BRANCH CIRCUITS
  1. In no case shall the total load exceed the branch-circuit ampere rating nor the max. loads specified in NEC sections 220-4.

  2. An individual branch circuit shall be permitted to supply any load for which it is rated.

  3. Branch-circuit conductors shall have an ampacity not less than the max. load to be served.

  4. Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household  cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the max. load to be served. 210-19(c).

  5. For ranges of 8 3/4 kw or more rating, the min. branch-circuit rating shall be 40 amperes. 210-19(c).

  6. A min. 40-amperes branch-circuit rating would be as follows:
    No. 8 AWG copper, Type TW= 40 Amps, OR

    No. 6 AWG aluminum, Type TW= 40 Amps
    See NEC, Table 210-24 for other applications. There are other exceptions- see 210-19(c).

  7. Arc-Fault Circuit Interrupters, NEC 210-12: All branch circuits that supply 125-volt, 15 and 20-ampere outlets installed in dwelling unit bedrooms shall be protected by an Arc-Fault Circuit Interrupter(s), (AFCI). More discussions...

  8. Calculating the number of 15 and 20-ampere branch circuits that are needed in a single family dwelling: see example.

  9. What does "14-2" mean?

  10. Cables Marking.

  11. Conductors Identification.

  12. Jump to Application & Wiring Guide.

  13. See simple light circuits diagrams.

  14. Three-way switches diagram.

  15. Switch-controlled receptacles.

  16. For multi-conductor cables, see sketch.

  17. See receptacles and GFCI-receptacles sketch.
  18. Switches: the different kinds available.

  19. Electrical boxes.

  20. Electrical boxes fill calculations.
  21. A branch circuit supplying two or more outlets or receptacles shall supply only the loads according to its size- see table below:

    Summary of Branch-Circuit Requirements

    Circuit Rating 15 Amp 20 Amp 30 Amp 40 Amp 50 Amp
    Conductors: (Min. size)
    Circuit Wires*     		14 12 10 8 6
    Taps 14 14 14 12 12
    Fixture Wires & Cords       See NEC section 240-4  
    Overcurrent Protection 15 Amp 20 Amp 30 Amp 40 Amp 50 Amp
    Outlet Devices:
    Lampholders Permitted     		Any Type Any Type Heavy Duty Heavy Duty Heavy Duty
    Receptacle Rating** 15 Amps. max. 15 or 20 Amps 30 Amps 40 or 50 Amps 50 Amps
    Max. cord-and Plug connected load to Receptacle

     

    		12 Amps 16 Amps 24 Amps - -
    MAX. Load 15 Amp 20 Amp 30 Amp 40 Amp 50 Amp
    Permissible Load See NEC section 210-23(a) See NEC section 210-23(a) See NEC section 210-23(b) See NEC section 210-23(c) See NEC section 210-23(c, d)
    * Gauges are for copper conductors
    ** For receptacles rating of cord-connected electric discharge lighting fixtures, see NEC section 410-30(c)