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Discussion Starter · #1 ·
Hi all

get my first EV later this week ! Zoe 50 R135 rapid charge. Forgive the stupid question but I did search the forum and couldn’t find an answer.
Will my Zoe charge okay with a Project EV Pro earth charger ? I have read lots of comments about the Zoe being very intolerant of a poor earth.
My charger installer recommended the Pro Earth. Just hope it will work ! Anything I need to be aware of ?
Many thanks
 

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Discussion Starter · #5 ·
There will be no problem, as the CPC for this charge point connects directly to the incoming PE, as it has integral open PEN fault protection (that's what the "Pro Earth" bit stands for). The absolute highest value of Ze should never exceed 0.8 Ω for a TN-S supply, 0.35 Ω for a TN-C-S/PME supply. This means that Zs at the charge point is unlikely to be much above about 1 Ω. The Zoe charger measures Zs during it's initialisation stage, and will only refuse to charge if it exceeds 150 Ω, so way above the possible maximum from a charge point connected to either a TN-S or TN-C-S/PME supply.

The only problems with the Zoe are for installations where there is a local PE provided via an electrode, a TT installation. You won't have one of those, as if you did there is no point in fitting the Pro Earth version of this particular charge point. A TT installation can have a PE with an earth loop impedance that is higher than the 150 Ω that the Zoe will accept, as the regs allow Ra (the earth electrode resistance) to go up to 200 Ω *. This means that a few homes that have TT supplies, or charge points wired as TT to provide open PEN fault protection, can cause issues with the Zoe if they have a high, but acceptable, value of Ra. This is usually easy to fix, just means fitting a better earth electrode, and often the problem needs fixing anyway, to make the installation safer, especially with some older installations where things have degraded over the years.


* Technically, 200 Ω is not a hard limit, the regs allow Ra to be as high as 1667 Ω for a 30 mA RCD, but the guidance from the IET is that any measured value post-installation that's higher than 200 Ω isn't generally acceptable, to give a safe margin for Ra variation with ground conditions, etc,
thanks Jeremy for the very comprehensive reply. Good to know it will actually work ! Thanks
 

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Discussion Starter · #17 ·
Hi, seems you have some comfort from the various replies.

Given that the datasheet has a dearth of information regarding the standards that apply to some safety critical aspects, eg the RCD functionality and the issue as to whether the CE ( CHINESE EXPORT ?) actually means anything at all with regard to this same functionality, on-site testing is an area that needs care. Obviously onsite testing is not a substitute for proper design ( of say RCDs) and you might find that the installation contractor is not keen to highlight problems with kit he has himself supplied. As usual, go into these things with your eyes open.
Thanks Freddym. I do appreciate your comments and insight, clearly as part of the installation process I will ensure that the contractor does answer some of the concerns raised and also ensure that it is functioning properly. There are a lot being fitted now, screwfix and tool station also now sell them.
 
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