First install of EV charger

[An Buachaillín Bán]

Hi all,

Merry Christmas to everyone, and apologies for talking work during the holidays

I have my first EV charger install job early in the New Year, and I might be able to enjoy the holidays a bit better if I could ask your advice please.

I'm going to install a 7kw Zappi charger with built in Type A 30mA RCD protection.

The earthing arrangement is a TN-C-S system at the house. There is also a garage/granny flat fed off the house, with seperate earth rod. The client initially wanted the charging point located out on garage wall with supply being taken from garage Distribution board. Garage is fed from main house DB by a 10sq cable, but there's a cooker, pump shower, water heater, kettle, computers etc out there.

Client and I agreed to take supply from house and erect charging point, about 20m away in a suitable location. Long story short, my issues/queries are:

- my calculations tell me I need a 10sq cable, but I've spoken to a few other sparks who tell me they've all run 6sqs for 7kw chargers and have no issues.

- what cable do you recommend for this? It is a 20m external run so I'm thinking SWA EV ultra cable with the incorporated CAT5.

- I will be including a CT clamp to put on tails cable. Does this come with a lead on it that I simply join the other end of CAT5 cable from charger too?

- Zappi comes with PEN fault detection, so do I need to factor in any other earthing requirements?

- A 32A MCB at the Distribution board to feed to charger, and given that there is no Surge protection at the DB, I will need to install this too? I have seen SP mounted in enclosures closer to Charging points

Many thanks for any help all.

 

[Risteard]

Hi all,

Merry Christmas to everyone, and apologies for talking work during the holidays

I have my first EV charger install job early in the New Year, and I might be able to enjoy the holidays a bit better if I could ask your advice please.

I'm going to install a 7kw Zappi charger with built in Type A 30mA RCD protection.

The earthing arrangement is a TN-C-S system at the house. There is also a garage/granny flat fed off the house, with seperate earth rod. The client initially wanted the charging point located out on garage wall with supply being taken from garage Distribution board. Garage is fed from main house DB by a 10sq cable, but there's a cooker, pump shower, water heater, kettle, computers etc out there.

Client and I agreed to take supply from house and erect charging point, about 20m away in a suitable location. Long story short, my issues/queries are:

- my calculations tell me I need a 10sq cable, but I've spoken to a few other sparks who tell me they've all run 6sqs for 7kw chargers and have no issues.

- what cable do you recommend for this? It is a 20m external run so I'm thinking SWA EV ultra cable with the incorporated CAT5.

- I will be including a CT clamp to put on tails cable. Does this come with a lead on it that I simply join the other end of CAT5 cable from charger too?

- Zappi comes with PEN fault detection, so do I need to factor in any other earthing requirements?

- A 32A MCB at the Distribution board to feed to charger, and given that there is no Surge protection at the DB, I will need to install this too? I have seen SP mounted in enclosures closer to Charging points

Many thanks for any help all.

PEN fault protection is a UK-only derogation from IEC and harmonised standards so isn't relevant. You could not wire this into the installation as having a switching device in a protective conductor is expressly prohibited. You must use an RCD which interrupts all live conductors (e.g. double pole RCBO) - you cannot just wire in an MCB. 40A rather than 32A device would be better - you don't want a device running at is full rating for many consecutive hours.

 

[An Buachaillín Bán]

PEN fault protection is a UK-only derogation from IEC and harmonised standards so isn't relevant. You could not wire this into the installation as having a switching device in a protective conductor is expressly prohibited. You must use an RCD which interrupts all live conductors (e.g. double pole RCBO) - you cannot just wire in an MCB. 40A rather than 32A device would be better - you don't want a device running at is full rating for many consecutive hours.

Ok Risteard, thanks.
So you recommend a 40A DP RCBO at the distribution board. Thank you. Have you used the EV ultra cable at all?

 

[Risteard]

Ok Risteard, thanks.
So you recommend a 40A DP RCBO at the distribution board. Thank you. Have you used the EV ultra cable at all?

Yes I have. CEF in Letterkenny stock the SWA version of it. Manufacturer's data quotes a 20mm gland for 6mm^2 with Cat 5 though it is fairly tight. Have also used the ProInstall version from Eland cables - not the SWA version in this instance. It has Cat 6 data and the conductors are much more flexible (fine stranded) and will require ferrules on the ends. However although I've tried I haven't managed to get Eland to verify that it meets Dca, -s2, d2, a2 or higher standard under CPR although I suspect it does as it all seems to be LS0H. But without confirmation from the manufacturer I wouldn't use it within the State.

 

[Gavin John Hyde]

The zappi may and that is a cautious maybe use the 10mm to garage along with other circuits as load management can be set up with a secondary ct clamp set to monitor. Depending on installation method the ocpd for garage might be able to be uprated,

If you are running a new 6mm feed then fit a 40a mcb if install method allows but if using an rcbo make sure its double pole and suitable for ev. A lot of them dont like continuous loads. Do the cable calcs to determine size.
The zappi has built in type a rcd protection but they do recommend upfront as its questionable of the internal one is strictly compliant.
2options for the ct clamp - you can use ev ultra with built in cat5/6 or run seperate direct burial rated ethernet as its tougher.
The harvi will do this wirelessly but no acceptable if using to prevent main fuse being overloaded. Dnos stipulate it be hardwired.

