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Hello all,

I'm after some advice from those with knowledge on EV Charger installs.

Both my girlfriend and I believe we'll have an EV in the next couple of years

We're about to start a house and garage refurb, including new consumer unit etc in house, and power for garage (via armoured cable to be buried in garden that sits between house & garage).

So, the tech bit...

1. From what I see, newer chargers are around 32A. Should I be considering a supply in the garage that has 64A available for charging, for 2 vehicles, or is that excessive? I have (for some unknown reason) a 3-phase supply in the house, with only one phase running the house, so I could dedicate a whole 100A to the garage consumer unit, although 100A armoured cable is expensive!

2. I'm thinking that the EV charger would sit in the garage. No reason why not, right? (I've only ever seen them outdoors)

3. Other than spec'ing a fat (poss 100A) 3 core armored cable to the garage consumer unit, is there anything else worth considering while I'm pulling my house, garden, garage to pieces? I don't actually want to install the EV chargers now, as the budget is already blown, and they may sit unused for 3 years.

4. Earth-rod..... leave it for the EV charger installer when we get to that bit?


Cheers

James.
 

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I would manage your 3-phase that you have suitable power across 3 phases for 2 EV chargers (32A each), a Heat Pump, an immersion heater, a battery storage system and all Electric kitchen appliances. Maybe a resistive heater in living room too.
 

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personally, my option would be to future proof it, a 16mm 2 core to the garage (you cant export PME) then tie in the steel rebar to an earth rod with a 16mm earth cable to sort out your earthing at the garage board..
gary
 

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As I understood it the earth rod is for installs which are external i.e if your appliance is inside the garage an earth rod would not be necessary.

Also, the 32A chargers are on a single phase i.e. is possible to run a 3 phase 22kW charger as well, so depending on you EV choices, e.g. Zoe or Tesla you could be charging at 32a single phase 7kW or you could be charging at 3 times that rate car allowing. difference might mean having the car plugged in for less than 2 hours or 6.

There are quite a few cars that will charge at 11kW on 3 phase, so choices from a convenience perspective, do you have two lower rated chargers or a single higher rated one.
 

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As I understood it the earth rod is for installs which are external i.e if your appliance is inside the garage an earth rod would not be necessary.
From what I've seen the earth rod rule is for external chargers or chargers that could reasonably be expected to charge a vehicle standing outside.
I'm planning an 'in the garage' installation, but it will be right by the door and I'd expect to occasionally charge the car while it's outside, so I'll need the rod. If the charger is at the far end of the garage (from the car door) I guess you could say it's unlikely to be used for an outdoor vehicle. (Seems a bit grey; they could do with specifying a distance perhaps.)
 

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With a 3 phase supply, for the sake of future proofing I would definitely run 3 phase to the garage. The bigger the better cable wise, including a nice fat neutral in case you have unbalanced single phase loads. You can always sort out phase balancing as future house loads are added.
 

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In the past, garages have been fed power from a breaker in the house CU as loads have been low. I suggest you get the supply split before the house CU and 3x64A routed to garage.

Due to length and being outside, you will probably need protection just after the split, maybe a 3 phase RCBO? There are people more qualified on here who can hopefully advise?
 

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One detail you need to consider is what technology will specify in 2 years.
not long ago 50Kw charger was immense and now you will hear of home chargers for 12 and 22Kw.
Better to have spare power than thinking that for a few 100's you would have fitted the right supply.
All new type 2 chargers (in new cars) will require 3 phase power supply 100A supply will give you 22Kw MAX.
think that you may want to put the kettle on while your missus is in the shower (electric one 10 to 15Kw) and maybe you will have the heat exchange pump running (3 to 5KW).
You will have to calculate what will be the max power you will need if you have everything running and add 15% as safety.
 

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22kW has been here since 2014 or so with the Model S with Dual chargers on board, so it isn’t a future aspiration they have been here for years already.

The OP is in the unusual and fortunate position of having 3 phase to a domestic property which is great for them, even with a 75kWh car they could be charging from 10% to 90% in a few hours and not overnight because of it.

22kW is 3 phase at 32A so still leaves a lot of headroom for the kettle! About 208A by my reckoning.
 

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unless the garage is internal (part of the dewelling) it is an outbuilding.. PME cant be exported to an outbuilding.. it WILL require a TT method of earthing (earth rod)..
gary
 

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unless the garage is internal (part of the dewelling) it is an outbuilding.. PME cant be exported to an outbuilding.. it WILL require a TT method of earthing (earth rod)..
gary
This charger installation has made me wonder about my existing garage supply (the garage is detached).
When the charger is installed are the electricians going to have to convert that existing supply to TT as well?
 

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As i see it, yes, this has allways been the case.. but is it safer? dunno.. we are still arguing the point. there is a big worry that if for any reason the neutral was to come loose at the suppliers end, as the earth & neutral are combined, everthing could become live.. your tyres would insulate the fault from the ground.. and the first indication would be the burning smell from your hands as you simultaneously touched the door handle and your metal, well grounded, garage door.. some charger manufactures state they have internal monitors built in that will prevent this, if so i dont see a problem especially if the charger body is plastic.. but the more qualified amongst us dont seem to trust this yet so only time will tell..
gary
 

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As others have mentioned, this needs professional advice. One thing you (or the professional) needs to find out is how much power you can take from the cables feeding your home's supply from the street. Mine's si gle phase & only 10kw, so I could never charge my EV at double-digit kilowatts.
 

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One very simple and cheap thing you could do, if you are not sure what your final requirements will be, is to install a duct between house and garage (and anywhere else you might want power in the future).

It should start as close as possible to the main supply cabinet or board and terminate inside the garage where you intend to install a sub board.

You could run a basic 32 amp supply for lights and sockets to start with and pull through a heavier supply cable later if you need it.

Make sure the run is pretty straight or has only very gentle curves, and run three or four strong cords right through ready to pull any cabling through in due course.

If the duct has to go round a sharp corner, put an inspection pit with lid on the turn, much as you would for an underground drain.

You can buy reinforced plastic ducting designed for this purpose. This saves a lot of future pain especially if you are laying paving or brick on your driveway!
 

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NatureTech, just out of interest which country are you based in. In the UK it would be very unusual to be restricted to 10kW. That's equivalent to just 40A on a single phase supply. A much more ubiquitious UK minimum would be 63A.
 

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@James00 Like you, I have a 3-phase supply (primarily for off-peak heating), and many years ago I had a 10mm2 4-core armoured cable installed between our house and our garage, with the intention of having both peak and off-peak supplies available in the garage. The 'off-peak' pair of conductors were never used until I had a 32A charging point installed, when they were connected to a spare way on our primary (3-phase) consumer unit.

I would suggest that a 4-core 10mm2 SWA cable from your house to your garage should be sufficient for your likely needs - it can be configured either as two separate 32A single-phase circuits, or as a 32A 3-phase circuit.

How often do you expect both yourself and your GF to require a significant top-up charge when you get home from work before you both (separately) go out in the evening? This is likely to be the most testing use, as overnight charging has the time to be more gentle.
 
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