RCBO testing times

[sparky b]

Hi all,

I installed a cu today and one of the RCBO's tested as 1x 100ms and 5x 40ms. The other 11 all tested around 1x 25ms and 5x 8ms.

Is this a cause for concern or should i just leave it as it's within specified times?

Thanks

B.

 

[Manator]

Have you double checked the connections? If all the others tested out ok I would try to replace that RCBO and see what happens. I like them all to be within a few ms of each other, leaving it in may lead it to failure in the future due to user failure to use the test facility on a regular basis.

 

[sparky b]

Have you double checked the connections? If all the others tested out ok I would try to replace that RCBO and see what happens. I like them all to be within a few ms of each other, leaving it in may lead it to failure in the future due to user failure to use the test facility on a regular basis.

Yes, have checked all connections, will have to swap it out tomorrow!! Thanks Mantor

 

[tom1]

whats circuit is the rcbo for?

the times are in spec so stritly speaking no need to change, however i have not seen this before, and manator and others have more experiance

 

[Manator]

I did think of that tom1, but because all the others tested at the same times, it would appear there is nothing wrong with the way they were tested. If they were tested at say the extreme of a circuit as for a Zs reading, then there could be some small difference. I would like to have changed over the RCBO and done another test just to confirm.

 

[sparky b]

whats circuit is the rcbo for? the times are in spec so stritly speaking no need to change, however i have not seen this before, and manator and others have more experiance

It's for a 32a cooker circuit...

 

[Sidewinder]

sparkyb,

Where were you testing them, and, what are the other ratings please?

Could this be a cable capacitance thing perhaps?...

Depends on your exact test procedure though.

NOT saying you have done anything wrong mind, just throwing ideas into the pot.

 

[kme]

Was the cooker point switched on during the proceedure?

Were there any anomalous readings at the IR stage?

If "no" and "no"; then, as Manator suggest, I`d want to swap it out. You could also try testing with the outgoing final cct. disconnected from the RCBo

KME

 

[sparky b]

sparkyb,Where were you testing them, and, what are the other ratings please?

Could this be a cable capacitance thing perhaps?...

Depends on your exact test procedure though.

NOT saying you have done anything wrong mind, just throwing ideas into the pot.

Hi Sidewinder, had to test at the connection plate the hob due to the switch being stuck in place by a lovely granite splashback (same place I tested R1+R2). I did the same 3 lead test as I did on all the other circuits. The other ratings are 3x 32a, 1x 40a, 1x 16a & 6x 16a.

---------- Post Auto-Merged at 06:41 ---------- Previous post was made at 06:35 ----------

Was the cooker point switched on during the proceedure?Were there any anomalous readings at the IR stage?

If "no" and "no"; then, as Manator suggest, I`d want to swap it out. You could also try testing with the outgoing final cct. disconnected from the RCBo

KME

Mr KME, Yes and no (in that order), cooker point was switched on because I couldn't get the switch off the wall!! Will try testing without circuit connected...

Thanks gents

B.

 

[Sidewinder]

sparkyb,

I would suggest you try your tests at the rcbo with the cct disconnected to see if this changes the values as the circuit wiring and load can have an affect on the way the meter functions as I understand it.

 

[sparky b]

sparkyb,I would suggest you try your tests at the rcbo with the cct disconnected to see if this changes the values as the circuit wiring and load can have an affect on the way the meter functions as I understand it.

Will do Mr Winder, I'll post back tonight on what happens...... Thanks.

B.

 

[kme]

sparkyb,I would suggest you try your tests at the rcbo with the cct disconnected to see if this changes the values as the circuit wiring and load can have an affect on the way the meter functions as I understand it.

As per reply #8 above????????

 

[Sidewinder]

Yep, serves my right for not reading the thread correctly!!!

 

[PC Electrics]

For any electromechanical product, if the manufacturer has bought into good quality tooling and exercises good quality practices (eg sample testing and SPC on components and finished product), then all product coming off the end of the line should have similar performance characteristics. As you have 12 RCBOs, with one giving results that vary wildly with the others, I'd change it. This suggests a variance in the manufacturing process that hasn't been picked up. Or it's a manufacturer that cuts out those quality practices in persuit of reduced cost.

Put your test results on a piece of paper and attach to the returned item.

Also, that 5x figure is right on the limit. Not going to get better on it's own !!

I'm assuming you've tested consistantly and properly, and your meter is calibrated.

 

[Sidewinder]

PC it is possible that the "issue" is caused by external influences.

Given that the info the OP has provided is correct.

Also you points are very valid.

 

[PC Electrics]

Oh, absolutely Sidey. Hence my last line about being consistent. I'd also advocate repeat testing about an hour later.

 

[Manator]

I would agree with Sidewinder, the OP has given more information about the local of the actual test, testing at the point in question, and with the cooker switch on, outside influences could effect the characteristics of the RCBO. A simple test to confirm this would be to swap the RCBO for one that previously tested at the lower ratings, I would guess the results would be the same.

 

[S60TEM]

I have found this happen before, to rectify it I repeatedly pressed the test button and energised the circuit for quite a number of times and also retested it a number of times which I found rectified the problem. It may be that all the other RCBO's were manufactured at around the same time and the one that has the indifferent results may have been manufactured earlier and hence a little bit older and has some signs of mechanical siezure. Hence why we reccommend the quarterly testing of the button to illeviate mechanical siezures.

 

[NozSpark]

I have found this happen before, to rectify it I repeatedly pressed the test button and energised the circuit for quite a number of times and also retested it a number of times which I found rectified the problem. It may be that all the other RCBO's were manufactured at around the same time and the one that has the indifferent results may have been manufactured earlier and hence a little bit older and has some signs of mechanical siezure. Hence why we reccommend the quarterly testing of the button to illeviate mechanical siezures.

TBH I find it hard to beleive that people do the highlighted part to get a RCD or RCBO to pass testing..

You will only get the one chance for it to save your life, not several, so it should work first time... if it doesn't then it's faulty

the correct test procedure is 1x, 5x (if necessary), ramp (if you want to), manual test and then 1/2x

But yes.. the quaterly test button operation is very important

 

[steptoe]

although I would usually do 1/2 first, and then again at the end,

simply because my meter does 1/2 first, but a lot of people omit to doing it again for nuisance tripping once the 1x and 5x have loosened the contacts.