8.4  Voltage Drop Requirements

§130.5(c)

The voltage drop requirement is as follows:

Voltage drop of feeder + voltage drop of branch circuit must be ≤ 5%

The maximum combined voltage drop on both installed feeder conductors and branch circuit conductors to the farthest connected load or outlet must not exceed 5 percent. This is the steady-state voltage drop under normal load conditions.

The voltage drop permitted by California Electrical Code Sections 647.4, 695.6, and 695.7 are exempted from this requirement.

Voltage drop losses are cumulative, so voltage drop in feeders and voltage drop in branch circuits contribute to the load at the end of the branch circuit. Excessive voltage drop in the feeder conductors and branch circuit conductors can result in inefficient operation of electrical equipment.

Compliance documentation must include voltage drop calculations for each installed feeder and branch circuit conductor showing that the combined voltage drop for the farthest load for each type of load will not exceed 5 percent.

Example 8-10: Voltage Drop Calculations

Question: Do the following proposed designs meet the voltage drop requirement of §130.5(c)?

 

This figure shows two of three example design scenarios for meeting the voltage drop requirements of Section 130.5(c). Scenario 1 shows a feeder voltage drop of 2 percent and a branch circuit voltage drop of 3 percent. Scenario 2 shows a feeder voltage drop of 1 percent and a branch circuit voltage drop of 4 percent. to be continue next...

 

This is a continuation from the earlier example design scenarios for meeting the voltage drop requirements of Section 130.5(c). Scenario 3 shows a feeder voltage drop of 3 percent and a branch circuit voltage drop of 2 percent.

Answer:

All the above proposed design scenarios meet the voltage drop requirement of §130.5(c), as the combined voltage drop of the feeder and the branch circuit does not exceed 5 percent.

Example 8-11:

Question: Do healthcare facilities have to comply with the voltage drop requirement?

Answer:

Healthcare facilities must meet the voltage drop requirement in §130.5(c).