Sudden bright lights - overvoltage/spikes? What to do?

[hsabbers]

Well, the chap from the DNO turned up at 9.30pm. He was very nice but his testing amounted only to connecting a test rig to our home's incoming supply, at the meter box, and reading a voltage of 244v, which is well within the 216-253v operating margin.

However, as I said to him, with these spikes being intermittent, if the problem *is* coming from an external source all you're ever going to get from a one-off reading is a good reading (unless a spike just so happens to occur while his meter is attached).

So I don't really think this his visit has resolved anything (and, typically, no spikes occurred in the 20 minutes he was here). He recommended we get a spark out to check our household circuits, which I'm trying to do today.

Then, if the spark reports back no problems, the DNO will come out again to fit a voltage recorder - which I imagine is what will end up happening. But first, we gotta find a local spark. So, any recommendations as to where to go to find a reliable/qualified local spark?

Harry.

 

[EngStudent]

Then, if the spark reports back no problems, the DNO will come out again to fit a voltage recorder - which I imagine is what will end up happening. But first, we gotta find a local spark. So, any recommendations as to where to go to find a reliable/qualified local spark?

Harry.

Are you sure he only measured the voltage?

Word of mouth is the best way, but otherwise have a look here. Have a look for 'full scope'.

 

[hsabbers]

[/quote]

Are you sure he only measured the voltage?

Word of mouth is the best way, but otherwise have a look here. Have a look for 'full scope'.[/quote]

Well, no - I'm not an electrician so I in fact don't know for sure what he checked. I do know that he took the house meter apart, connected his own meter to the incoming cable and then reported back with a 244v reading. He didn't do anything else that I could see.

Perhaps his box of tricks does other things that I may not know about or understand but logic tells me that there's not a lot more you can do with a 2-minute test of cable other than read its voltage and check that the voltage hasn't spiked in that time.

He said, too, that he'd been to the local substation to check it but obviously, I have literally no idea what he may have done there.

But again, I feel confident that this does not amount to confirmation that the spikes are caused by an internal source.

Harry.

 

[bernardgreen]

He should also have measured the potential difference ( voltage ) between the neutral and true ground to verify the voltage on the neutral was within the limits

If he also measured that voltage while you switched on and off a kilowatt of load then the voltages on the neutral with and without that 4 amp change in current along the neutral would have provided some indication of the impedance / quality of the neutral feed to the property.

 

[hsabbers]

He should also have measured the potential difference ( voltage ) between the neutral and true ground to verify the voltage on the neutral was within the limits

If he also measured that voltage while you switched on and off a kilowatt of load then the voltages on the neutral with and without that 4 amp change in current along the neutral would have provided some indication of the impedance / quality of the neutral feed to the property.

Well, he *definitely* didn't measure anything while I switched stuff on/off. He pulled apart the meter, shut down the household electrics, attached his meter, looked at it for a minute or two then reported back with a 244v reading, which he said was within the normal range. Then he switched the power back on. As I said, the whole process took literally 2 minutes.

Also, while I accept that 244v is within the normal operating range for the UK (+/- 10% of 230v), a spark I've spoke to this morning said it is certainly quite high in his experience. He reckons he doesn't often see much more than 238v on domestic supplies. Does that tally with the experience of other sparks here?

Harry.

 

[EngStudent]

Also, while I accept that 244v is within the normal operating range for the UK (+/- 10% of 230v), a spark I've spoke to this morning said it is certainly quite high in his experience. He reckons he doesn't often see much more than 238v on domestic supplies. Does that tally with the experience of other sparks here?

Harry.

240v used to be standard over here, then it was dropped to be (I believe) in line with the rest of Europe - but rather than replace the transformers we just left them as they were. The actual tolerances are +10% and -6%. A lot of the newer transformers will be designed for 230v but like I said the older ones won't be replaced until there's something wrong with them.

A lot depends on the distance you are from the substation, and loading on the phases. The highest I've come across is 247v.

 

[EngStudent]

Double post.

 

[davelx]

I see 245V+ most of the time at my place - the only time it drops is at peak kettle boiling/cooking time.

(using a calibrated installation tester)

 

[hsabbers]

Just to keep this post up to date, as it may one day prove useful to someone else, we had a qualified electrician around today who gave the household electrics/circuits a clean bill of health. But the spikes continue.

As a result, the DNO has agreed now to return to fit a voltage-recording device (though this will take up to 10 working days, which is rather different from the 24-hour call out of last time!).

I'll update as an when we get any new information.

 

[hsabbers]

Right folks, bumping this topic up 'cos I think I've discovered some new information about the possible cause of my light-brightening situation and could do with some more advice.

I was, literally just five minutes ago, sat on the downstairs bog when I glanced up and noticed a water mark all around the light fitting, in the Artex. I'm almost certain this wasn't there when we moved in, a few weeks ago. I touched the stain and it didn’t feel damp or wet, which suggests it’s not completely new, obviously.

Now, remembering back to when I first noticed the light-brightening phenomenon in our house, I was laid out on the bed upstairs cooling down after a very hot bath. The bath is quite small and if I’m not careful sometimes when I get in it, water floods over the back and onto the floor. This probably happened on the night I had that bath and the lights started their alarming brightening behaviour.

Now, remember, all of this was more than a week ago. The light-brightening problem seems now to have gone away. I have tonight pulled away the bath panel and looked under the bath and, sure enough, there are plenty of water-stain marks. Now, the downstairs light fitting with the water stain around it is *not* directly below the bathroom but it is only about 4-5ft on the diagonal.

So, I’m theorising that that night I took my bath, I again flooded some water over the back, which then seeped through the floor. Then, thanks to perhaps a small natural diagonal incline in the ceiling panels below, this water travelled towards the downstairs bathroom light fitting and ended up pooling there somehow. Now, coincidentally (cos I’ve been away) I’ve not had a bath since (yes, I stink) but the fact that there’s been no more of my flood-causing baths would’ve given time for a new stain (if indeed it is new) in the downstairs bathroom to dry. It would also give time, perhaps, for any water in the electrics to dry up.

Two questions, then.

1. Does this sound like a really outlandish theory?
2. If it doesn’t sound too crazy then could the (hypothesised) water gathering in the downstairs bathroom light fitting somehow have caused this light-brightening phenomenon that we suffered for three nights? I think it’s fair to say that the downstairs bathroom isn’t used much, so the light itself is rarely switched on.

 

[bernardgreen]

2. If it doesn’t sound too crazy then could the (hypothesised) water gathering in the downstairs bathroom light fitting somehow have caused this light-brightening phenomenon that we suffered for three nights?

Very very UN-likely that the water caused it.