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EV Charger Design Advice

NE-ELEC-12

Hi All,

We are currently liaising with a Client regarding a project where they have not been with the D&B contractor in terms of quality of the installation, and ultimately the electrical design. The Client is asking for us via a new D&B Contractor to review the design and current installation to see what can / cannot be utilised going forward.

 One of the items of concern that stands out immediately is the original design is the use of a 5 core SWA cable to supply 2 No. EV charging points. With both charging points being single phase on separate ways within the distribution board. Way L1 using cores 1+2, with way L2 using cores 3+4 we have not yet opened up the EV Charge points to see if core 5 is spare with the SWA being a common CPC, or whether core 5 is used as common CPC. 

We have concerns regarding the use of a cable with multiple single phase circuits within it, and the use of a common CPC for both circuits, is this allowable with in the regulations?

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    As has been said, nothing wrong with two single phase circuits in the same 5 core cable. Also nothing wrong with these two circuits sharing a common earth.

    However in my view, the cable should be de-rated to about 85% of the published rating. I presume that the published rating assumes a 3 phase, 4 wire circuit in which only 3 cores are fully loaded. Use for two single phase circuits will result in FOUR cores being fully loaded which will produce more heat than three fully loaded cores. In many cases the cable size will be the same, but the next size up may be needed if the thee phase rating was already only just sufficient.

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  • 0

    As has been said, nothing wrong with two single phase circuits in the same 5 core cable. Also nothing wrong with these two circuits sharing a common earth.

    However in my view, the cable should be de-rated to about 85% of the published rating. I presume that the published rating assumes a 3 phase, 4 wire circuit in which only 3 cores are fully loaded. Use for two single phase circuits will result in FOUR cores being fully loaded which will produce more heat than three fully loaded cores. In many cases the cable size will be the same, but the next size up may be needed if the thee phase rating was already only just sufficient.

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