Electrical Safety.

Question 0

2. What is conductor ?

Answer 0

A material that allows electrons to flow through it.

Question 1

1. What is electrical current?

Answer 1

It is the flow of electrons through a conductor.

Question 2

3. What is an insulator?

Answer 2

Insulators resist the flow of electricity.

Question 3

4. What is resistance?

Answer 3

It opposes electron flow.

Question 4

5. What is an electrical circuit?

Answer 4

A loop where current flows.

Question 5

6. How does current flow in circuit?

Answer 5

DC current flows from negative to positive.

AC current flows mostly from hot to neutral.

Question 6

7. Parts of a simple AC circuit?

Answer 6

1. Electrical source.
2. Hot wire that sends electricity.
3. Consuming device.
4. Neutral wire that returns electricity.
5. Earth or ground.

Question 7

8. Name of event when something going wrong with a electrical circuit?

Answer 7

1. A faulted circuit.

2. Electrical fault.

Question 8

9. What is faulted circuit?

Answer 8

In a faulted circuit or electrical fault, current follows the wrong path and bypasses the normal load.

Question 9

10. Two ways of a faulted cicuit?

Answer 9

1. The short circuit.

2. The ground fault.

Question 10

11. What is short circuit?

Answer 10

Two hot wires or a hot wire and a neutral wire touch.

Question 11

12. What is ground fault?

Answer 11

The hot wire touches an outlet or tool casing.

Question 12

13. What does short circuit cause?

Answer 12

Shocks and damage equipment. They make excess heat that can start fires. With a short circuit, a tool usually will not work.

Question 13

14. What does ground faults cause?

Answer 13

Shocks. The outlet or tool may keep working until a person touches it - creating multiple paths to ground.

Question 14

15. What are the harmful effects of electricity?

Answer 14

Electricity can cause shocks, burns, fires, and explosions in the workplace.

Question 15

16. What is the number of leading cause of occupational death in construction for electricity?

Answer 15

The fourth.

Question 16

17. What can shock cause?

Answer 16

Electrocution or it may cause a physical reaction that results in a fall.
Current flowing through your chest, neck, head, or major nerves can stop your breathing.
Current through the heart can make it beat out of rhythm or stop.

Question 17

18. What are electric burns?

Answer 17

Burns may accompany shock. Resistance to current flow in your body turns into heat. Electricity can cook internal organs or cause internal bleeding. Internal effects may happen days later.

Question 18

19. What does cause electrical fires?

Answer 18

Heat from electricity can ignite fires.

Bad insulation or loose connections.

Question 19

20. What are electrical explosions?

Answer 19

They are the fires that burn very fast. Bad insulation, overloaded circuits, or sparking at switch contacts can ignite explosive mixtures in air.

Question 20

21. How do we work safely with electricity?

Answer 20

At a minimum, employers must follow the OSHA electrical standards (subpart K). This standards provide protection for using temporary wiring in construction.

Question 21

22. What are three protective methods the OSHA electrical standards (subpart K)?

Answer 21

1. Electrical isolation.
2. Grounding.
3. Circuit interruption.

Question 22

23. What is temporary wiring?

Answer 22

Electrical wiring installed for a construction project. It must use separate circuits for power and lights. OSHA does not allow power outlets or screw-in converters on light circuits. Power and light circuits must have separate circuit breaker boxes or fuses.

Question 23

24. Parts of temporary wiring?

Answer 23

1. Power from portable or vehicle-mounted generators.
2. Feeder boxes contain the main shut-off switch for site temporary wiring.
3. The system grounding electrode is located in the main box.
4. Circuit breaker boxes.
5. Circuit for power.
6. Circuit for lights.

Question 24

25. What is electrical isolation?

Answer 24

We isolate electricity by keeping it away from ourselves or our workplaces. To isolate electricity we do one or more of the following: 1. Insulate the wires. 2. Isolate the wires in enclosures. 3. Elevate the wires. 4. Bury the wires. 5. Cover the wires.

