Lighting

[walec]

I am new to this so please be gentle, I was changing a light and found there to be 54v on the live when the switch is open and 240v when closed, why the 54V and if I change the CU is it going to cause any problems? Thanks

 

[Mark.W]

It could be a faulty switch, isolate the supply at cu and test again! but surely you have isolated the supply before working on the circuit......
A simple change of a light shouldn't result in a cu change???

 

[zupos40]

I am new to this so please be gentle, I was changing a light and found there to be 54v on the live when the switch is open and 240v when closed, why the 54V and if I change the CU is it going to cause any problems? Thanks

It could be a fault or shared neutrals and you getting a back feed from the neutral down to the switch, or could be a neutral to earth fault with a break in neutral or have you checked that it not an earth fault.

 

[Modernelectric]

54 v between live and neutral or live and cpc?

 

[claire_r]

loose neutral from prev light in circuit?

 

[walec]

I dont think I explained very well.
This is s 1960s Bungalow, i was changing the light and was checking voltage before isolating. The fuse board is the replacable fuse type and I am going to change it as part of my inspection.
the wiring is all surface work lying on the ceiling across joists etc with JBs everywhere.
In truth the whole house could do with a rewire.
The 54v is between live & N & live & CPC.
I will check all scenarios tomorrow.
Thanks

 

[Modernelectric]

maybe from a borrowed neutral

 

[stef]

Could be a switched neutral, with the circuit open you then could get a floating voltage. Did you use a multimeter
or a proper two pole voltage detector?

 

[walec]

two pole voltage detector.