 

[An Buachaillín Bán]

The zappi may and that is a cautious maybe use the 10mm to garage along with other circuits as load management can be set up with a secondary ct clamp set to monitor. Depending on installation method the ocpd for garage might be able to be uprated,

If you are running a new 6mm feed then fit a 40a mcb if install method allows but if using an rcbo make sure its double pole and suitable for ev. A lot of them dont like continuous loads. Do the cable calcs to determine size.
The zappi has built in type a rcd protection but they do recommend upfront as its questionable of the internal one is strictly compliant.
2options for the ct clamp - you can use ev ultra with built in cat5/6 or run seperate direct burial rated ethernet as its tougher.
The harvi will do this wirelessly but no acceptable if using to prevent main fuse being overloaded. Dnos stipulate it be hardwired.

Thanks Gavin. I'm going to hard wire for the CT clamp. I'm going to have to stick a clamp meter on cable feeding garage to see what load is being drawn with everything on. If I can, I will come off the garage supply. This way I can run a 6sq.
If not, it's coming off the main DB. Will the one CT clamp suffice at the garage supply cable for load management?

 

[Risteard]

Thanks Gavin. I'm going to hard wire for the CT clamp. I'm going to have to stick a clamp meter on cable feeding garage to see what load is being drawn with everything on. If I can, I will come off the garage supply. This way I can run a 6sq.
If not, it's coming off the main DB. Will the one CT clamp suffice at the garage supply cable for load management?

It will (set at 63A if standard supply) if you run from the main DB. If you run from the garage DB then you'll need two CTs (though some would run the tails one from a Harvi, but I personally wouldn't).

 

[An Buachaillín Bán]

It will (set at 63A if standard supply) if you run from the main DB. If you run from the garage DB then you'll need two CTs (though some would run the tails one from a Harvi, but I personally wouldn't).

OK, so I'd need a CT clamp on tails to house DB and a second CT clamp on tails to garage? It wouldn't be possible for me to run a Cat5/6 cable back to both boards. Only one. Also, I checked in regs, and it doesn't give a definite mounting height for the EV units. Is there a general height?

 

[Risteard]

OK, so I'd need a CT clamp on tails to house DB and a second CT clamp on tails to garage? It wouldn't be possible for me to run a Cat5/6 cable back to both boards. Only one. Also, I checked in regs, and it doesn't give a definite mounting height for the EV units. Is there a general height?

I would keep any socket-outlet below 1200mm but the screen/display (if there is one) a bit higher for readability. The Zappi comes with a mounting template with heights. Bear in mind that an EV chargepoint is classed as an appliance. Don't forget the rotary isolator.

 

[baldelectrician]

You may be easier to run a new 16mm / 25mm {depending on cable calcs} to the garage (you could use a EV ultra cable), then you will have a CT line in the CAT5/6 back to the main supply as well as a ethernet one)
You could change the consumer unit in the garage and provide a seperate RCD for the EV.

Here's a diagram I made for myself to combine the CT and ethernet in a single cat 5

If you only use 1,2,3 and 6 for the ethernet the speed drops to 100M but it gives the other 4 cores to CT use.

 

[An Buachaillín Bán]

You may be easier to run a new 16mm / 25mm {depending on cable calcs} to the garage (you could use a EV ultra cable), then you will have a CT line in the CAT5/6 back to the main supply as well as a ethernet one)
You could change the consumer unit in the garage and provide a seperate RCD for the EV.

Here's a diagram I made for myself to combine the CT and ethernet in a single cat 5

If you only use 1,2,3 and 6 for the ethernet the speed drops to 100M but it gives the other 4 cores to CT use.

View attachment 112479

Thanks very much. Very interesting what you did there to utilise the Cat5 cable. Unfortunately I don't think I be in a position to run a new cable out to the garage DB as it's a very long and difficult run(the older cable is buried underground with no way of pulling in a new supply as previous electrician didn't supply ducting.)

I haven't visited yet to see what load is being drawn on garage DB, but say for instance if it was ok to come off garage BD for supply to charger, and have CT clamp at incoming garage supply cable, do I have to have another CT clamp at the main DB in the house? If so, then why?

Thanks.

 

[baldelectrician]

Thanks very much. Very interesting what you did there to utilise the Cat5 cable. Unfortunately I don't think I be in a position to run a new cable out to the garage DB as it's a very long and difficult run(the older cable is buried underground with no way of pulling in a new supply as previous electrician didn't supply ducting.)

I haven't visited yet to see what load is being drawn on garage DB, but say for instance if it was ok to come off garage BD for supply to charger, and have CT clamp at incoming garage supply cable, do I have to have another CT clamp at the main DB in the house? If so, then why?

Thanks.

Yes, you require a CT (current transformer) at the supply end to prevent the service fuse overloading, other wise you may have to limit the charger to 16A or so.

 

[An Buachaillín Bán]

Yes, you require a CT (current transformer) at the supply end to prevent the service fuse overloading, other wise you may have to limit the charger to 16A or so.

I've ascertained that the service fuse is rated to 100A which would allow an ev charger to comfortably be installed. In this case I need not install a CT clamp at the main tails?

 

[Risteard]

I've ascertained that the service fuse is rated to 100A which would allow an ev charger to comfortably be installed. In this case I need not install a CT clamp at the main tails?

If it's an enhanced supply (16kVA) then there would be an 80A main overcurrent device. For 12kVA (standard supply) then there will be a 63A main overcurrent device. You shouldn't exceed this. The ESB's fuse rating is not relevant.

 

[baldelectrician]

I've ascertained that the service fuse is rated to 100A which would allow an ev charger to comfortably be installed. In this case I need not install a CT clamp at the main tails?

You need a CT clamp at main tails, it depends on the rules where you are - you used to be allowed wireliss ones (such as MyEnergi Harvi), these should be wired (for reliability)

If the charger is running at 32A and then a shower, cooker and heating is switched on then the current could go above 100A
The point of the CT is to allow the charger to drop power or stop if other stuff is pushing things to the limit of the service fuse