Discuss 3 phase EV headache!! in the Commercial Electrical Advice area at ElectriciansForums.net

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t01474

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Evening everybody.

It’s been a while since I’ve asked for the collective brains advice but this one has really got me stumped.

I’ve been asked to install a twin outlet 22kW EV charger at an office. Unfortunately the office is an old doctors surgery (3 storey ex-house, basement , pitched roof , loft , etc).

The supply is in the basement and the proposed site for the charger is on the driveway, 100m cable length away!

The only options I can see via the cable calcs are to install a 25mm sub main to a db which then via MCB , RCD turns into two 16mm SWA’s for the charger or 2 16mm SWA’s from the intake to the charger (with the db , MCB , RCD’s at the intake position).

I’d love to just put two 230v chargers in but don’t think I can due to further unbalancing an already unbalanced system.

Has anybody got any bright ideas?

There is a supply (single phase) already at the garage (32a) and if it wasn’t for the 400v main system I’d gladly come off of that and use load limiting via CT’s.

I can’t think of another job that I’ve done where having 3 phases has worked out to be less helpful than single phase!
 
What have the DNO said? I had an install for a 22kw and given the current loadings and unbalanced install they wanted it to be altered to be balanced out better or customer could have a 7kw unit only.
We rejigged all the circuits to make it more balanced but even then the dno were telling us it had to have a ct for all 3 phases or we couldnt fit the charger.
they want 22kw chargers but could you not get them to go for 2 x 7kw as then you get much greater flexibility in terms of load management and sharing. maybe even 2 x 11kw.... there are only a handful of cars which can use the 22kw anyway.... 11kw is getting more common though.
 
Going with a 7kW unit now. Pleased really as it would have a pig of a cable pull and almost certainly have caused damages to the building along the way. Interesting response that you got from the DNO. The EV rollout must be causing them some (well overdue) headaches
 
Going with a 7kW unit now. Pleased really as it would have a pig of a cable pull and almost certainly have caused damages to the building along the way. Interesting response that you got from the DNO. The EV rollout must be causing them some (well overdue) headaches
Its largely in part due to ev charging , heat pumps and renewables that WPD are putting all new supplies in as 3 phase to reduce the loads on network as it allows them to design the network better. I have had a cut out change for a customer recently and the joiners when unlooping him changed which phase he was on as others on the street already had 3 phase, they brought a 3 phase cable to the house and cutout but only use 1 fuse/phase.
The DNO have a love hate relationship with me, I let them know if cut-outs are in need of replacement, what is needed for charger etc with plenty of detail but they also hate that i give them lots of work to do and their sub contractors end up digging the roads up for ev chargers because of me.
 

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