Meters new and old

[Jimmy Boy]

Please explain old meters and new

why they trip old RCDS etc

 

[rick.oshea]

The old meters use a high fault current when loop testing (around 25A) which causes an imbalance in the RCD and causes it to trip - newer meters have a NO Trip setting which use a much lower current (15mA) which in most cases, doesn't trip the RCD. (although some electronic RCBO's can still be effected..... :-( )

Other meters saturate the core of the RCD prior to testing (called DC biasing) and it doesn't then pick up the fault current....

 

[Jimmy Boy]

I guess that is why my old meter that I still have will not test new RCD's ? It was bought a few years ago as a 'no trip' but I think it sends a DC pulse down to fool the RCD but I think new RCD's are DC sensitive?