Lighting Fault

[Sidewinder]

Zee,

Not silly at all and you don't need to appologise mate at all

 

[Andy™]

Can someone explain how an low IR on N-E will trip an mcb?...

DIY man has been and wired it wrong polarity. simples.

 

[ProDave]

Can someone explain how an low IR on N-E will trip an mcb?...

Simple.

Some of the current will return via the neutral, and some of it will return via the earth.

The RCD is expecting ALL of the current to return via neutral. Thus any leakage to earth will create the imballance between L and N and the RCD will trip.

 

[Andy™]

Simple.Some of the current will return via the neutral, and some of it will return via the earth.

The RCD is expecting ALL of the current to return via neutral. Thus any leakage to earth will create the imballance between L and N and the RCD will trip.

re-read the question...

---------- Post Auto-Merged at 19:59 ---------- Previous post was made at 19:56 ----------

I apologise if the DP MCB doesnt, I know they exist but I am not 100% sure of the exact mechanics of it.Andy

its 2x SP MCB's in one, interlinked so both on/off at same time. same as TP MCB smaller...

 

[ProDave]

re-read the question...[

Oops :coat

 

[steptoe]

[quote name='Andy

 

[keithbr13]

This is starting to do my head in now lol. replaced the lead cable, but am still getting 0.01 Meg on IR test! There are two metal multi bulb fittings but some bulbs do not work in either fitting could this some how be giving the bad reading ? I have even run IR test with bulbs in, dimmers connected and get the same result. Am i missing something obvious here or just going mad .

 

[kme]

It would appear your fault-finding proceedure is a little haphazard?

Segregate the circuit, and IR test the individual parts - this will narrow down the section of wiring to concentrate on........

just a thought - you HAVE disconnected the circuit from the DB completely, hasven`t you?

 

[S60TEM]

This is starting to do my head in now lol. replaced the lead cable, but am still getting 0.01 Meg on IR test! There are two metal multi bulb fittings but some bulbs do not work in either fitting could this some how be giving the bad reading ? I have even run IR test with bulbs in, dimmers connected and get the same result. Am i missing something obvious here or just going mad .

I would say you've just found your problem right there! Metal fittings if old are a prime target for low IR readings. If they have some lamps that aren't working on them too then this is probably down to the flex within the fitting which will have detiorated to a point which it is / has short circuiting hence the MCB tripping? I would drop the old metal fittings down and redue the IR tests and if the readings prove satisfactory ie: above 2Mohms then replace the fittings with plastic pendants or battons and hopefully that should sort it. Have you checked the metal back boxes also for grommets? Could the cables have rubbed through there?