Megger UL exceeded any advice?

[Jako13!]

Have any of you had your megger come up with UL exceed. I can’t work out what the issue is? Was trying to take a measurement on a sub main for ZDB with the 3 lead method but keep appearing with UL exceeded. The system has an earth and correct polarity any ideas anyone? Thanks

 

[westward10]

UL exceeded will indicate the meter is detecting a touch voltage above 50v.

 

[Julie.]

Have any of you had your megger come up with UL exceed. I can’t work out what the issue is? Was trying to take a measurement on a sub main for ZDB with the 3 lead method but keep appearing with UL exceeded. The system has an earth and correct polarity any ideas anyone? Thanks

Measure the voltage between N and earth.

Or use 2 wire method L to E

 

[Jako13!]

UL exceeded will indicate the meter is detecting a touch voltage above 50v.

Thank you westward I’m just trying to get my head round it. It’s a TNCS supply. When I tested L-N 230v N-E 0v and L-E 230v. Excuse me for being silly but where would these touch voltages be for the megger to recognise them?

 

[Jako13!]

Measure the voltage between N and earth.

Or use 2 wire method L to E

I can’t they’ve protected the sub main with an RCBO

 

[Julie.]

I can’t they’ve protected the sub main with an RCBO

The device is seeing more than 50v where it doesn't expect it, either n-e voltage, or L & N reversed on the meter

 

[westward10]

Is the board you are looping at switched on under load conditions.

 

[westward10]

One of the many reasons I use loop testers which are 20 odd years old they don't have the annoying quirks modern testers have.

 

[Jako13!]

Is the board you are looping at switched on under load conditions.

That was my next question I’m probably being silly when the main switch is on and all circuits off it’s all good but when the main switch is off it shows UL exceeded?

 

[Jako13!]

View attachment 94206

 

[westward10]

Does the switch also isolate the neutral.

 

[Jako13!]

One of the many reasons I use loop testers which are 20 odd years old they don't have the annoying quirks modern testers have.

I’m being an idiot

 

[Jako13!]

Does the switch also isolate the neutral.

Yeah that’s why I’m being an idiot

 

[Jako13!]

Yeah that’s why I’m being an idiot

Sorry guys aha I was testing on the neutral bar with the main switch off makes sense now

 

[Jako13!]

Thank you for your help guys. Not to self- double check before asking silly questions

 

[westward10]

No question is silly we are all guilty of such things. I was testing a fire alarm the other day and spent 20 minutes trying to clear a general fault only to realise I tested it with the mains power off and hadn't reinstated it once I had finished.