100ma RCD

[sparkie-leeds]

I have been to a job this morning, the outside carpark lights had a fault on them, i have rectified the fault. The system is TT with 100ma rcd incomer protecting the installation.

The problem is that if there is a fault on the lighting circuit throughout the night it takes the main 100ma rcd switch out shutting all power down.

If i put the outside lighting circuit on a 30ma rcbo would this over come the problem of tripping the main switch out if there is a fault and ONLY trip the 30ma rcbo for the outside lighting?

 

[ackbarthestar]

I found that you need to test each 100mA 'S' RCD with each 30mA RCD/RCBO combination to find out the precise time they disconnect. We know at 1 times they should operate between 130ms to 500ms and at 5 times they should operate between 40ms and 150ms but it is not always the case that discrimination is can be achieved.

The 4293 RCCBs have a lower front end of 200ms and maximum of between 300 and 400ms and often only trip near the maximum time allowed.

 

[Brightspark2]

think you meant to say "series"

ha ha how ironic...dont they teach that stuff? ha