-one at the IET, NAPIT, NICEIC, ECA etc etc will give in writing that it’s ok on a split load board.

 

[goasis]

Why on earth are split load boards still being installed?!

 

[Raptor0014]

Why on earth are split load boards still being installed?!

Cheapskate building contractors. Everything done to a cost. I wouldn’t mind but this is a near £700k house too.

 

[Risteard]

I have also had the same conversations. And had similar responses.

However see if you can get one of them to give it to you in writing. I’ll guarantee they won’t.

The technical manager of the ECA also argues against. I’ve banged my head against a brick wall over it. But no-one at the IET, NAPIT, NICEIC, ECA etc etc will give in writing that it’s ok on a split load board.

My personal interpretation is that the RCD (whether RCCB or RCBO) cannot be used by any other circuits, nor by multiple chargepoints off one circuit. I can't understand how dedicated can be understood otherwise.

 

[Raptor0014]

My personal interpretation is that the RCD (whether RCCB or RCBO) cannot be used by any other circuits, nor by multiple chargepoints off one circuit. I can't understand how dedicated can be understood otherwise.

That was my interpretation and I raised it as it meant you can’t stick a charge point in a split load board anymore. Even if it has the space and the correct type RCD.

So unless you can create a non-RCD way and get a DP RCBO (which there are very few single module versions) to fit. You’re always installing an additional board.

Depending on who you speak to you’ll get told it’s fine on split load as long as it’s only one charge point per RCD/RCBO. Then others say it’s not.

But no-one will give, in writing, that it’s fine on a split load.

 

[Gavin John Hyde]

My personal interpretation is that the RCD (whether RCCB or RCBO) cannot be used by any other circuits, nor by multiple chargepoints off one circuit. I can't understand how dedicated can be understood otherwise.

That is what i thought initially but when i asked the various bodies all said not as clear cut! If necessary and there is space i will fit a 40A mcb and route it via a DP type a rcd and job done. saves fitting a full board.

I was told by some of the people who wrote the regulation that it wasnt intended to stop people using split load boards and fitting a ev point from an rcd shared with otehr circuits but more to stop 2 chargers on one rcd largely due to leakage currents and overload. didnt quite get written like that though!

I think by the 3rd amendment if not then 19th there will be a much clearer sets of regulations and sections for ev, battery storage etc