- Reaction score
- 8,774
A builder friend calls me up to have a look at a "strange situation".
He points at a joint box above and outside a back door. "Old outside light?" I ask.
He's extended this into a new conservatory. "That's probably switched" I guess. "No I found a permanent live" he said.
He's run it into a light switch. The Blue wire is showing 230v to earth. The brown wire is showing nothing at all. Blue to Brown also show nothing.
The joint box isn't of interest, it's just black -> blue, red -> brown, cpc -> cpc and all good connections.
I look for evidence of a former switch and find a nearby 2 gang switch with only one switch connected. There's also a single black wire with a choc block.
The switch that's connected is for the kitchen light. Neither the red nor the black connected to the switch show any voltage with a 1 pole tester, a 2 pole tester to a known good earth, or using a non contact tester (volt stick). That applies in either switch position.
The loose black in the chock block shows continuity to the builders extended brown wire that was previously mentioned.
Yet the kitchen light works and switches on and off. All tools used work.
What might you suspect and how would you proceed to test and prove it?
I'm sure the usual crowd could answer very quickly, maybe a trainee wants to have a think about what they would do next in this real life example of it all going a bit off script?
He points at a joint box above and outside a back door. "Old outside light?" I ask.
He's extended this into a new conservatory. "That's probably switched" I guess. "No I found a permanent live" he said.
He's run it into a light switch. The Blue wire is showing 230v to earth. The brown wire is showing nothing at all. Blue to Brown also show nothing.
The joint box isn't of interest, it's just black -> blue, red -> brown, cpc -> cpc and all good connections.
I look for evidence of a former switch and find a nearby 2 gang switch with only one switch connected. There's also a single black wire with a choc block.
The switch that's connected is for the kitchen light. Neither the red nor the black connected to the switch show any voltage with a 1 pole tester, a 2 pole tester to a known good earth, or using a non contact tester (volt stick). That applies in either switch position.
The loose black in the chock block shows continuity to the builders extended brown wire that was previously mentioned.
Yet the kitchen light works and switches on and off. All tools used work.
What might you suspect and how would you proceed to test and prove it?
I'm sure the usual crowd could answer very quickly, maybe a trainee wants to have a think about what they would do next in this real life example of it all going a bit off script?
