T&E CPC Estimated 12% Undersize...?

[NickD]

Testing 2.5+1.5 socket ring, got r1 0.75ohm, rn 0.76ohm, r2 1.38ohm. Expected r2 is 1.25ohm (=0.75*2.5/1.5)...bit of a deviation. All CPC connections inspected appeared fine. Had a micrometer to hand (not calibrated admittedly) so measured conductors, live = 1.77mm dia, CPC=1.30mm which gives CSAs (pi * dia^2 / 4) of 2.46mm^2 and 1.32mm^2. Which gives predicted r2 of 1.40ohm (=0.75*2.46/1.32) which is satisfyingly bang on.

How bothered/interested would you be about that slightly undersized 1.32mm^2 CPC? Not sure what permitted tolerances on it are. Could do the adiabatic on it I suppose.

 

[GLENNSPARK]

theres a lot of chinky cable doing the rounds at the mo....undersized and sometimes just copper coated ally....

 

[NickD]

(Estimated 30yr old red+black stuff. Sorry, should have said.)

 

[GLENNSPARK]

(Estimated 30yr old red+black stuff. Sorry, should have said.)

yeah well some of that was 2.5/1.0......

theres quite a bit of it about....still good for continued service i may add..as long as IR and loop all come in that is....

 

[Guest55]

Testing 2.5+1.5 socket ring, got r1 0.75ohm, rn 0.76ohm, r2 1.38ohm. Expected r2 is 1.25ohm (=0.75*2.5/1.5)...bit of a deviation. All CPC connections inspected appeared fine. Had a micrometer to hand (not calibrated admittedly) so measured conductors, live = 1.77mm dia, CPC=1.30mm which gives CSAs (pi * dia^2 / 4) of 2.46mm^2 and 1.32mm^2. Which gives predicted r2 of 1.40ohm (=0.75*2.46/1.32) which is satisfyingly bang on.

How bothered/interested would you be about that slightly undersized 1.32mm^2 CPC? Not sure what permitted tolerances on it are. Could do the adiabatic on it I suppose.

may i suggest you get a life..........

;-)

 

[GLENNSPARK]

Testing 2.5+1.5 socket ring, got r1 0.75ohm, rn 0.76ohm, r2 1.38ohm. Expected r2 is 1.25ohm (=0.75*2.5/1.5)...bit of a deviation. All CPC connections inspected appeared fine. Had a micrometer to hand (not calibrated admittedly) so measured conductors, live = 1.77mm dia, CPC=1.30mm which gives CSAs (pi * dia^2 / 4) of 2.46mm^2 and 1.32mm^2. Which gives predicted r2 of 1.40ohm (=0.75*2.46/1.32) which is satisfyingly bang on.

How bothered/interested would you be about that slightly undersized 1.32mm^2 CPC? Not sure what permitted tolerances on it are. Could do the adiabatic on it I suppose.

and just how `satisfied` were you with this nick?..

i hope you wern`t making tents....

 

[uksparks]

It's quite interesting to see that you have actually measured the size of the conductor, I don't up pose most people would.

 

[NickD]

Re: T&E CPC Estimated 12% Undersize...?

yeah well some of that was 2.5/1.0......

theres quite a bit of it about....still good for continued service i may add..as long as IR and loop all come in that is....

Useful to know, cheers.

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i hope you wern`t making tents....

Nah, I'm a cowboy, not an Indian. ;-)

 

[GLENNSPARK]

Re: T&E CPC Estimated 12% Undersize...?

Useful to know, cheers.

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Nah, I'm a cowboy, not an Indian. ;-)

thought i`d seen you before:

 

[NickD]

Re: T&E CPC Estimated 12% Undersize...?

thought i`d seen you before:


View attachment 23900

E-I-C-R
It's fun to complete an E-I-C-R
You can raise some C3s
Fail it over f*** all
You can get on the client's balls
E-I-C-R...

 

[sparkymalarky]

Too far mate, too far!

 

[NickD]

Too far mate, too far!

I know...but I had the time to spare and I'm a pernickety sod. So if you had an expected r2 1.25 and measured 1.38, what would you do? Ignore it? I could understand ignoring it if measured r2 was lower than expected, could be parallel path within the CPC ring connected at at least two points. But higher?

 

[sparkymalarky]

It could be anything. Reduction in CSA for example.I would make sure the Zs complies. If you want to be that ---- about it make a note on the EICR. But I think everything is fine and it's a bit unnecessary.