Every December, the neighbor across the street lights up the block with an elaborate holiday light display. But every year dozens of outdoor light displays like this unexpectedly go out. You might have plugged in a small electric heater and turned it on to warm your feet. Or switched on a hair dryer. Or dropped a snack into the toaster. It’s not only the outdoor display that goes out, but perhaps most of the main floor lights too. The TV in the family room quits. The clock in the kitchen stops.
The problem? An overloaded circuit. The power needed by the outdoor lights added to the load from the refrigerator, the heater and any other devices connected to the same circuit, and all of them running at once exceeded the capacity of the electrical wiring.
Rest assured that an overload in a properly installed electrical system wouldn’t burn your house down. An “overcurrent protective device” at the main panel will automatically shut off the power before damage occurs. (Except for Federal Pacific Electrical Panels). In most cases, the device will be a circuit breaker that trips open. In older systems a fuse will “blow” (burn out). But finding a solution can be a hassle. Too many things plugged into an outlet on a circuit can cause an overload.
The nerve center of your electrical system is the main panel, usually a gray metal box about the size of a cookie sheet, which typically sits in some obscure spot in a utility room, the garage or the basement. Three large wires from the utility company feed the main panel. You might spot the wires outside if they’re overhead.
Circuit breakers (or fuses) in your main panel limit the power to a level that your wiring system can safely handle and funnel that power through branch circuits, the wires that run to various parts of your house. If you turn on too many appliances and the power demand on any one circuit exceeds the limits of the circuit breaker (or fuse), the breaker snaps open and shuts down the entire circuit, serving you notice that you have an overload or some other problem.
At first glance, the spider web of cables that spreads out from your main panel might look impossibly complex.
Fortunately, the National Electrical Code (NEC) imposes a kind of circuit logic that simplifies the system. The circuits in the main panel are roughly divided into two types—dedicated and general purpose.
Dedicated circuits include those serving a single large-draw appliance like the furnace, range, built-in microwave and garbage disposal.
Other dedicated circuits are for special uses like small kitchen appliances, laundry equipment and the bathroom. Most of these should be labeled at the main panel, although they often aren’t. And don’t be surprised if you find other outlets on these circuits in older and remodeled homes. Over the years the NEC has gradually increased the number of dedicated circuits, as electrical appliance use has grown.
General-purpose circuits, on the other hand, serve multiple outlets such as lighting and most of the rest of the receptacles (outlets) in your home. Normally you can tap into one of these circuits when you need extra power or want to add another outlet. But not always. If you’re adding a receptacle for a high-power use device such as an air conditioner or electric heater, you might have to run an entirely new circuit from the electrical panel.
You’ll need to run new circuits (Dedicated Circuits) or take loads off current circuits to avoid overloads.
Add up all the electrical loads on the circuit. If the load exceeds the limit allowed by the National Electrical Code, redistribute the load to other general purpose circuits or run new circuits to the largest loads.
Common Dedicated Circuits
- Appliance Power 1,200 watts and up
- Electric Range 5,000 watts (240 volts)
- Electric Dryer 6,000 watts (240 volts)
- Space Heater 1,000 watts and up
- Clothes Washer 1,200 watts
- Furnace (blower) 1,200 watts
- Microwave 700–1,400 watts
- Refrigerator 800 watts
- Freezer (not required) 700
- Dishwasher 1,400 watts
- Central Vacuum 1,000 watts
- Whirlpool/Jacuzzi 1,000 watts and up
- Garbage Disposal 600–1,200 watts
- Kitchen Countertop (two circuits):
- Toaster 1,200 watts
- Coffee maker 1,000 watts
- Toaster oven 1,400 watts
- Hair dryer up to 1,800 watts
Solutions to Overloads
The immediate solution to an overload is simple: Shift some plugged in devices from the overloaded circuit to another general-purpose circuit outlet. Then flip the circuit breaker back on or replace the fuse and turn the appliance back on.
In practice, however, it isn’t so easy to know that you’ve found a good, long-term solution. First you have to locate outlets on another general-purpose circuit. Then you have to find a convenient way to reach it. Resist the temptation to solve the problem with an extension cord. Extension cords are for short-term use. They’re not to be used as permanent wiring or fastened into place. They are fire hazards.
To trace your general-purpose circuits, begin with the labels on the main panel. They’re supposed to give you some idea where the circuits run. They’re usually accurate for dedicated circuits, but they’re often too vague to help you pinpoint general-purpose outlets. Chances are, you’ll have to map out these circuits yourself.
To trace a circuit, turn off its breaker at the main panel (or unscrew the fuse), then go through your home testing outlets—flipping on light switches and plugged-in devices and plugging in a test light into open receptacles.
Test both the upper and lower receptacle of standard duplex receptacles, because they’re sometimes wired to different circuits. And make sure switched receptacles are “on” before testing them. Check outdoor lights and receptacles too. Outlets that don’t work are connected to the circuit that’s off. Write your results down, or put them on a simple floor-plan diagram so you won’t forget or skip locations.
Repeat for other circuits until you know what’s what. Don’t be surprised if you find general-purpose outlets on dedicated circuits. It’s not unusual to find the family room on the same circuit as the refrigerator.
Once you’ve mapped out the general-purpose circuits (even better—all your circuits), sharpen your pencil and add up the existing electrical loads (watts) on them.
Light bulbs usually have their wattage stamped on them. Motors are often rated in amperes or “amps” (amps x 120 volts = watts), a figure you’ll find on a plate on the motor or elsewhere on the device. TVs and other electronics usually have a watt rating on a backside label. Then figure the additional load you want to add.
Devices temporarily plugged in, such as a vacuum cleaner or temporarily used portable electric heater, don’t count. Devices (for example, holiday lights or an often used electric heater) with long-term uses do count.
A circuit is overloaded if: The total load exceeds 1,800 watts for a 15-amp circuit. (120 volts x 15 amps = 1,800 watts.) Look for the amp rating of the circuit in tiny numbers on the circuit breaker switch or fuse. For a 20-amp circuit, the load limit is 2,400 watts. On a multiple-outlet circuit, you find any appliance or equipment rated at more than half the circuit rating, 1,000 watts for a 15-amp circuit. (These large-draw appliances should have dedicated circuits.)
Upon checking, if you find that this circuit exceeds both the 1,800 watt limit for a 15-amp circuit and the 1,000 watt limit for any one device. The best solution to solve this overload situation is to run a dedicated circuit to the biggest load. In practice, to avoid high installation costs, professional electricians run new circuits to the appliances they can reach most easily.
Practical advice: Don’t load your circuits to the maximum (figure about 70-80 percent). Otherwise, you’re more likely to have hassles with overloads when you temporarily plug in high-draw devices such as a vacuum cleaner (800 to 1,100 watts).
Call Richard Marton Electrical Contractor LLC and he can answer all your questions about overloaded circuits, electrical panels, breakers, fuses, dedicated circuits, electrical loads and more.
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Richard Marton Electrical Contractor LLC is a full service electrical contractor serving homeowners and businesses in Bergen, Passaic, Essex and Morris County New Jersey with electrical installations and repairs. We are also a certified Generac Generator dealer and installer.
Richard Marton Electrical Contractor LLC works with general contractors, residential architects, interior decorators, interior designers, painters, property management and property maintenance professionals, and professional organizers. We work with these professionals to give clients top of the line electrical installations within such projects as residential remodeling, residential renovations, plus build outs of new kitchens, bathrooms, home offices, add-a-level residential project and more.