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Electrical Vehicle Charging Points - True earth on solid floor

Apostolos
Good afternoon.

The problem with EVC Points in a few words is that it introduces the PME (the MET in reality) voltage on the metallic car body. Then, if someone touches the car (under PME voltage) and stands on the ground touching the TRUE EARTH potential he will be introduced to a high voltage in case of an open PEN incidence. 

There are some gross guidlines ( https://www.electricvehiclechargepoint.com/ev-resources/earthing )that say

-If the EVC is outside then TT is needed (the person touches the true earth)

-If the EVC is inside and no charging happens on the outside then PME can be used (the person does not touch the true earth)

Then my question is:
WHAT IS THE POTENTIAL OF A CONRETE FLOOR IF THE EVC POINT IS INSIDE THE BUILDING????

Why do we assume that the concrete floor inside the building is on PME potential and so the EVC can be on PME?

If it is a metal building then I can see somehow that the concrete floor is in touch with the metal skeleton which is bonded to the MET so the concrete floor could be assumed to be on PME potential (correct me please if I am wrong)

If the building is concrete, how on earth this solid concrete floor is considered to be at PME potential????

 


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  • 0
    mapj1 thank you very much because you have given me in the past a really good answer on another EVC question I had posted in the previous IET forum.

    I just remembered it now ?

    To the subject now, lets assume that this is a car park (to make it more realistic) with several EVC points perimetrically.

    Theoritically according to what I have read online the EVCs should be on PME.

    The building is a metal building which is bonded on the PME as regular practise.

    Can I assume that the concrete floor being in contact with the droping metal columns is at the same potential (i.e. PME)?

    Even if we assume that there is some rebar in the cement how sure can we be that this rebar is in direct contact with the metal structure?

    I think you can see why I am a bit reluctant to use PME on the EVC points although it is inside the building.

    ...........

    I guess the problem becomes even bigger in case of a  concrete building because I do not see how the rebar in the columns and in the floor will be bonded to the MET...

    ..........

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  • 0
    mapj1 thank you very much because you have given me in the past a really good answer on another EVC question I had posted in the previous IET forum.

    I just remembered it now ?

    To the subject now, lets assume that this is a car park (to make it more realistic) with several EVC points perimetrically.

    Theoritically according to what I have read online the EVCs should be on PME.

    The building is a metal building which is bonded on the PME as regular practise.

    Can I assume that the concrete floor being in contact with the droping metal columns is at the same potential (i.e. PME)?

    Even if we assume that there is some rebar in the cement how sure can we be that this rebar is in direct contact with the metal structure?

    I think you can see why I am a bit reluctant to use PME on the EVC points although it is inside the building.

    ...........

    I guess the problem becomes even bigger in case of a  concrete building because I do not see how the rebar in the columns and in the floor will be bonded to the MET...

    ..........

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