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

FaeLLe:

AJJewsbury:

[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.

This is why I got the Earth Neutral break monitoring device to disconnect power supply to my EV if there is a break in neutral.

I also considered converting the PME supply to something like TT with an earth rod but then decided that I did not have the resources to maintain the seperate earth connection infrastructure!

The electricity substation is less than 12 feet from my distribution box! So less chances of someone digging the street up between me and the LV board..

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.

Hi Andy I would be interested to read up and learn a bit more on this if you can point me to some documentation.


Also keen to understand what my lightning flash density is as I have now installed outdoor WiFi access points all around my land but conveniantly ignored the advise to get a lightnight surge protection device fitted in line with the Ethernet cable.


   - Andy.

 

 

So my situation has evolved slightly and I will now now be getting a lightning conductor for a 10m antenna as per my post - https://communities.theiet.org/discussions/viewtopic/1037/26122


Would appreciate any feedback on relevance of my SPD to the installation. Should I be making a TT island for the ametur radio unit (like a ham) connected to the antenna and putting the TT island behind a Type 1 SPD?

Hi Andy I would be interested to read up and learn a bit more on this if you can point me to some documentation.

Also keen to understand what my lightning flash density is as I have now installed outdoor WiFi access points all around my land but conveniantly ignored the advise to get a lightnight surge protection device fitted in line with the Ethernet cable.

This is why I got the Earth Neutral break monitoring device to disconnect power supply to my EV if there is a break in neutral.

AJJewsbury:

[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.

This is why I got the Earth Neutral break monitoring device to disconnect power supply to my EV if there is a break in neutral.

I also considered converting the PME supply to something like TT with an earth rod but then decided that I did not have the resources to maintain the seperate earth connection infrastructure!

The electricity substation is less than 12 feet from my distribution box! So less chances of someone digging the street up between me and the LV board..

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.

Hi Andy I would be interested to read up and learn a bit more on this if you can point me to some documentation.


Also keen to understand what my lightning flash density is as I have now installed outdoor WiFi access points all around my land but conveniantly ignored the advise to get a lightnight surge protection device fitted in line with the Ethernet cable.


   - Andy.

 

FaeLLe:

Sparkingchip:

Is it 257 volts whilst the car is charging or when the charger is offline?


 Andy Betteridge

Hi Andy, the voltage shown is what the car states when it is charging.

 

 

[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.

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

Sparkingchip:

Is it 257 volts whilst the car is charging or when the charger is offline?


 Andy Betteridge

AJJewsbury:

Agreed - the official range for mains is 230V-6%+10% - i.e. anything between 216.2V and 253V. But then you've got the accuracy of your meter to contend with (which are usually a lot worse than you would hope). If it really is high then the DNO should do something about it - but it might be a fight. I've been on a commercial site where several of the UPSs were complaining of high supply voltage every night (probably >254V) yet the DNO's logger allegedly couldn't see the problem.

[1] If I wanted to get the DNO to take a look what information might I want to give them? Would they just disregard it by saying your meter is just faulty?


If it's high on one or two lines, but low on the others - there is a possibility that there's a bad connection on the N and that's skewing things. (effectively the Ls are right but N (and Earth if TN) have moved from where they should be). That could be an early warning of quite a serious problem (broken PEN).

[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.

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.

Unusual - do you have lightning conductors on the building (or close by)? Generally a Type 1 is only specified where lighting in involved and typically only protects the type 2 SPD behind. Normally a Type 2 is needed to protect downstream circuits (and possibly a type 3 downstream of that to protect particularly sensitive equipment). There are combined Type 1+Type 2 where you need both at the same location.

[3] No lightning conductors nearby but I just wanted some assurance or protection from surges as the electricity substation is next door and the LV board is maybe 12 feet from my distribution box! I know it is the DNO's responsibility to not send surges down but hey I have several thousands worth of IT kit behind their network and if it goes out I am the one who gets impacted.....


Hager technical support teams told me the Type 1 SPD would protect all the cicruits in the DB and give it Type 2 and Type 3 protection as well :/

I just looked at the documentation and it looks like it is a Type 1 and Type SPD....


What is the best practice around SPD's should I consider any other type of protection for mine? I know the regs say it is based on risk assessment but what does that really involve?





   - Andy.

 

tattyinengland:

HI FaeLLe


I assume the ICP has connected you to the national grid - a public supply - and not a private supply? I assume you don't have your own transformer? 


In which case - other than maybe the 4 pole isolator - and how that makes/breaks the neutral; I'd let the national grid worry about the amount of volts they put out there. The kit can almost certainly take 257V. 


All should be OK I think.


Kind Regards


Tatty