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Electrical

Feeder

In Plain English

The heavy-duty wires that carry power from the main electrical panel to a sub-panel or large piece of equipment.

Definition

The conductors between the service equipment and the final branch-circuit overcurrent protection device. Feeders distribute power from the main service panel to sub-panels, large equipment, or other distribution points. Feeder size is determined by the calculated load and voltage drop requirements.

Why It Matters in Bidding

Feeder sizing is a major cost driver in an electrical bid because conductor, conduit, and termination quantities scale directly with ampacity and run length. Underestimating feeder lengths or missing a voltage-drop upsize on long runs erodes margin, while overlooking demolition or relocation of existing feeders during phased work can leave a sub short on the award.

Example

An electrical estimator measures a 400-amp feeder run to a rooftop chiller, upsizes the conductors for voltage drop over the long vertical riser, and prices the extra copper and larger conduit into the bid.

Related Terms

Electrical PanelConductorService EntranceBranch Circuit

Frequently Asked Questions

Estimators trace each feeder on the one-line diagram, scale the physical route on plans including vertical risers, then add allowances for terminations, bends, and slack. Conductor and conduit quantities are built from that length, so missing a riser or a long horizontal pull directly understates the copper and labor in the bid.
Long feeder runs can require upsizing conductors beyond the load calculation to keep voltage drop within code-recommended limits. That larger wire and conduit add material and labor that a quick load-only takeoff misses, so estimators check run lengths early to avoid a costly omission discovered after award.
Feeders carry power between distribution equipment and are sized for aggregated load, while branch circuits serve the final outlets and devices. They are taken off and priced differently, with feeders driving larger conductor, gear, and termination costs that materially affect the total electrical bid.

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