Lights keep tripping...

[Newbie90]

Hi all

Has anyone got any ideas why a lighting circuit would randomly trip the mcb?

The maximum Zs tested was 1.07 ohms.

Its only ever happened (3 or 4 times) when the 2 wall lights in the front room are switched on. They both have energy saving light bulbs and none of them ever blow.

It doesn't trip the rcd, just the mcb.

Thanks

 

[MDJ]

maybe, I expect there are several unknowns here :26:

 

[bigbaddave]

Do energy saving lamps ever cause nuisance tripping?

I did a full insulation resistance test on the individual circuit and measured >299 on L - N, L - E and N - E.

The only other possibility is that the tv amp has been tapped off the lighting circuit but that has a perminant feed and not being switched.

If your still at college bud then good luck. However when i was there and testing I thought that was the norm as we were testing 3m or so of new cable therefore all results were that. Unless I got greater than 299m i assumed there was a fault.

Real life things are different though. Event after a full rewire global IR can be lower then 299m due to a number of factors. Therefore for you to have 299m. Either your not testing right or the install is in very very good nick

 

[Octopus]

Do energy saving lamps ever cause nuisance tripping?

I did a full insulation resistance test on the individual circuit and measured >299 on L - N, L - E and N - E.

The only other possibility is that the tv amp has been tapped off the lighting circuit but that has a perminant feed and not being switched.

Excuse me for asking this, but if the TV amp is on a permenant supply off the lighting circuit how can you justify your >299 on L-N??

 

[bigbaddave]

Excuse me for asking this, but if the TV amp is on a permenant supply off the lighting circuit how can you justify your >299 on L-N??

Arr Darn.. You clearly aint drunk as much as me... I recon maybe 0.018 is more realistic

 

[Octopus]

I think we should all be concious of the posters experience:

http://www.electriciansforums.net/e...0-consumer-unit-change-advice.html#post688246

Hum......

 

[bigbaddave]

Ahh... I enjoyed that one..

 

[Newbie90]

I think we should all be concious of the posters experience:

http://www.electriciansforums.net/e...0-consumer-unit-change-advice.html#post688246

Hum......

Domestic experience is very minimal as I am an employed as an electrical technician dealing with very expensive equipment.

Therefore I am not as good domestically as most people on the forum but I doubt many people would be as good as me at my job.

So no need to degrade me is there

 

[Newbie90]

Excuse me for asking this, but if the TV amp is on a permenant supply off the lighting circuit how can you justify your >299 on L-N??

Being an electrician yourself, I assume you have heard of disconnecting things... Obviously not :S

 

[Octopus]

Domestic experience is very minimal as I am an employed as an electrical technician dealing with very expensive equipment.

Therefore I am not as good domestically as most people on the forum but I doubt many people would be as good as me at my job.

So no need to degrade me is there

So why don't you leave the safety of your fathers tenents to a professional then?

 

[bigbaddave]

Can you Explain your IR values though bud. You sure there correct? No one knows everything but with what you said above something aint true bud

 

[Newbie90]

So why don't you leave the safety of your fathers tenents to a professional then?

Because I am capable of replacing a consumer just needed a bit of advice of a few bits due to experience.

You learn from asking questions. If no1 asked any questions then everyone would be making a lot of mistakes.

 

[Octopus]

The only other possibility is that the tv amp has been tapped off the lighting circuit but that has a perminant feed and not being switched.[/QUOTE]

Your words, not mine, No mention of it being isolated or disconnected.

 

[bigbaddave]

Because I am capable of replacing a consumer just needed a bit of advice of a few bits due to experience.

You learn from asking questions. If no1 asked any questions then everyone would be making a lot of mistakes.

Your test results are the dogs though bud... What age is the install?

 

[bigbaddave]

The only other possibility is that the tv amp has been tapped off the lighting circuit but that has a perminant feed and not being switched.[/QUOTE]

Your words, not mine, No mention of it being isolated or disconnected.

Tapped off the lighting curcuit and has a perminant feed. Sounds pretty. Sounds pretty fixed to me like

 

[Newbie90]

If it what a dead short as people have mentioned, then surely it would happened every time the light is switched on.

It's only happened a few times in the past week.

I will double check the insulation resistance tomorrow to be 100%.

Installation is probably 20 years old but cable runs are very short as its a small flat.