rcd test picking up faulty appliance??

[chrisreid186]

evening all

just before i start this thread i would like to point out that rcd tests should be carried out at the load side of the rcd

got a call out to a fault where the a 30ma rcd kept blowing to the stage where it wouldn't reset, there were only 2 circuits involved one 6a lighting and one 16amp radial, all the wiring i did from new about a year ago

1st thing i did was turn the power off and swap the rcd for a new one, power on and the rcd never tripped.
did a full auto rcd test on load side of rcd with breakers off and the results were good

ok so i've got the power working again but haven't found the fault that originally blew the rcd,
out of curiosity i wondered if doing a full auto rcd test at each mcb would highlight any problems
tested the light circuit and the results were good
tested the radial circuit and at x1 my fluke tester gave a error 4 message which is a earth error

wasn't sure if i was on to anything here so i unplugged everything from the radial and insulation tested it, all fine,
then when everything was disconnected i also rcd tested from the mcb which gave a good results no error 4
then i decided to start plugging in appliances one by one to see if effected the rcd test
got to a fridge freezer and the error 4 came back,

still not totally convinced this appliance was faulty i decided to put the fridge freezer on a different rcd and wait to see if this rcd trips

hopefully find out if it was the fridge freezer on Tuesday

would be handy to know if this method of testing does pick up faults in the appliances ????

the best thing to do would be to pat test the appliance or attach a clamp meter to the cpc and record any earth leakage, but didnt have those tools on me

 

[Engineer54]

would it be reasonable to assume that the fridge freezer is creating the 50v fault voltage ? as it only appeared when the fridge freezer was plugged in>

So what do you think is going to be your next course of action, if you confirm that your MFT is indeed set up correctly???
Do you have a PAT tester and an earth leakage clamp?

 

[GLENNSPARK]

Does your MFT have an earth leakage test facility?

 

[chrisreid186]

the fridge freezer is now on the old house rcd, as i was leaving i explained to the customer that if the old rcd tripped then he needs to get a new fridge.
that way i don't need to come back and he won't get charged again.

i have a clamp meter but the fault current will probably only be apparent after a couple of hours of use as it did not trip the rcd immediately.
also i'm not sure if a pat tester would pick up the fault?

the tester doesn't have a dedicated earth leakage facility it just wont work if theres over 50v on earth

 

[GLENNSPARK]

Will your MFT measure current in milliamps chris?