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Discussion Starter · #1 ·
On the verge of purchasing a Zoe (22kWh), have ready access to 3 phase at home (a farm), planning on building an EVSE anyway, the 3phase kits are only slightly more expensive (like 15 quid), is there any reason not to just build and fit a 22kW chargepoint?

Yes, i won't need the speed often, but i'm thinking, what if i drove 20 miles to pick up my daughter, take her 15 miles further on to the beach for the day, drop her back and get home myself, then still want to go out that evening, 22kW could be very handy on a day like that. I know i can charge away from home, but on a precious day with her i don't want to be hunting chargers, sitting at them for too long, etc...
 

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If you have 3 phase anyway, then it makes sense. I doubt you'll see a huge benefit unless that scenario comes up often, but it future-proofs your installation should you get a car with a larger battery (as long as your next car can take a 3 phase charge).

You might also find the Zoe charges more efficiently at 22kW than 7, so you'll make the £15 back anyway
 

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The only thing to be aware of is some cars can’t limit their charge speed. Like the Zoe.

So if for some reason you don’t want to charge at 22 kW, then you’ll need a charger that can limit the power.
 

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You may need a ground rod fitting, as not all the PEN-loss devices work on 3-phase setups. Consult the experts here/ your sparky! Viridian (ecoharmony website) are a UK company who do good quality EVSEs, also 3-phase ones, so I'd be looking at theirs. It's also easily repaired if any item fails, you're not tied to one mfr with an expensive custom PCB who have you in their hands! Their custom controller module is the only such item, it's very reasonable priced & is often used to update other failed EVSEs. I used their parts to upgrade my Rolec by myself to latest standards and am very pleased with the result.
 

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Discussion Starter · #8 ·
You may need a ground rod fitting, as not all the PEN-loss devices work on 3-phase setups. Consult the experts here/ your sparky! Viridian (ecoharmony website) are a UK company who do good quality EVSEs, also 3-phase ones, so I'd be looking at theirs. It's also easily repaired if any item fails, you're not tied to one mfr with an expensive custom PCB who have you in their hands! Their custom controller module is the only such item, it's very reasonable priced & is often used to update other failed EVSEs. I used their parts to upgrade my Rolec by myself to latest standards and am very pleased with the result.
Yes I was looking at veridian.
I'll investigate the earthing situation
 

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Ultimately TT earthing is more reliable,bless to go wrong. On a farm you would be crazy not to go TT unless you are on solid rock, in which case it wouldn't be a farm I guess.

Our farm was TT, so was my uncles. Not worked on any around here, but I suspect almost all are TT. One issue is that they can struggle to get Ze low enough to be TN-C-S, or even TN-S, because it's pretty common to have long LV runs out to farms.
 

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There's a 3 phase charger I've seen featured on Efixx YouTube channel that could be worth looking at as if you wanted to install more units it makes it much easier as well.

May be worth looking at a tariff like Octopus Go as well as in that 3-5hr window on 3phase you could pull down a lot of power. More so if you start electrifying other machinery too and storing that energy, say hot water tank or such.
 

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Discussion Starter · #12 ·
There's a 3 phase charger I've seen featured on Efixx YouTube channel that could be worth looking at as if you wanted to install more units it makes it much easier as well.

May be worth looking at a tariff like Octopus Go as well as in that 3-5hr window on 3phase you could pull down a lot of power. More so if you start electrifying other machinery too and storing that energy, say hot water tank or such.
I'm restricted on changing tariff because I am an tenant on my parents farm without my own supply. Parents have a soul ev which they only ever granny charge at the top of the farm I'm at the bottom of the farm next to a workshop with a 3P DB.
 

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Our farm was TT, so was my uncles. Not worked on any around here, but I suspect almost all are TT. One issue is that they can struggle to get Ze low enough to be TN-C-S, or even TN-S, because it's pretty common to have long LV runs out to farms.
With long overhead lines, voltage dips can be a problem. Depending on transformer arrangement, voltages can also go high. So definitely best to go TT.
 

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With long overhead lines, voltage dips can be a problem. Depending on transformer arrangement, voltages can also go high. So definitely best to go TT.

Biggest problem is usually Ze, though. Some of the rural properties around here are TT simply because Ze is too high for them to be TN-C-S/PME. Not hard to get Ze way over the maximum allowable value of 0.35 ohms for a PME installation on any sort of long cable run. Might be able to get down to the max Ze for TN-S of 0.8 ohms, but even that can be a challenge for somewhere like a farm at the end of a long LV run. The bigger farms around here all tend to have their own PMTs, to get around the problems caused by running LV long distances. Creates issues from time to time, as at least one farm I know of locally owns its own PMT, no idea how that came about. My guess is that the farmer did a deal with the old electricity board to run 11 kV to the farm, and bought his own PMT because he could get it cheaper than they would supply one for.
 
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