In general, most bids are conservative regarding the bill of materials when it comes to Conductors and Conduit. Typically wire is purchased in bulk as opposed to individual runs for equipment. Also, there is usually a mark up at the end to account for material drop as well as all unexpected and expected changes to a branch circuit, lets face it, things can change in the field and you definitely don't want to underestimate materials needed on a job.
The following is the math behind how lengths of a circuit are calculated for the bill of materials:
Length of Conductor = Number of Conductors x (Horizontal Length + Gear Slack) x 110%*
*110% is to account for all the material drop and unexpected field issues that may arise
Lets run an example:
If the horizontal length reads out to 35.71 ft on the map, than the bill of materials would calculate as follows.
Length of Hot Conductors = 3 Wires x (35.71 ft + 18 ft) x 1.1 = 177.24 ft
Length of the Ground Conductor = 1 Wire x (35.71 ft + 18ft) x 1.1 = 59.11 ft
The following is the math behind the Conduit calculation in the bill of materials:
Length of Conduit = Number of Conduits x ((Horizontal Length) x 110%*
*110% is to account for all the material drop and unexpected field issues that may arise
Lets run an example:
If the horizontal length reads out to 35.71 ft on the map, than the bill of materials would calculate as follows.
Length of Conduit = 1 Conduit x 35.71 ft x 1.1 = 39.28 ft
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