Separate connections to a EV charger and garage supply

[iggabuga]

Hi all,

Newly qualified electrician here who is in the process of re-wiring my own property.

I have recently converted my old CU (if I can call it that!) in my 1950's property to a full RCBO C.U. (No SPD).
Main fuse is 100A. Double pole isolator fitted prior to C.U.. 100A double pole switch internal to C.U., 63A RCCB and then the various RCBO's to supply the house. 4 spare ways in the CU.

I have ran two times SWA supplies (10mm2) - Yes, I know overkill. This cable wasn't my first choice but was leftovers from an install job through work.

My idea is to have two dedicated supplies, one for a dedicated EV charger (7kW maximum on single phase) and then one supply dedicated for the garage. The SWA is buried direct in the ground, with some mechanical protection around the cable. I will not go near the current carrying capacity of the SWA I know but it is in there now and is done.

My questions are these however:

1. Do I run both cables to the garage and terminate both in the garage on separate secondary consumer units? EV charger CU and Garage CU?

If I was to complete this, do I just add two 50A RCBO’s (Schneider Easy9 Type B) in the house board, local rotary isolators for each CU, 40A main switch in the EV charger CU and garage CU, and then for the EV charger CU, a 32A Double Pole Type B RCD and for the garage CU, 32A MCB for sockets and 6A MCB for lights, with a couple spare ways.


2. Do I bin the separate consumer units off and just connect in the main board?

I quite like the idea of having a garage CU and EV cu closer to where I would be working/ plugging a car in.
How would I connect and protect these adequately if I was to connect ONLY in the main house? Bearing in mind 4 spare ways left in the house CU.


3. Is there an easy way of doing all of this?!

Apologies for the long windedness of all of this but would just like to clarify this all up.
Thanks in advance.

 

[UNG]

Hi all,

Newly qualified electrician here who is in the process of re-wiring my own property.

I have recently converted my old CU (if I can call it that!) in my 1950's property to a full RCBO C.U. (No SPD).
Main fuse is 100A. Double pole isolator fitted prior to C.U.. 100A double pole switch internal to C.U., 63A RCCB and then the various RCBO's to supply the house. 4 spare ways in the CU.

What is the purpose of the RCCB

I have ran two times SWA supplies (10mm2) - Yes, I know overkill. This cable wasn't my first choice but was leftovers from an install job through work.

My idea is to have two dedicated supplies, one for a dedicated EV charger (7kW maximum on single phase) and then one supply dedicated for the garage. The SWA is buried direct in the ground, with some mechanical protection around the cable. I will not go near the current carrying capacity of the SWA I know but it is in there now and is done.

My questions are these however:

1. Do I run both cables to the garage and terminate both in the garage on separate secondary consumer units? EV charger CU and Garage CU?

If I was to complete this, do I just add two 50A RCBO’s (Schneider Easy9 Type B) in the house board, local rotary isolators for each CU, 40A main switch in the EV charger CU and garage CU, and then for the EV charger CU, a 32A Double Pole Type B RCD and for the garage CU, 32A MCB for sockets and 6A MCB for lights, with a couple spare ways.


2. Do I bin the separate consumer units off and just connect in the main board?

I quite like the idea of having a garage CU and EV cu closer to where I would be working/ plugging a car in.
How would I connect and protect these adequately if I was to connect ONLY in the main house? Bearing in mind 4 spare ways left in the house CU.


3. Is there an easy way of doing all of this?!

Apologies for the long windedness of all of this but would just like to clarify this all up.
Thanks in advance.

No point having an EV CU just go direct to the EV chargepoint and don't forget to install a data cable for the EV chargepoint while you are doing it. If you are worried about local isolation for the EV chargepoint just install an isolator in the garage
A CU for the garage circuits makes sense

 

[davesparks]

What is the 63A RCCB doing?

Why RCBO's for these 2 circuits?

