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Discussion Starter · #1 ·
I've got a lease EV (Zoe) on order, and in the process of sorting home charging. My house is set back from my parking spaces, I have measured and reckon its 30m from meter to probable point location. The company recommended by the lease co is saying in addition to the standard cost they're looking at £900 from me purely for the extra 10mm SWA cable and the additional time required. They suggested I contact a local electrical company to install the wire, and they can then come and wire it in at each end.

Do I need 10mm SWA cable - i've read a lot of posts suggesting 6mm is fine. Should I just get the local guy to do the whole job including supply an untethered box?
 

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I've got a lease EV (Zoe) on order, and in the process of sorting home charging. My house is set back from my parking spaces, I have measured and reckon its 30m from meter to probable point location. The company recommended by the lease co is saying in addition to the standard cost they're looking at £900 from me purely for the extra 10mm SWA cable and the additional time required. They suggested I contact a local electrical company to install the wire, and they can then come and wire it in at each end.

Do I need 10mm SWA cable - i've read a lot of posts suggesting 6mm is fine. Should I just get the local guy to do the whole job including supply an untethered box?
Probably best for your sanity to get a local sparky involved: he might subcontract some if the digging back to you of you are up for it 😀
 

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Discussion Starter · #3 ·
Probably best for your sanity to get a local sparky involved: he might subcontract some if the digging back to you of you are up for it 😀
It's all above ground, just around the edge of my very concrete courtyard 😕
 

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Discussion Starter · #7 ·
My furthest charge point is 34m from the supply, and still well within the 5% allowable voltage drop limit by a fair margin.
Is that using 6mm or 10mm cable? (There's me asking questions like I know something about this 😆)
 

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Is that using 6mm or 10mm cable? (There's me asking questions like I know something about this 😆)

6mm², which is OK up to about 45m for a non-lighting supply. The basic rule is that 5% voltage drop is allowable for non-lighting loads, 3% voltage drop is the maximum allowable for lighting loads. The reason for the difference is solely to do with light flicker, in that at 5% voltage drop older tungsten lamps would dim slightly as loads were turned on, then brighten as loads turned off, causing a slight nuisance. In reality, with LED lighting that has constant current drivers this isn't an issue at all, except, perhaps, on some types of dimmable LEDs.

As this isn't a lighting circuit, it's OK to go up to a 5% voltage drop. Over 30m, the voltage drop using 6mm² will only be 7.58 V at 32 A, so only 3.296%, well within the 5% allowable limit. @freddym 's point is valid, though, you do pay for the very small power loss in the cable, but it really is pretty small, and it's debatable whether you'd recover the additional cost of the bigger cable in any reasonable lifetime.
 

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8 X 32 is 250watts ish.

I'm too mean to leave a 250 watt spotlight burning all night whilst I charge my £100k Tesla so I'd put in the bigger cable😜
Given that the OBC, BMS and battery pack will be wasting more than double that anyway, perhaps more as the charge starts to taper, I'm not sure I'd lose any sleep over it, TBH. A Tesla wastes around 250 W or so whenever it's awake but not turned on, anyway, as it keeps it's main processor and sensors activated.
 

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The answer is probably to buy and run the cable yourself - no point paying sparky rates for manual labour. Run a cat5 while you're at it ( or use a combined power+data cable)
Definitely this if you're using a local electrician, as running and cleating the cable will take as much time as the rest of the job, in all probability. However, being cynical, I suspect that the big companies have a fixed price, so may not reduce the price because you've saved a bit of time in running the cable.

6mm² three core SWA is around £3 per metre, ideally try and get single phase 3 core, as it will have the right core colours (worth checking, as it's common to find 3 core has brown, black, grey cores for three phase delta).. EV Ultra cable is more than double the price, but includes a data cable for the CT clamp, if needed, so can be useful, but be aware that you may actually need to run Ethernet to the charge point, as at 30m outside the house you may find wireless connectivity for charge points that need it a bit iffy (I am doing battle with exactly this problem right now). At the moment, EV Ultra doesn't come with a full internal Ethernet option, which is a bit of a PITA if you need to get data to the charge point.

