Provisions for a future EV home charge point?
Discussion
Not sure if this should be here or in the homes/DIY section, so if mods wish to move, please feel free.
This spring I’m doing some work on the house which will mean it will be quite convenient to install a cable between the consumer unit and the outside wall of the garage where I would probably want an EV charge point.
I don’t have an EV at the moment, but the reality is, that like it or not, in the next ten years or so we will probably have at least one in the household. So, it seems to make sense to put the provision for a charger in now in now, to save hacking floors/ceilings about at a later date.
I have no intention of connecting the cable up to the consumer unit at this stage and would either leave the other end (inside the garage) unconnected, or maybe terminated in an appropriately rated isolator.
I’m unsure what cable to use, the run is about 10m long so 6mm2 should be fine for a 7kw charger which seems the norm for most household use at the moment. But I’m toying with using 10mm2 in case chargers are a bit “beefier” by the time I get one.
Does this seem sensible, or a bit of an overkill? As the 10mm2 cable is quite a bit more expensive than the 6mm2
This spring I’m doing some work on the house which will mean it will be quite convenient to install a cable between the consumer unit and the outside wall of the garage where I would probably want an EV charge point.
I don’t have an EV at the moment, but the reality is, that like it or not, in the next ten years or so we will probably have at least one in the household. So, it seems to make sense to put the provision for a charger in now in now, to save hacking floors/ceilings about at a later date.
I have no intention of connecting the cable up to the consumer unit at this stage and would either leave the other end (inside the garage) unconnected, or maybe terminated in an appropriately rated isolator.
I’m unsure what cable to use, the run is about 10m long so 6mm2 should be fine for a 7kw charger which seems the norm for most household use at the moment. But I’m toying with using 10mm2 in case chargers are a bit “beefier” by the time I get one.
Does this seem sensible, or a bit of an overkill? As the 10mm2 cable is quite a bit more expensive than the 6mm2
You should be fine with 6mm. Some installers seem happy to use 4mm for up to 10m, though 6mm is better, so you are already going on the 'right' side of a spec for this, and which will have a degree of headroom built in.
A 7kW charger is actually pretty good - I can charge my Tesla 100D overnight on one - and given the main use of a home charger is overnight it is probably all you need. Some people have gone for three phase, which is a good way of getting an even faster charge into the car, but unless you already have that at home (and most do not) then it is probably not an option.
A 7kW charger is actually pretty good - I can charge my Tesla 100D overnight on one - and given the main use of a home charger is overnight it is probably all you need. Some people have gone for three phase, which is a good way of getting an even faster charge into the car, but unless you already have that at home (and most do not) then it is probably not an option.
Edited by Biggles111 on Tuesday 4th February 12:57
Cotswold Jim said:
I’m unsure what cable to use, the run is about 10m long so 6mm2 should be fine for a 7kw charger which seems the norm for most household use at the moment. But I’m toying with using 10mm2 in case chargers are a bit “beefier” by the time I get one.
They won't get more powerful because they are limited by the available power in your home. You have 100 amps for your home and 32 is the most you can use for a charger without impacting other electrical uses in your home. 6mm will be fine.FWIW, I used 10mm2 when I had my charger put in. Mostly because other than a small increase in overall cost, there wasn't a single downside in my situation. The run was over 10m and in places could have arguably been iffy for cooling, hence wanting to go safe. I also had need for some 10mm2 elsewhere.
6mm PVC T&E is rated at 34A in worst-case installation situations (Ref Method A), which was a wee bit tight for my liking. I do admit to paranoia though!
10mm2 gets you some decent headroom, which means lower operating temperatures and less voltage drop.
6mm PVC T&E is rated at 34A in worst-case installation situations (Ref Method A), which was a wee bit tight for my liking. I do admit to paranoia though!
10mm2 gets you some decent headroom, which means lower operating temperatures and less voltage drop.
From Wickes 16.5m of 6mm is £35.67 & 10mm is £49.50. For the sake of £13.83 I'd consider running 10mm in.
https://www.wickes.co.uk/Products/Electrical+Light...
https://www.wickes.co.uk/Products/Electrical+Light...
Some questionable advice on here...
First, you need to define how the cable will be run... embedded in the wall, trunking, insulation etc. Cable ratings vary depending on how it is installed.
A 7kW charger pulls just shy of 30A.
Also, you may need a separate earth.
Just going through this myself, ours will just have a 50mm duct under the drive and an earth rod. Two core (no earth) armoured will then go through that duct at a later date. Regulations may change by the time we need to actually commision it.
First, you need to define how the cable will be run... embedded in the wall, trunking, insulation etc. Cable ratings vary depending on how it is installed.
A 7kW charger pulls just shy of 30A.
Also, you may need a separate earth.
Just going through this myself, ours will just have a 50mm duct under the drive and an earth rod. Two core (no earth) armoured will then go through that duct at a later date. Regulations may change by the time we need to actually commision it.
I've had 2 installers give differing opinions on my 6mm run to the garage, so to be safe, I'd go 10mm.
The one who said it wasn't suitable seemed to focus on a situation where everything in the garage was running at the same time, even though all I've got in there is a small power tool charger & some led tube lights!
The one who said it wasn't suitable seemed to focus on a situation where everything in the garage was running at the same time, even though all I've got in there is a small power tool charger & some led tube lights!
Thanks all.
The garage in question is a integral garage, so part of the house, not an underground cable.
CU is in utility room at back of house, cable run will be through uninsulated ceiling void (between ground and first floors) above hallway, downstairs loo, and through into garage where it will probaly go inside some conduit/trunking down the wall the an indoor isolator. This is where it will finish for now, with a view to go from the isolator through the wall to the charge point on the outside when required.
The garage in question is a integral garage, so part of the house, not an underground cable.
CU is in utility room at back of house, cable run will be through uninsulated ceiling void (between ground and first floors) above hallway, downstairs loo, and through into garage where it will probaly go inside some conduit/trunking down the wall the an indoor isolator. This is where it will finish for now, with a view to go from the isolator through the wall to the charge point on the outside when required.
Cotswold Jim said:
Thanks all.
The garage in question is a integral garage, so part of the house, not an underground cable.
CU is in utility room at back of house, cable run will be through uninsulated ceiling void (between ground and first floors) above hallway, downstairs loo, and through into garage where it will probaly go inside some conduit/trunking down the wall the an indoor isolator. This is where it will finish for now, with a view to go from the isolator through the wall to the charge point on the outside when required.
Sample manufacturer's table of ratings for Twin and Earth. https://www.whyprysmian.co.uk/6241Y-_6242Y-_6243Y....The garage in question is a integral garage, so part of the house, not an underground cable.
CU is in utility room at back of house, cable run will be through uninsulated ceiling void (between ground and first floors) above hallway, downstairs loo, and through into garage where it will probaly go inside some conduit/trunking down the wall the an indoor isolator. This is where it will finish for now, with a view to go from the isolator through the wall to the charge point on the outside when required.
It would appear that in theory, 6mm cable will supply 32A when in conduit.
As mentioned by another poster, that is theroretically okay, but a bit too close for my likeing, particularly when that current will be drawn for a reasonably long time (some hours). 10 sq mm would be what I would go for.
For completeness, another poster thought 4 sq mm would be okay... possibly, but only if the cable is not in conduit, surface mounted.
Also, if the vehicle can be charged outside, the I believe the present regs require separate earthing and not PME.
Disclaimer: I am not a 'certified' electrician.
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