How Trenches Work
MV Trenches


Width = (i - 1) * s + i * 2* d + 12"
Depth = 36" + 2 * d
Here:
i is the number of MV cables in the trench,
s is the distance between the MV cables in the trench, in inches;
d is the cable diameter in inches;
12 inches is the distance from the beginning of the trench to the first cable.
DC Feeder Trenches


Width = (i - 1) * s + i * 2* d + 6"
Depth = 36" + d
Here:
i is the number of DC Feeder cables in the trench,
s is the distance between the DC Feeder cables in the trench, in inches;
d is the cable diameter in inches;
6" is the distance from the beginning of the trench to the first cable.
AC Feeder Trenches

Width = (i - 1) * s + i * 3* d + 3"
Depth = 24" + d
Here:
i is the number of AC Feeder cables in the trench,
s is the distance between the AC Feeder cables in the trench, in inches;
d is the cable diameter in inches;
3" is the distance from the beginning of the trench to the first cable.
Whip Trenches

Width = (i - 1) * s + i * g/2* d + 3"
Depth = 30" + 2 * d
Here:
i is the number of whip cables in the trench,
s is the distance between the whip cables in the trench, in inches;
g is the number of whips in the group, equal to 8;
d is the cable diameter in inches;
3" is the distance from the beginning of the trench to the first cable.
Whip and Feeder Trenches

Width = Width Whip Trenches + Width Feeder Trenches
Depth = 30" + 2 * d
Here:
d is the cable diameter in inches.