Megger kept tripping RCBO

[chris day]

hello guys
My megger kept tripping out a Wylex 10a RCBO today, the circuit i just installed and polarity had been checked at evey point i don't understand what the problem could be? I obviously set the meter to no trip

 

[telectrix]

i assume you were diong loop tests. did you connect all 3 leads in the right order.?


I'm playing all the right notes, but not necessarily in the right order. Eric Morecambe

 

[chris day]

i assume you were diong loop tests. did you connect all 3 leads?

The tester has a 2lead low test, I also carried out the three lead Low test and the same issue

 

[Octopus]

Can you try it on another RCD or rcbo?

 

[chris day]

Can you try it on another RCD or rcbo?

Yes and it worked fine on a different RCBO

 

[telectrix]

if doing the test with loads connected, could be that there is some leakage on the circuit and the 15mA that the megger puts into the test takes it over the RCBO's threshold.

 

[Billythekid]

What type is the RCBO?
Have you performed an RCD test to the RCBO - if so, what were the results?

 

[chris day]

if doing the test with loads connected, could be that there is some leakage on the circuit and the 15mA that the megger puts into the test takes it over the RCBO's threshold.

Hmm good point, a ramp test maybe would be good?

 

[telectrix]

hit it with a hammer.it should not trip below 30 ft.lbs.

 

[Octopus]

Yes and it worked fine on a different RCBO

I would be double checking the ir on the new circuit .....

 

[Billythekid]

Most test kits are designed to saturate the sensing coil with DC, if you have a type of RCBO that is designed to trip Under these circumstances then that’ll be the issue.

 

[chris day]

What type is the RCBO?
Have you performed an RCD test to the RCBO - if so, what were the results?

To be honest it got to 6pm this evening and I will be going to tomor

I would be double checking the ir on the new circuit .....

Hmm yes I am going back tomorrow to Finnish up so will do

 

[ipf]

hit it with a hammer.it should not trip below 30 ft.lbs.

No...but the contacts will still break.....

 

[Billythekid]

Please see photo, FYI

 

[KEV 1 N]

I've had bother with wylex rcbos tripping on loop tests before, I remember now the only way it stayed on for the test to work was to remove all load from the circuit. I've carried out loop tests before on other makes of rcbos with load on and they don't trip.

 

[Octopus]

I've had bother with wylex rcbos tripping on loop tests before, I remember now the only way it stayed on for the test to work was to remove all load from the circuit. I've carried out loop tests before on other makes of rcbos with load on and they don't trip.

Always the best way of doing it!

 

[KEV 1 N]

Always the best way of doing it!

I know, but not always possible when doing EICRs or if you happen to miss unplugging an item during the inspection.