Cannot get RCD test to work?

[HappyHippyDad]

Evening chaps..

I have just fitted some downlights in a bathroom and needed to give them RCD protection as there was none. I fitted the following:



The test button works fine and the unit trips when a fault occurs (touching neutral to earth) but I cannot get the MFT to test it for trip times which I need for the MWC. Its a fairy decent MFT and I've never had any trouble with it testing RCD's before but I have never tested this sort of RCD before, it has always been in the CU. I make contact with the live/neutral/earth of something which the RCD is feeding, I get the little 'tick' on the MFT and then it just wont test.

Am I missing something simple here? Is this unit tested in the same way as you would an RCD in a CU?

 

[R G]

however....you say it works on the test button.....but not at the load...

whip that RCD fcu off and make sure the outgoing CPC is connected....it may have come out when you pushed the front on...

or it may be that you didn`t connect it at all....as if the sleeving moved over the conductor then it could have given the impression that a secure termination had been asheaved....when in reality its not...

Should have proven all that if he's done the EFLI test before RCD test ,,

 

[HappyHippyDad]

If the Zs is 0.9 then I don't see the touch voltage being set @ 25V being the problem, I would check the continuity of the CPC all the way through the circuit though.

I would also try the test at the outgoing terminals of the RCD with the outgoing circuit disconnected first too, to narrow down where the problem may lie, it maybe simply that the RCD is faulty.

Continuity of CPC was proved.

That is a very good idea Spark68 and I should have done that.

Which implies that he has not tested at the load terminals of the device. You test the device not the circuit

Would you not test the circuit as well Trev? When you test an RCD in a CU you test that on the circuit somewhere, generally a socket?

 

[trev]

Which he did, via the circuit which was connected to the load side of the RCD FCU.

So you're ignoring the correct methodology of testing RCDs. Fair enough.

 

[jackhammerJIM]

"Noisy" earth?

not familiar with the metrel . a noisy earth would show on the earth loop test .

 

[trev]

Would you not test the circuit as well Trev? When you test an RCD in a CU you test that on the circuit somewhere, generally a socket?

No, you test the RCD at the load terminals of the device.

 

[Meggerman]

I have had one of those units duff before. Would not trip at 30ma. Did 100ma Ramp test and it operated at 70ma. After that it operated at 23Ma. Still returned it as felt it could be unreliable.

 

[GLENNSPARK]

Should have proven all that if he's done the EFLI test before RCD test ,,

yes of course...

sorry guys.

 

[MDJ]

So you're ignoring the correct methodology of testing RCDs. Fair enough.

It is getting a bit like Fred Carney's circus in this forum lately Trev LOL

 

[SirKit Breaker]

I don't know what all the fuss is about, i once spent and age trying to find out why an RCD wouldn't trip, i was testing on the supply side, took a while for the penny to drop, and not before i had stripped the bloody thing out before i realised what i had done.

So maybe i am a waste of space after all! :dunce2:

 

[Meggerman]

No, you test the RCD at the load terminals of the device.

Yes, I would for a dead accurate reading of device not affected by earth leakage out on the circuit.

 

[R G]

Unbelievable all this Lol,,,

 

[Knobhead]

Keep going kid, the hole you're digging is getting deeper.

 

[Meggerman]

I don't know what all the fuss is about, i once spent and age trying to find out why an RCD wouldn't trip, i was testing on the supply side, took a while for the penny to drop, and not before i had stripped the bloody thing out before i realised what i had done.

So maybe i am a waste of space after all! :dunce2:

I never inferred that about you. This OP seems to get a lot of grief and I felt he was about to get a load more when he just wanted some help. I guess I was wrong.

 

[MDJ]

I don't know what all the fuss is about, i once spent and age trying to find out why an RCD wouldn't trip, i was testing on the supply side, took a while for the penny to drop, and not before i had stripped the bloody thing out before i realised what i had done.

So maybe i am a waste of space after all! :dunce2:

Howard you have over 720 Thanks from us members here, your no waste of time M8, there are numties here though, and shhh, Don't tell anyone but there may be one in this thread hehe, I said maybe lol

 

[Meggerman]

Keep going kid, the hole you're digging is getting deeper.

Go on then old sage, enlighten me

 

[trev]

Yes, I would for a dead accurate reading of device not affected by earth leakage out on the circuit.

I'm completely at a loss to understand what you're saying here. A bit back you're backing his method when it was pointed out (calmly and respectfully) that he was carrying out the test wrongly now you appear to be backing up what I said but only to get "a dead accurate reading"
Why would you not want a dead accurate reading?

 

[shanky887614]

Have you checked the fuse?

 

[NickD]

I get the little 'tick' on the MFT and then it just wont test.

My guess is something's not right with the circuit, possibly that other tests ought to have revealed, which leads to the MFT being unwilling to test. Hope that's vague enough for you.

 

[Meggerman]

I'm completely at a loss to understand what you're saying here. A bit back you're backing his method when it was pointed out (calmly and respectfully) that he was carrying out the test wrongly now you appear to be backing up what I said but only to get "a dead accurate reading"
Why would you not want a dead accurate reading?

Is he not just trying to confirm if unit is faulty. Probably only a got a bathroom light and a fan on load of this unit. He done I/R and ZS and said it was good. Why disconnect load in this case? just more for him to do? That was where I was coming from.

 

[GLENNSPARK]

Continuity of CPC was proved.

That is a very good idea Spark68 and I should have done that.



Would you not test the circuit as well Trev? When you test an RCD in a CU you test that on the circuit somewhere, generally a socket?

does this mean you carried out a Zs?

and if so have you disturbed anything sinse then....but before attempting RCD testing?

 

[HappyHippyDad]

I'm completely at a loss to understand what you're saying here. A bit back you're backing his method when it was pointed out (calmly and respectfully) that he was carrying out the test wrongly now you appear to be backing up what I said but only to get "a dead accurate reading"
Why would you not want a dead accurate reading?

I suppose really its a 'live' accurate reading. A 'dead' accurate reading wouldn't be great for a RCD test..

Sorry Trev, couldn't resist... just trying to lighten the mood!

 

[GLENNSPARK]

wheres he gone?..

that haphippyhaphip bloody fella?...

 

[R G]

does this mean you carried out a Zs?

and if so have you disturbed anything sinse then....but before attempting RCD testing?

Not sure what this guy has done mate ,,,lol,,,

 

[GLENNSPARK]

oh rite...

your still here then..

 

[trev]

Why disconnect load in this case? just more for him to do?

I see what you're getting at but it's the correct way to carry out the test. Forgive my ---- retentiveness

 

[trev]

Ordinarily with an RCD at the CU you'd isolate the circuit via the MCB. In this case that's not possible so he should disconnect.

 

[jackhammerJIM]

well happy hippy you need to revisit the job and do what trev has said ...

disconnect load side and test at load side .

prove the rcd . take it from there.


take a spare if its a long way to wholesalers

 

[GLENNSPARK]

oye happy/hipy:

how did you prove continuity of CPC?

was a Zs carried out...?

after all fronts/accessories were fixed into their final positions?

 

[Meggerman]

I see what you're getting at but it's the correct way to carry out the test. Forgive my ---- retentiveness

Honestly that's cool. I seemed to of ****ed everyone off in this thread tonight. I gonna go watch Moto GP highlights and shout a the TV instead

 

[MDJ]

Honestly that's cool. I seemed to of ****ed everyone off in this thread tonight. I gonna go watch Moto GP highlights and shout a the TV instead

Go and find a little bloke with glasses and start a fight lol