Kitchen Ring earth fault?

[Ross1]

Hi guys,

Customer woke up this morning with the Main switch/RCD tripped. He narrowed the problem down to the kitcken ring so He unplugged all the counter top appliances and switched all the big under counter appliances off at the switches.

I got there and turned the mcb on then plugged the toaster in first and the RCD tripped. I then punplugged the toaster and reset the RCD. I then plugged everything in the kitchen in One by one and left each appliance plugged in individually for 5 - 10 mins each, the only thing that that tripped the RCD was when I plugged the freezer in.

I checked the wiring behind each socket and all was ok. So I plugged everything in except for the freezer and the RCD didnt trip. I waited for nearly an hour and no trip even with the toaster plugged in and the switch turned on.

I didnt have any test equipment on me but I`m going back tmrw with test equipment, so my question is can anybody advise on possibley the quickest way to iddentify the cause of the fault?

Thanks

 

[Engineer54]

Just curious, ...Why would you go to the customers house which is known to have a fault on a RFC without your test equipment???

No-one can give you any real direction here, not until you come back with some actual test results!!!

 

[Southern Spark]

ramp test the rcd, I wouldnt be surprised if it is a bit sensitive

 

[Deleted member 9648]

Do an IR test on the circuit......always the first call with earth faults.
You are just guessing otherwise.
IR test the circuit with all loads disconnected first,and if that is ok start IR testing loads.....remember you are looking for an earth fault with a tripping RCD,so test L-E and N-E.....not L-N.

EDIT.....a ramp test will only tell you at what level the rcd trips....it wont tell you the cause,waste of time until you have proved satisfactory IR.

 

[Ross1]

Just curious, ...Why would you go to the customers house which is known to have a fault on a RFC without your test equipment???

No-one can give you any real direction here, not until you come back with some actual test results!!!

Hi E54,

Coincidence has it that I was going there today anyway to change 2 light fittings, I keep my Fluke1653b in the house and for got to take it and on top of all that Im not that hot at fault finding mate.

 

[ezzzekiel]

as already stated only an IR test is going to help narrow this problem down.

Test each circuit one at at time with Ir tseter with loads/appliances removed and see if any circuits come back low.

If no work has been carried out then thre is a good chance its an appliance at fault and not fixed wiring but it could be.

try a quick test between N/E bar at consumer unit and if a low reading is showing up disconnect the neutrals one at a time till low reading clears and you wil have identified the offending circuit.

 

[Ross1]

Do an IR test on the circuit......always the first call with earth faults.
You are just guessing otherwise.
IR test the circuit with all loads disconnected first,and if that is ok start IR testing loads.....remember you are looking for an earth fault with a tripping RCD,so test L-E and N-E.....not L-N.

EDIT.....a ramp test will only tell you at what level the rcd trips....it wont tell you the cause,waste of time until you have proved satisfactory IR.

Hi wirepuller,

Not sure how you go about IR testing loads. Im new to testing.

 

[ezzzekiel]

to be honest I wouldnt worry to much about the appliances being the problem at this stage, test the fixed wiring first

 

[Mark_Burgess]

Hi guys,

Customer woke up this morning with the Main switch/RCD tripped. He narrowed the problem down to the kitcken ring so He unplugged all the counter top appliances and switched all the big under counter appliances off at the switches.

I got there and turned the mcb on then plugged the toaster in first and the RCD tripped. I then punplugged the toaster and reset the RCD. I then plugged everything in the kitchen in One by one and left each appliance plugged in individually for 5 - 10 mins each, the only thing that that tripped the RCD was when I plugged the freezer in.

I checked the wiring behind each socket and all was ok. So I plugged everything in except for the freezer and the RCD didnt trip. I waited for nearly an hour and no trip even with the toaster plugged in and the switch turned on.

I didnt have any test equipment on me but I`m going back tmrw with test equipment, so my question is can anybody advise on possibley the quickest way to iddentify the cause of the fault?

Thanks

Hi E54,

Coincidence has it that I was going there today anyway to change 2 light fittings, I keep my Fluke1653b in the house and for got to take it and on top of all that Im not that hot at fault finding mate.

You almost answered the problem yourself, when you remember you tester, give the freezer a once over.

 

[Mark_Burgess]

Will you be issuing a MWC for those lights you are changing?

 

[telectrix]

MWC not necessary for replacement of fittings. the circuit has not been altered.

 

[Ross1]

Will you be issuing a MWC for those lights you are changing?

No i wont mate

 

[richy3333]

Just curious, ...Why would you go to the customers house which is known to have a fault on a RFC without your test equipment???

That was the first thing I thought. Always surprised when a thread starts with 'am going back to do some testing...' My tester(s) are always with me when I'm working

 

[richy3333]

MWC not necessary for replacement of fittings. the circuit has not been altered.

Best read page 336 of the BRB. I would issue a MW cert (and always do)? Why are people replacing accessories without knowing the circuit is safe, which you find out through inspection and testing?

 

[telectrix]

you can ndo as many tests on the circuit as you like. you don't have to complete a MWC, although doing so may be of benefit if the crap should hit the fan through some cowboy following you.