If national grid ignore voltage being out of spec and it damages equipment are they liable?

Chrysalis

National grid are here fixing a power cut, I reported my own fault as by coincidence the same day of this power cut my input voltage jumped above 253v.

I showed the tech present the reading and he was like its your problem mate if our voltage is out of spec, he also has the opinion the power cut is unrelated as its a different leg.

They are sending out a voltage reader though, which I think is within 48h (had to push a bit to get them to do this), but I am curious of the consequences if any of my electrical equipment gets damaged because of out of spec voltage feed into the property, am I on the hook for it?

I did check Ofgem website before posting but that seems to only have compensation for power cuts, not for power fed to property outside of UK specifications.

Netexporter

253V is within the legal limit.(just)

In the village I previously lived in all the council houses had solar panels. On sunny days the voltage would regularly go up to 253V as the inverters all chased each other upwards, so that they could export the surplus power.

Chrysalis

Its 255v currently.

The 48h is also working days, so its going to be closer to within 84h.  Potentially 4 days running on illegal voltage.

prowla

Any device rated at 250V which can't handle 255V is probably pretty ropey.

(Incidentally, Volts are uppercase 'V'.)

Netexporter

The voltage range on most kit goes well beyond the grid legal limits, these days. It's generally spikes that cause damage but you can use anti-surge devices to mitigate that. 18th Edition consumer units have surge protection that covers the whole house.

Chrysalis

Netexporter said:

The voltage range on most kit goes well beyond the grid legal limits, these days. It's generally spikes that cause damage but you can use anti-surge devices to mitigate that. 18th Edition consumer units have surge protection that covers the whole house.

I think I was getting spikes earlier in the day which brought my attention to the issue, as UPS kept flipping to battery, and its default is to flip over at 260V.

Its back down now to 250-251V fluctuating. (higher than before, but I will take it)

Seems the power cut was linked to it in the end as it went down as they were finishing.

Scot_39

https://www.spenergynetworks.co.uk/pages/voltage_changes.aspx

230V -6,+10% so 253V upper limit - as per your measurement.

Claims most EU spec devices power systems should be able to handle 2000V transiently - but doesn't give the actual duration.

And also claims can take them 6 months - possibly longer - to fix the problem if outside spec.

Re daily transients

Most people are barely used to the concept of normal voltage, current and many misuse the terms power and energy even here on the energy board.

AC - especially with reactive or even highly transient resisitive loading - and switching / fault conditions and transient  / sub transient responses  - a complete mystery to many.  At grid DNO or domestic levels.

Domestically - that includes inductive loads - e.g. motor - and other even resistive loads with high inrush currents (e.g. old style tungsten filament lighting had high inrush currents - some upto 10-15x nominal) - everyday sources (in the past in later case I suspect) - in many homes.  Switching either on / off - enough to potentially generate notable transients in your home. 

Which is why your £10 timer switch from the high street - probably has a resistive and an inductive rating - to protect contacts / arcing etc.  

And in the past - in US for instance - remember one I used having a lower "tungsten" rating - just over 1/2 it's resistive ratings - no inductive specified on label at all. You could however get one's with three ratings - adding a HP rating for AC motor inductive load switching.


Edit

And if your worried about mains surges - if you dont have a protected consumer unit - you could buy some surge protection power strips.  They start around £10 on line.

I've used them on TVs, HiFi, computers etc for decades domestically.


 

Chrysalis

Ironically when thinking about it, most of my equipment is behind some kind of surge protector.

BarelySentientAI

There's not really a simple answer, because the voltage limit isn't a hard limit.  So much so that I'm involved in several court cases about the interpretation of exactly this question.

I presume you're talking about National Grid Distribution here (the DNO bit) rather than the transmission part?

The relevant document for the limits is the ESQCR, at Clause 27(6):

"Every distributor shall ensure that, save in exceptional circumstances, the characteristics of the supplies to consumer’s installations connected to his network comply with the declarations made under paragraph (1)"

That sets out their duties, but for determining whether they are liable for any damage there tends to be two important parts to the argument  - firstly whether there was actually a high voltage that the distributor could have done something about (i.e. did they know, had they done sufficient investigation to determine that it was a persistent problem, was there actually any technical way it could be fixed within their equipment....), and secondly whether the voltage excursion was exceptional (was if from a lightning strike, digger through a cable, sudden change in the system....)

There was at least one very famous (in the right circles) case where it was determined that the companies had all failed in their statutory duties to inspect cut-out fuses, but none had to pay damages because the judge thought that even if they had done the inspections, there was no reasonable expectations that they would have noticed them failing before they caused the eventual house fires.  No such precedent case for this issue though.

Chrysalis

Thanks, sadly its fluctuating rapidly now between about 252V and 259V.

I got another text today reminding me incident is still open and I will get a response in a few days, unlucky this happened on a bank holiday weekend I guess.

Also ordered a volt meter, possibility might be a rogue , smart plug, socket or something in my home, so will check with that.

prowla

252-259V: that's a 7V variation, or about 3%.

I'm amazed that the service can provide that stable a value over all of the infrastructure.