non trip loop test still trips the rcd

[jools p]

I have a megger 1552 and the no trip setting works fine, until today. Can't get a loop reading on a sub main in workshop. It keeps tripping the RCD back in the house. Some RCD's I have found to be ultra sensitive but not this one. Cutting cables all day on switched off circuits and never a trip but go and do the test and pop off it goes. Whats that all about..

 

[Spudnik]

Exactly as you said, some RCD;s are more sensitive then others.

I have just fitted a new GE budget CU today and none of it tripped once.

I have had crabtree and hager which sometimes trip and sometimes dont.

Make sure your probes are pushed in tight before and during the test. Sometimes if one is loose that will also cause them to let go.

 

[jools p]

This time i was using the plug attachment thingy though

 

[WarrenG]

I have a megger 1552 and the no trip setting works fine, until today. Can't get a loop reading on a sub main in workshop. It keeps tripping the RCD back in the house. Some RCD's I have found to be ultra sensitive but not this one. Cutting cables all day on switched off circuits and never a trip but go and do the test and pop off it goes. Whats that all about..

I take it you have RCD discrimination between house board and sub board?

Can't see how this would make a difference but it would be interesting to try the test in the sub board with the RCD in the house board isolated?

I have a Megger MFT 1552 silly question but your not using HI-Loop?

 

[jools p]

No, on the no trip setting. Never had it before.

 

[Tiger]

check your tester on a system you know to be ok. your house. that will tell you your testers ok.
Did you do a rcd nuisence trip test? see if the rcd's ok

 

[spamwize2]

hi you need to check your meter first, if ok then work towards your garage i suspect faulty rcd, not meter