Discuss Kitchen Ring earth fault? in the Australia area at ElectriciansForums.net

Ross1

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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
 
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!!!
 
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.
 
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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.
 
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.
 
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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.
 
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.
 
MWC not necessary for replacement of fittings. the circuit has not been altered.
 
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 :)
 
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? :confused:
 
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.
 
A little earth leakage clampmeter would come in handy here, clamp on the earth of the ring then operate each appliance one by one and monitor the earth leakage, or you could switch the appliances in one by one and monitoring the leakage as you go, and see if it is anywhere near the RCD tripping current, which is very rarely 30mA, Ive had an RCBO trip at 21 this week
 
Are some sparks are above BS7671?

Page 336

...'This certificate (Minor works) may also be used for the replacement of equipment such as accessories or luminaire,'...

Nuff said me thinks, as whoever wrote the Regs clearly thought different about when to use the MW certificate
 
Hi Tel'

Sorry, but I can't agree with you there mate.

As you haven't been more specific I presume you are referring to 631.3 when you refer to the word 'may'?

631.3 Where minor electrical installation work does not include the provision of a new circuit, a Minor Electrical Installation Works Certificate, based upon the model given in Appendix 6, may be provided for each circuit altered or extended as an alternative to an Electrical Installation Certificate.'

The devil is in detail of the grammar? This section does not give an electrician permission to obviate the requirement to provide a certificate? The paragraph doesn't say ... a certificate may be provided...' i.e. complete a certificate if you feel there is a need to do so, otherwise don't? So to the question that the next amendment might change the word 'may' for 'must' - I doubt that would happen so specifically because it would change/alter the context of the paragraph and in any event there is already a requirement to supply certification for work completed by way of one of the 3 certificates detailed in BS7671. Personally I cant understand people bemoaning about completing certs - it's part of an electricians job, a necessary evil, just something that has to be done.

This section uses the word 'may' to offer an alternative to an electrician to use a MW cert rather than a full EI cert.

I would suggest that some electricians could chosen to read this section as they see fit rather than having due consideration for the correct punctuation.

Page 148 of the Onsite-guide also states when a MW cert should be used. Nowhere does it say that the use of the MW cert (or any other cert) is optional as part of our job.

Page 19 of the Onsite-guide for the Building Regs (England & Wales) says that when undertaking minor works a MW cert should be issued, or where work is undertaken by a DIYer then compliance to the Building Regs can be shown by having an electrician insect, test and certify the work by way of a MW cert.

Page 79 of the NICEIC guide for Inspection, testing and certification states that 'BS7671 requires inspection and testing to be carried out, and appropiate certification to be issued,...'

Certificates also assist in providing defences under Reg 29 of EAW Regs.

If anyone can show me where in BS7671 it says specifically that certification is optional then I am happy to change my view...

Back to the thread...

I would support the comments that you should undertake the IR tests and then put an earth leakage clamp meter on the appliance as it sounds as though this is at fault.
 
631.3 Where minor electrical installation work does not include the provision of a new circuit, a Minor Electrical Installation Works Certificate, based upon the model given in Appendix 6, may be provided for each circuit altered or extended as an alternative to an Electrical Installation Certificate.'



sorry I agree with telectrix here, as replacing a fitting is not altering or extending a circuit, which I beleive is what the reg is refering to.
 
the other thing to note is the MWC itself asks for "details of the modified circuit". replacing a fitting /accessory is not modifying the circuit. therefore, IMO, no certificate is required (although i do not dispute the idea that it may be advantageous to complete a test of the circuit and issue a MW

edit:sorry, double post.
 
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the other thing to note is the MWC itself asks for "details of the modified circuit". replacing a fitting /accessory is not modifying the circuit. therefore, IMO, no certificate is required (although i do not dispute the idea that it may be advantageous to complete a test of the circuit and issue a MWC). a like for like replacement can be carried out by any householder without any paperwork whatsoever.
 
agree with tel,otherwise the diy sheds could not sell any electrical accessories as the diy bloke couldnt change a socket without having to call someone out to test and inspect/issue a mwc.
 
agree with tel,otherwise the diy sheds could not sell any electrical accessories as the diy bloke couldnt change a socket without having to call someone out to test and inspect/issue a mwc.

