146 Modern Commercial Wiring
Copyright Goodheart-Willcox Co., Inc.
• Appliance branch circuit—A branch circuit
that supplies a single appliance load.
• Multiwire branch circuit—A branch circuit
with two or more ungrounded conductors and
one grounded conductor.
Branch-Circuit Rating
A branch circuit is sized for the load it will supply.
Sizing the circuit for additional future loads is good prac-
tice. The rating of a branch circuit depends on the rating
of the overcurrent device protecting the circuit.
Branch circuits serving only one device can have any
rating, while a circuit supplying more that one load is
limited to ratings of 15, 20, 30, 40, or 50 amps.
Branch-Circuit Voltage
Branch-circuit voltage limits are contained in Section
210.6 of the Code. These limits are based on the equip-
ment being supplied by the circuit:
• In residences and hotel rooms, circuits supplying
lighting fixtures and small receptacle loads
cannot exceed 120 volts.
• Circuits that are 120 volts and less may be used
to supply lampholders, auxiliary equipment of
electric-discharge lamps, receptacles, and perma-
nently wired equipment.
Figure 12-1. Conductors are classified based on their location in the electrical supply system.
Main service
disconnect
Feeders
Subfeeders
Branch
circuits
Service
conductors
Distribution
center
Panelboard
(final OCPD)
Panelboard
(final OCPD)
Figure 12-2. Branch circuits are classified as individual or
multioutlet, appliance or general.
B
A
Individual Branch
Circuit
General Purpose
Branch Circuit
Individual Multiwire
Branch Circuit
Neutral
Neutral