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EV Charger mounting post - earthing arrangement

Martin Johnson

I'm looking for advice for mounting an EV Charger on a metal post that a customer has installed for this purpose, it's located in his parking space on his driveway. The charger he has purchased is a Pod Point model which has inbuilt PEN fault detection. The armoured cable to supply it will be protected by a double pole type A RCD. The supply is PME. My thoughts are:-

  1. The metal post set in the ground is an extraneous conductive part. The EV charger earth will not be connected to this metal post and therefore there will be a small potential difference between it and the car charger earth (which I guess is connected to the car?)
  2. I don't like the idea of bonding the (PME) supply to the metal post.
  3. Has anyone installed an EV charger on a metal post?  Several manufacturers sell them as accessories to their range of EV chargers, nearly all have built-in PEN protection now.
  4. All advice and comments will be gratefully received.
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    IF they are attached to this post for other reasons,  then even painting it would probably reduce any touch contact current to less than problematic even in the most unlikely event. (though not an official answer, it goes some way to permitting you a lesser degree of concern.)  

    Shock current is really all about contact area of skin, ideally sweaty wet skin, so  a painted surface, even one with quite a few scratches, is a long way from giving a large area of contact, even if you clench it. (after all enameled wire works really very well, and that is just  a layer varnish of 5 to ten  um thick on thin wires and 10-30um on the chunkier stuff,  though perhaps that should cue hissing and spitting from wire makers that it is not any old varnish but very pure and carefully applied in layers..  )

    Although the regs do not really acknowledge it, a full mains voltage shock to a small area like a pin prick or a nail head is a lot less serious than larger area  low resistance contact like a hand rail or a tap at say half mains voltage. A  great many folk have survived a ‘nip’ from a low area contact, not that it is to be recommended of course. 

    Actually the forum did touch on this in another thread that was really about disconnection times  a few months back

    here it is , you'd need to read about halfway down the thread to get to the resistance/ voltage shock current part if you are interested.

    Mike

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  • 0

    IF they are attached to this post for other reasons,  then even painting it would probably reduce any touch contact current to less than problematic even in the most unlikely event. (though not an official answer, it goes some way to permitting you a lesser degree of concern.)  

    Shock current is really all about contact area of skin, ideally sweaty wet skin, so  a painted surface, even one with quite a few scratches, is a long way from giving a large area of contact, even if you clench it. (after all enameled wire works really very well, and that is just  a layer varnish of 5 to ten  um thick on thin wires and 10-30um on the chunkier stuff,  though perhaps that should cue hissing and spitting from wire makers that it is not any old varnish but very pure and carefully applied in layers..  )

    Although the regs do not really acknowledge it, a full mains voltage shock to a small area like a pin prick or a nail head is a lot less serious than larger area  low resistance contact like a hand rail or a tap at say half mains voltage. A  great many folk have survived a ‘nip’ from a low area contact, not that it is to be recommended of course. 

    Actually the forum did touch on this in another thread that was really about disconnection times  a few months back

    here it is , you'd need to read about halfway down the thread to get to the resistance/ voltage shock current part if you are interested.

    Mike

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