So I'm In A House Today And I Notice A 30ma Rcd On The Wall

[OnlQQker]

It feeds an outdoor socket. On the comsumer unit is a 60ma Rcd and everything is covered by this.

I'm just wondering if the 30ma Rcd would trip before the 60ma Rcd trips (if that makes sense)

It's just my mind wondering about stuff, the chap who owns the house said it's never tripped out, yet I wondered if 30 ma would trip first because it's lower than the 60ma in the consumer unit. To me I'm guessing it would?
Anybody helping explain this would mean I might get some sleep tonight without thinking about it in bed, I've tried searching the net for the answer but no luck!

 

[davesparks]

Not now, it was only a glance because high up. Will make an excuse to have a look again tomorrow. Now if it is a 30ma they will both trip right, or would the closest one go first?

An RCD mainswitch will probably go first as it will likely have some normal earth leakage from all of the connected circuits biasing it to trip first.

 

[ipf]

I thought it was an iceberg that sunk the Titanic. I didn't realise it was an rcd

Always thought it was bloody big floating lettuce...!

 

[littlespark]

An RCD mainswitch will probably go first as it will likely have some normal earth leakage from all of the connected circuits biasing it to trip first.

Not always. As I mentioned before, an rcd could trip at anything up to 30mA.
Circuit could trip at 19, main switch at 29... fault current may sit at 24..

It’s possibly down to whichever rcd is the most awkward to reset.
e.g a static caravan has an rcd mainswitch in its consumer unit, there is also a 16A rcbo in the hookup box outside.
if there’s a fault, it’s 9/10 that it’s outside that trips..... in the middle of the night...... when it’s raining.....

 

[R-fur]

The only way to make RCDs discriminate is to put a time delay on the upstream one,