micc on rcbo

[buzzlightyear]

micc on rcbo will not set

 

[Octopus]

WTf???

More info please

 

[Leesparkykent]

Hi buzzlightyear, can you expand a little on your post please. Have you conducted any tests like insulation resistance? Is this a circuit you've installed or existing circuit?

 

[The Ghost]

I get ya, very Zen

 

[buzzlightyear]

to day I have changed a metal cu. micc cable on to rcbo will not set. I then exchange to mcb holds. this existing circuit

 

[Leesparkykent]

to day I have changed a metal cu. micc cable on to rcbo will not set. I then exchange to mcb holds. this existing circuit

What was your insulation resistance test results for this circuit?

 

[buzzlightyear]

>999 good

 

[tomspark93]

need far more information. Have you insulation resistance tested to the electrical main earth or to the earth of the micc? What does the cable feed? Could there be a crossed neutral? Is the RCBO faulty (disconnection times met and ramp test)

 

[Deleted member 72666]

Still not enough info.

 

[buzzlightyear]

tested from live to earth on micc conductor on lighting all good

 

[Leesparkykent]

tested from live to earth on micc conductor on lighting all good

Both live conductors?

 

[Deleted member 72666]

Okay, what is the circuit feeding and all test results obtained, also what other circuits are there and test results.
How many lighting circuits are there? Are there any more rcbo's or rcd's ?

 

[mattg4321]

Another topic Dave Sparks would love.

 

[Pete999]

to day I have changed a metal cu. micc cable on to rcbo will not set. I then exchange to mcb holds. this existing circuit

What have you changed it from? RCBO detects earth leakage MCB detects Overcurrent, so swapping from RCBO to mcb tells you what exactly, not rocket science is it?

 

[Pete999]

tested from live to earth on micc conductor on lighting all good

What about N to E??

 

[tomspark93]

Another topic Dave Sparks would love.

not seen him on here in a while

 

[Pete999]

Wonder why with posts like that??

 

[buzzlightyear]

the old breaker was bs 3871 6 amp >999 installation good

 

[westward10]

Have you done IR neutral to earth as already mentioned, what does the circuit supply.

 

[Deleted member 72666]

Extraction of info seems to be particularly difficult this evening.

 

[buzzlightyear]

I westward 10. just lights

 

[Octopus]

biting my lip!

 

[Pete999]

Ive bitten mine.

 

[westward10]

Does it need rcd protection, if the circuit is MICC throughout it probably doesn't need it.

 

[buzzlightyear]

yes westward 10 the micc is buried in the wall

 

[Octopus]

So go on then, tell us the N-E IR reading.....

 

[Pete999]

yes westward 10 the micc is buried in the wall

Is the cable earthed?

 

[buzzlightyear]

yes pete999 tested line to earth >999 neutral to earth >999

 

[westward10]

Is the cable earthed?

I don't think rcd protection is required but he would need to fully verify that.

 

[Octopus]

So the RCBO trips, yet the MCB holds and the IR N-E is 999 - so maybe change the RCBO?

Were the lights "on" with the laps removed when you did your IR?

 

[buzzlightyear]

all micc lighting cables are buried in the walls in the flat that I working in .

 

[westward10]

Does it go into the shower/bathroom.

 

[Pete999]

yes pete999 tested line to earth >999 neutral to earth >999

When you swapped from RCBE to MCB is there a chance you could take an earth leakage reading, that may throw some light on the problem, as the problem is pointing to a leakage fault somewhere.

 

[buzzlightyear]

possible pete 999 .

 

[Lucien Nunes]

IR seems good so cable probably sound. If the total circuit length is great, capacitive leakage can be significant. Use a leakage clamp to measure differential current of L & N, not CPC current and report your findings, also the results for a ramp test of the RCBO.

 

[Richard Burns]

With good IR results for both L-E and N-E I would ask if you have you got the neutral connected correctly?

 

[buzzlightyear]

yes. mr burns no neutral out. and class 2 light fittings & switchs

 

[Richard Burns]

I am asking if the neutral core is connected to the RCBO and not to the neutral bar, as if you have been swapping back and forth MCB to RCBO this could get missed.
If the light fittings are class II then there cannot be an earth fault there so there must be something else causing the problem.

 

[westward10]

There could still be an earth fault even if it is all Class 2.

 

[hightower]

This thread made me chuckle. What's been said in it could have been said in 3 posts if the OP had put all the information in to begin with.

OP, does your internet provider charge you extra for using prepositions and the like in sentences? Or where you just replying while there was water on the boil?

 

[Deleted member 72666]

I am asking if the neutral core is connected to the RCBO and not to the neutral bar, as if you have been swapping back and forth MCB to RCBO this could get missed.
If the light fittings are class II then there cannot be an earth fault there so there must be something else causing the problem.

That is my thought as well especially if all the ir tests come back fine. I didn't mention it because he/she has ignored all my questions.

 

[Pete999]

Don't know if this has been asked and I can't be bothered to look back, what voltage was the IR test done at?

 

[telectrix]

with the ciircuit connected to MCB, get an earth leakage clamp meter on the job. IR test can sometimes be inconclusive.

 

[LeeH]

Is it normal to use MICC in a flat??

Some real old council block maybe?

 

[Pete999]

Used MICC in Council new build flats in the 60s (1960s for the comedians out there)

 

[drzsta]

Used MICC in Council new build flats in the 60s (1960s for the comedians out there)

Yep, the old council spec was mostly either steel conduit or micc both for the flats and communal areas on the local authority where I used to work.

Nowadays its thrown in, cheap and work that a bloke pulled off the street could put his hand to in a day. ​

 

[westward10]

Used MICC in Council new build flats in the 60s (1960s for the comedians out there)

Dark art that Pete.

 

[buzzlightyear]

when back to day to look at the job.on to test the micc the reading went mental on IR
looked at the bathroom enclosed light the bowl was full of water & the base
the only thing was missing a gold fish . found out the flat above had a leek
went to the flat below

 

[Deleted member 72666]

yes pete999 tested line to earth >999 neutral to earth >999

when back to day to look at the job.on to test the micc the reading went mental on IR
looked at the bathroom enclosed light the bowl was full of water & the base
the only thing was missing a gold fish . found out the flat above had a leek
went to the flat below

Now I'm really confused!

 

[Pete999]

Now I'm really confused!

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