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

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.

 

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.