One for our EV experts

[littlespark]

I got one of these ready built consumer units for my father in laws EV install. Got the cables run in, mounted the charge point etc…. Then took the cover of this.
I don’t know, maybe still peed off standing in the rain all afternoon… but this got me confused.



Left to right, RCD, 32A MCB, SPD

Incoming feed into N and 2 of the RCD…. But where do I take the cable out to the charge point?
Top N of the RCD goes to SPD, 1 of the RCD into top of MCB. Out bottom of MCB into SPD.

So logically, my outgoing needs to be top N of RCD, and Live from the bottom of the MCB… both in beside a ferruled linking cable.

Compared to a regular consumer unit, everything’s upside down.

 

[Gavin John Hyde]

You pretty much got it...
Not a fan of these units for this reason. there are quite a few that have just a dp rcbo and spd module with both the spd and charger fed from the bottom of rcbo

 

[loz2754]

Not quite. The MCB is only to protect the SPD. You need to take both line and neutral from the top of the RCBO.

 

[loz2754]

The Fusebox EV32AX has a main switch, a 32 amp MCB for the SPD, a double pole type A RCBO, metal busbar, and terminal bars for neutral and earth.

 

[littlespark]

ah gotcha i see its an RCBO now i can read the EN number as 61009.... not 61008.

So out the top.

I did wonder.... because a 32A charge point will risk tripping out a 32A breaker.... would need to be a 40.

Cheers.


I might get the FB box for the other install ive got up in Aviemore.

 

[loz2754]

If you prefer a 40 amp RCBO, the Fusebox EV40AX is the one.

 

[littlespark]

If you prefer a 40 amp RCBO, the Fusebox EV40AX is the one.

This Eris box is a 40 rcbo, and a 32 mcb

 

[Julie.]

OK I am going against the flow here, I believe the incoming supply should be to the top N-1 connections, and the outgoing (EVCP) to the bottom N-2 connections.

There are two reasons, firstly if the supply comes in from below then the SPD is downstream of the RCD/RCBO, this would be in breach of 534.4.7 as a general RCD doesn't have the surge withstand of 3kA , generally the only RCDs with 3kA surge withstand are type S.
Also if the SPD is type 1 this shouldn't be downstream of an RCBO with 3kA surge withstand anyway.

The second reason is a bit pedantic, and realistically often ignored quite justifiably.

That is if the supply comes from the top, when the RCD/RCBO is open, nothing is connected to the supply, however when supplied from the bottom (in this case) even with the RCD/RCBO open, the supply would still be connected to the internal electronics.

This is a minor point obviously, it's the SPD downstream of the RCD function which would be the non-compliance with the regs.

 

[Julie.]

Just to add, I don't know if that's a type 1 or 2 SPD, BTW.

And going off the original post I thought it was a RCD - so most of the comments relate to RCD, RCBOs usually have the 3kA surge withstand I think.

 

[davesparks]

This is a minor point obviously, it's the SPD downstream of the RCD function which would be the non-compliance with the regs.

I completely agree but then with the SPD upstream of the RCD in one of these units there's potentially no way to fully isolate it as the RCD is the mainswitch for these little CU's.

I'd say it's a lose/lose situation with these units.

 

[littlespark]

Confirm, the RCBO is the mainswitch for this as it’s coming direct from the Henley blocks.

 

[Julie.]

I completely agree but then with the SPD upstream of the RCD in one of these units there's potentially no way to fully isolate it as the RCD is the mainswitch for these little CU's.

I'd say it's a lose/lose situation with these units.

It does have the MCB to isolate the SPD

 

[Markyd]

Why a C curve RCBO? And cant make out if its a type A

 

[littlespark]

Why a C curve RCBO? And cant make out if its a type A

Bloody well should be a type A!... its for EV points.

 

[Julie.]

It is a type A - the symbol just below [and to the right of] the type number shows it as type A

 

[loz2754]

Just to add, I don't know if that's a type 1 or 2 SPD, BTW.

And going off the original post I thought it was a RCD - so most of the comments relate to RCD, RCBOs usually have the 3kA surge withstand I think.

It's a type 2, bottom left corner.

 

[loz2754]

Why a C curve RCBO? And cant make out if its a type A

It's clearly a type A

 

[Julie.]

It's a type 2, bottom left corner.

Fair enough, I didn't know if the T2 was type 2 or part of their references, unrelated to type.

 

[davesparks]

It does have the MCB to isolate the SPD

Yes but im not too comfortable with that arrangement, especially in a domestic installation where the average person would reasonably expect the main switch of a unit to isolate everything else within the unit.

I'd say it possibly falls foul of 462.1.201 in bs7671

 

[Markyd]

So why a C curve and not a B curve