Erroneous test during pre testing

[Macca65629]

Hi,
While doing the Erroneous test during my pre test I came across abit of a headache.
When I was doing a lighting circuit it was coming in a short eg. 0.04ohms but once I disconnected an LED light in a bathroom it went away, same with socket circuits which had USB sockets connected on them, is this normal or am I getting something wrong ?? Everything else is fine rp+re and IR test between you phase&neutral to earth.
I had all mcbs up in the on position except the circuit i was testing and went from the phase busbar to the top of the mcb I had switched off.
Thanks

 

[westward10]

If you are testing across line and neutral with loads connected such as the LED lamp and socket which incorporates a USB port it is bound to indicate a connection between the conductors.

 

[Macca65629]

I was testing between the line busbar and and the line load side of the off mcb, I wasn’t going between line and neutral? This was for an erroneous test between my line conductors..

 

[westward10]

Was the main switch on..................................

 

[timhoward]

For those wondering, as I myself was a minute ago, I think this is an extra test required in Irish regs to detect inter-connections between circuits.
I believe it's a (dead!) test between the busbar with all but one MCB on, and the outgoing side of MCB.

Not having ever done this myself, I'm still working out how this works as there will be resistances through any connected loads back to the N bar, back through other loads to the other MCB and the bus bar. So I'm wondering if you are supposed to have N's disconnected for this test?
Please can a RECI put us out of misery!

 

[timhoward]

Ah - to answer my own question:
4/15 - Test 6 - Erroneous connections
The following test shall be carried out in order to detect erroneous connections between circuits: For each circuit, its protective device shall be switched off and an insulation test in accordance with Table 61A applied between phase conductors of that particular circuit and all other phase conductors.
Note 1: This is an additional test to those specified in CENELEC HD 384.6.61:1992 Note 2: All loads in the circuit under test must be disconnected e.g. appliances switched off, lamps removed.

 

[timhoward]

but once I disconnected an LED light in a bathroom it went away, same with socket circuits which had USB sockets connected on them, is this normal or am I getting something wrong

There's your answer - no loads at all, including USB sockets.

 

[Macca65629]

There's your answer - no loads at all, including USB sockets.

Thanks very much Tim,

For those wondering, as I myself was a minute ago, I think this is an extra test required in Irish regs to detect inter-connections between circuits.
I believe it's a (dead!) test between the busbar with all but one MCB on, and the outgoing side of MCB.

Not having ever done this myself, I'm still working out how this works as there will be resistances through any connected loads back to the N bar, back through other loads to the other MCB and the bus bar. So I'm wondering if you are supposed to have N's disconnected for this test?
Please can a RECI put us out of misery!

Thanks very much Tim for the info great to find out abit more from someone with more experience ?

 

[RMS Electrical]

I was testing between the line busbar and and the line load side of the off mcb, I wasn’t going between line and neutral? This was for an erroneous test between my line conductors..

Macca, please find my question posted yesterday under the erroneous testing forum.
Shalom, RMS

 

[RMS Electrical]

For those wondering, as I myself was a minute ago, I think this is an extra test required in Irish regs to detect inter-connections between circuits.
I believe it's a (dead!) test between the busbar with all but one MCB on, and the outgoing side of MCB.

Not having ever done this myself, I'm still working out how this works as there will be resistances through any connected loads back to the N bar, back through other loads to the other MCB and the bus bar. So I'm wondering if you are supposed to have N's disconnected for this test?
Please can a RECI put us out of misery!

Hi Tim, thanks for input.
I'm a RECI and still in the dark over this issue. Erroneous testing is a post connection test without any connected load. That's why I think there is a hidden load or spurred neutral causing a backfeed. The confusing thing is: I've done the erroneous test across each of the mcb's in the RCD group, * and had a voltage at every circuit, ranging from 90Vac to 238Vac. All loads were disconnected.
* You de-energise the mcb or circuit being tested, while all other circuits on same busbar are energized. The (voltage) test is performed between the busbar and to the load side of the isolated mcb, to test for crossfeeds/erroneous circuits.*

Please help me guys. Even a first-year appie might be able to throw us some clues. It's wrecking my head.
Robert

 

[Pretty Mouth]

All loads were disconnected.

How did you confirm this?

 

[westward10]

@RMS Electrical can you keep your problem to the thread you started on the same issue to save confusion.

 

[RMS Electrical]

@RMS Electrical can you keep your problem to the thread you started on the same issue to save confusion.

Will do.

 

[RMS Electrical]

How did you confirm this?

Good question.
I disconnected all known socket loads physically (unplugging), and lighting by isolating at switches. Water heater was isolated.
That's why I suggested there could be an unknown load or a back-feed.
Look, I've heard almost every approach possible from this group of sparks.
I'm going back to the job again and will try out your suggestions. I will check each and every point even with a no-contact tester and every other way.
Thank you all

 

[RMS Electrical]

If you are testing across line and neutral with loads connected such as the LED lamp and socket which incorporates a USB port it is bound to indicate a connection between the conductors.

Concerning your request to stay with the thread I started: I only replied to a point that Tim queried, requesting info from a RECI. So I gave him an explanation of the Irish regs concerning certification with a link. I did not intend to cause (thread) confusion