RCBO vs RCCB

[David Wieser]

I'm a Canadian electrician thrown into the 'European' wiring world (not in Europe though).

I was just reading up on RCCB in that they are 'similar' to our GFCI's but do not provide over current protection, therefore, an RCBO is required as the O in RCBO is over current protection.

As I've been doing my PM's on the buildings here, I've found that the test button is not longer functioning on the RCCB's and I was replacing them with the same, RCCB's. Now that I read that RCCB's don't provide over current protection, it looks like I should not have been replacing them with the same product.

Did the person before me install them incorrectly, and have I been continuing on with the same mistake?

Is the cable between the electrical panel (distribution board) and the secondary distribution panel only protected by our MCCB's? Or I should say, not protected at all between the DB and secondary distribution panel?

 

[telectrix]

when using RCCBs without overcurrent protection, in the UK we always protect each circuit with it's own MCB. frequently several circuits will be shared on 1 RCCB.

 

[shanky887614]

I'm a Canadian electrician thrown into the 'European' wiring world (not in Europe though).

I was just reading up on RCCB in that they are 'similar' to our GFCI's but do not provide over current protection, therefore, an RCBO is required as the O in RCBO is over current protection.

As I've been doing my PM's on the buildings here, I've found that the test button is not longer functioning on the RCCB's and I was replacing them with the same, RCCB's. Now that I read that RCCB's don't provide over current protection, it looks like I should not have been replacing them with the same product.

Did the person before me install them incorrectly, and have I been continuing on with the same mistake?

Is the cable between the electrical panel (distribution board) and the secondary distribution panel only protected by our MCCB's? Or I should say, not protected at all between the DB and secondary distribution panel?

i would recommend an rcd ramp tester mate.

it is the easiest way to test rcd's,rccb's etc.

put it in auto and it tells you what it tripped at

 

[Engineer54]

In what country are you working in at the moment, i'm assuming it'll be somewhere in the Middle East??

 

[David Wieser]

In what country are you working in at the moment, i'm assuming it'll be somewhere in the Middle East??

Correct. In the middle east. I've gotten a hang of the old british wiring colour standards and the new one… gotta love those blue's and black's!

Still have lots to learn though.

 

[ImpededLoop]

i would recommend an rcd ramp tester mate.

it is the easiest way to test rcd's,rccb's etc.

put it in auto and it tells you what it tripped at

The fault is that the test buttons aren't working so the units need replacing.

 

[shanky887614]

The fault is that the test buttons aren't working so the units need replacing.

did you try it disconnected from the board?

 

[ImpededLoop]

did you try it disconnected from the board?

I'm not the OP, but I would imagine that they were connected when tested. If not, the test button definitely wouldn't have worked!

 

[David Wieser]

The fault is that the test buttons aren't working so the units need replacing.

I have been replacing the RCCB's that are no longer functioning with new RCCB's. However, my concern is, should I really be installing a RCCB again or should it be a RCBO? The 100 A or 63 A rating of the RCCB's I have been installing, from what I've read, it's not providing over current protection?

 

[ImpededLoop]

The 100 A or 63 A rating of the RCCB's I have been installing, from what I've read, it's not providing over current protection?

That's correct, it's the current that they can safely disconnect, not overload protection.

There's usually a fuse or circuit breaker either before or after the RCCB. If so, this provides the overcurrent protection.

Is this a domestic or commercial environment?

 

[David Wieser]

That's correct, it's the current that they can safely disconnect, not overload protection.

There's usually a fuse or circuit breaker either before or after the RCCB. If so, this provides the overcurrent protection.

Is this a domestic or commercial environment?

Commercial.

We have the typical 10/15/20/30 A circuit breakers (which you would call MCB's?), then the RCCB within the same panel (which for me would be a 100A "Main Breaker" in Canada, which would provide overload protection), then the cable leaves the panel and goes to a Secondary Distribution Panel which contains a variety of Molded Case Circuit Breakers (MCCB's).

 

[shanky887614]

Commercial.

We have the typical 10/15/20/30 A circuit breakers (which you would call MCB's?), then the RCCB within the same panel (which for me would be a 100A "Main Breaker" in Canada, which would provide overload protection), then the cable leaves the panel and goes to a Secondary Distribution Panel which contains a variety of Molded Case Circuit Breakers (MCCB's).

the main switch offers no overload protection, it is just a 100amp switch. no different to a lightswitch

 

[Engineer54]

Commercial.

We have the typical 10/15/20/30 A circuit breakers (which you would call MCB's?), then the RCCB within the same panel (which for me would be a 100A "Main Breaker" in Canada, which would provide overload protection), then the cable leaves the panel and goes to a Secondary Distribution Panel which contains a variety of Molded Case Circuit Breakers (MCCB's).

The RCCB's purpose in this final circuit DB is to provide earth leakage protection to multiple circuits protected by MCB's of the appropriate ratings. The supply to the RCCB being provided by an upstream OCPD.

Not the best way of doing things i agree, as it can be a bloody nightmare tracing an earth leakage fault over several circuits, not to mention the cumulative normal/natural leakage to take into consideration. DP/SP+N or even SP RCBO's are a much better arrangement. But the arrangement does satisfy BS7671... So basically, continue replacing any faulty units you find with
a replacement unit!!!