Strange Fault

[ian]

Hi Guys

First post on here for some time.

I was called to a fault earlier today which I cant get my head round. the lights in the house are flickering. Not all that unusual I hear you cry, however they are flickering when they are switched off, and at random times, often in the evening or very earl in the morning.

I have tested the installation and everything is ok, no neutral problems, polarity, Ze & Zs are fine. I have seen a similar problem previously and the cause was a pump nearby pumping station dumping a load of fault current, however I called united utilities and there is no pumping station for miles.

Hope someone can help.

Ian

By the way it’s a TNS-S system.

 

[Ross Trician]

Hello there, not sure if it will help but I did the electric install in an extension on a house. when I had connected up and went to power up I had a night mare, lamps blowing, rcd wouldn't trip then couldn't get it to reset, was getting stupid voltage readings...just generally a night mare.

when i tested the incomming voltage it was 300+ V...after several hours of head scratching, teast, ripping my install apart and questioning all i had done it all just began to work properly. I tested the incomming supply again and was "normal"....all tested right and tripped and reset etc.

The customer rang there supplier following day and they sent someone to check things out. they said they couldn't find anything wrong but the next day they replaced the main cable along the road and low and behold there were no further problems at all.....when they got talking to neighbours they had all been experiencing problems for some time.

 

[Sav]

Are any of the lights the low energy type. They look like tube light fittings with 2 pins on top. They fit into ceiling pendants.

If so, they can flicker due to voltage leakage, even the slightest. There is some kind of resister that you can fit which should cure the problem.
Hope this helps,
Sav

 

[Sintra]

Are the lamps low energy compact flourescent type?

Beat me to it sav.

 

[ian]

They are mainly energy seving, CFL's or low voltage downlights

 

[Sintra]

This is caused by an induced voltage normally on a 2 way circuit.

Your options are to fit snubbers at affected fittings or to change the 2 way switching to the conversion method.

 

[Sav]

Sintra,
you took the words right out of my mouth...nicely worded as apposed to mine !!!

Best regards,
Sav

 

[Spudnik]

they said they couldn't find anything wrong but the next day they replaced the main cable along the road and low and behold there were no further problems at all.....when they got talking to neighbours they had all been experiencing problems for some time.

Typically, a supplier get out clause.