2. Electrical Safety

This is shown in the left panel of figure 2 9 2 on the

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Unformatted text preview: rcuitry includes a transformer whose magnetic core surrounds both the hot and neutral/ground wires, and the electronic circuit (shown with a triangle in Figure 2- 11), which compares the input and output currents. If the difference between these currents approaches the Let- Go threshold, the GFCI automatically and promptly opens the circuit (as shown in the right panel of Figure 2- 11) to ensure that the harm to the user is minimal. <Sidebar> Ground Fault Circuit Interrupter (GFCI) measures the difference between the input and output currents to/from the appliance; it automatically and promptly opens the circuit if their difference approaches the Let- Go threshold. This protects the user from a deadly electric shock. Figure 2- 11. Ground Fault Circuit Interrupter (GFCI) measures the difference between the input and output currents (left panel). If it exceeds 6 mA, the GFCI automatically opens the circuit. Thus, even if the insulation fails and the user touches the metal case of the appliance, the current that enters the human body remains below the Let- Go threshold. Take a second look at Figure 2- 8. Note that every power receptacle equipped with GFCI has two buttons, labeled Reset and Test. You have to press the Reset button in order to restore power after the GFCI opened the circuit. Every month test the operation of the GFCI by pressing the Test button. © 2013 Alexander Ganago Page 19 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 The take home message is straightforward: Inspect your house or apartment and make sure that each power outlet in the kitchen, bathroom, basement, near the washing machine, and at all other places where electricity is near water, is equipped with GFCI. If you rent, talk to your landlord and require prompt replacement of all receptacles lacking GFCI. If you own, hire an electrician to do it. © 2013 Alexander Ganago Page 20 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 The basic rules of electrical safety Our learning in this Unit can be summarized with the following safety rules that provide straightforward guidance:...
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This note was uploaded on 12/06/2013 for the course EECS 314 taught by Professor Ganago during the Fall '07 term at University of Michigan.

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