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Why are the lights not working!!!!!

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HappyHippyDad

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Just popped in to a friends house on the off chance that I could quickly remedy some none working lights before heading off to work. Unfortunately it was all a bit odd!

Over the past 2 years the ground floor lights have stopped working perhaps 3 times. They stop for either days or weeks then start working again.

None of the ground floor lights are working at present, so I started at the origin, I.e the CU. There was 240v on the line conductor (to earth) leaving the RCBO, but also 240V on the neutral conductor (to earth) leaving the CU. I realise it's unlikely to be a faulty RCBO, but I have come across a faulty protek MCB before, along with a faulty chint RCD. Only 2 faulty breakers in the past 10 years, as it's nearly always something else that's at fault. I'm only mentioning this to explain why I dived in with 'faulty breaker', plus I was hoping for a quick fix.

However, in the meantime they all started working and there was no longer 240V on the neutral terminal of the outgoing RCBO. All I had done is take the lid off of the CU and switched a few light switches on and off.

As stated earlier i considered a faulty RCBO, so I put the ground lights on a different RCBO. They then all stopped working again, and there was now 240V on the outgoing neutral terminal of this RCBO (along with 240V on the line). I put them back in the original RCBO and they all worked again.

Also, the test button on the RCBO's didn't work when there was 240V on both the line and neutral, when this cleared the test button worked.

Also, the test button didn't seem to work on the spare RCBO's that had power going to them, but no outgoing conductors in place. However, they did work on one of the RCBO's that was spare (without conductors). I checked the busbar and it was correctly in place for all RCBO's.

Ground lights are now switched off and I'll return, but I'm embarrassed to say I really can't think of what to do. Usually, a fault shows up, I break the circuit down, find it and fix it, but this is different to usually. Any suggestions?

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......I am a smoker and wouldn’t recommend it to anyone but it does have the advantage of giving me a reason to escape, stand outside and consider what I am dealing with and come up with a plan of attack...

When I was an apprentice we were taught by a journeyman who always said smokers make far better refrigeration techs than non smokers because things take time with refrigeration and smokers are a lot more patient, they'll light up a smoke and wait for an outcome or result to an action without getting bored and skittish.
 
I am a smoker and wouldn’t recommend it to anyone but it does have the advantage of giving me a reason to escape, stand outside and consider what I am dealing with and come up with a plan of attack.
I'm not a smoker but sometimes just to get outside and gather your thoughts can be very beneficial
Whatever fault it is that is confusing, nearly always has a logical cause, sometimes it is just a case of saying to the customer that you need to pop out to the van and “find your spare flux capacitor or calibrated test meter”
Use the time to stare at the clouds and summon your logical brain into action.
I find the millionaire option is good and phone an electrician friend I do some of the bigger jobs with for the sanity check he does the same with me a couple of his in the past have had the DNO digging up the street after talking to me
Anyone who has never misdiagnosed a fault is either a lucky person that has never had a difficult fault to figure out or a liar.
Has never done any fault finding or has been incredibly lucky on the faults they have tackled
Don’t beat yourself up, we have all had days where we are the plonker, let’s face it if I had a pound for every mistake I have made, maybe I wouldn’t quite be a millionaire Rodney but I would certainly have enough to go to the Bahamas for a week.
It can be so frustrating when it becomes glaringly obvious that you have spent a lot of time not seeing the wood for the trees but that is what experience is just log it for next time
 
I returned today.

All the neutral fly leads were terminated correctly. It turns out there was intermittent continuity between the end of the fly lead and the neutral termination on the RCBO. Hence the 240V (actual voltage) on the neutral on occasion. New RCBO used :)
 
Unusual one! They may be making contact, but I'd dispute that they are terminated correctly. On 3, 5 and 6 at least, the terminal screw appears to have missed the ferrule completely and is tightened down on the copper.
Good call and poor terminology on my part. I have actually moved them all down a little now as I wanted to check them all, they are now making contact with the ferrule. Actual problem was with the RCBO though.
 
I hate intermittent faults.
I've had two tripping RCDs this week, and whenever I'm there there is adequate IR results and negligible earth leakage results. No smart meter. Everything visible plugged in and running, all lights turned on. One one of them I've rigged up a temp board with fridge freezer on an extension lead as my latest theory is there is a defrost heater on a 24 hr timer.
On the other one I've exchanged two circuits each side of the board, and we'll see which RCD trips next time.
Luckily these customers understand the needle-in-haystack aspect of this challenge!
 
I hate intermittent faults.
I've had two tripping RCDs this week, and whenever I'm there there is adequate IR results and negligible earth leakage results. No smart meter. Everything visible plugged in and running, all lights turned on. One one of them I've rigged up a temp board with fridge freezer on an extension lead as my latest theory is there is a defrost heater on a 24 hr timer.
On the other one I've exchanged two circuits each side of the board, and we'll see which RCD trips next time.
Luckily these customers understand the needle-in-haystack aspect of this challenge!
What did you mention the smart meter for Tim? It sounds as though that could help in some way.
 
What did you mention the smart meter for Tim? It sounds as though that could help in some way.
The era has largely passed now, but certain RCDs e.g. Square D can be affected by the radio signal from Smart Meters, causing endless confusion. So a tripping RCD and a brand new smart meter is a combination to raise an eyebrow at.
 
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