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Electrical

Circuit

In Plain English

The complete electrical path that power travels along — from the panel to the outlet or light and back again.

Definition

A closed loop of electrical conductors through which current flows from the power source, through the load, and back to the source. Circuits consist of a hot conductor, a neutral conductor, and often a ground conductor. In AC systems, circuits are protected by overcurrent devices such as fuses or circuit breakers.

Why It Matters in Bidding

Circuits are the basic unit by which electrical takeoff is organized, so counting and sizing them drives quantities of wire, conduit, breakers, and labor on every project. During estimating, the number and length of circuits, conductor size, and routing all affect material and labor cost, and misreading the panel schedule or one-line diagram leads directly to underbid or overbid electrical packages.

Example

Working from the panel schedule during takeoff, an electrical estimator counts the branch circuits, measures each home run back to the panel, and tallies the wire, conduit, and breaker quantities to price the rough-in labor.

Related Terms

Branch CircuitCircuit BreakerConductorElectrical Panel

Frequently Asked Questions

A branch circuit is the final wiring from the last overcurrent device to the outlets, lights, or equipment it serves. A feeder is the larger conductor running from the service or main panel to a subpanel. Estimators take off both separately because conductor sizes, conduit, and labor rates differ significantly.
Each circuit adds conductor length, conduit, terminations, a breaker, and labor for the home run and devices. The panel schedule and one-line diagram define how many circuits exist and their loads, so accurate circuit counts and home-run lengths are central to pricing the rough-in and trim phases correctly.
Conductor size is set by the circuit's load and length to limit voltage drop and meet code ampacity. Larger conductors cost more in material and are harder to pull, raising labor. Estimators read the specified wire gauge per circuit rather than assuming, since guessing low understates cost and guessing high pads the bid.

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