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" Churning with voltage and resembling an explosion at the wire factory, the breaker panel exudes mystique. But it&amp;#039;s just a big switch, filled with other smaller \u00ADswitches, which lead to the switches that any home\u00ADowner can fearlessly flip. Doing so conjures a current of electrons that runs along copper wires, energizing our appliances, lights and modern lives. Breaker-panel literacy isn&amp;#039;t only for voltage veterans who recite the National Electrical Code. Even if all you wonder is whether your humble hot tub dreams are electrically attainable, or why the toaster oven kills the kitchen lights\u2014the panel has a thing or two to tell you.    NEUTRAL AND HOT WIRES Current flows from the panel toward the load along the hot wires and returns along the neutral. Each hot wire&amp;#039;s copper tip ultimately connects to its control switch at the circuit breaker, and each neutral connects to a common terminal called a bus bar.  BREAKER SIZES  Main breaker  This is the on/off switch to the entire breaker panel. A 200-amp breaker is appropriate for a home upwards of 2000 square feet. Smaller buildings can use 150-amp or 100-amp; small homes and subpanels can use as little as 50-amp.  Double-pole breaker  Uses the entire 240 volts available to the panel. The 15-amp and 20-amp breakers often handle baseboard heaters, 30-amp serve water heaters and electric dryers, 40- and 50-amp are for electric ranges, and the 70-amp could serve a large air conditioner or a subpanel. Single-pole breaker  The 15-amp and 20-amp are all-purpose breakers, running everything from lights and outlets to garage-door openers.  15-amp AFI breaker  Arc-fault-circuit-interrupter breakers can prevent fires caused by accidental electrical discharge. WIRE GAUGE  12-gauge wire  Common for low-demand connections to light switches and outlets, attached to either 15- or 20-amp breakers. 14-gauge wire  Too thin for anything other than 15-amp breakers under small loads. 10-gauge wire  Appropriate for a two-pole 20-amp breaker or a single-pole 30-amp breaker. 8-gauge or 6-gauge wire  Used for 40-, 50- and 60-amp two-pole breakers; large appliances. Also used to serve subpanels. GROUND WIRES Grounding prevents a conductor not meant to carry current (such as the metal side of a clothes dryer) from causing injury if it&amp;#039;s energized by a frayed hot wire. In a properly grounded system, appliances and metal boxes connect back to the grounding bus of the breaker panel. From there, the system is grounded to the earth via buried ground rods.  HOW ELECTROCUTION HAPPENS Ventricular fibrillation, the erratic, lethal spasm that occurs as electric current passes through the heart, happens when both of a person&amp;#039;s hands touch hot and neutral conductors, causing the current to complete its circuit through the chest. In a ground fault, current can flow into a single hand, zapping the heart as it passes through the body on its way to the ground. When changing live fuses in the old days, electricians worked with one hand while keeping the other in their back pocket--this spared the heart by isolating the current to the nerves of the one hand in the fuse box.  What Is the Watt?    Found in electrical reference books everywhere, the Ohm&amp;#039;s law wheel simplifies conversions between watts, volts, ohms and amps. The most important calculation for a consumer is voltage times amperage, which equals wattage\u2014an appliance&amp;#039;s power requirements\u2014and the basis of the unit in which electricity is sold.  Juice Routes As home-brewed electricity gets more sophisticated, expect to see items now sold as separate hardware\u2014such as solar panel inverters and AC/DC disconnects, or generator subpanels and transfer switches\u2014merge into single, standard parts, which are easier to install and understand.  Installing a Backup Generator: In a power outage, a backup generator provides electricity to designated circuit breakers. Natural gas or propane fuels the generator&amp;#039;s engine, which spins an alternator to create a magnetic field that sends current to the home. It&amp;#039;s critical that no electricity from the generator back-feeds to the grid\u2014linesmen working to restore power could be electrocuted. An automatic transfer switch isolates the generator&amp;#039;s electricity to keep it off the grid until power is restored. Then the generator shuts down and the transfer switch reverses. Wiring Wind Turbines or Solar Photovoltaics: Solar panels and wind turbines feed DC power into an inverter, which converts it to AC for home use. AC and DC disconnect switches allow parts to be isolated for service. These systems constantly back-feed to the grid, but during a blackout\u2014to some grid-tied customers&amp;#039; surprise\u2014their power can&amp;#039;t be used. One solution: Store power in a battery backup system. Inverters like Outback Power&amp;#039;s Flexpower One cut equipment costs with prewired battery connections and circuit breakers. New micro-inverters convert DC to AC at the panel, eliminating DC wiring runs.   The Smart Grid in Your Basement Some benefits consumers could see upon completion of a national smart grid are already available in products like Computerized Electric Systems&amp;#039; Smart Panel. Computer hardware hacked onto a standard breaker panel allows this tool to monitor individual circuits, transfer and balance loads between power sources, or manage power remotely. Simply having more information about each breaker&amp;#039;s power consumption can be the start of a more electrically efficient lifestyle\u2014leave the refrigerator&amp;#039;s door open, witness the real-time consumption spike, and get motivated. "^^<http://www.w3.org/2001/XMLSchema#string>
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