Lights flickering & going off on lighting circu when pulling power on socket circuits

[kels bels]

Hi everyone

I have a problem that has totally mystified myself and my colleagues - hoping someone could shed some light...

Called out to a flat today, where when they put the kettle on the lights flickered and when they turned on the washing machine, the lights went out (but the fuse did not trip).

There was a hager fuseboard (pre 2008) - socket circuits on RCD protected side, and 2 lighting circuits on non RCD side. All looks installed very well. No loose connections. No reverse polarity on supply or in the installation anywhere.

Insulation resistance check on all cables were 299+

Lights are all run from 5a sockets (no ceiling lights), and wall lights for hallway.

I did continuity tests between neutrals, earths and lines with the MCB's and RCD's off, nothing unusual.

However...

When I tested continuity between each side of the MCB on the Hob circuit with the RCD off and MCB off I got an open circuit, but with the RCD ON and MCB off, I was getting a closed circuit with 700+ reading. With the RCD on, and all MCB's off, I got continuity between the lighting circuit line and the Hob circuit line.

What does this mean? Surely I shouldn't be getting continuity between 2 line cables on 2 different circuits on seperate sides of the fuseboard even with the RCD on?! What does this mean?

Anyone ever seen or heard of this before....

You're thoughts are gratefully received, because I left the customer with the Hob circuit MCB off and the lights were ok with no flickering when pulling power on the sockets. I would like to get their hob circuit back on without it causing problems for the lighting circuits!

Thanks

Kelly x

 

[kels bels]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

This all started happening when their tumble dried blew up and stopped working. Even with it disconnected, the flickering lights problem started.

 

[telectrix]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

your continuity between 2 circuits could be through the load and the neutrals. i suspect a loose connection somewhere in or near to the CU. possibly on a neutral. could even be at the meter .

 

[kels bels]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

Thanks telectrix, I did check all connections, even inside the meter but everything was tight - I could check again!! Will Have to go back tomorrow and let you know. There's no local cut out fuse, could it be a loose connection down at the main intake where the cut out fuse is?

 

[wildgoose]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

Make yourself up a baton holder with some short leads attached and fit it with the old type 100w tungsten bulb. Use this as a testlamp and start with the supply incoming fom meter.

When it doesn't flicker anymore, then you know you are upstream of the fault. Have known this problem to be caused by a poor joint on the incoming supply which had to be fix by the DNO - hence the need to start at that end first!

 

[kels bels]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

So I attach the test lamp to the live and neutral at the meter and use sockets, of lights don't flicker then it's a problem after the meter?

 

[Deservices]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

Defiantly sounds like a loose connection, have you tested the voltage? I presume the lights are low energy ones as they turn off when voltage gets to low. If you put filament bulbs in you will probably find they glow dim. It's probably the main incoming cable I had one last week, you would need to pull the main fuse to test the connections thou and remember its live on the lower side.

 

[kels bels]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

Yes they are low energy bulbs and I did test the voltage, steady at 241 and down to 234 when pulling power. Will check the supply cables and let you know how I get on!
Thanks for all your support guys!!!

 

[drew35]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

I would check the voltage first, but you could try putting the lights on and manipulating the tails in and out of the meter, head, see if it affects the lights. It definitely sounds like a loose connection somewhere like others have said.

 

[kels bels]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

The lights only flicker when the circuit for the HOB is ON. This is what I find strange.
And I have checked the voltage and it's normal.

 

[Deservices]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

The voltage shouldn't be dropping down really even thou 234 is ok. I'd still say loose connection at supply fuse may even be suppliers connection coming into the property iv had that before and took a lot to convince manweb it's there fault but in the end they fixed it by digging up the road lol hope this isn't the case and its just the incoming connections

 

[kels bels]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

Cool - I'm going back tomorrow!

 

[oldtimer]

Re: Lights flickering & going off on lighting circu when pulling power on socket circ

Yep telectrix is right its a loose connection and this shows up when you put a heavey load on ie shower,tumble dryer,kettle,immersion heater so in your case the kettle is on a power circuit the lights are on a lighting circuit so whats common well the consumer unit and before you say connection checked I have seen problems with the CU main switch ie internal so how do you prove this well.....................................