RCD Trip

[JohnW2]

I don't think I've done that but I have changed MCB to RCBO and forgotten to move neutral but of course it trips as soon as any load is applied so no hopefully I haven't left site in that condition.

Interestingly, I'm not sure that 'applying a load' (to anything) is necessarily part of an electrician's usual 'testing regime' (I must check 'in the book'!) - although it is, of course, the only sort of 'testing' that many a DIYer does

I have 'done it', at least once, but not through any ignorance or incorrect intent - I've known jolly well which neutral bar I should connect to, and why, but my brain and/or fingers have disobeyed my intent and connected it to the wrong one! However, no matter what the book says (or does not say), 'applying a load' is always the final thing I do as part of testing a circuit

Kind Regards, John

 

[SUNRAY]

Interestingly, I'm not sure that 'applying a load' (to anything) is necessarily part of an electrician's usual 'testing regime' (I must check 'in the book'!) - although it is, of course, the only sort of 'testing' that many a DIYer does

I have 'done it', at least once, but not through any ignorance or incorrect intent - I've known jolly well which neutral bar I should connect to, and why, but my brain and/or fingers have disobeyed my intent and connected it to the wrong one! However, no matter what the book says (or does not say), 'applying a load' is always the final thing I do as part of testing a circuit

Kind Regards, John

Time and time again I've been on inspection/repair etc where the customer has said I tested it, the frequent test device seems to be the electric drill or vacuum cleaner, presumably as they were used to install the new accessory.

Several times I've heard something like; 'I don't understand, it lights my voltstick/screwdriver/voltmeter but trips when I switch anything on.'

 

[SUNRAY]

I came across some boards a while back where the neutral bars had different coloured markings, IIRC blue / black, and dark/light blue. and were fed by matching coloured wires.

 

[JohnW2]

Time and time again I've been on inspection/repair etc where the customer has said I tested it, the frequent test device seems to be the electric drill or vacuum cleaner, presumably as they were used to install the new accessory.

Indeed - but, as I said, I get the impression (still haven't checked 'in the book') that an electrician's 'testing' may fail to include that final 'functional test' - which means that they might well sometimes miss the sort of problems we're discussing.

Kind Regards, John

 

[SUNRAY]

Indeed - but, as I said, I get the impression (still haven't checked 'in the book') that an electrician's 'testing' may fail to include that final 'functional test' - which means that they might well sometimes miss the sort of problems we're discussing.

Kind Regards, John

Yes I uderstood your comment and have the same thought.
However does the test not include RCD function?

 

[SUNRAY]

Yes I uderstood your comment and have the same thought.
However does the test not include RCD function?

Silly arse Sunray, even that will not identify the error.

 

[JohnW2]

Silly arse Sunray, even that will not identify the error.

I think it actually might, in some situations, if the testing resulted in tripping of an RCD other than the one 'being tested' (instead of, or as well as, the one 'being tested'), mightn't it?

Kind Regards, John

 

[SUNRAY]

I think it actually might, in some situations, if the testing resulted in tripping of an RCD other than the one 'being tested' (instead of, or as well as, the one 'being tested'), mightn't it?

Kind Regards, John

Yes of course that would, I was only thinking of the 'non RCD' neutral.

 

[SUNRAY]

Yes of course that would, I was only thinking of the 'non RCD' neutral.

Second thoughts; if the test is between 'L' & 'E' then no. I've not looked into how RCD testers work.
A plug in RCD

uses both 'L' & 'N' for the test so will (or could) trip either or both RCDs in the CU.

 

[JohnW2]

Second thoughts; if the test is between 'L' & 'E' then no. I've not looked into how RCD testers work.

I'm not sure, either. However, much of what I wrote before is still true - namely that IF the RCD testing resulted in some other RCD tripping, that would be a sure sign that there was something wrong with the wiring!

However, that doesn't alter that fact that the 'functional test' (with drill, vacuum cleaner or maybe something more modest!) would be a sure way of detecting a misconnected neutral!

Kind Regards, John

 

[sparkwright]

Indeed, but I suspect it may be a case of "hands up any electrician who has never done it" ... although hopefully most of them will have detected (and rectified) the problem before they left the 'premises'!

Kind Regards, John

I would say every electrician has only done it once .

 

[SUNRAY]

Just had an interesting chat over the phone with a friend, and mentioned this thread and putting the neutral wire in the wrong bar.
He described an inspection on a CU which had been upgraded to all RCBO but one RCD had been left in place feeding a neutral bar shown purple, all the RCBO neutral wires only got a neutral supply if the unused RCD was on. The outgoing neutrals were in another neutral bar which was proper neutral shown orange.
The customer was happy with the work until they noticed the RCD was 'off' and flicked it 'on', things tripped and they called sparks in when they couldn't leave every trip 'on'.

I couldn't see how it could work until I drew it out, I hope I've interpreted it correctly.

 

[JohnW2]

I would say every electrician has only done it once .

Probably only once 'out of ignorance' (or due to ack of thought). However, instances like the time I 'did it' probably could happen more than once - since I fully knew where I should be connecting the neutral, and why - but somehow my brain and/or fingers disobeyed that instruction (maybe because I was distracted by something) ... and I suppose that could happen again.

Kind Regards, John