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NORA Oilheat Technicians Manual

Chapter 8 Basic Electricity Figure 8-5: Fuse or circut breaker protects the circut Figure 8-6 Fuse Switch Power Source Load overcomes resistance to create flow. Any change in ohms will cause the opposite change in amps because volts from the power source are relatively constant. An increase in ohms reduces amps. A decrease in ohms increases amps. Increasing volts increases amps, this is called Ohms Law, Figure 8-6. It states: “It takes 1 volt to push 1 amp through 1 ohm.” Chapter 8—Basic Electricity 8-7 A complete circuit should always include a load of some sort. If you just run a conductor from the source back to the source without going through a load, you have a short circuit. Since there is no resistance to slow up the electrical current, the amps just keep going higher and higher. This increases the heat build-up from the resistance in the conductor until it gets so hot it starts a fire. Fuses or circuit breakers are installed in the circuit to prevent this from happening. Circuit breakers are automatic switches that cut off the current if it starts to reach dangerous levels. Figure 8-5. The primary resistance to flow in a circuit is the thing doing the work, the “load”. It converts the electrical energy into another from of energy. However, the conductor can also restrict the flow, especially if it is undersized, too hot, or too long. Resistance (ohms) opposes flow. Voltage


NORA Oilheat Technicians Manual
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