Hi
Wife bought a new light for the porch and pestered me to fit it this evening. It should have been a five minute job to be honest as all I needed to do was switch off the electricity, mark the wires, remove the ceiling rose and put up the new light.
I quickly identified the switched live and wrapped some insulation tape on it but I obviously didn't wrap it well enough because a minute later whilst sipping my cup of tea the insulation tape fell off pulling with it the red sleeve marking my switched live.
As soon as I realised what had happened I could feel that sick feeling in my stomach as I knew now that I had to quickly identify the switched live before it went dark otherwise we'd be without lights.
Without a multimeter to hand my brain went into overdrive thinking of a way to do a continuity test on the cables. Then I grabbed an old headtorch which had a flip open cover where the batteries were housed. I could see that the batteries were connected together when the cover was shut so I decided to use this to test for continuity.
Three grey cables, all with red, black and earth wires in each.
I took the first grey cable and connected the red wire to one battery and the black wire to the other battery. No light on the torch so got the wife to flick the wall switch and still no light on torch, so knew that wasn't the wire.
Took the second grey cable and did the same, the torch light came on, told the wife to flick the wall switch but the light still remained on. So I thought this mustn't be the the switched live either.
Took the third and last grey cable and did the same again. No light on the torch at first but when my wife flicked the wall switch the torch light came on. I knew that this must be the switched live but I was intrigued as to why the torch had lit on one of the other cables.
Anway, I wired up the new light as per the previous ceiling rose configuration and put the power back on to find all lights working fine and new porch light and switch working just fine.
My query is this, why did the torch light on one of the other cables during the test?
Is it because I never turned off the MCB for the lighting circuit despite turning off the main power?
Thanks in advance.
Wife bought a new light for the porch and pestered me to fit it this evening. It should have been a five minute job to be honest as all I needed to do was switch off the electricity, mark the wires, remove the ceiling rose and put up the new light.
I quickly identified the switched live and wrapped some insulation tape on it but I obviously didn't wrap it well enough because a minute later whilst sipping my cup of tea the insulation tape fell off pulling with it the red sleeve marking my switched live.
As soon as I realised what had happened I could feel that sick feeling in my stomach as I knew now that I had to quickly identify the switched live before it went dark otherwise we'd be without lights.
Without a multimeter to hand my brain went into overdrive thinking of a way to do a continuity test on the cables. Then I grabbed an old headtorch which had a flip open cover where the batteries were housed. I could see that the batteries were connected together when the cover was shut so I decided to use this to test for continuity.
Three grey cables, all with red, black and earth wires in each.
I took the first grey cable and connected the red wire to one battery and the black wire to the other battery. No light on the torch so got the wife to flick the wall switch and still no light on torch, so knew that wasn't the wire.
Took the second grey cable and did the same, the torch light came on, told the wife to flick the wall switch but the light still remained on. So I thought this mustn't be the the switched live either.
Took the third and last grey cable and did the same again. No light on the torch at first but when my wife flicked the wall switch the torch light came on. I knew that this must be the switched live but I was intrigued as to why the torch had lit on one of the other cables.
Anway, I wired up the new light as per the previous ceiling rose configuration and put the power back on to find all lights working fine and new porch light and switch working just fine.
My query is this, why did the torch light on one of the other cables during the test?
Is it because I never turned off the MCB for the lighting circuit despite turning off the main power?
Thanks in advance.
