How Many Lights Can You Put on One Circuit?
On a summer's day, with the air conditioner keeping your house cool, the coffee maker keeping your coffee hot, and your hairdryer, dishwasher and microwave oven running, you may run into a problem. If you try to draw too much electricity through a circuit, it will shut down. The answer to the question of how much is too much, depends on the circuit. Does this Spark an idea?
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History
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The first homes in the United Stated to be wired for electricity were within one mile of Thomas Edison's Pearl Street Power Station in New York in 1882. This system generated direct current (DC) electricity, instead of the alternating current (AC) that we use today, and DC power could be transported only about one mile.
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Household Wiring
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Modern households are wired for a heavy electrical load. Our appliances, electronics and computers, when added together, can draw an enormous amount of energy. Electrical power comes into our homes through a meter so the local utility can bill for usage. Once in our homes, the wires are connected to either a fuse-box or a circuit panel, both of which have the same function--preventing a dangerous situation by limiting the amount of electricity that can flow through a wire at one time.
Volts and Amps
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Household electrical service is measured in amperes, or amps. Amps are a measure of the flow of electricity. A large house might have a 200-amp service. Voltage is the name for the pressure that pushes electricity through wires. Some electrical outlets have one live wire and one neutral, for 120 volts. Some larger appliances, like refrigerators or electric dryers use 240 volts so the outlet they are connected to will have two live wires and no neutral.
Watts
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Watts are a measure of output of electrical energy. A typical light bulb might put out 60 watts of energy as light. A hand-held hairdryer might put out nearly 2000 watts as noise, heat and wind.
Watts are related to volts and amps with a simple formula. Divide the number of watts you need by the voltage of your outlet. That number must not exceed the number of amps on a particular circuit. For example, if I have 20 60-watt bulbs on a 120-volt outlet, that would be 1200 / 120 = 10. Those 20 bulbs require 10 amps of electrical flow to be all on at the same time. If the outlet is connected to a 10-amp circuit, you have reached the limit of that circuit.
Significance
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Electric stove The technical explanation above is helpful in specific situations. In general, it's important to know that an appliance that has an electrical heating element (usually a bar that glows red) uses quite a lot of electricity. These can include a dishwasher, hair dryer, curling iron, space heater and an electric stove or clothes dryer. Once that load is on a circuit, it's a good idea to limit other items on the same circuit, especially sensitive electronic equipment. Another good piece of practical advice: Before resetting a circuit that a computer or stereo equipment is connected to, unplug that device. There is a small power surge on reset that can damage your electronics.
Warning
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Firefighters battle a blaze. All but the simplest home electrical repairs should be done under the supervision of a licensed electrician. Beside the risk of electrocution, improper wiring can cause a hidden fire danger. Consult someone with experience before starting any electrical projects. The National Fire Protection Association website (nfpa.org) offers good advice about electrical safety in your home.
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References
Resources
- Photo Credit Image by Flickr.com, courtesy of Mitchell Laurren-Ring Image by Flickr.com, courtesy of traveling for about a month) (Jeremy Barwick
