Roller spacing will vary with cable weight, tension, construction and roller height above the tray. To estimate roller spacing, the following equation can be used.

The distance will be conservative for armored cable because the equation assumes a perfectly flexible cable. When possible, a length of cable should be used to determine maximum spacing under no tension, as a check for the calculated values.

Symbol
$s_{\mathrm{roll}}$
Unit
m
Formulae
$2 \sqrt{2} \sqrt{\frac{F_{\mathrm{out}} h_{\mathrm{roll}}}{m}}$
Related
$F_{\mathrm{out}}$
$h_{\mathrm{roll}}$
$m$