still problems with lighting

[Rockomuir]

Hello there,

Been having a few problems with an intermediate switch that i was asked to look at. The original problem was that the int switch did not work properly as you could only turn the lights on and off at the top and bottom of stairs if you opened or closed the intermediate switch. I understand intermediate switching but i am used to the way it is wired in new installs. This one has three core between the switches but the cables meet in a jb under the floor. At the last switch they wired a 2nd three core where it looks like they are using the blue and red as a switch line and feed for the hallway lights. The yellow core goes into the l1 of another gang of a three gang switch which i think is being used as a seperate s/l for something else. I will post pics to try and explain.

I was just starting some intial testing when turning off the upstairs mcb and leaving on the downstairs mcb that i found that the upstairs hallway lights did not turn off. They would only become dead when i turned both the breakers off. I ran out of time today so am going back tommorow but was after any advice on why the breakers would not indepently isolate each circuit( maybe a borrowed neutral) and intermediate switching through a jb rather than looping in switch.


Thanks

 

[somersetsparks]

You have a borrowed neutral (or borrowed live) whichever you prefer. Sounds like it might feed an outside/cupboard light and they have just nicked the neutral from upstairs, would need a diagram really though mate.

 

[Rockomuir]

Thank You for the reply,
I think it might be for a loft light. Would a borrowed neutral have some link to the mcb problem/int switch. Sorry if this sounds stupid but i have not come across a borrowed neutral before as did my training on house bashing.

 

[somersetsparks]

It sounds more like just the landing lights being fed from the downstairs circuit to be honest which is O.K. A borrowed neutral is where a light uses the live of one circuit and the neutral of another.
I think what you need to do is work out what cores you have and where they go and what you need in diagram form it will become much clearer to you then! I often do it with switching problems

 

[Rockomuir]

Thanks, I will draw it out tomorrow and hopefully have some success