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Discussion Starter #1
Hi - new here, sorry if discussion topic already exists!

Looking to installing some EV charging equipment for a business but want to make sure that I’m not getting ripped off by contractors bidding to do the work. When it comes to the cabling connecting to the building’s power, are there recommended cables to be used depending on the max power output of the charger? Also if I were to use a 22kW capable charger, but with the intention of only making available 7.4kW, could I use 7.4kW ‘suitable’ cabling at the back end?

Cheers!
 

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22kW is three phase (3*7kW) so each core needs to be able to sustain 7kW (or 32 Amps).

To use a 22kW unit at 7kW just use a single phase cable from the unit to the car. Most current EV's are single phase anyway and will charge at 7kW on a 22kW unit. Those like the Ampera and Leafs with 3.3kW chargers will take less. 3phase capable cars may be 11kW or 22kW think ZOE for example

Cable sizes 6mm² to 10mm², the larger will be needed in enclosed cable runs.
 

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If it's going to be bid, get a competent person to draw up a technical specification of what all the bidders have to install. Your competent person who may be an Electrician will determine the cable type and size and check out a lot of other stuff as well. Probably best to get the competent person to directly correspond with the DNO as well.
 

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Discussion Starter #4
Thanks for the advice. Will definitely get a tech spec written up ahead of time. I guess my thoughts are that if the charger will only ever be used at 7.4kW, is there any need for the three-phase electrical cabling connecting the charger to the power source? There’s a reason I’m looking at a 22KW rated charging unit instead of just a 7.4kW as it’s to do with some strange regulations here.
 

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is there any need for the three-phase electrical cabling
Bear in mind that as it's only an extra core or two for 3-phase vs single-phase, and it's likely to be an armoured cable, the cost difference is likely to be not that big. Once you get into the total project cost with the labour then that difference is minimal, especially if you are having to trench or do other less straightforward installation work.
As such, for proofing against any future upgrade, it may be better to install cabling for 3-phase with a decent headroom of current capacity, even if the equipment used at this time is single-phase, 7kW.
 

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Discussion Starter #7
Whereabouts are you located?

Which regs?
Over in Singapore. Basically if the installation is rated below a certain amount you have to be assessed by an organisation here who are already involved in EV Charging, can create a bit of conflict of interest. Hence thinking of using 22kW chargers even if they will only be used as 7.4kW to get around this.
 

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Discussion Starter #8
Bear in mind that as it's only an extra core or two for 3-phase vs single-phase, and it's likely to be an armoured cable, the cost difference is likely to be not that big. Once you get into the total project cost with the labour then that difference is minimal, especially if you are having to trench or do other less straightforward installation work.
As such, for proofing against any future upgrade, it may be better to install cabling for 3-phase with a decent headroom of current capacity, even if the equipment used at this time is single-phase, 7kW.
Thanks mikegs. I’ve looked into this further and you are correct that the costs will be not be too much higher with the 3-phase cable.

Thanks to everyone who helped here, it‘s allowed me to move forward with what I want to do in this instance! :)
 

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If you are in Singapore, you are outwith the expertise of vast majority of anyone on this forum: if going 3 phase is possible, that seems like a valid approach to a regulatory issue.
 
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