The ammeter can be redlined at 100 percent of the generator  or alternator rating in installations with the ammeter in the  generator or alternator lead, and the regulator system does  not limit the maximum current that the generator or alternator  can deliver. If the ammeter reading is never allowed to exceed  the red line, except for short, intermittent loads, the generator  or alternator is not overloaded. Where the use of placards or monitoring devices is not  practical or desired, and where assurance is needed that the  battery in a typical small aircraft generator or battery power  source is charged in flight, the total continuous connected  electrical load may be held to approximately 80 percent of  the total rated generator output capacity. When more than  one generator is used in parallel, the total rated output is the  combined output of the installed generators. Means must be provided for quickly coping with the sudden  overloads that can be caused by generator or engine failure if  two or more generators are operated in parallel and the total  connected system load can exceed the rated output of one  generator. A quick load-reduction system can be employed  or a specified procedure where the total load is reduced to  a quantity that is within the rated capacity of the remaining  operable generator or generators. Electrical loads should be connected to inverters, alternators,  or similar aircraft electrical power sources in such a manner  that the rated limits of the power source are not exceeded,  unless some type of effective monitoring means is provided  to keep the load within prescribed limits. protected by the circuit breaker of the next higher rating to  that shown in the table. All resettable circuit breakers should open the circuit in which  they are installed, regardless of the position of the operating  control when an overload or circuit fault exists. Such circuit  breakers are referred to as trip-free. Automatic reset circuit  breakers automatically reset themselves periodically. They  should not be used as circuit protection devices in aircraft. A specifically designed switch should be used in all circuits  in which a switch malfunction would be hazardous. Such  switches are of rugged construction and have sufficient  contact capacity to break, make, and carry continuously  the connected load current. Snap-action design is generally  preferred to obtain rapid opening and closing of contacts  regardless of the speed of the operating toggle or plunger,  thereby minimizing contact arcing. The nominal current rating of the conventional aircraft  switch is usually stamped on the switch housing. This rating  represents the continuous current rating with the contacts  closed. Switches should be derated from their nominal current  rating for the following types of circuits:  Figure 4-117  shows an example of the table used in selecting  the circuit breaker and fuse protection for copper conductors.  This limited table is applicable to a specific set of ambient  temperatures and wire bundle sizes and is presented as a  typical example only. It is important to consult such guides  before selecting a conductor for a specific purpose. For  example, a wire run individually in the open air may be  The circuit breaker or fuse should open the circuit before the  conductor emits smoke. To accomplish this, the time/current  characteristic of the protection device must fall below that  of the associated conductor. Circuit protector characteristics  should be matched to obtain the maximum utilization of the  connected equipment. Conductors should be protected with circuit breakers or fuses  located as close as possible to the electrical power source  bus. Normally, the manufacturer of the electrical equipment  specifies the fuse or circuit breaker to be used when installing  the equipment. Figure 4-117. Wire and circuit protector table. Switches  Circuit Protection Devices 1.  High rush-in circuits—circuits containing incandescent  lamps can draw an initial current that is 15 times  greater than the continuous current. Contact burning  or welding may occur when the switch is closed.  2.  Inductive circuits—magnetic energy stored in solenoid  coils or relays is released and appears as an arc as the  control switch is opened.  4-68 5.0 7.5 10.0 15.0 20.0 30.0 40.0 50.0 80.0 100.0 125.0 5 5 10 10 15 20 30 50 70 70 100 150 150 22 20 18 16 14 12 10 8 6 4 2 1 0 Wire AN Gauge Copper Circuit Breaker Amperage Fuse Amperage