Discuss Can anyone explain the best way to fault find on a ring main. in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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Hi,
Can anyone help please. I am doing an assignment for college level 3. I am trying too understand how to find a fault on a ring main circuit. I have read about splitting the ring, finding which end has the fault test again until the fault is found. But could anyone explain step by step on how you do this and whats involved.
Many thanks,
Derry0178.
 
easier done than explained. guess the mid point ( don't need to be exact). split ring here, then perform your test/s ( continuity, IR ) on 1 leg then the other ( obviously after safe isolation). then forget the leg that's OK. split the faulty leg and repeat, untill you trace the fault.
 
Okay, so if you choose the mid point, do you unscrew the socket front, disconnect the six wires Lx2, Nx2, and CPCx2 and test one side of the ring then the other, by IR Test. Is this correct, as this is how I imagine you do it?
 
2 basic faults 1. open circuit or high resistance of a conductor ( continuity). 2. short circuit or low resistance between conductors ( IR test).

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Okay, so if you choose the mid point, do you unscrew the socket front, disconnect the six wires Lx2, Nx2, and CPCx2 and test one side of the ring then the other, by IR Test. Is this correct, as this is how I imagine you do it?

basically, yes.
 
If it's for college they probably want you to go through the standard testing procedure until you get a result which you shouldn't, explain what the fault is and how you would fix it, then test again.
 
Okay, so if you choose the mid point, do you unscrew the socket front, disconnect the six wires Lx2, Nx2, and CPCx2 and test one side of the ring then the other, by IR Test. Is this correct, as this is how I imagine you do it?

Make sure it is completely disconnected at the ccu too, so you have two totally separate lengths of cable
 
After safe isolation, what about the first test, visual inspection utilizing the human senses; sight, hearing, smell & touch. If the installation is new, then that is done during installation. If it's an existing installation you are testing, then it should have been previously tested, so something has physically changed. You can locate some faults just by visual inspection first, i.e. lose fittings, missing fixing screws suggesting someone has tampered with the installation, enviably the householder. If you know there is a fault, visual inspection is the first part of the process.
 
Also, if the cable is long and the fault is not obvious at a socket, you can use R1R2 value and resistance tables in BS7671 to workout how far along the cable the fault is. That's if you are getting a dead short (0.0 meg ohm) on the IR test.

This method lends itself better to say a long radial circuit, where the circuit cable length is easy-ish to work out.

Are you at S.T.College? Is Greg P still teaching?
 
I think what the college is saying is how would you go about finding a fault on a ring or in other words what should you do.

1. Disconnect ring
2. Test continuity ie L-L or N-N or E-E
3. Do your IR test L-E or N-E or L-N
4. R1 +R2 and so on if these tests are done then you will be able to prove any faults
 
I went up there a few weeks back with my son to scout out where to do his A levels, Greg is still there and teaching. Still as daft as a ship's cat too

Glad to hear it, not spoke to him in yonks but have a lot of time for him. Good fella he is, taught me everything I know!

He used to find very interesting ways of keeping the uninterested ADT apprentices interested!!
 

Reply to Can anyone explain the best way to fault find on a ring main. in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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