Hager RCD weirdness

[Andy™]

Hager Tech did also say that ramp testing isn't a required test and so I probably shouldn't have done it. Maybe the ramp test broke the RCCB?

next they will be saying its not a good idea to touch a live wire creating an earth fault, in case you break the RCD

 

[Rob_the_rich]

next they will be saying its not a good idea to touch a live wire creating an earth fault, in case you break the RCD

I have phoned rcd manufs before and the first thing they asked was what was the result of the ramp test. I couldn't do a ramp test with the machine I had at the time, but it was a test that they wanted to know the result of. Shame on hager for suggesting it was unnecessary and not required.

 

[Evans Electric]

I've no idea if doing the tests in a particular sequence has any effect.  To be honest I just follow  the way the setting switch goes , 1/2 ...then rated current ....X5  ....test button.  

I do , however , think more importance should be attached to the consumer using the test button at the various intervals , given the fact that they can just stop working at any time it would seem .     Also I've had more than a few that didn't work from new. 

Something I've noticed with the RCBO's  , I normally fit Control Gear boards and their RCBO's ..all of them ..all trip in 20mS  never had one different .

Problem I have with them is Zs test knocks them out because they're SP  , they don't like my older tester . 

 

[Sidewinder]

I like GB, but he can be a bit cranky on times, mind he does know his stuff.

Had a few debates with him on some stuff @ Elex and he also has a LOT of experience.

I do agree with Noz on the test sequence, why it should be that way, and why we test the RCD, i.e. to make it fail if possible because it's a safety device.

I also prefer the sequence that Noz suggests, however, I have become lazy, and I use the auto test sequence these days.

I have had RCD's fail even on the programmed sequence.

One at 18:00 on a Friday evening taking the power out to the whole property.

I was NOT a happy bunny, got the patient back on supply, & Screwups made a fair bit out of me that day, but what can you do, not costed into the job, but, the client wouldn't have been interested, and they were all in the pub by that time, or doing something more interesting.

Patient/resident, wasn't interested either, all they wanted was their power on!

 

[Rob_the_rich]

I've no idea if doing the tests in a particular sequence has any effect.  To be honest I just follow  the way the setting switch goes , 1/2 ...then rated current ....X5  ....test button.  

I do , however , think more importance should be attached to the consumer using the test button at the various intervals , given the fact that they can just stop working at any time it would seem .     Also I've had more than a few that didn't work from new. 

Something I've noticed with the RCBO's  , I normally fit Control Gear boards and their RCBO's ..all of them ..all trip in 20mS  never had one different .

Problem I have with them is Zs test knocks them out because they're SP  , they don't like my older tester . 

sbs dave's standard rcbos in the last CU I did all had virtually the same trip times, the cert looks like there is only 1 rcd.

If the customer is there, I like to get them involved in the testing by resetting the rcd on the auto test. Makes the process easier to understand, they shut down PCs first and it is painless, usually. Then  tell them to do it again in 3 months. Can still be done with the manual tests I will do in future.

 

[brummydave]

Thanks for all your input guys! When I went back the next day, the Hager RCCB did work briefly, but then stopped working again. All connections were ok so I swapped it out. No problems with the replacement - hurrah!

Told the customer that it probably hasn't been tested for years, my testing had revealed it probably wouldn't have lasted much longer, and possibly not have worked at all if needed to for their safety.

It'll be a faulty connection, often had it where it doesn't sit on the bus bar correctly. Or hasn't been tightened to correctly (maybe this is why they introduced torque drivers???)

Other than that it'll be a faulty one. 

Although I have found a few loose connections in the DB and the installation, the RCD connections were all good. (And I do have a torque driver).

I’d go with the faulty connection. Each successive test has jolted the terminals until one had given up.

What does a jolted terminal look like? :C

Tap the side with handle of  screw driver 

That last post is worth noting ....   tap it with a screwdriver  is not so daft as it sounds .

I had at least one  brand new  Crabtree  RCD that tripped  for no apparent reason ....after two trips back to the job investigating to no avail  ..... I swore at the offending device then tapped it with a driver to teach it a lesson and it tripped out .     Reset it .... the front door slammed shut and it tripped again .    Cause identified , replaced RCD , problem solved .

I think the tapping test should be added to the recommended test procedures .

1)  Carry out Half rated current test .

2) Carry out  100% rated curent test .

3) Try test button .

4)  Hit device with large screwdriver.

No amount of tapping made a difference Whether insulated screwdriver or birmingham screwdriver!

OK so lets firstly agree that an RCD is a device which (if working) will get a chance to save our lives if/when we do something stupid..

Now lets say that we do that stupid thing,,,, the RCD has one and only one chance to operate,,, if it doesn't then we're going to be put at a higher risk than we should be.

So... given that, we should never exercise a RCD before or during the tests to achieve the prescribed trip times  -  you won't get that benefit if you're getting an electric shock I can assure you!!

And now to my reasoning,, given the above

1x first - when I test a RCD I want to be sure that it'll trip the first time 99.9% of the time,,, if you carry out the 1/2x test first then you could be pre stressing/exercising the mechanism a bit... I know it won't be much, but the trip coil will have had some current passing through it and it will have had a mechanical effect on the mechanism

1/2x last - like I've said,, this is the order I do things... 1x 0deg, 1x 180deg,5x 0deg, 5x 180deg, ramp, manual and then 1/2x

so when I test I have already done 6 tests on the RCD before the 1/2x test,, that's 6 operations of the mechanism.... IMHO this is the most likely time that a RCD will fail the 1/2 times test

When I'm testing a RCD I am looking for it to fail,,, I'm not looking for it to pass................. mostly they pass though, and for that I'm happy as I know that I've thrown everything that I can at it

Oh... and I have a MFT 1502.... It doesn't have an auto test!

Thanks Noz, I never really thought about the order of tests. just assumed the way in gn3 was correct, same as auto on tester, x1/2, x1 then x5 last then test button.

I have had a read around this evening and I am tending towards what Geoff Blackwell has been saying for some time, x5 first. For basically the same reason as you, if there is any stickiness it should be tested for, not negated/mitigated by doing a x1/2 test, and especially by not pressing the test button (should always be the last test). His reason for x5 first instead of x1 is that it is the more onerous test , 40ms instead of 200, and that a faulty rcd would be more likely to show up. Testing first at 30mA (x1) is not really a "life threatening" situation whereas testing at 150mA is, and it seems to make sense to do this test first.

brummydave, did you test the rccb with all loads disconnected?

Edit; that is pith-poor customer service from Hager BTW.

I had always assumed that Fluke knew best as well. Will put more thought into RCD testing!

Yes I did have every load disconnected. It's an empty one bed flat so thankfully that wasn't an onerous task.

Agreed that the Hager chap did throw me with his abruptness and non-help.

I have phoned rcd manufs before and the first thing they asked was what was the result of the ramp test. I couldn't do a ramp test with the machine I had at the time, but it was a test that they wanted to know the result of. Shame on hager for suggesting it was unnecessary and not required.

I may try a call back and see if someone else is more helpful!

TTFN.