RCBO testing times

S60TEM · Mar 9, 2011

It's like anything mechanical though. A brand new car will not perform to it's full potential until it has been ran in due to mechanical tolerances within the manufacturing process etc. Why should an electrical component with mechanical components defy this? Yes, the RCD / RCBO will have been tested after manufacture but how long has it sat on the shelf after that before being put into service? You can't test them every 3 months on a shelf. Freeing up the mechanical components within the RCD / RCBO and the continuous current flow through it should keep it in working order once installed. If after continued testing upon installation I find that its still too close to allowable trip times then I would replace it.

NozSpark · Mar 9, 2011

Ok then lets take a car as a comparison.

Lets say a brand new car was parked up in a compound somewhere for 3 months before you bought it, would you accept that the brakes had to be pumped a few times on their first use or would you consider that to be s fault?

Or the seatbelt, you expect that to work first time wouldn't you?

Its a safety device, it has to be able to work first time... because that first time could be the time you need it.

S60TEM · Mar 9, 2011

Ok then lets take a car as a comparison.Lets say a brand new car was parked up in a compound somewhere for 3 months before you bought it, would you accept that the brakes had to be pumped a few times on their first use or would you consider that to be s fault?

Or the seatbelt, you expect that to work first time wouldn't you?

Its a safety device, it has to be able to work first time... because that first time could be the time you need it.

Brakes, yes they will need to be pumped a few times to circulated the fluid etc and perfectly acceptable and normal.

Seatbelts, hardly a comparison tbh. Yes they're a safety device but they either work or they don't. Simple. Hardly the same as an RCD whereas it could still work but be outside allowable times etc.

All I am suggesting is that some mechanical stresses and tolerances give way after being used for just a couple of times. ie: The pins / rocker mechanism for the "toggle" within the RCD may just be that little bit tight because its new but after being opperated 2 or 3 times manually by using the test button will free it up. I've had an RCD that would not trip at all on the test but once I pressed the test button it tripped. Now, I tested again and it worked 100% after that. I tested it at least 20 times on x5 and it tripped WELL within limits. I even tested it again the following week when I went back to collect my payment for the job and it was perfect. My MFT has never let me down either so couldn't be that. I'm not saying it's every one but it can be a select few.

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oh and as for first time it must work.......

its not the first time for safety though really as we test and reset them at least 6 times before putting them into service don't we? Well at least I do.

1) On energising to test the button

2) x1 0-180 degrees

3) x1 180-360 degrees

4) x5 0-180 degrees

5) x5 180-360 degrees

6) mechanical test of button again for column marked "Other" on test cert.

So by the time it trips for the first time under fault conditions, it has already proved itself 6 times within that specific installation.