Light Socket Shows 176 Volts

[PosiDave]

Anyone any ideas what would reduced down a porch light socket from 240 to a now 176 volts. Examined hall light by from door and all voltages perfect. I just have no idea why the voltage would be down to 176 and this is the bare wires ( removed hanging light fitting). Asking for ideas before I cut into the ceiling....

 

[DetlefSchmitz]

Depends what you were measuring with. If it was a multimeter - maybe the light was switched off.

 

[PosiDave]

Yep pretty good with installing and testing electrics with voltages and yes these readings were with mulimeter hence specific voltage of 176.. Just no idea what would cause the drop. All other lighting electrics within the house near porch read correct

 

[sparkwright]

Disturbed hidden joint above porch light wiring?

 

[PosiDave]

Really good recent wake consumer box fitted and no issues with lighting circuit and yes reading is with light switch turned on. Checked light switch unit which also is good.

 

[PosiDave]

If a joint was disturbed would it not be either no voltage or correct 240 ? Not sure what scenario would drop it to 176 - what do you think have you encountered this before.. Still clutching before digging into ceiling

 

[bernardgreen]

Best guess is open circuit Neutral capacitively coupled to Earth in the cables. There will be enough energy through the capacity to create a voltage in the meter.

Put a lamp holder on the ends and fit a filament lamp. Switch on and if the voltage across the lamp is zero then it is an open circuit Neutral.

Or use a low impedance ( moving needle ) meter and see if the 176 drops lower.

 

[AndyPRK]

A poor joint would show a lower voltage

I assume no lamp was fitted at the time ?

 

[PosiDave]

Yep when lamp attached no light .. If the neutral was touching a ground would the red not fire on the consumer unit? ... Really appreciate all your help here guys as this is last attempt before opening up above....

 

[JohnW2]

A poor joint would show a lower voltage

With no load, a 'poor' (but not open-circuit) joint ought to result in a 'normal' (230V or whatever) reading on a high-impedance voltmeter.

As bernard has said, it's possible that the neutral is completely O/C and that the voltage being shown (with a high-impedance meter) is resulting from capacitive coupling to N or E. As bernard has said, measuring on-load is probably the simplest way of clarifying.

Kind Regards, John

 

[deadshort]

I would check continuity between N +E at the light fitting with the main switch on, before you cut the ceiling open




Regards, DS

 

[JohnW2]

I would check continuity between N +E at the light fitting with the main switch on...

Could you perhaps clarify what you mean? I presume you are not advising the OP to conduct a continuity test on a live circuit?

Kind Regards, John

 

[deadshort]

No the circuit is off hence, the continuity test.

Regards,

DS

 

[JohnW2]

No the circuit is off hence, the continuity test.

Fair enough, but I still don't really understand (and fear that the OP may not understand) what you meant by ".. with the main switch on".

Kind Regards, John

 

[deadshort]

Yep pretty good with installing and testing electrics with voltages and yes these readings were with mulimeter hence specific voltage of 176.. Just no idea what would cause the drop. All other lighting electrics within the house near porch read correct

The OP is confident enough to understand what is meant by continuity

Regards,

DS