Question 25

26. What is grounding?

Answer 25

A separate, low resistance pathway for electricity when it does not follow normal flow from hot to neutral.

Question 26

27. How does grounding work?

Answer 26

In case of a ground fault, most of the electricity takes the ground to source. This helps keep you from becoming part of the circuit.

Question 27

28. Where has OSHA extensive requirements for grounding?

Answer 27

In 1926.404(f)(1) through (11).

Question 28

29. Does grounding always work?

Answer 28

No. Grounding won't work if your resistance is less than the ground path. For example: 1. If you are holding a metal pipe that goes directly to ground. 2. If you are standing in water. 3. If your tool doesn't have a ground connection.

Question 29

30. What makes a proper ground path?

Answer 29

A proper grounding path must do two things: 1. Prevent electricity from flowing between the enclosure of an electrical circuit or system. 2. Provide a path for fault current to flow back to its source that is less resistant than other paths.

Question 30

31. What 4 conditions must the grounding path meet?

Answer 30

1. The path to ground must be permanent and continuous. 2. The path must have ample capacity to cause the operation of the over current device. 3. The path must have low resistance. 4. All circuit parts must be bonded together.

Question 31

32. The last method of electrical protection required by OSHA subpart K?

Answer 31

Circuit interruption.

Question 32

33. What is circuit interruption?

Answer 32

Circuit interrupters break a electrical loop or a circuit, so the electricity does not flow.

Question 33

34. Two types of circuit interruption?

Answer 33

1. Circuit breakers or fuses for wiring and equipment protection. 2. Ground fault protection for shock protection.

Question 34

35. How do circuit breaker and fusesbwork?

Answer 34

Circuit breakers or fuses connect in the path of the hot wire. When hot wire flow is over the rating of the circuit breaker or fuse , it opens. This interrupt the circuit before the wire or equipment is damaged.

Question 35

36. What is the reason for blowing fuses or breakers?

Answer 35

1. Grounding problem. | 2. Overload.

Question 36

37. Who should change the rated capacity of breakers or fuses on a circuit?

Answer 36

Only qualified electricians.

Question 37

38. What are limitations of over current devices?

Answer 37

A circuit breaker's job is to protect equipment from heat build-up caused by overload and faults. For protection from electrocution, you need Ground Fault Protection.

Question 38

39. What is ground fault protection?

Answer 38

If a short circuit or ground fault happens, electricity should return along the ground path to the source. At the source, this higher rate of current flow opens the circuit breaker or fuse.

Question 39

40. 2 OSHA alternative mandatory provisions required "in addition to any other requirements for equipment grounding conductors"?

Answer 39

1. GGCI or ground fault circuit interrupter. | 2. Assured equipment grounding program.

Question 40

41. What is a GFCI?

Answer 40

GFCI stands for ground fault circuit interrupter. They are installed in the path between the hot and neutral wires of a circuit. The GFCI is not an overcurrent device. A GFCI only cares about the difference in current between the hot and neutral conductors. So a GFCI cannot replace circuit breakers for overcurrent protection. GFCIs are used in combination with - not instead of - fuses or circuit breakers. While circuit breakers and fuses protect wiring and equipment, GFCIs protect you from shock.

Question 41

42. How does a GFCI work?

Answer 41

By detecting differences in current between the hot and neutral wires. If the difference exceeds 5 milliamps, or 5/1,000th of an amp (.005 amp), the GFCI opens the circuit. This difference in current flow is typically well below the threshold of a circuit breaker or fuse. As a result, ground faults-which would never open a circuit breaker will open the GFCI. For example, if a ground fault directs 6 mA (.006 amp) of current through you, it reduces the current returning to the source on the neutral by the same amount. Because the difference is less than 15 amps, the circuit breaker will not open. But the GFCI will trip because the difference is greater than 5 mA. You are saved from a shock.

