Help please, What would you do?

[Happychappy]

I have a customer who has 4 12v spotlight that are intermittent. The original installer decided to install the transformers where they couldn't be accessed from below so the only way to get to them is by lifting carpets and flooring above. Once the floor was lifted and the transformers were located I found that even though the lighting circuit is 1mm sinlges with CPC the installer had wired the 230v side of the transformer in 0.75mm flex with no CPC. Obviously the 12v side doesn't have a CPC but the cable supplying the 230v side should have a CPC to protect the cable itself. I could see the junction box so I thought I'd replace it with the correct cable to cover my back. I opened up the junction box and there was a neutral cable wired to the CPC. I don't know if someone has actually wired neutral to CPC or if someone had used a neutral cable as a CPC so I did an insulation resistance test. I got 0 ohms between all conductors to earth. I then removed the neutral cable from the junction box and retested but still got 0 ohms (all lamps where still connect but no florescents or anything I could see that would have an earth leakage). I obviously wasn't going to now install new cable to this junction box when I can't confirm what this neutral cable is doing connected to the CPC. My question is, because it's maintenance, do I just replace the transformers to the existing 0.75mm flex, when also knowing there is a potential neutral to cpc fault and let the customer know about the issues or do I just not touch it?

Cheers in advance for your opinions.

 

[SparkyChick]

Without being there it's hard to say... but have you looked in the switch that controls these?

It could be that the CPC in the red (grey sheated single) is actually being used as the permanent live. If that's not the case have you been able to establish where that black single connected to the CPC goes?

I'd also be concerned about the materials of those black singles. They look remarkably like rubber so your client may have a bigger problem as that stuff should have been dealt with when the lights were installed (at least in my opinion, I wouldn't be making changes/additions to an installation wired in rubber).

 

[Happychappy]

Without being there it's hard to say... but have you looked in the switch that controls these?

It could be that the CPC in the red (grey sheated single) is actually being used as the permanent live. If that's not the case have you been able to establish where that black single connected to the CPC goes?

I'd also be concerned about the materials of those black singles. They look remarkably like rubber so your client may have a bigger problem as that stuff should have been dealt with when the lights were installed (at least in my opinion, I wouldn't be making changes/additions to an installation wired in rubber).

Thanks for your reply.

I did check the switch and that was all in red singles. The neutal connected to earth went in a different direction into another room so would have had to lift more and more flooring to try and follow it.

All the cable is pvc, no rubber.

 

[SparkyChick]

In that case, I might proceed as follows... With the black single connected to CPC disconnected, I'd confirm the CPC in the grey single is actually connected to earth with either a long lead test back to the board or by a simple continuity between it and the neutral in that box. I'd then safely contain the end of that black single and restore power and check earthing elsewhere on the circuit and ensure everything else is working as expected.

If it transpires it provides the CPC for some other point in the circuit I would mark it up as such and crack on with the job. If in fact it provides the neutral, then check the earthing, mark it up and connect it correctly.

 

[Happychappy]

In that case, I might proceed as follows... With the black single connected to CPC disconnected, I'd confirm the CPC in the grey single is actually connected to earth with either a long lead test back to the board or by a simple continuity between it and the neutral in that box. I'd then safely contain the end of that black single and restore power and check earthing elsewhere on the circuit and ensure everything else is working as expected.

If it transpires it provides the CPC for some other point in the circuit I would mark it up as such and crack on with the job. If in fact it provides the neutral, then check the earthing, mark it up and connect it correctly.

That is a good method for identifying what the connection actully is. Would you not replace the transformer unless that is done or because it's maintenance would you be prepared to change the transformer and tell the customer of the problem and what needs to be done?

 

[SparkyChick]

I think my priority would be identifying that conductor and it's true purpose. Obviously if the customer isn't willing to cover the costs associated with that, I'd have to have a serious talk with them and try and explain why it needs sorting. If they still weren't willing, I'd probably restore it to the state it was and leave and then be sure I sent them a detailed email/letter explaining why the situation is potentially dangerous.

If for example, that cable is actually a neutral I'd be seriously considering disconnecting the circuit at the CU as there is the potential for a break in the CPC between that point and the CU could see mains voltages on the CPC and any metalwork connected to it.

 

[Pete999]

I would show the customer/client what you have discovered, and submit a price for redoing this install properly using the correct materials for 1 a maintenance free Joint box, in my opinion that's a terrible installation.
Cable sheaths not entering the JB cables not secured in anyway apart from the terminals, awful job.

 

[telectrix]

i'd collect a fee for telling them it's a mess and then straight to the pub..