High power supply to domestic garage

Hi all,

Can anyone tell me the feasibility of providing a high power supply to a domestic garage for electric vehicle charging.

First choice is a simple single phase 45A supply similar to a shower circuit via an rcd.

Second not so easy, would be a single phase 80A supply, I’m assuming the supply to an average house would be 100A so someone taking a shower at the same time would pop the main fuse, as would the lady of the house cooking the Christmas dinner.

Third choice would be 3 phase 32A supply, simple to do but what is the legality of using 3 phase in a domestic premises? I would presume that the garage would need a dedicated supply from the street and be prohibitively expensive.

Can’t find any reference in the 16th ed regs, so thought I would run it past you boys out there in the real world.

Do you REALLY need 80A? What is being charged for xxxx sake?
Is 80A what the spec says?

If so you cant hook into the existing supply. You would need either:

1. The supply to the house to be changed to 3 phase and then you can use one phase for the existing house and one of the other phases for the garage.
You'd need to facilitate the run from the incomer to the garage in very meaty cable - split concentric probably

2. Have the DNO provide a new, separate, single phase supply to the garage.

Both of the above have very large ££££ attached to them.

Thanks for the reply,

Just read the charger manual again, I would need 3 chargers running in parallel, each charger is rated at 24A input at full load (72A). Hence needing a 80A circuit as that is the nearest mcb size.

The chargers have an input voltage range of 170V to 265V so obviously the 24A input is at 170V, making a 230V input a mere 17.3A ( total 52A ) assuming rated full load output of 3.3kw, at efficiency 83%, giving an input power of 3.976kw divided by 230V supply.

I would therefore need a 63A supply and not an 80A as I first thought.

So I am guessing that a 63A supply fed from the cu, or a separate supply from the incomer would be perfectly practical.

The 3 phase unit would be 28A per phase, But I really don’t think having 3 phase installed is a viable option.

The preferred device is still under development but would run at aprox 44A so would just about run off a standard 45A circuit. Is there a standard current supply to new build domestic garages? The largest ‘conventional’ circuit mentioned in the 16th ed seems to be 45A.

The chargers have an input voltage range of 170V to 265V so obviously the 24A input is at 170V, making a 230V input a mere 17.3A

Click to expand...

That would be a reasonable assumption if those are switch mode chargers. Are they?

The voltage range seems about right for switching power supplies tbh, so my quid is on the table

They are indeed switch mode supplies, even so they are quite a size. The three phase unit is a monster!

I think the 63A supply to the garage would be the one to go for wouldn't you say?