Page 167

NORA Oilheat Technicians Manual

Chapter 8 Basic Electricity Figure 8-9: Series and parallel circuits A = Series circuit B = Parallel circuit Figure 8-10: A B A B 120 Volts A = Series circuit B = Parallel circuit 120 Volts Chapter 8—Basic Electricity 8-9 that section of the common line. Unlike in a series circuit, the current may vary in different parts of a parallel circuit. As the number of branch circuits increases, the total current draw increases. If you plug too many appliances into an extension cord the amp rating of the wire might be exceeded. The wire will get hot. The overloaded circuit could cause a fire. Overloaded circuits also decrease the voltage to all the loads. As the wire heats up, its resistance increases. The wire starts acting like a load in series with the other loads, and starts stealing electricity from all the loads in the circuit. This is why the oilburner should be wired with its own individual circuits, not sharing the circuit with any other loads. Combination circuit Oilheating systems use what is called a combination circuit. The switches and limit controls are in series with the primary control. If any one of them opens, the electric current to all the loads stops. All loads are wired parallel to each other to allow individual component control and to ensure full voltage is supplied to each load. Safe capacity for 120 volt circuits To be sure you will not overload a circuit, check the amps needed for each of the loads connected to the circuit. This information is on the label of the load. Add up all the watts to be sure they are within the safe capacity. The rated ampacity of controls, switches, and conductors must be followed. AC/DC Electric current is either direct current (DC) or alternating current (AC). Direct current typically comes from a battery. It only flows in one direction, from the negative side of the battery through the circuit to the positive side. Alternating current is what the electric company supplies. It changes direction, flowing back and forth in the wire. Each back and forth change is called a cycle. In North America,


NORA Oilheat Technicians Manual
To see the actual publication please follow the link above