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EV charger installation question – I don't want to bury the cable

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Renewable-powered transport (EVs & e-bikes)

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Hem

(@hem)

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Topic starter 19/04/2024 11:19 am

I'm planning to install EV charger to front of garage.

Main supply is at the other corner of the house and garage is built on the other corner, after the garden.

I'd like to have an EV charger connected back to existing house supply, but not have to bury the cable.

Please help me with your expertise.

This topic was modified 2 years ago by Mars

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Transparent

(@transparent)

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19/04/2024 11:37 am

Hello @hem. And I see that @editor has very quickly found a suitable spot for this topic! 🙂

An outside cable like this would normally be Steel Wire Armoured (SWA).
For a standard domestic EV charger, it would need to be able to deliver 32A (assuming a charger rated at 7.5kW).

There will be voltage drop along the cable route. The distance matters.
But you can quickly assess the required cable size by using an online cable cable calculator, such as this one from TLC.

There is no requirement for an SWA cable to be buried underground.

You could run it above ground, clipped at low level to a wall or a fence, for example.
The important issue is that it must be protected from mechanical damage.

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Hem

(@hem)

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Topic starter 20/04/2024 3:05 pm

Thank you Transparent.

in on of the forum you had suggest SWA - 4 CORE ( Can't remember where). is that you suggest for EV charger installation.

I have no knowledge of electrics , please ignore my stupidity.

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Transparent

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20/04/2024 3:44 pm

I can't remember where either 😖

Can I check if you are intending to use a recognised EV Charger installer in order to take advantage of a grant?
Or are you simply buying a charger and getting a local electrician to fit it?

It's possible that the grant-aided schemes only work if they supply the cable.
That needs checking first.
However, the approved installer might still offer a discount if you were offering to run such a long cable yourself!

If the choice of cable is entirely up to you, then I'd usually expect it to be a 3-core SWA type.
That means both the armoured sheath and one of the cores is earth.

If it was simply a run to provide power in the garage, then an electrician might've been happy with 2-core cable.
But earthing on EV chargers is a 'hot topic' and I'd be surprised if an installer would be prepared to use an earth connection which operates only through the steel armour. It's not a great conductor if a fault should occur.

Having said all that, some EV charger installations require a local earth rod, rather than depending on a connection back to the house.

To assess that, can you say whether your house currently has its own earth rod?
Or is the earth provided by the Electricity Distribution company?

A photo of your 100A service fuse and meter would be helpful.

This post was modified 2 years ago by Transparent

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IanMK13

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20/04/2024 4:18 pm

@hem

Depending on the charger you install, an option may be to use an SWA cable with an integral cat5 cable. This may be used either for an internet connection if it is a 'Smart' device, to avoid using WiFi, or to connect remote current transformers to facilitate load management features in the charger (so as not to draw too much power from your home supply. Your electrician should be able to advise.

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Transparent

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21/04/2024 8:59 am

@hem that's a good observation from @ianmk13

Here's a link to that SWA with integral CAT5e data cable, also from TLC Direct.
Note that they sell it per metre, which is very helpful.

If you zoom back out to the wider selection of products sold by TLC for use with EV chargers, you'll notice that the combined power and data cable is only available with 3-cores. That's a pretty strong indication of what the market is using!