rcd testing

[Farmelectrics]

your thoughts just pulled in 6 4mm radials all enclosed in dado trunking all tests were ok rcd testing x half no trip on all 6 radials x1 tripped 29ms x5 tripped 29ms now i no these readings are all exceptable but found it a bit strange that it was 29ms for all circuts at x1 and x5 usually your x5 trips in about 8ms aslong as it trips in under 40ms its ok anyone had same

 

[telectrix]

was that on auto test or manually setting the x1 and x5?

 

[Farmelectrics]

manual

 

[telectrix]

could be that when you switched to x5, you didn't click the switch in properly, or a meter fault. either way, i would retest, on auto ,i f your meter has this function.

 

[Joules Burn]

Did you perform both x1 and x5 at 0 degrees and 180 degrees?

 

[brizospark]

I was testing hager RCBOs today - out of 10 x RcBOs 8 of them at x1 came back at between 8 and 9 ms and at x5 the same- seems v strange - awhich meter are you using is it the new megger>?

 

[yellowvanman]

your thoughts just pulled in 6 4mm radials all enclosed in dado trunking all tests were ok rcd testing x half no trip on all 6 radials x1 tripped 29ms x5 tripped 29ms now i no these readings are all exceptable but found it a bit strange that it was 29ms for all circuts at x1 and x5 usually your x5 trips in about 8ms aslong as it trips in under 40ms its ok anyone had same

Seen this many a time and in some cases quicker @ x1 than x5. Wouldn't worry about it as long as they are within spec!

 

[yellowvanman]

I was testing hager RCBOs today - out of 10 x RcBOs 8 of them at x1 came back at between 8 and 9 ms and at x5 the same- seems v strange - awhich meter are you using is it the new megger>?

Did you do the 0 and 180 tests? When I do Hager RCBOs I usually get 28ms @ x1 and 18ms @ x5 worst case.

 

[Farmelectrics]

Yes I done tests at o and 180 my tester is a metrel all in one tester

 

[Farmelectrics]

Yes yellow that's what readings I usually get with tester for my tests the meter has only just been calibrated I no there acceptable readings but just didn't seem right 29ms for all six circuits might retest tommorow

 

[MarkieSparkie]

I was testing hager RCBOs today - out of 10 x RcBOs 8 of them at x1 came back at between 8 and 9 ms and at x5 the same- seems v strange - awhich meter are you using is it the new megger>?

This is not unreasonable, most RCBOs use electronics to increase the sensitivity, speed and repeatability. This means there is often very little variation in speed of operation at x1 and x5, or between a batch of protective devices.

 

[Farmelectrics]

thanks markie wasnt aware of that

 

[Farmelectrics]

retested circuts again today and got same readings oh well job done issued certs on to the next one

 

[Engineer54]

Where were you testing the RCD/RCBO, at the device terminals or at the socket outlets downstream??
All RCD devices should be tested at the device terminals for your recorded values, and not at the extremities of the circuit. The circuit will/should have already been tested/proved via ELI, Continuity, Polarity and IR tests etc...
You are therefore only testing the RCD devices themselves for conformity, not the wiring...

 

[Farmelectrics]

i checked at the sockets engineer54 i no you can check at rcd but its easier to just plug in at sockets rather than wrestle with leads and try an press test button with your nose ha ha i wouldnt of thought it would alter the readings or does it ive allways checked at sockets for rcd tests

 

[mickys86]

Where were you testing the RCD/RCBO, at the device terminals or at the socket outlets downstream??
All RCD devices should be tested at the device terminals for your recorded values, and not at the extremities of the circuit. The circuit will/should have already been tested/proved via ELI, Continuity, Polarity and IR tests etc...
You are therefore only testing the RCD devices themselves for conformity, not the wiring...

that's not how we're taught at college........

 

[Silly Sausage]

that's not how we're taught at college........

Look @ page 56 of GN3, 'Test Method', basically test on load side of the device and the load should be disconnected.

That's good enough for me!

 

[mickys86]

Look @ page 56 of GN3, 'Test Method', basically test on load side of the device and the load should be disconnected.

That's good enough for me!

Thank you, I'll bring it up in class.....

 

[Engineer54]

that's not how we're taught at college........

Seems we have yet another collage lecturer teaching duff information to students!! This is getting to be a regular occurrence these day's!!!

Well i would suggest you get your lecturer to contact the manufacturers, who will all tell him to test RCD devices at the load terminals, and not at the circuit outlets!!

Nothing to stop you checking from circuit outlets, but not when your testing the device's trip/time parameters, when officially recording the results on report record sheets etc...

 

[mickys86]

Seems we have yet another collage lecturer teaching duff information to students!! This is getting to be a regular occurrence these day's!!!

Well i would suggest you get your lecturer to contact the manufacturers, who will all tell him to test RCD devices at the load terminals, and not at the circuit outlets!!

Nothing to stop you checking from circuit outlets, but not when your testing the device's trip/time parameters, when officially recording the results on report record sheets etc...

In his defence he is actually a good teacher and a lot better than most at the college. I think if you asked a lot of electricians they would test at the circuit outlets


No matter how good you are, you'll never know everything. Always learning.....

 

[Farmelectrics]

It's a good shout e54 I was also shown to test at socket outlets but was aware the gn3 says at device and I've had my 2391 since 1998 so I have tested both ways over the years so surely the trip times would be quicker at the device will retest at device

 

[Engineer54]

In his defence he is actually a good teacher and a lot better than most at the college. I think if you asked a lot of electricians they would test at the circuit outlets


No matter how good you are, you'll never know everything. Always learning.....

It would be even better, for both you and the rest of this lecturers students, if what he was teaching was correct and to BS7671 guidelines....

 

[Farmelectrics]

was back on site today e54 you couldnt possibly get your test probes on to these dorman smith rcbos so the test would have to be done at socket outlets but on your domestic dual rcd boards you could just test at the device thanks

 

[Engineer54]

was back on site today e54 you couldnt possibly get your test probes on to these dorman smith rcbos so the test would have to be done at socket outlets but on your domestic dual rcd boards you could just test at the device thanks

If the test meters probes don't/can't reach the terminals, because of deep tunnels then connect a short length of cable (6'' or so) and test from these short tails. In fact some manufacturers actually recommend this approach to testing there RCD devices.... I personally don't like D. Smith MCB/RCBOs, and never have!!! lol!!