Excessive voltage drop...

[Deleted member 307320]

Mother in laws kitchen lights (bog standard LED bulbs) keep going really dim, particularly when something drawing a high current is turned on (usually the kettle)...

They're on different circuits (kitchen lights on their own radial, sockets on their own ring) so I'm not sure why one is affecting the other, unless we've got a poor connection into the house (Victorian semi on TN-S which is shared with next door)

I'm going to test it all tomorrow, but this has been happening for a while and last time I tested it was all absolutely fine!

Any ideas?

 

[JohnW2]

Mother in laws kitchen lights (bog standard LED bulbs) keep going really dim, particularly when something drawing a high current is turned on (usually the kettle)...
They're on different circuits (kitchen lights on their own radial, sockets on their own ring) so I'm not sure why one is affecting the other, unless we've got a poor connection into the house (Victorian semi on TN-S which is shared with next door)
I'm going to test it all tomorrow, but this has been happening for a while and last time I tested it was all absolutely fine!
Any ideas?

Presumably (as you suggest) "a poor connection into the house" or, probably much more likely, a poor connection within the CU.

If it's a sufficiently poor connection that it's markedly dimming lights, I would think it needs to be addressed urgently, because it could represent a 'fire risk'.

Kind Regards, John

 

[Deleted member 307320]

Presumably (as you suggest) "a poor connection into the house" or, probably much more likely, a poor connection within the CU.

If it's a sufficiently poor connection that it's markedly dimming lights, I would think it needs to be addressed urgently, because it could represent a 'fire risk'.

Kind Regards, John

No sign of anything loose, no sign of any excess impedance or heat damge. CU was fitted in 2017, no problems at all until recently

 

[ericmark]

I have just been listening to a Youtube video on a broken PEN, it seems it is increasing, this report says

Due to the characteristics of not only the PME system but also the water and gas services and other factors such as` steel foundations and the older TT systems, it cannot always be easily identified that there is an issue with the PEN conductor.

so I would contact the DNO and report it, let them make up their mind as to if broken PEN or something else.

 

[SUNRAY]

Mother in laws kitchen lights (bog standard LED bulbs) keep going really dim, particularly when something drawing a high current is turned on (usually the kettle)...

They're on different circuits (kitchen lights on their own radial, sockets on their own ring) so I'm not sure why one is affecting the other, unless we've got a poor connection into the house (Victorian semi on TN-S which is shared with next door)

I'm going to test it all tomorrow, but this has been happening for a while and last time I tested it was all absolutely fine!

Any ideas?

Do they dim for a split second or stay dim?

 

[JohnW2]

No sign of anything loose, no sign of any excess impedance or heat damge.

What do you mean by "signs of excess impedance"? Have you measured some impedance(s) and, if so, of what? 'Heat damage' obviously may take some time to develop.

CU was fitted in 2017, no problems at all until recently

That, of course, doesn't really prove anything. Something has obviously changed, whether within the CU or somewhere else!

Just in case eric''s thought is relevant (I personally very much doubt it) ,it would be worth checking with neighbours (not just the next-door-neighbour - include ones which are 2 or 3 doors away) to see if anyone else in the vicinity has had similar recent experiences.

Kind Regards, John

 

[JohnW2]

I have just been listening to a Youtube video on a broken PEN, it seems it is increasing, this report says so I would contact the DNO and report it, let them make up their mind as to if broken PEN or something else.

As I've just written, I would personally suggest that one should check with neighbours before contacting a DNO.

Despite the YouTube material you quote, I would think that it's probably pretty unusual for a broken/lost PEN to go unnoticed at such for a significant period of time, particularly during high-demand times of the day. Indeed, if parallel paths to earth were of so low impedance that one was not experiencing obvious malfunction of electrical items, I wouldn't expect serious dimming of lights to be occurring, would you?

Kind Regards, John

 

[Murdochcat]

How do you plan to “test” it?

 

[ericmark]

How do you plan to “test” it?

Not sure who the question is aimed at, I would think if the PEN is sound the ELI will be 0.35 Ω or better, the 0.35 Ω is required to keep within volt drop with 100 amp supply, I would think with a broken PEN it would exceed that figure.

However I have said where I work we have a TN-C-S supply and metal framed buildings, with are earthed and connected to 8 mile of railway line so would not think one would detect a broken PEN in that case, but neither would a broken PEN cause much of a voltage variation on single phases, so would think with a voltage variation if due to broken PEN the ELI would be higher than permitted for a TN-C-S supply.

However I have in the UK only found a broken PEN once, abroad that jumps up, but UK only once due to road works.

 

[Murdochcat]

How do you plan to “test” it?

Aimed at the OP

 

[Deleted member 307320]

Aimed at the OP

MFT...

 

[ericmark]

Note with a TN-S the ELI is max at 0.8 Ω, however as end user we have no way of knowing if TN-S or TN-C-S as the earth and neutral could have been combined anywhere along the route.

 

[Murdochcat]

Thing with these observations it could be in the house wiring, the CU, the service head, under the ground or a local high load

 

[EFLImpudence]

Note with a TN-S the ELI is max at 0.8 Ω, however as end user we have no way of knowing if TN-S or TN-C-S as the earth and neutral could have been combined anywhere along the route.

So is there any point keeping on mentioning it?

 

[ericmark]

So is there any point keeping on mentioning it?

@biancothegiraffe has said TN-S or no I would not mention it.