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.

 

[Mr.Si]

Thanks SMB. I suspect it will be one light rather than both, so could possibly try some insulation resistance tests at the junction box on a nearby tree, where I believe the lights are both spurred from, so I can see if the individual cables to the light fittings are the problem, rather than the circuit as a whole.

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.

Might have to invest in one of those - they sound useful! Any recommendations on which one?

 

[SMB]

Near-by tree?


Trees move / grow......cables don't like tree movement and growth.

 

[pushrod]

Might have to invest in one of those - they sound useful! Any recommendations on which one?

Can't argue with the value of the Metrel TEK633 AC DC Earth Leakage Clamp Meter - think Tel has just bought one.
HERE if the link works.

 

[topquark]

Tried to replace mine the other day and metrel are not making them anymore, you may be lucky enough to find someone with one in stock though.

 

[Goody]

Thanks SMB. I suspect it will be one light rather than both, so could possibly try some insulation resistance tests at the junction box on a nearby tree, where I believe the lights are both spurred from, so I can see if the individual cables to the light fittings are the problem, rather than the circuit as a whole.

Might have to invest in one of those - they sound useful! Any recommendations on which one?

Would this be any good? -> Metrel TEK 633 AC DC Earth Leakage Clamp Meter | eBay UK

Cheers!

 

[pushrod]

Would this be any good? -> Metrel TEK 633 AC DC Earth Leakage Clamp Meter | eBay UK

Cheers!

Can't argue with that price - a lot of ELCMs are well over £100!
and 100% positive feedback

 

[Mr.Si]

Well, an update...

I was there 6 hours getting my head around the installation and found a couple of delights in the Gewiss IP56 junction boxes...





So much for IP Ratings, (but I suppose since they were mounted on trees and a little warped it's to be expected) however, I found the holes and sealed them.

Sadly the issue still persists but seems to be a couple of problems remaining and I think I've found the problem being 1 of the 2 floods.

They're Azar Nordex 70W units. I think they're just old to be honest.

When live, there seems to be 230v between Line & CPC, but Insulation Resistance at 500v is >500 Meg Ohms, (However the only Insulation Testing I did was the end cable to the light fittings from the Junction boxes). so when I'm next there, I'll need to test the rest of the cabling to check for insulation resistance issues between line and CPC.


Also, I was shocked, but are HID 70W lamps really so expensive?! £50 on Kew Electrical's website! But the light fitting and Lamp together is £51.80...

 

[Deleted member 9648]

Well, an update...

I was there 6 hours getting my head around the installation and found a couple of delights in the Gewiss IP56 junction boxes...




So much for IP Ratings, (but I suppose since they were mounted on trees and a little warped it's to be expected) however, I found the holes and sealed them.

Sadly the issue still persists but seems to be a couple of problems remaining and I think I've found the problem being 1 of the 2 floods.

They're Azar Nordex 70W units. I think they're just old to be honest.

When live, there seems to be 230v between Line & CPC, but Insulation Resistance at 500v is >500 Meg Ohms, (However the only Insulation Testing I did was the end cable to the light fittings from the Junction boxes). so when I'm next there, I'll need to test the rest of the cabling to check for insulation resistance issues between line and CPC.


Also, I was shocked, but are HID 70W lamps really so expensive?! £50 on Kew Electrical's website! But the light fitting and Lamp together is £51.80...

What were you expecting between Live and CPC ?

 

[pushrod]

Hi Mr Si, i had to sort a similar installation and embarrassingly assumed that all the grotty outdoor enclosures were the problem . Having sorted them the problem persisted - i then discovered the owner had put up a new curtain rail 2 months earlier (neatly drilling through the cable in the process) but had not used the garden lights since! I now no longer try to jump to conclusions even when something is glaringly obvious . The boxes had been part of the problem but not the only one - stick to the logical approach

 

[Mr.Si]

not 230! I'd have expected 0. But now you question me, I'm now questioning myself.

I'm still fairly studentish but have a lack of practice...

 

[Mr.Si]

not 230! I'd have expected 0. But now you question me, I'm now questioning myself.

I'm still fairly studentish but have a lack of practice...

Yep, my bad, I was forgetting about PD. it should be 230 after all.

 

[Deleted member 9648]

Newly married mate......my mind wouldnt be on the PD between L and CPC either

 

[Wiredspark]

If you've done your IR on the individual fittings and they're clear I.e. your reported results show they are (<500Mohms) then you have to IR the rest of the circuit it's that simple. Before Looking at your pics mate, I was gonna ask what type of cable is supplying but I can see it's an Armour, so it's unliekly there is gonna be enough damage to that to be causing your fault, unless someones been lazy with the depth to which it should be buiried and a wee bit over zealous with the spade whilst gardening, but you never mentioned the wee low voltage transformer, have you checked this?

 

[Wiredspark]

Just looked at your pics again and noticed that it says 50W MAX, and your running 70W lights off them!!!!!!

edit it says 50W MAX on the LV transformer

How many fittings are running off each trannie?

 

[Mr.Si]

Sorry Wiredspark, those ELV transformers are for different lights - they supply the "other" lights around the garden which are just 12v halogen types, of different styles and for the pond light. They are all fine, it was just the floods which were the problem, but due to the original design, they are mounted in the same junction boxes and take their supply from the multicored SWA.

Sorry, it was a red herring putting those photos with the transformers in, without dis-regarding their relevance. My bad.

After lots of deliberation, it may well be that the replacement of the units will fix the issue - age and deterioration, but I shan't be able to report back until after my honeymoon, as electrical work for me at present is a saturday thing

Have found some nice new units at the local wholesalers, I think they're by Thorn, but I could be wrong because I can only find them which ae 150W and above. Either way, they're fully perspex.