Some advice needed! Testing

[ashley1789]

Hi,

I’m wondering if anyone would know that when I switch a light switch off I am still getting 40v at the light. I have ir tested all of the circuits in the installation and all passes. Surely this means they’re is a leakage though? 40v is a bit too high?

 

[Pete999]

Hi,

I’m wondering if anyone would know that when I switch a light switch off I am still getting 40v at the light. I have ir tested all of the circuits in the installation and all passes. Surely this means they’re is a leakage though? 40v is a bit too high?

What were the IR test results?

 

[DPG]

Can you be a bit more specific about 'having 40V at the light'. Measured between which two points? What did you get for these:
L-E voltage?
N-E voltage?
L-N voltage?
And as Pete says - what were ther IR figures?

 

[ashley1789]

L-N - 40v
L-E - 40v
N-E - 0

The ir test is 870 mohms

 

[Octopus]

switch off other circuits and see if it disappears ...

 

[MFS Electrical]

What kind of switch you got?, doesn't happen to be one of those with the neon that doesn't require a neutral feed by any chance?

 

[ashley1789]

I’ve turned all other circuits off but it’s still there.

It’s just a normal 2 gang switch

 

[kenny7askew]

out of curiosity what are you using to measure the voltage

 

[ashley1789]

I am just using one of those fluke t5- 1000 multi meters

 

[kenny7askew]

I am just using one of those fluke t5- 1000 multi meters

try using a low impedance voltage tester,multimeters can pick up false/stray readings,there is probably no voltage there

 

[Pete999]

What type of cable has been used?

 

[ashley1789]

try using a low impedance voltage tester,multimeters can pick up false/stray readings,there is probably no voltage there

I’ll try a low impedance tester tomorrow and see what I get with that

 

[ashley1789]

What type of cable has been used?

It’s pvc singles 1,5

 

[Pete999]

It’s pvc singles 1,5

In conduit or trunking, I hope

 

[ashley1789]

In conduit or trunking, I hope[/QUOTE

Yes, it’s in conduit

 

[DPG]

False reading caused by pick-up sounds likely.
You need to be specific and accurate with your measurements though. Voltages are between two points, not 'at somewhere'. IR readings are in MR, not mR - unless the reading you gave us was indeed in milliohms. And between which 2 points was the IR reading you gave taken?

 

[ashley1789]

False reading caused by pick-up sounds likely.
You need to be specific and accurate with your measurements though. Voltages are between two points, not 'at somewhere'. IR readings are in MR, not mR - unless the reading you gave us was indeed in milliohms. And between which 2 points was the IR reading you gave taken?

The reading is between L- E.

 

[Pete999]

False reading caused by pick-up sounds likely.
You need to be specific and accurate with your measurements though. Voltages are between two points, not 'at somewhere'. IR readings are in MR, not mR - unless the reading you gave us was indeed in milliohms. And between which 2 points was the IR reading you gave taken?

Good point on the use of capitals DPG never gave that a thought.

 

[ashley1789]

Good point on the use of capitals DPG never gave that a thought.[/

It was a reading in M ohms. Sorry I didn’t think of that.

 

[Adam W]

Is it actually causing a problem or is it just something you've noticed?
Since it's below 50v I'd put it down to being induced from elsewhere (seems more common with singles) and move on.