Electric circuit overload – volts x amps = watts

Too many items plugged into a circuit can cause an overload. Exceeding the limit should automatically shut off the circuit at the main panel. Power strips don’t always protect you.

A dedicated circuit serves a single large-draw appliance like the stove or furnace.

The general-purpose circuits serve multiple sources as lights and plugs.

But, if you connect a high-power use appliance like heaters or an air conditioner, you may need it on only a dedicated circuit.

Maximum load: For 15 amp circuit – 120 volts x 15 amps = 1800 watts. For 20 amp circuit – 120 volts x 20 amps = 2400 watts.

Maximum load on each circuit isn’t the goal because a margin of safety of 80% is best. For a 15-amp circuit, the safe load is 1,440 watts; for a 20-amp circuit, it’s 1,920 watts. On a multiple-outlet circuit, limit any individual appliance to half the circuit rating – 900 watts for a 15-amp circuit.

If all the connections add up to more than the limit allowed by the National Electrical Code, you need to remove some load to other circuits or run a new circuit for the largest appliances to avoid overloads.

Signs of an electrical circuit overload or short circuits:

  1. Tripping a breaker.
  2. Burning smell.
  3. Lights dimming when you turn on appliances or more lights.
  4. Burnt or discolored outlets.
  5. Buzzing outlets or switches.
  6. Warm light switch covers.
  7. Appliances, tools or electronics lack power.