Rather than use the old school cleats, I tried out some neater ones recently, these Linian super clips, that are really great in brick/blockwork: https://uk.farnell.com/search?st=LINIAN

Really neat and tidy, and very quick to use.
 

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I've not measured, but I had a charge point installed which involved going round 2 sides of the lounge, along the side of the garden and under a gate. Over 20m at least, total cost including grant £1100 ish.
 

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Definitely this if you're using a local electrician, as running and cleating the cable will take as much time as the rest of the job, in all probability. However, being cynical, I suspect that the big companies have a fixed price, so may not reduce the price because you've saved a bit of time in running the cable.

6mm² three core SWA is around £3 per metre, ideally try and get single phase 3 core, as it will have the right core colours (worth checking, as it's common to find 3 core has brown, black, grey cores for three phase delta).. EV Ultra cable is more than double the price, but includes a data cable for the CT clamp, if needed, so can be useful, but be aware that you may actually need to run Ethernet to the charge point, as at 30m outside the house you may find wireless connectivity for charge points that need it a bit iffy (I am doing battle with exactly this problem right now). At the moment, EV Ultra doesn't come with a full internal Ethernet option, which is a bit of a PITA if you need to get data to the charge point.

Rather than use the old school cleats, I tried out some neater ones recently, these Linian super clips, that are really great in brick/blockwork: https://uk.farnell.com/search?st=LINIAN

Really neat and tidy, and very quick to use.
The Linian cleats come in fire rated varieties, useful for the indoor runs if you have them.
 

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The Linian cleats come in fire rated varieties, useful for the indoor runs if you have them.

Good point, especially as it seems to be taking some time for the change in the regs regarding prevention of premature collapse to percolate down. Not at all uncommon for find plastic clips/cleats still being used where they really should have a few metal ones around to help prevent collapse. TBH, it might makes sense it they just stopped selling plastic clips altogether, rather than have the half-assed situation we have now, where enough metal ones have to be used to keep cables in place, but plastic ones can still be used where there's no premature collapse risk.
 

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Definitely this if you're using a local electrician, as running and cleating the cable will take as much time as the rest of the job, in all probability. However, being cynical, I suspect that the big companies have a fixed price, so may not reduce the price because you've saved a bit of time in running the cable.

6mm² three core SWA is around £3 per metre, ideally try and get single phase 3 core, as it will have the right core colours (worth checking, as it's common to find 3 core has brown, black, grey cores for three phase delta).. EV Ultra cable is more than double the price, but includes a data cable for the CT clamp, if needed, so can be useful, but be aware that you may actually need to run Ethernet to the charge point, as at 30m outside the house you may find wireless connectivity for charge points that need it a bit iffy (I am doing battle with exactly this problem right now). At the moment, EV Ultra doesn't come with a full internal Ethernet option, which is a bit of a PITA if you need to get data to the charge point.

Rather than use the old school cleats, I tried out some neater ones recently, these Linian super clips, that are really great in brick/blockwork: https://uk.farnell.com/search?st=LINIAN

Really neat and tidy, and very quick to use.

You can get EV ultra in two variations,
Data which is just a twisted pair or full on cat 5.
 

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Regarding cable size / length and voltage drop ... there are some on-line calculators, for example the TLC website (if you're not an electrician/not sure what you're doing, just use it as a guide) - you'll probably find that for 8kw over a 30-40m cable distance, 10mm is a little over the top, but on the "safe-side" better to be over-the-top. Regarding a Cat5e cable, far cheaper to run it separately in a copex/conduit alongside, but keep separation to prevent interference. My spark suggested I got my SWA from Superlecdirect (I did - no complaints).

As others have said - you can probably save a significant amount by doing the cable run yourself (I did), but only after checking with the electrician who's going to do the final connection/certification, that your using the correct cable, and they are happy with the route.
 

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FYI: 40m of 6mm 3 core swa is £129 delivered. 40m of 10mm swa is £225 delivered. These prices are from electriccable.co.uk who I've used before and seem well priced and competent. I'd definately over specify the cable a bit incase you want to add lights etc later.
 
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