How come some rcds dont trip when testing voltage to earth

[michaelsf90]

So I recently installed a new circuit to my loft as a dedicated burglar alarm and cctv circuit. When checking polarity and voltage with my test lamps/voltage indicators it didnt trip the rcd when testing live to earth and neutral to earth. It's an rcbo which works when using the functional test button. I'm off work but when im back in I will bring a test kit home and test it properly

What I dont get is why do some rcds/rcbos trip and some dont when testing voltage to earth and some dont? I tested a lighting circuit voltage and as soon as I touched the earth the rcbo tripped

 

[cliffed]

So I recently installed a new circuit to my loft as a dedicated burglar alarm and cctv circuit. When checking polarity and voltage with my test lamps/voltage indicators it didnt trip the rcd when testing live to earth and neutral to earth. It's an rcbo which works when using the functional test button. I'm off work but when im back in I will bring a test kit home and test it properly

What I dont get is why do some rcds/rcbos trip and some dont when testing voltage to earth and some dont? I tested a lighting circuit voltage and as soon as I touched the earth the rcbo tripped

Most voltage testers test with minimal leakage to earth

 

[pc1966]

RCD/RCBO are typically 15-30mA to trip, but most voltage testers only a few mA so they don't trip normally.

Is your a modern LED one or one of the traditional filament lamp types? They would have a singificant inrush as well as being less reliable than LED so might trip some RCD. I would get a new one if so!

Those with a test button I guess divert some 30mA to allow that to be checked.

 

[michaelsf90]

My tester is a fluke 117. I just find it strange that on one it tripped and on another it didnt. However the burglar alarm supply is a 2.5 and the load will be tiny. The downstairs lights probably had a bigger load on the circuit. Wether that would contribute to it tripping