Determination of R1 and R2: Theoretically

[Engineer54]

Then off to the trainee section with him...lol!!

There's been a few threads on similar lines recently, and some of the posts on those threads makes you wonder if they were posted by electricians to be honest....

 

[GB.Kayak]

Well my question was targeted at, say, a lighting circuit. A ring circuit MAYBE different with little r1 and little r2. My brain hurts. But I do remember in class something about r1+r2/4

Thanks for clarifying that ... I should have NB'd the conductor size!

 

[telectrix]

So, is it R1 or r1 in this case? I have just gone to BGB and GN3:

R1 + R2 = (r1 + r2) / 4 ... my money is on Pete!

In design, use the mOhm / m value for the conductors in use eg 2.5 mm2 Line and Neutral and 1.5 mm2 Circuit Protective Conductor. Multiply the Resistance per Metre by the cable length in Metres to give the resistance per conductor in mOhm and divide by 1000 to get Ohms for r1, r2 and rn. Then apply the equation above to get R1, R2 and Rn if required.

the table in osg refers to radials. so the result is R1+R2 ( caps.).

 

[GB.Kayak]

the table in osg refers to radials. so the result is R1+R2 ( caps.).

Thanks Tel, as my previous post, I missed the fact that the subject was a lighting circuit implied by the cable sizes and the later discussion had passed me by. I hadn't looked up the ref in OSG.