Fault or not? Domestic Ring Final

[claret73]

Had a Minor, Non Notifiable to do for a friend. Moving 2x sockets in the bedroom. After looking at it and from a response on here, took new legs up into the loft (it's a top floor flat) and joined in a 30A JB to the Incoming legs off the circuit.

Came to test it, as was supplying a BS7671 MW Cert. (I guess this will smack of hindsight in that I never did sample tests first) I did a continuity check end to end and had no reading on the Line conductors. Cross linked legs, L-CPC & did R1+R2 at every point. Got readings on the Meter at each outlet. Confused as continuity on the Line was effectively showing open circuit?? Did IR at 250V as a starter and got over 250MOhms on L-E, N-E. L-N was showing short (possibly a Neon that I hadn't picked up?) at 500V all at 0.35MOhms...even did L&N Together to earth and got same reading.
Did ZS and got 1.10 Ohms for a 32A 60898 Type B, so within Max ZS. Did RCD disconnection and that was around 30.5ms for 1x.

So, I'm getting confused on the Continuity, the fact it's showing none, yet get a reading & voltage at every point...IR Readings are a worry. Nothing plugged in. The only thing I can put to it was, on the way out I noticed a loose socket, so offered to tighten it up. The Pin wasn't in at one side so removed it. The opposite Pin had gone through 1 Line Cable and so snipped this off & re-terminated into socket. I need to clarify that this may have had a changed reading or not??

Finally, the Earthing Conductor is 6.0mm for a PME & Equipotential Bonding is 4.0mm (which really I should look to upgrade). The 6.0mm using the adiabatic not having measured Ze, could I take Max Ze at 0.35 to get Fault Current? Would this be at it's worst case using Max Ze?

Any thoughts on any of this?? I've tried asking the Electrician I'm working with but wasn't either convincing or too obliging...
Cheers!

 

[cagedanimal2010]

firstly you will get power even if theres no continuity, thats why ring final circuits suck!!! did you re-test after you terminated loose socket??is it a split load board? how old is the installation?
Just wondering you did all them test, and didn't feel it necessary to test the Ze- why?

Danny

 

[claret73]

Danny
If there is a break on the Ring, would I not get power but only at selected points. Am I missing the fact that if there is a break in a leg surely I wouldn't get Voltage at that particular socket where it's incoming? A quick buzz with the socket tester gave correct polarity at each point & confirmed this with the Loop Tester. It's a Single RCD Protected board. Customer has lived in the flat 26 years, so would suggest the installation is older than that but has had additions, such as a new kitchen 18 Months ago (No Part P Cert etc though...) I'm going to re-test the dead tests again. I'll have to add that I'm no Test Maestro! Level 3 C&G Spent testing most of the year. MW does not ask to record Ze but would do that as to calculating the acceptance of the 6.0mm Earthing Conductor.

 

[Amp David]

Your other leg of the ring will be energized though, hence the voltage. If you had 2 breaks then there would be a certain amount of the ring without volts

 

[MarkieSparkie]

When your dead tests showed doubtful results, why? why? ooh why? did you go ahead and do live tests ... this is nieve, utterly stupid and unprofessional. Sorry to be so blunt mate. I hope you have learnt a salutary lesson from the mess you've got yourself into. For safety sake the required sequence of tests are to be performed in order, if one fails or you get suspect results you correct that before repeating the sequence from the beginning.

 

[tony mc]

Aggree with Markie on this.

You have a fault on the final ring circuit as you need to confirm r1 rn & r2 continuity before you cross connect in a figure of 8 or go to any sort of live testing!!!!

You will still get readings at the socket outlets but the resistance readings will be much higher as it is not divided in 4.
Also you will still get line neutral & earth at each point when live.

Your IR tests shows a load still connected as stated.

Your bonding at 4mm needs to be upgraded as the minimum is 6mm.

I would upgrade the bonding to 10mm and the main earth needs to be a minimum of 10mm but 16 mm would be what I would install.

If you do a adiabatic on 0.35 you will come back with a very low result but remember this is a PME earthing arrangement and you are governed by reg 544.1.1 .

Hope this helps!!

 

[claret73]

MarkieSparkie - Thanks for being Blunt, has taught me a lesson in being more logical and procedure...no offence taken honest! Glad of your response...
TonyMC - Again, your input really helped. I went back to the Regs and looked upon what I needed to know...

As an update I went back and retook the r1,rn,r2 and IR Tests. All OK! Phew!!! The open circuit was the partially broken line conductor that I found only to being picky seeing a socket on the skew. The low IR L-N was the Microwave! Daft to miss this, but there you go...

Whilst I was there, the connection in the N & CPC Bars are not in sequence so was tracing for my benefit exactly what I'd got. I found in the Meter Cupboard 3x CPC's in the MET:
1x 6mm Earthing Conductor to CU which I do need to upgrade.
1x 10mm Equipotential Bond to Incoming water
1x 4mm into Storage Heater Meter

I opened the Storage heater CU to see what was going on as I found from being in the loft 2x CPC's are connected from the CPC Bar into a Choc Block, which joins the T&E Feeding 1 of the Heater's FCU. Why the extra CPC Cables from the CU into the Choc Block with the CPC of the Feed for that Heater from the CU? (Pics 37 & 42) The Storage Heater CU has no earth from MET but has its own supply tails. Not too certain what they've done and will be connecting this into an enclosure when I go back to fit the Sockets at 2nd fix.

The Equipotential Bond does attach to the Water pipe but after branches? (Pic 40) The Old 4mm is still attached on its own Earth Tag and still terminated at the Main CU. I got a reading on this of 0.55Ohms not the 0.05 Ideal. Is this reading something to be concerned with? Half an Ohm...

Apart from my initial Cock up with the testing, which I've redone and now have satisfactory readings for the MW...

 

[VMan]

i had a similar problem today testing IR, there was a socket behind a partition with a transformer in for LED lights in the kitchen!!! took me ages to figure it out!!!

 

[claret73]

Least I'm not alone! Sometimes it's the simplest things that get you...or me sometimes being Simple?...

 

[mogga]

iv been doing a hotel this week when floor I started today was gettin weird readings on I.R sockets nearly the same every circuit I looked in duct cupboards Ruddy boost pumps for showers its all in the fun of the job