Use this illustration as a guide to understand what electrical equipment Detroit Edison is responsible for and what equipment is your responsibility.
Detroit Edison installs and maintains your service line (1) and electric meter (6).
Installation and maintenance of the service bracket or hook (2), weather head (3), pipe riser (4), meter can (5) and service entrance cable (7) are the customer's responsibility. A licensed electrician should install and maintain this equipment.
If your service line (1) or electric meter (6) is damaged, please call 800.477.4747.
Meters record the amount of electricity used in kilowatt-hours. The difference between the last meter reading and the present meter reading is the amount of kilowatt-hours used. Energy bills are based on this measurement.
Electric meters have several dials that look something like watch faces. These dials have pointers that turn very slowly when electricity is being used. They don't turn in the same direction; every other one turns counter-clockwise. They keep track of the amount of electricity flowing through the meter by measuring kilowatt-hours.
The main switch serves as a main disconnect for the flow of electricity to a building. When the main switch is pulled, or turned off, the flow of electricity to all of the circuits in the building will stop. The main switch should be located within six feet of where the wires (entrance cable) enter the building.
Circuit Breakers and Fuses
The service wires (service line and entrance cable) deliver electricity to a home through the meter, then on into the main fuse or main circuit breaker. Each main fuse or circuit breaker feeds a number of branch fuses or circuit breakers. To better understand this process, circuits of a home can be compared to the branches of a tree. The tree trunk feeds the branches like the main fuse or main circuit breaker feeds the branch circuits. Each branch circuit serves part of the home. It may feed four or five wall outlets and a ceiling fixture. Another branch circuit may feed all of the wall outlets in a kitchen. Another circuit may feed only one outlet that is for a large appliance, such as an electric dryer.
The usual home voltage for a circuit is 120 or 240 volts. On a regular 120-volt household circuit, the combined wattage of appliances in use at one time cannot exceed the rating of the fuse or circuit breaker.
Newer homes, and many older ones that have been re-wired, will have circuit breakers. Each breaker controls the power to a group of lights, outlets and appliances. It is generally a good idea to label each breaker with what it controls. Circuit breakers protect the wiring and fixtures by turning off the power. If a fixture shorts out, or if a circuit gets overloaded, the breaker will "trip."
That cuts power to the circuit and protect the wires and fixtures from damage. The most common reason for a breaker to trip is too many appliances and lights on one circuit. A tripped breaker usually looks like it's between the ON and OFF positions. To reset a breaker, it should be flipped to OFF and then ON again.
Fuses perform the same function as a circuit breaker, except when a fuse blows, it has to be replaced.
There are cartridge fuses and screw-in fuses. Cartridges look kind of like a shotgun shell. They mount in a little rack that pulls in and out of a bracket. Screw-in fuses screw in and out like light bulbs. Some have a glass window on top and metal threads on bottom.
When a fuse blows, its internal metal strip breaks and the window may get discolored. It should be replaced with a fuse that has the same amperage-rating.
Fifteen and 20 amp fuses are the most common size ratings. Some fuses have a smaller screw base and are called "non-tamperable, type-S" fuses. The threads vary in size so they can't be accidentally replaced by another type. When installing a fuse, it should be screwed in snugly, then given an extra 1/4-turn to make a solid connection. Other fuses are rated as "slow-blow" or "time delay." They take a little longer to blow and are made to withstand short, extra surges of power -- like a motor starting.