2. Electrical Safety

This strategy also applies to electric potentials on

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: pliance: A. In some appliances, the internal wiring is different for the live and neutral wires so that it becomes possible to ensure that the live wire does NOT contact the case. Such appliances are equipped with “polarized” plugs, in © 2013 Alexander Ganago Page 17 of 28 Last printed 2013- 07- 07 12:28 AM File: 2013 EEW 1- 02 Electrical safety.docx Engineering in the Electrical World (EEW) Part 1 Unit 2: Electrical safety which the live wire is connected to the narrower blade, and the neutral wire is connected to the wider blade. A polarized plug can fit the receptacle in only one way because the openings are of different widths (see Figure 2- 6). <Sidebar> Polarized plugs, which have the two blades of different widths and can be plugged into the receptacle only one way, provide an additional protection against electric shock. B. Another solution requires that a third wire is always connected to the ground and to the metal case of the appliance. If the live wire has a faulty insulation and accidentally contacts the metal case of the appliance, electric current will return to the receptacle through the power cable, and probably trip the circuit breaker. However, the user will not suffer any electric shock because both points of contact connect the user’s body to the ground. This solution is shown in Figure 2- 10, which also lists the colors of insulation for each wire according to the US National Electric Code. <Sidebar> The third wire, which connects the metal case of an electric appliance to the ground, protects the user from electric shock. Figure 2- 10. Three- wire connection of an electric appliance includes the ground wire, which ensures that the metal case of the appliance is always grounded. If the live wire accidentally connects to the metal case, the current will return to the source through the power cable without entering the human body; most likely, the circuit breaker will trip. © 2013 Alexander Ganago Page 18 of 28 Last printed 2013- 07- 07 12:28 AM File: 2013 EEW 1- 02 Electrical safety.docx Engineering in the Electrical World (EEW) Part 1 Unit 2: Electrical safety C. The third solution requires a special device called the Ground Fault Circuit Interrupter (GFCI). Its ci...
View Full Document

Ask a homework question - tutors are online