Tester lighting up on Neutral

[Glyn1959]

Hi i have two lights in conservatory which are both simple spurs of lighting circuit. One of the lights failed to light and a bulb chaonge didnt solve the problem. I swapped the fittings and the one that failed to light worked and the one that previous worked didnt suggesting it could be the switch. I bypassed the switch but no change. There is power to the live terminal of the light (checked using a neon tester) but the tester also lit up on the neutral! Should this happen. The light has worked fine for months by the way. Any ideas?

 

[Scoby_Beasley]

TBH a neon test screwdriver is the most unreliable (read UNSAFE) method of checking circuits.

It sounds to me that the "dead light" spur has a loose connection somewhere, most likely the neutral.

Do you have any other means of testing for continuity (with the power OFF!!)?

 

[Glyn1959]

Hi, just learnt that a heater was fixed below the light at the weekend and the light has not worked since! Drill mishap? Customer is getting the sparky back!

 

[Scoby_Beasley]

Hi, just learnt that a heater was fixed below the light at the weekend and the light has not worked since! Drill mishap? Customer is getting the sparky back!

Lost me there!! Heater fixed below light? Where's the light (up or down)? Where's the heater (opposing to light)?

But yes, the most likely scenario is that the last piece of building work, of any type, is the reason for a once reliable (??) fitting to no longer work is down to the fact that something has recently interfered with it (not always, but an excellent starting point).

 

[securespark]

Does sound like an open neutral. Check continuity.

 

[Scoby_Beasley]

Sorry, should've read original post. The heater was being hung below a light fitting (I guesstimate).

 

[mikeyd]

the tester also lit up on the neutral

Neon testers should be banned.

If the lamp (bulb) was in the fitting when you tested it then it does suggest a broken neutral supply as the neutral is connected to the live through the filament and no current is flowing so no voltage drop. A meter would also have read somewhere around 230V (depending on the impedance of the meter).

So next time use a proper meter but also double-check after removing the lamp.

Off topic (sorry): The manufacturer of my boiler sent an 'engineer' out under warranty who diagnosed a failed PCB and claimed it was because the thermostat neutral was sending 230V to the PCB (presumably after he measured it disconnected but with the live still connected) Refused to reconnect Thermostat but replaced PCB as a 'goodwill' gesture.