Lights suddenly get brighter in house

[HappyHippyDad]

I was at a customers house changing a socket and they asked me a question about their lights.

Some of the lights in the house suddenly get brighter and then go back to normal. This happens a few times every week.

Not all the lights in the house do it, only the LED downlights and only the ones on a dimmer switch. However, there are 4 separate dimmer switches all doing different banks of lights. All of these are on the same circuit.

I 'think' that when this happens the lights in question are partly dimmed down. The customer is going to keep them on full brightness and see if it still happens.

It seems clear that this is happening because the lights in question are on a dimmer switch, but it doesn't explain why it is happening.

In addition, the cooker hood extractor fan was on during one of these spikes and it switched itself off and on again within a second or 2.

I'm at a bit of a loss how to fault find this. Could this be a poor connection somewhere? Could it be voltage fluctuation in the electricity supply?

They have solar panels and also a battery storage system. Not sure this information is of any use, but adding just in case.

 

[Eric12]

Has the place got a switchfuse feedin the CU per chance. Found this once a while back lights keep going off/on and it was a loose neutral in old switchfuse feeding the flat upstairs

 

[RetiredNY]

Could it be voltage fluctuation in the electricity supply?

Sounds like it is, I have experienced a similar issue in the past.

 

[HappyHippyDad]

Has the place got a switchfuse feedin the CU per chance. Found this once a while back lights keep going off/on and it was a loose neutral in old switchfuse feeding the flat upstairs

Would this not affect everything in the house? Although, I expect it would be more obviously with lights, and especially low powered lights like LED's?

 

[Marvo]

I'd start by doing the usual supply impedance tests followed by N-E voltage with the installation under some load. Also visually inspect and tightness check all terminations in the CU and check the premises for any appliances with very high load or nasty ugly start or inrush currents such as big single phase air compressors etc..maybe even a high powered EV charger. If nothing stands out during the initial check you need to establish if it's an internal or external supply problem. Maybe a voltage logger on the supply for a few days if you have one available. Depending how deep the rabbit hole goes and how deep the customers pockets are you may end up installing a PQA and collect some data for a week or so