Going to look at my parents' outdoor lighting on Saturday (weather permitting)...

[Mr.Si]

They've got a few different circuits supplied from a separate CU in the shed, all protected behind a single RCD. Controlled by a 6 way switch in the house.

There's one circuit which trips the whole outdoor installation, which is basically 2 flood lights. Initially they turn on, but shortly afterwards the RCD goes.

I'm thinking this is an insulation resistance issue between Phase to Earth or Neutral to Earth but will need to test this to confirm. Though it might just be an issue with water ingress, causing the insulation resistance issue. Does that sound about right?

Since it's an RCD protected circuit, I assume I'll need to remove Ph & N and join together in a choc-bloc or in a croc-clip and test between here and earth, is that right?

I'll have my GN3 and Onsite guide etc, but just wanted to run it by you all first...

I'll appreciate your comments.

 

[telectrix]

sounds about right. however 250v may not be enough to show up the fault. if not, remove lamps then test each phase conductor to earth at 500v. water ingress sounds favorite.

 

[i=p/u]

or could be your parents winding you up to see your serious electrical head

 

[Mr.Si]

Thanks Telectrix,

Oh I'd have done a 500v regardless as I'd have removed the RCD from the equation first.

or... not sure here - can't remember - but can't you test at 500v with ph&N joined together?

Oh I see, 250v with lamps in, or 500 with lamps out. (Bit slow today)

 

[Mr.Si]

or could be your parents winding you up to see your serious electrical head

Lol, sadly I've just moved out about 6 months ago and had a quick look before but it's actually been a problem for a long time!

As an aside... whilst it's a nice with the 2 floods lighting up the trees with a sodium glow, I prefer the look of when I stuck about 8 PAR Cans out there with different colours, it looked better...

 

[i=p/u]

do you have to test line/neutral together @ 250v, wouldnt of thought so???? correct me

Thanks Telectrix,

Oh I'd have done a 500v regardless as I'd have removed the RCD from the equation first.

or... not sure here - can't remember - but can't you test at 500v with ph&N joined together?

Oh I see, 250v with lamps in, or 500 with lamps out. (Bit slow today)

 

[i=p/u]

il get me book out

 

[Farmelectrics]

you can test at 500v with LN together i usually test at 250v first and then 500v if the readings good

 

[telectrix]

an eartyh leakage clamp meter would be useful here.

 

[Goody]

an eartyh leakage clamp meter would be useful here.

On what principle an Earth Leakage Clamp Meter works, I haven't used one so far.

Cheers!

 

[pushrod]

just a clamp meter that is sensitive enough to measure current imbalance in milliamps betweeen either L and N or in the cpc, when the circuit is on.

 

[SMB]

An insulation resistance test at 500v is what I would do first.

Disconnect the lights which you suppect to be causing the fault and test between L/E, L/N, N/E at source. (Be sure to reconnect the lighting circuit in connectors before carrying out IR test).

If the fault is no longer there after this test then you have almost found your problem.....

 

[Mr.Si]

(Be sure to reconnect the lighting circuit in connectors before carrying out IR test).

Sorry to appear dumb, but which connectors do you mean - do you mean in the MCB?

 

[SMB]

Hi

no, what i ment was to connect all the cables back together at the light fittings (in connectors) if the lights are wired 3 plate.

 

[SMB]

disconnect the lights.

if they are wired 3 plate then reconnect the wires in connectors then re-test.