5 x Trip 40.4

[Gravid]

Hey up, testing a 6 amp RCBO protecting a lighting cct, on this cct there is an emergency light wired directly into the breaker, no key switch, on the RCBO tests my results are as follows

>1999, 28.5/18, 40.4/18.3.

Now thats a fail on the five times right ?? So i changed the RCBO and got exactly the same results.
When i disconnected the emergency light cct i got.

>1999, 28.5/18, 28.9/18.3. Why is this ? what is it that is making the emergency light affect the rcbo trip times?

 

[ryanryan]

i dont think that fails, i think you record the x1.

 

[ses]

I wouldnt fail it for that.
The 5 x is going to be what you want to comply because a fault current will be high so you want to know that it trips as fast as poss within the 5 x

 

[Gravid]

Ok cheers for the answers, i thought an RCD or Rcbo had to trip under 40ms on the 5x test. I'll have to get my head into my testing notes, I realise its only just over.
I still don't understand why the emergency light is making such a difference to the trip times, if you could explain that would be great.

 

[Phil Mumford]

If you test a circuit with a neutral-earth fault you can get spurious results. Disconnect wiring and tests are OK.

Maybe the fitting is simulating a neutral-earth fault at 5X setting?

Just a thought.....

 

[xraytek]

I am a little confused about the 5x result being irrelevant
My understanding is that an RCD can be used for fault protection and/or supplentary basic protection.
So if it was a domestic TT installation with surface wiring (for example) then the RCD provides fault protection so the 1x figure is relevant.
If it was a domestic TN system with concealed cables then the RCD is providing supplementary protection so I would have thought that the 5x figure is the only one thats relevant.

 

[Christech]

It passed ,IEC61009(or is it 61008) only requires a functional test of the RCBO . So if tripping times are within the manufacturers parameters for functional test then you have nothing to worry about, you then have to look at other factors e.g Capacitence to Earth ,tester being used etc

 

[Gravid]

I thought all trip times were relevent, if not could somebody explain why, and under what circumstances they aren't. Cheers.

The Rcbo is there for additional protection, it is a BSEN61009.

Christech what do you mean only requires functional testing and capacitance to earth factors, thanks.

 

[Lou7]

415.1.1 rcd must have operating time not exceeding 40mS at a residual current of 5 X In

 

[rob1967]

415.1.1 rcd must have operating time not exceeding 40mS at a residual current of 5 X In

So if a RCD trips at 67.3 at x 1 then that would be a fail?

 

[Guest123]

So if a RCD trips at 67.3 at x 1 then that would be a fail?

No that would be fine. 5 x I delta N is 150mA tripping current (for a 30mA RCD) 1 x I delta N is 30mA tripping current - 200ms max.

 

[ses]

no 1 x is 300ms if bsen or 200ms if its the old type bs

 

[Guest123]

Dam these fat fingers o mine!!

 

[electricAl]

Think it`s quite possible that the conflicting posts in this thread are due to the fact the OP HAS proven the RCD operates as per its parameters - only just not when attached to a particular cct.
The fact is, the device PASSED.
Before carrying such tests out, loads are to be removed/disconnected.
Okay, if we think we can leave things attached & the RCD still passes, great. Altho for accuracy of values its not exactly spot on, but no massive issue...
However, if an RCD is over its ceiling, we have to ensure we`ve followed procedure before condemning it - remove loads.

So the RCD passed. Period.

As to ChrisTechs comment re: compliance with 61009 only, fair play to him if he`s got the b0115 to shun BS7671 requirements. The BRB specifically states we must verify that RCDs acting as Additional Protective Devices meet their disconnection times (even if Guidance Note 3 says it don`t ~ page 55 always thought the wording was odd)

 

[xraytek]

415.1.1 rcd must have operating time not exceeding 40mS at a residual current of 5 X In

415.1= Additional protection, so not always applicable

Think it`s quite possible that the conflicting posts in this thread are due to the fact the OP HAS proven the RCD operates as per its parameters - only just not when attached to a particular cct.
The fact is, the device PASSED.
Before carrying such tests out, loads are to be removed/disconnected.
Okay, if we think we can leave things attached & the RCD still passes, great. Altho for accuracy of values its not exactly spot on, but no massive issue...
However, if an RCD is over its ceiling, we have to ensure we`ve followed procedure before condemning it - remove loads.

So the RCD passed. Period.

As to ChrisTechs comment re: compliance with 61009 only, fair play to him if he`s got the b0115 to shun BS7671 requirements. The BRB specifically states we must verify that RCDs acting as Additional Protective Devices meet their disconnection times (even if Guidance Note 3 says it don`t ~ page 55 always thought the wording was odd)

Good post