RCBO Testing

[chopper]

why dont u tst at the DB on socket circuits?, know its easy to go to a socket but it is quicker to just do it at the DB

 

[pencilpusher]

That's just the way I choose to do it.

 

[chopper]

no worries i was just curious, trying to increase my knowledge

 

[chopper]

so do u , put the probes on the load side of rcbo, and just put a crock on the earth bar (with all other earths and bonding at it )

 

[Engineer54]

sorry to jump on this thread, but is this thread saying that it is ok to test rcbos at the DB rather then at the end of line, is this same in domestic and industrial i thought we had to go do it at end of line

It is the ONLY place to test RCD's when conducting proving tests, check with any of the manufacturers and you will be told the same thing!! No problem testing that RCD's are working from remote socket outlets etc, but when conducting time and current trip functions, these should always be conducted at the terminals of the RCD device itself!!

Yes there is one or maybe 2 manufacturers that suggest or prefer short bits of wire be connected to the RCD and tested conducted from the ends of those short wires...

 

[jamie-spark]

Had a similar problem with hager rcbo's once and after a call to there technical dept. Was told the reason they do not trip with load connected is well known because of capacitance in the circuit.

 

[ian65]

Exactly the same way as you'd test an RCD: 0.5Idn (no trip within 2 sec), Idn 0deg, Idn 180deg, 5Idn 0deg, 5idn 180deg.
As mentioned, you may need a long, thin probe to make a connection to the Neutral out terminal of the RCBO, as they are recessed by 25-30mm or so on most types.

Also, you need to disconnect the outgoing circuit when performing insulation resistance tests on it. The disconnection is only single pole so the Neutral will go straight through to the busbar.
You should disconnect the Neutral flying lead when testing on the busbar side of the RCBO
Many have a functional earth connection, so this should be disconnected for IR testing too (manufacturer's instructions).

Simon.

Many thanks for the info don't think i replyed before but i bet that one don't come up in the February exam as a re take from October.

Thanks again..Ian.