Get your point however they still sell Consumer Units to anyone. See a fully loaded G.E one for £50 in there the other week.
Surely a board change is not considered like for like is it?
 
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Have you tried PAT testing the appliances.

My apologies for swearing!

If your IR tests are acceptable, PAT testing is another option.

There I did it again, swearing!
 
Get your point however they still sell Consumer Units to anyone. See a fully loaded G.E one for £50 in there the other week.
Surely a board change is not considered like for like is it?

Could be I suppose, if the configuration and protective devices are all identical to the existing...ie a replacement due to damage to the existing....a CU upgrade would not be like for like though.
 
Thanks to most of you guys for all your responses apart from the odd 1 or 2 of you. If you got nothing helpful to say, I`d rather you not comment on my threads.


I was back on the job today with my tester, I done ring end to end continuity 0.51 L-L 0.52 N-N 0.84 E-E. IR test, lowest reading i got was 250M Ohm.


Everything in the house stays on, under load aswell untill I plug the freezer in and.....boom RCD trips within 30secs. So my conclusion is the freezer is the problem ( its a smeg under counter job if that helps ) Ive never claimed to be an 20 - 40 year experienced spark, thats why I am on this forum which I find a great source of info from lots of experienced sparks.

Im new to testing and fault finding so am I missing something Guys?
 
most probably be the freezer pal, as said above if all IR test is clear l-e, n-e, then circuit is fine,
just to prove you have found the fault a PAT on the applience would show leakage to earth,
 
most probably be the freezer pal, as said above if all IR test is clear l-e, n-e, then circuit is fine,
just to prove you have found the fault a PAT on the applience would show leakage to earth,

Thanks chopper, never done PAT and aint got the equipment. Any tests I could do with my multifunction tester on the appliance mate. Its my mates house and dont want him to have to call out a PAT man and part with his cash.

Thanks
 
not too sure , maybe try a continuity test between l-e , and n-e see iff anything shows up, not sure if you could do an IR TEST ON THE APPLIENCE AT 230V
 
Hi mate,

you could join L-N of the appliance and IR test @ 500v (test @ 250V first) to earth/metalwork of the appliance, it would be better if the appliance was disconnected from the fixed wiring for this, as this is all a PAT test would do with regards to the IR test part. and see what you get.
 
Hi mate,

you could join L-N of the appliance and IR test @ 500v (test @ 250V first) to earth/metalwork of the appliance, it would be better if the appliance was disconnected from the fixed wiring for this, as this is all a PAT test would do with regards to the IR test part. and see what you get.

cheers mate, do you think that anything under 2M Ohm could be suspect as is usually the case?
 
under 2M Ohm could be suspect as is usually the case?

I would expect anything less than 1 Meg for class 1 to be suspect, others may wish to correct me if Iam wrong.

This method does not replace a PAT test per se, but will show up faulty equipment.

Ps. if the appliance is faulty, I would expect your IR result to be a lot lower than 1 Meg, as a 30mA RCD will trip with a combined 'leakage resistance to earth' anywhere from about 8K ohms to about 15K ohms, depending on the actual RCD tripping current checked on the Ramp test
 
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the other thing to note is the MWC itself asks for "details of the modified circuit". replacing a fitting /accessory is not modifying the circuit. therefore, IMO, no certificate is required (although i do not dispute the idea that it may be advantageous to complete a test of the circuit and issue a MW

edit:sorry, double post.

Hi Tel.

Just looking at the MWC in the BRB (page 335). Could you clarify where it refers to 'details of modified circuit' in the certificate?
 
Thanks to most of you guys for all your responses apart from the odd 1 or 2 of you. If you got nothing helpful to say, I`d rather you not comment on my threads.


I was back on the job today with my tester, I done ring end to end continuity 0.51 L-L 0.52 N-N 0.84 E-E. IR test, lowest reading i got was 250M Ohm.


Everything in the house stays on, under load aswell untill I plug the freezer in and.....boom RCD trips within 30secs. So my conclusion is the freezer is the problem ( its a smeg under counter job if that helps ) Ive never claimed to be an 20 - 40 year experienced spark, thats why I am on this forum which I find a great source of info from lots of experienced sparks.

Im new to testing and fault finding so am I missing something Guys?

I stand vindicated!

As to are you missing something, it’s just experience which will come with time.
 
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