lights not working - broken neutral?

[Speleo]

Hi,

My stair lights (4 way switched circuit) and attic lights have stopped working. When they first failed they were flicking for a while and then just stopped. I’ve had an electrician out twice to fault find. First time they started working again just before he arrived, and second time the electrician took one look at it and said he didn’t have the right tools (still sent an invoice – unpaid).

I’ve not rewired anything on the circuit but may have loosened some faceplates for painting. Testing the circuit shows I’ve got 240v between live and earth but nothing between live and neutral. My understanding is that this points to some kind of broken neutral in the circuit. Is this a correct assumption?

By switching the circuit off at the consumer unit I can identify that all the upstairs lights are fed from that breaker. My problem is that I don’t know the layout of the circuit to identify the order in which the lights are run. The house predates electricity so the wiring has been retrofitted in what may be along a non contiguous route. Is there a method to identify the order in which the circuit is provided?

Any ideas would be most appreciated.

 

[Big_Spark]

Speleo, firstly, where are you testing this neutral? There are no neutrals in switches, except in the case of double pole switches or in connector blocks.

The black in a switch plate is not a neutral, it is a switched live (should be marked red by rights) and if you put a tester across it, there is a good chance you will not get a reading at all..some testers will show 230V on some lighting circuits if there is then a neutral path via the fitting.

If you have loosened faceplates, check all the connections are tight, it is possible that the live has been looped through the switches rather than the cieling roses (no problem with that) and one may have come loose and is causing a break in the circuit that may have been missed.

 

[Speleo]

Thanks for coming back on this. I was thinking the connections to the actual switch are "live" runs and the return route is which is connected outside the switch was the "neutral".

Most of the light fittings are on wall sconces rather than ceiling roses.

If I've got power running thu the switches can I assume that the loose connection is not on the switch but rather the return loop? Should save some time with testing...

 

[Big_Spark]

If all connections in the switches are tight and secure, and the power is running through the switch when operated then Yes, you can assume that part is OK.

The next step in the fault find process would be to remove each light in sequence and see if the power is arriving at the switch OK, if not it is broken somewhere, and if you have 230V registered across the LIVE and NEUTRAL terminals of the fitting. If you have, then the problem is further up the circuit, if not, you know the problem is elsewhere, but before you currently testing.

Fault finding needs to be logical and methodical, always work safely, never take uneccessary risks and you will eventually find the source of your problem so it can be corrected.

 

[Speleo]

Thanks for the advice. I used to be an IT hardware engineer back in 80's so I know about working from 1st principles and hear your advice on keeping it safe.