odd rcd trip times with a metrel?

[dcwuk]

Occasionally when carrying out rcd testing with a metrel 3100 I have had failures which upon investigation have been caused by me inadvertently leaving a piece of equipment connected to the cct the readings being x1=156 x5=>40 unplug or disconnect the piece of equipment and the readings return to normal. This as happened on various installations and the equipment that was found to be in cct always has a motor (fridge ect) Has anyone else experienced this problem?

 

[malcolmsanford]

Occasionally when carrying out rcd testing with a metrel 3100 I have had failures which upon investigation have been caused by me inadvertently leaving a piece of equipment connected to the cct the readings being x1=156 x5=>40 unplug or disconnect the piece of equipment and the readings return to normal. This as happened on various installations and the equipment that was found to be in cct always has a motor (fridge ect) Has anyone else experienced this problem?

Why are you concerned about these times?

Yes leaving an appliance plugged in can affect tripping times on an RCD, but those times you have posted are more than acceptable.

Though it is easier to plug the BS 1363 lead into a socket to test and RCD, I always try and do it at the CU just to save me going around and unplugging things

 

[loop3]

X5 should be<40mS

 

[malcolmsanford]

X5 should be<40mS

Thanks Loop the eyes are going I read 5=>40 as ok but your right it is above 40ms and so it out

The second part of what I wrote though IMO is the best way to test an RCD

 

[dcwuk]

Thanks for the replies. this particular job is in an hotel where I am replacing mcb`s for rcbo`s and because I am testing the impedance of the ccts and the boards legends are inaccurate I am testing the RCD at the room rather than at the DB. The question is are the trip times an anomaly or is the appliance in fact preventing the RCD tripping within the times? I probably need to try another RCD tester on the Circuit and in the meantime have emailed Metrel for advice. I just wondered if anyone else had come across this problem?