kda3310
Senior Member
- Location
- Dry Prong, Louisiana
Article 240.4(D) Small Conductors. Unless specifically permitted in 240.4(E) or 240.4(G), the over current protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum after any correction factors for ambient temperature and number of conductors have been applied.
You can only run 30 amps through a number 12 AWG before the insulation starts to melt. Amps are a measurement of heat. Ambient temperature is a measurement of heat. Rise the ambient temperature and combine the heat of the load and that wire will be hot. Ambient temperature can be raised by other conductors in the same conduit. I believe the over current rating is to help not to rise the temperature up so high it melts the insulation of the conductor because of how much load gets put on general use outlet.
You can only run 30 amps through a number 12 AWG before the insulation starts to melt. Amps are a measurement of heat. Ambient temperature is a measurement of heat. Rise the ambient temperature and combine the heat of the load and that wire will be hot. Ambient temperature can be raised by other conductors in the same conduit. I believe the over current rating is to help not to rise the temperature up so high it melts the insulation of the conductor because of how much load gets put on general use outlet.