37v present in switched off lighting circuit!

[RF Lighting]

Yep, it's a TN-C-S with the supply sheath bonded.

It's done quite alot round here, normally when the TN-S has failed.

 

[Leedsposter]

It looks like some sort of TN-CS conversion done by the DNO, possibly to earth the sheath of their supply cable. There doesn't appear to be any of the earthing leaving the supply head area to your side of things so you could quite easily be on a TT system.
Can you post a pic of your consumer unit?

Here's the circuit breaker:

Untitled

• Leedsposter
• 28 Feb 2010
• 1

Is that what you want? The two righthand large cables at the bottom go to the meter (see earlier picture)

 

[Leedsposter]

Yep, it's a TN-C-S with the supply sheath bonded.

It's done quite alot round here, normally when the TN-S has failed.

thanks

 

[Spark123]

Can you see one of the green/yellow wires between the consumer unit and the earthing on the DNO cutout?
Is there anthing else in the meter tails between the meter and the CU?

 

[Leedsposter]

Can you see one of the green/yellow wires between the consumer unit and the earthing on the DNO cutout?
Is there anthing else in the meter tails between the meter and the CU?

Just two heavy duty wires from breaker box to the meter as depicted 2 posts above. (wire on the left of these two just goes to bell transformer)

You can see two green/yellow going upwards from the breaker box; one goes to the gas pipe, and one up into the garage ceiling.

 

[Spark123]

There is a real possibility that your installation does not have an effective means of earthing, my advice is to get an electrician in to check this out as soon as possible.

 

[Leedsposter]

There is a real possibility that your installation does not have an effective means of earthing, my advice is to get an electrician in to check this out as soon as possible.

gulp!

I guess I should get it checked, though I remembered I had a full structural survey including an NICEIC report back in 96 before I bought the house; I looked it up and has "TN-S" ticked. But re-reading it now, I notice it suggest a full re-check after the recommended rewire, so maybe it's time to do that now

 

[Leedsposter]

I just realised I never posted the upshot of this -- I got an electrician in who did put in an earth between the breaker box and the master supply. The 37v problem was finally traced to a miswire in the double pole switching units in for the lights -- though not sure exactly why this caused it. Any how, problem got sorted . Thanks to all for their advice.

 

[bernardgreen]

Getting back to the original question and one more common cause

//www.diynot.com/forums/viewtopic.php?p=1811080#1811080