Mains Electric Cable puzzle.

macabethiel · 20-01-2015, 17:14

I am helping a friend repair an illuminated sign that was vandalised by either kids or possibly cable thieves.

The armoured cable has been ripped out of the junction box leaving it live and exposed to the elements. I have fitted a new junction box but due to the lamp wiring having been ripped out I am having trouble identifying the correct connections.

The armoured cable is about 20 years old and consists of two yellow cables, a black cable and a blue cable. One of the yellow cables is sleeved as earth, the second yellow cable is clearly live and has signs of faded red marking on it. This yellow cable lights up my Neon Screwdriver and tests at mains voltage on my Multimeter.

I am trying to work out if the neutral is black or blue and up to now have been unable to trace where the wiring enters the building.

Is there any reliable way of establishing which is the neutral from the junction box end or is it essential to find the other end of the cable where it enters the building ?

20-01-2015, 17:14	#1
macabethiel Senior Member Join Date: Aug 2008 Location: Derby Vehicle: Freelander & Jeep GC 3.0 Posts: 4,416	Mains Electric Cable puzzle. I am helping a friend repair an illuminated sign that was vandalised by either kids or possibly cable thieves. The armoured cable has been ripped out of the junction box leaving it live and exposed to the elements. I have fitted a new junction box but due to the lamp wiring having been ripped out I am having trouble identifying the correct connections. The armoured cable is about 20 years old and consists of two yellow cables, a black cable and a blue cable. One of the yellow cables is sleeved as earth, the second yellow cable is clearly live and has signs of faded red marking on it. This yellow cable lights up my Neon Screwdriver and tests at mains voltage on my Multimeter. I am trying to work out if the neutral is black or blue and up to now have been unable to trace where the wiring enters the building. Is there any reliable way of establishing which is the neutral from the junction box end or is it essential to find the other end of the cable where it enters the building ?