Chapter 12 Branch Circuits and Feeders 169 Copyright Goodheart-Willcox Co., Inc. 12.2.1 Branch-Circuit Rating A branch circuit is sized for the load it will sup- ply. Sizing the circuit for additional future loads is good practice. 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 than one load is limited to ratings of 15, 20, 30, 40, or 50 amps. 12.2.2 Branch-Circuit Voltage Branch-circuit voltage limits are contained in Section 210.6 of the Code. These limits are based on the equipment being supplied by the circuit: • In residences and hotel rooms, circuits supplying lighting fixtures and small fi 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 permanently wired equipment. • Branch circuits exceeding 120 volts but not exceeding 277 volts may supply mogul- base screw-shell lampholders, ballasts for fl uorescent lighting, ballasts for electric- fl discharge lighting, plug-connected appliances, and hard-wired appliances. Incandescent lighting operating over 150 volts is permitted in commercial construction. • Circuits exceeding 277 volts and up to 600 volts can supply mercury-vapor and fl uorescent lighting, provided the lighting fl units are installed at heights not less than 22′ above grade and in tunnels at heights no less than 18′. 12.2.3 Conductor Size and Ampacity The amperage rating of branch-circuit con- ductors must be greater than the maximum load the circuit will provide. For multiple-load branch circuits, the conductor ampacity must correspond to the rating of the overcurrent pro- tective device. However, for circuits supplying hard-wired devices (such as electric heaters, air- conditioning units, and water heaters), the fuse or circuit breaker can be rated at the next higher rating. The conductor is acceptable if its rating is at least that of the load current, even if the over- current protective device rating is higher. The smallest general-purpose conductor for branch circuits is 14 AWG. Tap conductors can be smaller. See Section 210.19 for more information. 12.2.4 Multiwire Branch Circuits A branch circuit can be either a two-wire or multiwire branch circuit. A multiwire branch circuit consists of a grounded conductor and two or more ungrounded conductors. A mul- tiwire circuit can be an individual circuit or a multioutlet circuit. B A Individual Branch Circuit General Purpose Branch Circuit Individual Multiwire Branch Circuit Neutral Neutral Goodheart-Willcox Publisher Figure 12-2. Branch circuits are classified as individual or multioutlet, appliance or general.