Earth Fault

[yelloperil]

I have recently fitted some lights in an attic and when I came to testing found the cpc showing 60 volts. I switched each mcb off in turn and the fault dissapeared when I turned off the downstairs lighting mcb. I am going back this weekend to sort the problem out so will start with an IR test. the house is only 10 years old and the customer has changed all the downstairs lights and switches.Is it fair to say that the fault should be on the downstairs lighting circuit?

 

[Amp David]

Sounds like a bit of a wind up to me?

 

[morph]

i thought that
next he will be saying does he need to check the sockets next door LOL

 

[Amp David]

You do don't you? Wondered why my testing seems to take for ages, just don't know where to stop!

 

[morph]

thats why sparks travell so much

 

[jdtae]

On your minor works cert you only record the Zs value of the circuit that you have worked on.

Thanks pushrod.

What if I installed a new ring final circuit at the kitchen newerly buit in the same property above and only contains 5 sockets which connected directly to DB as a ring final circuit 4.

Q. Should I do all Zs testing for the circuits (1,2,3) to look for higher vale?
The reason I am asking is that the ring final circuit 4 would be much further distance than
other circuit.

Your answer gave me a lot of understandings and hope more.

JD

 

[pushrod]

A new ring in the kitchen would have its own installation certificate (and is notifiable in a domestic property) - only test and record the results of the circuits you are working on unless you are doing a periodic inspection and test.

 

[Deleted member 9648]

Thanks pushrod.

What if I installed a new ring final circuit at the kitchen newerly buit in the same property above and only contains 5 sockets which connected directly to DB as a ring final circuit 4.

Q. Should I do all Zs testing for the circuits (1,2,3) to look for higher vale?
The reason I am asking is that the ring final circuit 4 would be much further distance than
other circuit.

Your answer gave me a lot of understandings and hope more.

JD

I have a question for you jdtae,....do you understand the significance of the results of your Zs tests?...or put another way what are the results telling you?

 

[jdtae]

I have a question for you jdtae,....do you understand the significance of the results of your Zs tests?...or put another way what are the results telling you?

In my understanding, it would be to see whether Zs value is low enough to let the current flow to operate the protective device in required time.
Can you please explain me if you see it defferently?

JD

 

[oldtimer]

I have recently fitted some lights in an attic and when I came to testing found the cpc showing 60 volts. I switched each mcb off in turn and the fault dissapeared when I turned off the downstairs lighting mcb. I am going back this weekend to sort the problem out so will start with an IR test. the house is only 10 years old and the customer has changed all the downstairs lights and switches.Is it fair to say that the fault should be on the downstairs lighting circuit?

You will find this is "Induced AC" in other words it is common to get 60-70 volts (picked up with a multimeter) on an earth that is not connected to the earth in the DB from a T&E due to the magnetic fields produced by the L&N. Once you earth it properly no more 60 volts.
This can also be a reason for false activations on burglar alarms as the cables a run along side mains cables and they also get AC pick up

 

[Deleted member 9648]

In my understanding, it would be to see whether Zs value is low enough to let the current flow to operate the protective device in required time.
Can you please explain me if you see it defferently?

JD

just checking mate

 

[jdtae]

A new ring in the kitchen would have its own installation certificate (and is notifiable in a domestic property) - only test and record the results of the circuits you are working on unless you are doing a periodic inspection and test.

Thanks again Pushrod.
I wonder if you can help me to clarify about the type of forms used for each cases.
1. Additional socket as a spur to existing ring final circuit.
-Minor electrical installation cert only or should I still fill the forms for Schedule of Inspections & Schedule of Test Results?
2. Same question for the newly added ring final circuit in the kitchen
(A new installation ring final circuit connected to DB)
I can understand that Schedule of Inspections & Schedule of Test Results should be accompanied by Periodic Inspection Report when carrying out Periodic Inspection.
But I believe that all three documents need to be filled in if I do Inspection and Testing for newly constructed building. - Would this be correct?
Just trying to tidy my head up which forms are to be filled in for the different circumstances.

JD

 

[pushrod]

minor works only for the spur.

Electrical installation certificate, schedule of inspections and schedule of test results for the ring.

yes you are correct for the periodic inspection and test.