the best ever voltage drop calculation spreadsheet

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elec master
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This voltage drop calculator will provide an approximate value for use in project design and it is based on the following public domain formula.

NEC Rules controlling Voltage Drop:

NEC article 210.19(A)(1) FPN No.4 and 215.2(A)(3) FPN No.2 :

These FPN’s (Fine Print Notes) suggest that a design with no more than 3% voltage drop for feeders and no more than a total of 5% voltage drop in branch circuits to the farthest outlet will provide reasonable efficiency at operation.

Note: Even though FPN’s (Fine Print Notes) in this case are not code requirements but recommendations, it is still good engineering practice to closely follow these guidelines

NEC article 647.4(D):
For Sensitive Electronic Equipment, The voltage drop on any branch circuit shall not exceed 1.5 percent and the combined voltage drop feeder and branch-circuit conductors shall not exceed 2.5 percent.

NEC article 647.4(D) (1):
For Fixed Equipments, The voltage drop on branch circuits supplying equipment connected using wiring methods in Chapter 3 shall not exceed 1.5 percent and the combined voltage drop of feeder and branch-circuit conductors shall not exceed 2.5 percent.

NEC article 647.4(D) (2):
For cord-connected equipment, The voltage drop on branch circuits supplying receptacles shall not exceed 1.0 %. For the purposes of making this calculation, the load connected to the receptacle outlet shall be considered to be 50 percent of the branch-circuit rating. The combined voltage drop of feeder and branch-circuit conductors shall not exceed 2.0 %.

NEC Article 695.7:
For Fire pumps, the voltage at the controller line terminals shall not drop more than 15 percent below normal (controller-rated voltage) under motor starting conditions. The voltage at the motor terminals shall not drop more than 5 percent below the voltage rating of the motor when the motor is operating at 115 percent of the full-load current rating of the motor.

Exception: This limitation shall not apply for emergency run mechanical starting. [NFPA 20, 6.4]

This spreadsheet includes three different worksheets as follows:

1-Voltage Drop Calculator worksheet
2-Summary worksheet
3-Information worksheet