2400 watts. 20-amp 20 amps x 120 volts Equals 2,400 watts on a 120-volt circuit. If your heater uses more than 2,400 watts, you will need more than one 20-amp fuse/breaker in your electrical panel.

The voltage of an electric heater is measured in milliamps (mA). Heaters that use less than 20 mA are considered low power and can be bought at major appliance stores. Higher-power models usually require a special contractor's license to install them in **your home**.

Heaters that use more than 20 mA are called high-power heaters and should only be installed by licensed electricians.

High-power heaters use more electricity than standard models and can amount to $100 or more per month if you live in an area with very cold winters. They are not required by law to have **any sort** of energy-saving feature, so they can be quite wasteful if not used properly. However, lower-cost model heaters often do have some form of automatic shutoff mechanism that will turn off the power if it gets too hot. This can save **up to 30 percent** of energy usage compared to **conventional heaters** that don't have this feature.

120 volts equals 2400 watts x 20 amps. 120 volts is enough electricity to light 80 watts of lightsbulbs for 20 minutes. So, a circuit that can handle 20 amperes will not be damaged if some bulbs on the circuit burn out.

The voltage of a battery depends on **its size**. The larger the battery, the higher the voltage. Batteries come in various sizes from **1 centimeter** (cm) squared to 1 kilo (kilo) watt hours (KWH). A common household battery has 12 volts and this would be a small battery if it were used in a flashlight or radio. A car battery has 36 volts and is large enough to run an automobile engine. Batteries can get too hot to hold comfortably, so do not put **your hand** directly onto them without washing it first with soap and water.

The current rating of a circuit determines how much electricity it can safely use. Current is the flow of electrons through a conductor such as a copper wire. The more current that flows, the brighter the bulb will glow. Most homes are built to handle 20 amperes of current, which is why electric circuits usually contain multiple wires called conductors.

Watts are equivalent to Amps times Volts.

- 0 Amps x 120 Volts = 1200 Watts.
- Amps x 240 Volts = 1200 Watts.

Watts are equal to Amps multiplied by Volts. 10 amps multiplied by 120 volts equals 1200 watts. One watt is one joule per second. One amp for one second would mean **one watt**.

This is enough power for one or more heavy appliances such as heaters, air conditioners, and dishwashers.

The total energy used by household appliances is called the load. The more load that an appliance carries, the more electricity it will use. Applying **more than one light bulb** in a room will not make them use less electricity because each will consume about 12 watts even though they are only drawing 0.8 watt each. It takes more electricity to produce light bulbs today than it did in 1980 because technology has improved and manufacturers are able to generate greater amounts of electricity from oil and natural gas per unit of output.

Appliances that use much **more electricity** than others—such as **air conditioners** and heat pumps—are called big loads. They use more electricity because they have larger motors which need **more electrical power** to run them. For example, an air conditioner with a capacity of 4 tons requires 4 times as much electricity as one that weighs 1 ton. A big load also uses more electricity during periods of high demand, such as at night when many people turn on their lights and other appliances.

Small loads use little electricity.

The maximum capacity of a 20-amp circuit operating under the same potential difference of 120 volts is 20*120, or 2400 watts. Most electricians, however, recommend that you only utilize 80 percent of the whole capacity. This is the circuit's maximum safe load. The remaining 20 percent of the capacity is wasted energy and should be reduced as much as possible to below **20 amps**.

The voltage across any resistor is constant, so if the current through it changes, its power also changes. Power is rate times voltage over distance. In other words, power is rate of change of energy over time. Since energy is mass x velocity squared, power is mass x velocity. As an example, if a 200-watt heater requires 15 amps to operate, then its power rating is 240 watts. If the current through the resistor needs to be increased to 25 amps for some reason, then the power required will be 300 watts. The resistance of the resistor must increase by **about 30 percent** to handle **this extra load** without melting away.

Power = voltage * current so if we double the voltage but stay at 20 amps, the power goes up to 40 watts. Therefore, the resistor needs to be capable of withstanding 40 watts rather than 30. Or, in other words, it should be able to carry 2 times the current it does now.

The circuit must be listed for **120 volts** or better if you want to be safe. Other factors such as type of load, size of wires, etc., will affect **how much power** you can draw. In general, the more amps through a circuit, the less power it takes to cause damage.

You should always use the proper current rating for any wire that goes between two live parts of a house wiring system. For example, if you're using 14 AWG wire, then your maximum allowable current is 140 amperes. If you go over this amount, you could get a fire started by accident.

The rule of thumb for home wiring is this: If you can see it, plug it in! Use **only those outlets** that are marked "Outlet" or "Plugged In." Outlets that are labeled "Unknown" or "UNPLUGGED" cannot be used to supply electricity to appliances. They are there for **emergency use** only. Do not use them as regular outlets because they may not work when you need them most.

It's good practice to use voltage-testing devices to make sure that no circuits are overloaded.

If a 100 amp circuit breaker is utilized, the answer is 100 amps * 240 volts, or 24,000 watts. This means that the equipment on **your circuit** will consume 2,400 watts of power.

The average household in the United States uses **about 2000 watts** of electricity per day. So if a household was on your circuit all the time, it would use more than 100 amp hours of electricity which would be equivalent to having a 40A circuit. If this were possible, other people who are not using much electricity would be able to hear loud noises when they turn on their lights or other electrical devices.

This example shows how important it is to match voltage and current capacity on circuits. If these had been matched properly in **the first place**, there would have been no need for the repair person to change **either the size** of the wires inside the house or the breaker box.

In conclusion, 100 amp circuits should be used only for heavy duty applications such as air conditioners, heat pumps, and dishwashers. Other things that can cause damage if they are connected to a circuit rated at 100 amps or more include lawnmowers, leaf blowers, and hedge trimmers.