At 120 and 60 Hz, exactly how much current and power is provided through a common wall plug in the United States? Anyone here know (or can provide a credible reference)?

Wall plugs typically run on fifteen or twenty amp circuits. Kitchens are run on twenty amp circuits.

I was an electrical apprentice for about seven months. To tell whether how many amps the circuit in question has, you can take the outlet cover off and study the inside of the electrical box. If the wire running into the box is yellow, it's a good bet that it's a twenty amp circuit. If it's white, and the house was built recently, it's generally a fifteen amp circuit, but twenty amp wire does exist that is colored white.

As for power, power == volts times amperage, so it would appear that the maximum power output from a fifteen amp circuit is 120v x 15a = 1.8 KW, before the circuit breaker kicks. That's with no other load on the circuit. If you needed more, perhaps for a temporary application, one could easily replace the circuit breaker with one rated for a higher amperage, but be aware that you risk burning your house down if you keep it this way for an extended period. If one wanted to create a circuit rated for a higher wattage, one would have to add it inside the panel and either run higher rated ROMEX wire through the wall, under the ground, or just on the floor for a temporary application, terminating the line inside an electrical box for safety and using an outlet rated for the higher amperage.

Thanks :cool:

What Napster is referring to is related to the size of the breaker - which fixes the max amps flowing thru the circuit.

How much power & current is supplied depends what you plug in. If you plug in a 50W lightbulb - then the power is 50W and the amps is 0.42 Amps (50/120)

The 60 Hz you mention has no impact at all - this is just the frequency at which the voltage is oscillating (Alernating current)

Also the color of the wire insulation makes no difference. The size (gauge) of the wire affects it's current carrying capacity. The insulation determines the size of the breaker. Breakers and fuses are to protect the insulation from melting because current flow causes the wire to heat up again because of the size of the wire. (my 2 cents)

Yes, but please don't reach inside the electrical box to try to determine what gauge the wire is.

Also the color of the wire insulation makes no difference. The size (gauge) of the wire affects it's current carrying capacity. The insulation determines the size of the breaker. Breakers and fuses are to protect the insulation from melting because current flow causes the wire to heat up again because of the size of the wire. (my 2 cents)

No, Napster was right. It's not foolproof but checking the color of the romex is a good indication of the amps of the circuit. 15A / 20A curcuits have different guage wire 14g vs 12g which have different color insulation.

The problem is though - often 12g wire is used on 15A circuits too & also if a house is old it might have add ons using different guage wire.

Don't go playing with wires without a fair understanding of what you're getting into, and the one tool you absolutely need is a good circuit tester. A good quality multi-volt/ohm meter can be purchased at virtually any big box store in the U.S. for less than $20. That little tool will save your life, as it tells you clearly when there is current in the wire.
Many newer homes are being wired at much higher limits, I'm seeing 50amp for stoves & some tankless water heater applications. Dryers typically run 30amp or better. Even standard wall circuits are often run at 20amp rather than the 15 that has been the norm.