EV cable to charger - DIY

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Discussion

James6112

Original Poster:

5,429 posts

35 months

Wednesday 10th July
quotequote all
Hi

I have a 32 amp cable (ex hottub) fairly close to where EV charger will be sited. Say add 5m to existing 10m.

Will that be suitable to hook up, extend, to EV charger?

Or better to run a new cable in?
It’s a pita to run, board under stairs in middle of the house.

If I need to run a new cable, I could run it in DIY, what’s the best cable to use?

No ideas for a name

2,408 posts

93 months

Thursday 11th July
quotequote all
James6112 said:
Hi

I have a 32 amp cable (ex hottub) fairly close to where EV charger will be sited. Say add 5m to existing 10m.

Will that be suitable to hook up, extend, to EV charger?

Or better to run a new cable in?
It’s a pita to run, board under stairs in middle of the house.

If I need to run a new cable, I could run it in DIY, what’s the best cable to use?
Depends, but the fact you have to ask the question is a bit of a bad start.
The EVSE will draw 32A peak, so generally its feed is a little beefier - usually on a 40A breaker. That then needs a cable that can take that 40A, plus there is a volt drop calculation for the length.
You almost certainly want to have a data cable too. Can be separate, or maybe use a combined cable.

Also it depends on your electrician - some might not want to use a cable they haven't put in themselves.
Depends on your layout but most of the work is groundworks and cable routing - if your electrician specifies the cable, he might let you do the digging.
Always best to put a duct in, as that then make furure changes/upgrades easier.


SpidersWeb

4,065 posts

180 months

Thursday 11th July
quotequote all
James6112 said:
Hi

I have a 32 amp cable (ex hottub) fairly close to where EV charger will be sited. Say add 5m to existing 10m.

Will that be suitable to hook up, extend, to EV charger?

Or better to run a new cable in?
It’s a pita to run, board under stairs in middle of the house.

If I need to run a new cable, I could run it in DIY, what’s the best cable to use?
Is the electricity meter in the middle of the house under the stairs?

If not and it is outside, then most sensible installers these days simply split the feed at the meter, add a mini-consumer unit just for the EV charger, and then run the cable from there to the charger.

andy43

10,608 posts

261 months

Thursday 11th July
quotequote all
Depends if it’s 6mm or 10mm - I used 10mm for a commando socket for a Tesla.
Google tlc cable size calculator and have a play on that. I’d guess 6mm over a longish run might be marginal.

James6112

Original Poster:

5,429 posts

35 months

Thursday 11th July
quotequote all
SpidersWeb said:
Is the electricity meter in the middle of the house under the stairs?

If not and it is outside, then most sensible installers these days simply split the feed at the meter, add a mini-consumer unit just for the EV charger, and then run the cable from there to the charger.
Unfortunately no access to outside wall from the meter location..

I’ll get electrician to check if he can use the dedicated 32A cable that used to feed a hottub, he installed it say 10 years ago & I have the paperwork for that somewhere.

Otherwise i’ll run in cable from under stairs to charger location. Involves lifting the floor upstairs etc, a pain!

No digging required, just from the cupboard to the outside wall, opposite end on the living room..

ashenfie

846 posts

53 months

Thursday 18th July
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Hi, Not sure where you are located. I am in the UK and regulations have changed quite a bit in the last 10 years. Simply getting one of the energy company installation deals, would like cost around the 1/3 more than you can get the parts.

TheDeuce

25,227 posts

73 months

Thursday 18th July
quotequote all
Why not just put a 32a commando socket on the old hot tub circuit, and then plug in one of these: https://thirdrockenergy.co.uk/products/type-2-to-c...

Not a lot of money, and if the cable does feel overly warm you can step back the charge speed on the on cable charger brick to 28a, 25a, whatever.

The feed they installed for the hot tub should be man enough for the job, hot tubs have powerful heaters that draw continuous current when raising the temperature or in use, just like an EV load.

I would however perform a physical inspection of the circuit at the very least - terminal screws and clamps tend to loosen after a period of years, especially outdoors - although really it's best to get the installer back to test it thoroughly.