Circuit Design...

[junksamiad]

Hi there,

Just hoping something can clear another small item up for me at all.

When designing a circuit and looking at cable length for a Ring Final, would you consider the length used in the R1+R2 formula to be the length of the full ring or just half the ring?

For example, if I have a ring final with one socket on it (hypothetical situation of course) in 2.5mm T&E and the socket is 10metres from the box, would the cable length in the calculation below be 10metres or 20metres. 20metres being the length of the circuit to get to the socket and back as a ring? I guess the question could be whether for RF's you use the radial distance or the ring distance?

So,

19.51 x 10 / 4000 = R1+R2

or

19.51 x 20 / 4000 = R1+R2

Silly question I know, but just something I need to be sure on.

Any help as always, most very welcome and so helpful as ever.

 

[Julie.]

No, there is a specific process for ring finals, you calculate the whole loop - end to end then use R1+R2 =(R1loop+R2loop)/4