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3 phase 100A power supply - voltage at each phase goes up to 250+ Volts should I be worried?

Former Community Member
Former Community Member
New 3 phase power supply installed and live from an ICP (independent connection provider) and meter installed, the service is all sealed up and live.


My NICEIC electrician has now installed an 18 way distribution box after the 4 pole isolator from meter tails and everything seems to be all ok, we also made sure to achieve compliance with 18th edition amendment 1 as I have an electric vehicle on the property that will be charged.


I also got a 4 pole Type 1 surge protection device to be installed (Hager JK101SPD) in-line with the mains incomer so that all the ciruits behind it will be protect.


The car is protected behind a Type A and Type B RCD which is 4 pole and 40A (as per the manufacturer's guidelines). The charger also has other safety features such as earth monitoring and neutral-earth fault detection.

However, the car shows at peak and middle of the night the voltages around constant at 250V and sometimes sits as high as 257V (does not seem to go beyond that).


Is this something I need to be worried about? Or should be I be okay?


Appreciate your insights please.


Parents
  • 0

    [2] Broken PEN has been something I was paranoid about so I got an ABB device that monitors earth and neutral breaks, I think it is called RC223.

    Basically have it to protect the outdoor EV charging point to comply with 18th edition amendment 1; did not want to have someone wandering around touch the car when it is wet and get electrocuted.



    Broken PENs are nasty things - not only is there the shock hazard from things that should be earthed, but there's the general issue of anything up to 400+ volts appearing between L & N - which tends to do permanent damage to a lot of equipment. SPD don't help much in that event either - they can only really deal with very short pulses of over voltages - not something that might last for hours or days.

     

    I know the regs say it is based on risk assessment but what does that really involve?





    Just plugging numbers into a formula and see if you get an answer above or below 1000. The numbers come from whether your situation is rural/suburban or urban, lightning flash density your location (the regs supply a map for the UK), and the features of the last 1km of the network that supplies you (whether underground or overhead and how much of that 1km is HV or LV). I can dig out the details if you're interested.


       - Andy.
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  • 0

    [2] Broken PEN has been something I was paranoid about so I got an ABB device that monitors earth and neutral breaks, I think it is called RC223.

    Basically have it to protect the outdoor EV charging point to comply with 18th edition amendment 1; did not want to have someone wandering around touch the car when it is wet and get electrocuted.



    Broken PENs are nasty things - not only is there the shock hazard from things that should be earthed, but there's the general issue of anything up to 400+ volts appearing between L & N - which tends to do permanent damage to a lot of equipment. SPD don't help much in that event either - they can only really deal with very short pulses of over voltages - not something that might last for hours or days.

     

    I know the regs say it is based on risk assessment but what does that really involve?





    Just plugging numbers into a formula and see if you get an answer above or below 1000. The numbers come from whether your situation is rural/suburban or urban, lightning flash density your location (the regs supply a map for the UK), and the features of the last 1km of the network that supplies you (whether underground or overhead and how much of that 1km is HV or LV). I can dig out the details if you're interested.


       - Andy.
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