RCD tripping on circuits after new board change nitemare

[Jdsparky]

I think mixed up the two rings might be a good call so try end to ends first as u should have done already but if not that might be the culprit....as its unlikely to be both rings that have faults on but not impossible, especially if u have put one ring on one side and one on another and both rcds trip, u may have them mixed up as I say

 

[Baconhead]

Always a good idea to carry out a few pre tests prior to carrying out a CU change in my opinion,Can save a whole lot of hassle at the end of the change.

 

[tony mc]

I think some more info is required as to what dead tests were performed.

If you say the neutrals are on the correct bars is that because you carried out the 3 step dead tests on the ring finals.

If they are correct and everything is disconnected and both RCD 's are tripping its down to IR testing.

With a 30 mA RCD it should hold above 7666 ohms so once you start IR testing if you get a 0.00 M ohms reading its time to switch over to low ohms and start to work out where the fault /faults are by spliting the ring etc as has already been mentioned!

Is there any quick test with your Megger???

If you get a low ohms reading when testing as a guide to get nearer the fault you can use a bit of maths to give you a rough distance to the fault as you will know the resistance of the cables you are testing.

Once you have completed the dead IR tests let us know the readings !!

 

[Engineer54]

Always a good idea to carry out a few pre tests prior to carrying out a CU change in my opinion,Can save a whole lot of hassle at the end of the change.

Yep!! At the very least it will tell you if any problems are found, it's not from any mistakes that you have made at the CU on completion... I mean how long will it take to carry out a few brief tests prior to changing the CU anyway??

 

[ezzzekiel]

Never understood why after a cu change people start having problems due to existing faults, if you aren't prepared to address them then should you really be changing the board in the first place?

 

[Farmelectrics]

Always do eicr on installation before you change board slow down do the tests properly once there ok you can change board in few hours it's easy knowing in advance your board is not going to trip learnt the hard way myself when I was younger lol

 

[vernam616]

Testing before or afterwards dont suppose really matters does it, its still a fault

A better thing when quoting would be to inform the client of the price and then notify them that you have a hourly charge for finding faults on on completion of the new board

Ironically i changed a board this morning, never tested before hand and powered it up, from experience i had already pre determined that they maybe a borrowed neutral from landing light, and there certainly was, so lighting circuits went onto the same mcb, not conventional maybe but not really breaking any rules

 

[micknew]

Testing before or afterwards dont suppose really matters does it, its still a fault

A better thing when quoting would be to inform the client of the price and then notify them that you have a hourly charge for finding faults on on completion of the new board

Ironically i changed a board this morning, never tested before hand and powered it up, from experience i had already pre determined that they maybe a borrowed neutral from landing light, and there certainly was, so lighting circuits went onto the same mcb, not conventional maybe but not really breaking any rules

The only rule it is breaking is that a potentially dangerous situation exists for any electrician working on the circuits who assumes that the wiring was done correctly in the first place.
Seen an electrician thrown off steps due to a borrowed neutral.

 

[vernam616]

Well whats he doing working live then?

The lighting circuits are on the same MCB, so if anyone needs to work on this circuit they should be isolating

I could understand your point if i had put them on seperate mcbs on the same side

 

[telectrix]

even then, you isolate the circuit, then before anything else, check (at the fitting or whatever you are working on) for dead.

 

[micknew]

Still a wiring which was not carried out correctly due to ignorance of the original installer.
You cannot condone borrowed neutrals left on an installation.

 

[vernam616]

Have a little think about what you post before hitting "post reply" button Mick

 

[micknew]

even then, you isolate the circuit, then before anything else, check (at the fitting or whatever you are working on) for dead.

Agree Tel.

 

[micknew]

Have a little think about what you post before hitting "post reply" button Mick

I did.

 

[vernam616]

Nobody said they condoned it, but if the client doesnt want damage or cannot afford to have the circuit altered the alternative is putting them onto the same mcb, yes not conventional but practical and still safely protected by mcb and rcd. Do you understand that if someone isolates that mcb that the neutral wont be live?