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NORA Oilheat Technicians Manual

Did You Know? When the switch is open, the electricity flows out of the power source to the open switch. It can go no farther. In a fraction of a second, the potential on the power side of the switch reaches the same as the potential from the power source, and there is no further flow of electricity. At the same time, the potential on the other side of the switch reaches the level from the other side of the power source, and there is no current. When we close the switch, the negative charge instantly goes to the positive potential on the other side and electricity flows through the circuit. Chapter 8 Basic Electricity Chapter 8—Basic Electricity 8-11 gauge number (14/2 and 14/3). Only insulated wires are counted, so 14/2 has a black, white, and a bare ground wire which is not insulated and therefore not in the count. 14/3 has an added red wire. Thermostat cables can have from two to seven wires in them, depending on the added functions of the thermostat (air conditioning, humidifier, and fan functions.) To make identification easier, the colorcoding of the wire insulation is standardized. The spot where wires are joined together or hooked to a control is the weakest link in a circuit. Be very careful when making these connections. All connections must be in a junction box or protected control box with clamps at the entrance and exit to be sure stress is not placed on connections if the wires are pulled. If exposed to high heat or humidity, connections may become dirty or corroded. Always check exposed connectors (like the terminal block on primary controls), and always seal hidden connections with electrical tape. Copper wire is recommended for all oilburner wiring and is required in some cases. Armored cable Any wiring around an oil-powered appliance should be protected by either flexible metal conduit or armored cable. There are two kinds of armored cable: BX and MC. BX has no ground wire. Its metal sheathing serves as the ground. Some people mistake the thin metal bonding strip in the cable for a ground wire. The strip is easily broken and is used only to make a conductive connection to a metal junction box. Older BX used heavy steel sheathing. Aluminum is now used because it is lighter, easier to cut, and is a better conductor. MC cable is like BX, but with a green insulated grounding wire. Most codes require MC instead of BX for a sure ground. Flexible metal conduit has no conductors installed in it. The National Electrical Code® specifies how it can be used and how many conductors may be installed in the conduit. Switches Switches are used to stop the flow of electricity. It is a simple idea; just cut the conductor and put an insulator (air) between the two cut pieces of the conductor. A switch is like a drawbridge installed in the middle of a race course. Imagine what would happen if during a race, you suddenly opened the drawbridge, leaving a big hole in the track. All the cars would stop; there would be no more current flow. Thanks to the car brakes, the resistance would be very high but there would still be voltage. The cars would still have all that


NORA Oilheat Technicians Manual
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