First install of EV charger

[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