If the supply is protected by a 50A OCPD then a 40A main switch is nor adequate in the garage CU!

Theres no need for a rotary isolator before the garage CU, may be sensible for the charge point though.

 

[PeakSteve]

As others have said, if you are using RCBOs you dont normally also want an RCCB - as that would be cascading RCDs. Also, if the cable is armoured all the way, you dont need an RCD on the Distribution circuit(s), just an MCB - in which case, I would be inclined to run just one 10mm SWA (@ 50A) to a new CCU in the garage, where the appropriate RCD-protection can be applied. Note, some EV Charge Points (e.g. the Zappi) don't want RCD-protection at all, as it would cascade with its internal RCDs - so your secondary CCU could accomodate RCBOs and/or MCBs as required).
If the garage is any distance from the house, dont forget to consider a separate (TT) Main Earth electrode.

You could use the second 10mm SWA just for the charge point - and it need only feed an isolator switch and the charge point - but it would need carefully labelling, to avoid confusion with the local consumer unit!

 

[PeakSteve]

As others have said, if you are using RCBOs you dont normally also want an RCCB - as that would be cascading RCDs. Also, if the cable is armoured all the way, you dont need an RCD on the Distribution circuit(s), just an MCB - in which case, I would be inclined to run just one 10mm SWA (@ 50A) to a new CCU in the garage, where the appropriate RCD-protection can be applied. Note, some EV Charge Points (e.g. the Zappi) don't want RCD-protection at all, as it would cascade with its internal RCDs - so your secondary CCU could accomodate RCBOs and/or MCBs as required).
If the garage is any distance from the house, dont forget to consider a separate (TT) Main Earth electrode.

You could use the second 10mm SWA just for the charge point - and it need only feed an isolator switch and the charge point - but it would need carefully labelling, to avoid confusion with the local consumer unit!

P.S. Dont forget, EV Charge Points require at least Type A RCDs upstream of them.

 

[Risteard]

As others have said, if you are using RCBOs you dont normally also want an RCCB - as that would be cascading RCDs. Also, if the cable is armoured all the way, you dont need an RCD on the Distribution circuit(s), just an MCB - in which case, I would be inclined to run just one 10mm SWA (@ 50A) to a new CCU in the garage, where the appropriate RCD-protection can be applied. Note, some EV Charge Points (e.g. the Zappi) don't want RCD-protection at all, as it would cascade with its internal RCDs - so your secondary CCU could accomodate RCBOs and/or MCBs as required).
If the garage is any distance from the house, dont forget to consider a separate (TT) Main Earth electrode.

You could use the second 10mm SWA just for the charge point - and it need only feed an isolator switch and the charge point - but it would need carefully labelling, to avoid confusion with the local consumer unit!

In fairness I always install RCD protection upstream of a Zappi installation as the internal RCD is not to any of the following Standards: BS EN 61008-1, BS EN 61009-1, BS EN 60947-2 or BS EN 62423.

 

[davesparks]

Also, if the cable is armoured all the way, you dont need an RCD on the Distribution circuit(s), just an MCB -

This is not necessarily true, we don't have enough information to know whether RCD protection is required or not.

If the garage is any distance from the house, dont forget to consider a separate (TT) Main Earth electrode.

Why would distance matter for this? The decision to establish a seperate earthing system would be based on bonding and equipotential zone requirements, not anything to do with distance. We know the SWA is 10mm, this is more than likely going to be 3 core so it will satisfy the requirements for bonding.

 

[Markyd]

Why no SPD fitted?...............

 

[littlespark]

Why no SPD fitted?...............

maybe the job started before it was a requirement.... awful lot of threads getting resurrected recently

 

[Markyd]

maybe the job started before it was a requirement.... awful lot of threads getting resurrected recently

My bad just noticed that, thing is still not an actual requirement

 

[littlespark]

My bad just noticed that, thing is still not an actual requirement

Required under certain circumstances.