Zs testing on a light circuit.

[JONNY BRIGGS]

Hi,

Need some help on Zs testing on lighting circuits.

I am an electricians mate, recently passed my 2330 and 2392 test/inspection. I have been doing live testing on a lighting circuit and when I test earth and phase on earth loop I seem to always get trip on my megger testers. As I havent been testing long im not sure if im doing something wrong so any help would be great. I know lots of people say you shouldnt live test but I'm working in pubs where you cant dead test to get R1 + R2 readings.

I am not as experienced as you guys so please explain it in a way I can understand.

Many thanks

Jonny.

 

[onions1066]

It is more than likely just your tester, which one you using?

- - - Updated - - -

I mean model

 

[electric will]

Are you using 3 test leads?

 

[Deleted member 26818]

Does your tester have a 'no trip' setting for the earth loop test?

 

[onions1066]

I mean model of megger , do you get the reading before it trips? The problem is some mcb's will trip under test. You would then need your R1 + R2 to calculate your zs.

 

[bigbaddave]

Do you mean it trips the RCD? if so you should have trip lock function on your tester? Slightly less accurate but doesnt trip the rcd

 

[telectrix]

Zs testing on lighting will sometimes trip MCB. are you using 3 lead no-trip loop test? if the lighting circuit is not RCD protected, and you use the hi current test, this current will trip a 6A MCB.

 

[Sintra]

Jonny you can always test R1 + R2 you just have to isolate the circuit. Alternatively just do an R2.

Back to your original question. Is there an RCD / RCBO on the circuit where the meter would require 3 leads and set to no trip or is it simply a 2 wire test you are doing?

 

[bigbaddave]

Come on Johnny.. The wife has said im on a promise...

Is it RCD proteted??

 

[telectrix]

Come on Johnny.. The wife has said im on a promise...

Is it RCD proteted??

but you know a woman is lying if her lips move

 

[MDJ]

hahaha

 

[onions1066]

I think you've got time to go and deal with the mrs Dave we aren't expecting Jonny for the next 3 minutes or so . :2guns:

 

[MDJ]

the questions are just too tough for him unfortunately, once 3 wire tester got mentioned it was all over haha

 

[JulianC]

If you just mean that your Megger says 'trip' on the display while you are trying to carry out your Zs test, and the MCB &/or RCD stays on, it's probably because your probes are loosing contact with the terminals momentarily. Push hard. No, harder. Goddam it man, harder than that....

 

[bigbaddave]

Im back.. she has a headache..

Right... We sorted ?