Main breakers must be properly sized

Electrical · System Grounding · printed page 91 (PDF page 92)

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Book index entries

Main Breakers Must be Properly Sized Proper Sizing of Main Electrical Fuses Electric Service – Box

Text in the illustration

to ground
main breaker
A
the main breaker size should match the capacity of the service entrance wires
service entrance wires
B
the box rating should match or be larger than the main breaker size
neutral bus bar
bus bars
grounding terminal
100

Generated explanation

The illustration shows an electrical service panel with its cover removed, exposing a main breaker, branch circuit breakers, bus bars, neutral bus bar, and grounding terminal. Service entrance wires enter at the upper right, with the red and black conductors connected to the main breaker. A green conductor runs from the neutral bus bar toward ground. Annotations explain that the main breaker rating should match the capacity of the service entrance wires and that the panel box rating should equal or exceed the main breaker rating.

Components

electrical service panel panel enclosure main circuit breaker branch circuit breakers service entrance wires branch circuit wiring neutral bus bar bus bars grounding terminal grounding conductor

Materials

metal enclosure insulated electrical conductors