Cable Design Formulas

Weight	=	340.5 D2 GNK = lbs./1,000 ft.
D	=	diameter of conductor in inches
G	=	specific gravity of conductor material; (8.89 for copper, 2.71 for aluminum)
N	=	number of strands
K	=	weight increase factor for stranded conductor. (K = 1 for solid conductor)

No. of strands	K
19	1.02
37	1.026
49	1.03
133 or more	1.04

Weight	=	340.5 ( D2 – d2 ) G = lbs./1,000 ft.
D	=	diameter over insulation in inches
d	=	diameter over conductor in inches
G	=	specific gravity of insulation

Weight	=	340.5 ( D2 – d2 ) G = lbs./1,000 ft.
D	=	diameter over jacket in inches
d	=	diameter under jacket in inches
G	=	specific gravity of jacket material

Weight	=	1362 Gt ( ( d+t )+( d+3t ) f ) = lbs./1,000 ft.
G	=	specific gravity of tape
t	=	tape thickness in inches
d	=	diameter of cable under tape in inches
f	=	multiplying factor from % lap

% Lap	f
17.5	0.35
25.0	0.5
33.0	0.67
50.0	1.0

 

Weight	=	N x L x W = lbs./1,000 ft.
N	=	number of conductors
L	=	twisting loss factor = 1.03
W	=	weight of one conductor

 

To determine the approximate O.D. of the finished cable, double the wall thickness of the wire, add this figure to the O.D. of the desired stranded conductor and multiply this dimension by the indicated factor for the number of conductors to be in the cable. Add 0.025″ for a bare, tinned, or silver-plated copper shield of #36 gauge wire; e.g., 6 conductors of 24 gauge, 19/36 stranded, Type E wire with overall shield – 2 x 0.010″ (wall) = 0.020″ + 0.025″ (conductor O.D.) = 0.045″ (finished wire). Taking 0.045″ (finished wire) x 3 (Factor for 6 conductors) = 0.135″. Add the 0.135″ to the shield diameter of 0.025″ which yields a finished cable diameter (no jacket) of 0.160″.

Weight	=	N x C x W x 1.03 = lbs./1,000 ft. cos (a)
N	=	number of ends per carrier
C	=	number of carriers
W	=	weight of one of the shielding strands (lbs./1,000 ft.), see above
a	=	braid angle