Ring main.

[ProDave]

What would the risk be if I had left one earth in? If everything was earthed? Could you plz explain the risk plz? Obviously it's sorted as I found the fault and corrected it but out of curiosity and just help understanding please. Thanks anyone?

One earth may not have been able to take the fault current. The whole philiosophy of a ring final is there are two cables in parallel (effectively) to share the load.  With one earth disconnected, in the event of a fault (short circuit) that one earth core would be overloaded as it is missing it's partner to share the load.

Also you have left the other half still with it's N-E fault. I have a suspicion there is more to it than that as why didn't that n-e failt trip the rcd? perhaps the erath on that end was disconnected? who knows, we are not there.
 

 

[Andy™]

One earth may not have been able to take the fault current.
 

it should be able to take the fault current - no different to a spur

but still not idea and really should be fixed and not ignored

 

[steptoe]

it should be able to take the fault current - no different to a spur

but still not idea and really should be fixed and not ignored

it could be a 1mm earth for all we know,,,,  :C

 

[Geoff1946]

There is some other factor to this, or simply breaking the earth would not prevent tripping the RCD. I wonder if it really is a simple ring, or perhaps the fault was in a spur? That would explain the symptoms.

 

[Tony S]

Adammyman

You can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time. Abraham Lincoln.

I’ll elaborate my pun about this thread, you don’t ring true.

 

[Sharpend]

In the words of the legend David Bowie "absolute beginners' ?!

 

[apprentice87]

Ok, but say you have a ring. You now neatly snip it in half. You have NOT just created two radials, you have just created a broken ring, which, at it's farthest point will now have double the Zs for the ring ITSELF that it did have, possibly too high for the OCPD employed, and also the cables themselves will be underrated... [Best get a different OCPD....]

john..

 

[Adammyman]

Different ocpd? What kind? All very new to me. So far everything is on and working. Not been called back.Get EFLI Test on all sockets. Highest reading is 0.95 ohms. 

 

[Murdoch]

Different ocpd? What kind? All very new to me. So far everything is on and working. Not been called back.Get EFLI Test on all sockets. Highest reading is 0.95 ohms. 

Hum.... What training have you had? What does your boss say? 

 

[apprentice87]

I "think" you may find that the existing ring is protected by a 32A MCB. You SHOULD be doing proper cable calcs, but IF you change the MCB for a 20A one, then depending on some other factors, all "should" be ok.... [you hope]

john..

 

[Tony S]

In America it is illegal for a non registered electrician to carry out remunerative work. It’s time we had that here, NFPA-NEC is statute law, BS7671 is advisory.

Who has it right?

The prize doesn’t go to BS7671

 

[Murdoch]

What did your schemes tech support team suggest?

TBH matey this should be relatively easy to locate doing an R1 + R2 on each leg of the circuit from the CU

You didn't answer me on the other forum - will you answer me on here?

 

[Adammyman]

I have not mUch just got 3 years experience of installing but hardly any on fault finding so my understanding is limited. So how dangerous would the n-e fault be ifi had left it? As I had nipped the N on the back box when putting front back. I would like to hear the risk behind it plz? Since this has happened I have been trying to educate myself much more. 

What did your schemes tech support team suggest?

TBH matey this should be relatively easy to locate doing an R1 + R2 on each leg of the circuit from the CU

You didn't answer me on the other forum - will you answer me on here?

 Would r1 + r2 find a N-E fault then? 

 

[apprentice87]

Little r1 + little r2 are different from R1 + R2..

Google testing of ring finals

john..

 

[Adammyman]

I mean R1+R2? I'm trying but still quite can't understand how to find a N-E fault in the future quickly. Using that method 

 

[Sharpend]

The art of testing is not just how to test but to understand what the results are telling you. This is not something that is taught nor easily taught online, 

ideally you need to read a copy of the GN3 which will guide you with pics and text into the methods of testing then you really need to work alongside a seasoned tester to develop that learned knowledge. 

I mean R1+R2? I'm trying but still quite can't understand how to find a N-E fault in the future quickly. Using that method 

How would you find a L-E fault quickly? 

 

[Adammyman]

Thanks for the reply much appreciated I will buy gn3 and try get my head around the results. 

 

[Sharpend]

Adam please answer the question trying to assist you here. 

 

[apprentice87]

Can i just say that i am well impressed with the politeness shown here... This is how the forum SHOULD be conducted...

Well done all...

john..

 

[Sharpend]

Can i just say that i am well impressed with the politeness shown here... This is how the forum SHOULD be conducted...

Well done all...

john..

I'll second that