Slightly high CPC continuity on ring final

[EFLImpudence]

Excuse me. Just testing as I can't seem to post on the bonding thread.

 

[JohnW2]

Excuse me. Just testing as I can't seem to post on the bonding thread.

Strange - I've just successfully posted a test message to that thread.

Kind Regards, John

 

[EFLImpudence]

Yes, I get the 'awaiting approval'. An hour so far.

 

[JohnW2]

Strange - I've just successfully posted a test message to that thread.

Stranger ... I've just received e-mail notifications of two recent posts from you to the bonding thread (here) , but they're not there! I'll see if the mods can help.

Kind Regards, John

 

[1974stephen]

One drum was from CEF and the other from Toolstation. Both BASEC approved. I only have about 4m left, so too short to get a reading from.

 

[JohnW2]

One drum was from CEF and the other from Toolstation. Both BASEC approved. I only have about 4m left, so too short to get a reading from.

Maybe both 'BASEC approved', but that doesn't alter my question as to whether they are of a 'reputable' maker/brand . It wouldn't be the first time that 'BASEC approved' cables had been out-of-spec, or otherwise problematical!

What you have done seems to have got very close to 'proving' that the R1/R2 ratio of the cable you have used is just not correct.

Of course, on the basis of what you've told us so far, we can't know whether the CPC is too small or the L & N too large, but (since copper costs money!) I suppose the former is more likely

Kind Regards, John

 

[BS3036]

With only a small bit left, one action would be to measure the core diameters with a caliper.

 

[1974stephen]

Update! Put it all back together as I was resigned to not getting anywhere then checked a near-full drum of 1.5mm T&E to gauge that the meter was right in relation to the ratio between 1.5mm and 1.00mm readings (and it was) so just for a laugh checked again at the CU once everything was connected back up. The r2 reading had increased from 1.18 to 1.47 but the r1 and rn had both increased even further to 0.88 and 0.89, matching exactly what the calculated value should be. I'm perplexed but happy it's the correct reading!

 

[plugwash]

So all your readings increased by about 0.3.

My best guess would be that your initial readings were taken with an incorrectly zero'd meter

 

[1974stephen]

Leads were nulled, and even if they weren't they only add 0.08ohms. Glad it's sorted though!

 

[SimonH2]

Bit late to the party, but one method is to put a known current through the conductor under investigation and go round measuring the volt drop. I used this method to map the RFC at my last house.
12V battery (one of those portable booster packs), spare headlight bulb (giving around 4-5A), split the CPC at the CU and connect the current source across it. Connect L and/or N to one end of the CPC to provide you with a reference (no current in that conductor), then go round plugging into each socket and note the voltage between the conductor under test and the reference. It should increase progressively round the ring, reaching it's max when you get back to the CU. Spurs will register the same voltage as the point they are spurred off.