RCD Earth Leakage

[garysparky1]

I Need a little help i recently fitted a new consumer unit for a mate. The house is empty and up for sale so i thought no problem as not in a hurry continuity was ok on all circuits IR ok ,Ze 0.09,PFC 2.95kA so i changed the board then powered up and the 80a 30Ma RCD tripped i disconnected each circuit and reset it tripped on each circuit. I've since gone back with a clamp meter and found 29-39Ma running through the bonding. I clamped ( on lowest setting)the neutral and line seperately on each circuit and got kitchen N-0.70 L-0.46Ma and downstairs lights N-0.47 L 0.10 surely these differences in reads are too high can anybody steer me in the right direction. :frown2:

 

[Top Cat]

If you say it tripped out on each circuit (mcb) then it looks like a neutral fault.

Disconnect all neutrals and do IR again. If it is a 17th edition board with 2 RCD's make sure you have not got neutrals crossed between RCD's. Finally check if upstairs lighting has a "borrowed" neutral ie. The landing light has not got its neutral from downstairs lighting circuit.

 

[plugsandsparks]

Are these readings with loads on the ccts. Is polarity correct ? You mentioned just one rcd, is there another one ?

 

[Top Cat]

If you say it tripped out on each circuit (mcb) then it looks like a neutral fault.

Disconnect all neutrals and do IR again. If it is a 17th edition board with 2 RCD's make sure you have not got neutrals crossed between RCD's. Finally check if upstairs lighting has a "borrowed" neutral ie. The landing light has not got its neutral from downstairs lighting circuit.

Correction meant to say upstairs!

 

[garysparky1]

it's an 8 way BG board with only one 80a 30Ma RCD the readings are taken from clamping each circuits line and neutral as the RCD keeps tripping MCBs are fine what do you make of the 29-39 Ma current going through the bonding ?

 

[Top Cat]

it's an 8 way BG board with only one 80a 30Ma RCD the readings are taken from clamping each circuits line and neutral as the RCD keeps tripping MCBs are fine what do you make of the 29-39 Ma current going through the bonding ?

So it's not a 17th edition board, i think you only have a clip on Amp meter, are you an electrician?

 

[garysparky1]

hmm its a British General 17th edition Board a digitron clamp meter and im 17th edition mr cat

 

[Top Cat]

hmm its a British General 17th edition Board a digitron clamp meter and im 17th edition mr cat

I don't see how it is 17th edition with only 1 RCD.

Yes you have a clamp meter, good for you. You have not said whether it is your only meter.

Do you have an IR meter.

You did not answer whether you are an electrician or not.

Thank you Mr Gary

 

[Plonker 3]

Did you carry out a EICR before changing the DB?

Have you checked for a shared neutral?

 

[WPD Lad]

Sounds like a 16th edition board

 

[mickys86]

Sounds like a 16th edition board

Ditto

 

[Geoffsd]

If you mean milli-amps it's mA.

Have I missed something?

How can you be testing for (and measuring some) current when the RCD won't switch on?

Have you wired the RCD neutrals correctly?

 

[garysparky1]

Thanks guys i appreciate your feedback i use a kewtech kt 65 for testing and used the recently acquired clamp meter to test for earth leakage but i think ive used it incorrectly as should have (correct me if i'm wrong )been testing current going through line and neutral seperately for circuit(meter set for Amps not mA) as imbalance i thought it would identify problem circuit. RCDs were removed so i could live test as wont reset, neutrals into are correct polarity. I need to check for shared neutrals and do a more thorough investigation. I am fully qualified and registered but i hav'nt done any board changes so i foolishly thought it would be straight forward !

 

[nickblake]

Its very rarly straight forward you will need to retest , shared and crossed neutrals are normally the culprit ,or even a crossed earth where a neutral and earth are crossed see this a few times in lighting circuits even a trapped neutral ,so i think the best way forward is to re test , as for the earh leakage you should test for this round the earths of the circuit ,so main earth then each circuit earth till you find the circuit with the highest earth leakage and using an earth leakage tester

 

[Top Cat]

Thanks guys i appreciate your feedback i use a kewtech kt 65 for testing and used the recently acquired clamp meter to test for earth leakage but i think ive used it incorrectly as should have (correct me if i'm wrong )been testing current going through line and neutral seperately for circuit(meter set for Amps not mA) as imbalance i thought it would identify problem circuit. RCDs were removed so i could live test as wont reset, neutrals into are correct polarity. I need to check for shared neutrals and do a more thorough investigation. I am fully qualified and registered but i hav'nt done any board changes so i foolishly thought it would be straight forward !

You say you use the Kewtech kT65 for testing but it seams as though all the testing on this board is done with the Amp meter.

You have removed RCD because it wont reset!!!!!

You will find the faults by setting the Amp meter to Amps not mA!!!!!

You say on an earlier post the C/U has only 1 RCD so why look for shared neutrals?

Should you really be doing this?????

 

[Edward Amsden]

Is it a split load board with one rcd and a couple of rcbo's ?

 

[Octopus]

Can you post a photo of the CU?

 

[Guest55]

cowboys like you keep me in a job......

Actually its the other way round , electrical trainee's keep you out of work.....

As i sit here with 17 yrs experience and a jib gold card , twiddling thumbs wondering where all the work has gone.
Now i know , its gone to all the "qualified" sparks who have yet to do a CU change.
Im thinking its time to get out of electrical or bugger off abroad to ply my trade.

 

[Top Cat]

I wonder if garysparky1 will come on line to let us know how he got on with his fault finding (with his clip on Amp meter)?

Personally i cant wait!

 

[Knobhead]

----- cats enjoy playing with a mouse before they kill it.