Requiring only a handful of inexpensive components, the circuit breaker in Figure 1 responds to both overcurrent- and overvoltage-fault conditions. At the heart of the circuit, D 2, an adjustable, ...

Breaker or Fuse (amps) Min. copper wire size (AWG) 15 14 20 12 30 10 40 8 55 6 70 4 For the full story, you'd have to start with table 310.15(B) (16) in the National Electric Code, but there are a ...