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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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    Greetings to ONE & ALL - this is my first Post ever on a IET Site - In brief now "retired" I still enjoy Electronics & of course Electrical work having started in 1970 in the Society of Electronic & Radio Technicians (SERT). Then the 16th in Cornwall some years ago, (TT -  still rules on Farms), my Electronics is from HM Forces (Grey Funnel Line - Royal Navy) now living in a Village in East Sussex therefore TN-C-S with of course PME !! - As I am now & can only be considered, an "enthusiastic amateur" I have embarked on a "Major Re Wire."  Firstly a,  "Full Surge Protection" system & a  Mains Voltage Optimiser to "condition" Mains some days can realise 253 volts plus - Three (3) Separate DBs One (1) Power - One (1)  Luminaires & One (1) Critical/Auxillary  Load(s) - The Critical Loading is fed by a Uninterrupted Power Supply (UPS) the "Generator" will supply Critical Loads on sensing UPS operation - I appreciate sleep at night can be a "Challenge"  & so finally onto EVC. The Charging Point will be outside the Garage, (no room in the garage for a car). The Site has had the, "GOV. Grant  Survey" I am using 10mm SWA from my Sub Station to the Garage - I was told 6 mm was "ok" BUT would get warm on "rapid charge"  - My Point on "True Earth on Solid Floor" is very simple - Electricity will NEVER miss the chance to find "Earth" - as was explained to us in South Shields Marine College.  We are only, "RESISTIVE SHUNTS." Then having debated Footwear from Flip Flops to Hob Nail Boots & "No Footwear" whatsoever. Whether it is raining or washing the Car/Caravan & people do pursue these occupation(s) on Sundays & the Car can be half in & out of the Garage (Scenarios are numerous) !! - MY personal view is to install an "Isolation Transformer" the price is worth the Life !! - after all we have installed them in Shower/Bathrooms standing "Bare Foot" (wet shave is bestest). No "TT" stick required - O well, back to studying PME & Generator (7.5 KVA) Earthing. Remember the "Ole Pneumonic" SIDE = Switch Off - Isolate - Dump & Earth  I cannot wait for PME to fail "deal with the challenge."
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  • 0
    Greetings to ONE & ALL - this is my first Post ever on a IET Site - In brief now "retired" I still enjoy Electronics & of course Electrical work having started in 1970 in the Society of Electronic & Radio Technicians (SERT). Then the 16th in Cornwall some years ago, (TT -  still rules on Farms), my Electronics is from HM Forces (Grey Funnel Line - Royal Navy) now living in a Village in East Sussex therefore TN-C-S with of course PME !! - As I am now & can only be considered, an "enthusiastic amateur" I have embarked on a "Major Re Wire."  Firstly a,  "Full Surge Protection" system & a  Mains Voltage Optimiser to "condition" Mains some days can realise 253 volts plus - Three (3) Separate DBs One (1) Power - One (1)  Luminaires & One (1) Critical/Auxillary  Load(s) - The Critical Loading is fed by a Uninterrupted Power Supply (UPS) the "Generator" will supply Critical Loads on sensing UPS operation - I appreciate sleep at night can be a "Challenge"  & so finally onto EVC. The Charging Point will be outside the Garage, (no room in the garage for a car). The Site has had the, "GOV. Grant  Survey" I am using 10mm SWA from my Sub Station to the Garage - I was told 6 mm was "ok" BUT would get warm on "rapid charge"  - My Point on "True Earth on Solid Floor" is very simple - Electricity will NEVER miss the chance to find "Earth" - as was explained to us in South Shields Marine College.  We are only, "RESISTIVE SHUNTS." Then having debated Footwear from Flip Flops to Hob Nail Boots & "No Footwear" whatsoever. Whether it is raining or washing the Car/Caravan & people do pursue these occupation(s) on Sundays & the Car can be half in & out of the Garage (Scenarios are numerous) !! - MY personal view is to install an "Isolation Transformer" the price is worth the Life !! - after all we have installed them in Shower/Bathrooms standing "Bare Foot" (wet shave is bestest). No "TT" stick required - O well, back to studying PME & Generator (7.5 KVA) Earthing. Remember the "Ole Pneumonic" SIDE = Switch Off - Isolate - Dump & Earth  I cannot wait for PME to fail "deal with the challenge."
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