Question 42

43. How do GFCI and circuit breaker shock protection compare?

Answer 42

A GFCI opens at 5!milliamps. You might experience a painful shock, if you have dry skin. But you can let go of the wire. So even if your skin is wet or you are standing on a wet surface, the GFCI will open before you experience harmful effects. This flow is well below the threshold for lung paralysis, heart failure, heart paralysis, or burns. By contrast, a 15 amp fuse or circuit breaker does not open until 15,000 milliamps of power flow through it. This means enough current can flow through you so that you can't let go of the power.

Question 43

44. Where are GFCIs installed?

Answer 43

On all 120-volt single-phase 15 and 20-amp receptacle outlets used by employees on the construction site - accept outlets which are part of the permanent wiring of the building or structure. GFCIs are installed almost anywhere anywhere in the electrical circuit: 1. At the service entrance panel. 2. At the branch circuit panel. 3. At the outlet level. 4. On every extension cord used for power delivery.

Question 44

45. What must an employer who does not use have?

Answer 44

An assured equipment grounding program.

Question 45

46. What is an assured equipment grounding program?

Answer 45

1. Written program. 2. Competent person(s). 3. Inspection. 4. Testing. 5. Equipment availability. 6. Record-keeping.

Question 46

47. What i s written program of assured equipment grounding program?

Answer 46

Available for inspection and copying by OSHA or any affected employee.

Question 47

48. What is competent person(s) of assured equipment grounding program?

Answer 47

To do daily inspection and periodic testing.

Question 48

49. What is inspection of an assured equipment grounding program?

Answer 48

Each day before work, inspect for defects: 1. All cord sets. 2. Attachment caps. 3. Plugs and receptacles. 4. Any equipment connected by cord and plug even if fixed and not exposed.

Question 49

50. What is testing of an assured equipment grounding program?

Answer 49

Continuing testing on all equipment ground conductors before first use, following repairs, and at least every three months.

Question 50

51. What is equipment availability of an assured equipment grounding program?

Answer 50

All equipment is inspected and tested before use.

Question 51

52. What is record-keeping of an assured equipment grounding program?

Answer 51

The employer keeps a record of all test and inspections. The NECA color coding scheme is one way to keep track of inspections.

Question 52

53. What else does OSHA require accept circuit interruption?

Answer 52

Subpart K also includes detailed wiring designs, methods, and installation practices.

Question 53

54. How do we select an extension cord?

Answer 53

For portable power tools and appliances, OSHA permits only 3-wire extension cord sets designed for hard or extra hard usage.

Question 54

55. Extension cord marking?

Answer 54

1. Wire size. 2. Number of conductors. 3. Cord type. 4. AMP rating.

Question 55

56. Extension cord types?

Answer 55

1. Hard use: S, ST, SO, STO. | 2. Junior hard use: SJ, SJO, SJT, SJTO.

Question 56

57. Where can't we use an extension cord?

Answer 56

1. Do not pass through holes in walls, floors, or ceilings or through windows or doors. 2. Do not run behind building walls, ceilings, or floors. 3. Do mot attach to building surface (including hanging them from nails, staples or bare wire). 4. Do not use as a substitute for the fixed wiring of a structure.

Question 57

57. What is strain relief?

Answer 57

When cords are plugged in, a lot of pressure is applied th the prongs or to the connectors. This can loosen the prongs or the connection of the conductors to the prongs. The easiest way to prevent this problem is by using strain relief on the cords.

Question 58

58. How do we plug or unplug an extension cord?

Answer 58

Pull on the plug, not the cord. This prevents stressing the terminals where the conductors connect to the plug.

Question 59

59. What is the most unforgivable misuse of an extension cord?

Answer 59

Removing the ground connection.

Question 60

60. How do we maintain extension cords?

Answer 60

Clean, inspect, coil, and store extension cords. Wipe with a dry reg.

Question 61

61. How do you coil extension cords?

Answer 61

Using a figure 8, regular coil, reverse coil, or winding armature.

Question 62

62. How do you store extension cords?

Answer 62

Away from oil, dirt, solvents, acids, caustics, or moisture. Keep away from sharp tools.

Question 63

63. How do we inspect extension cords?

Answer 63

Visually at least once each day, before use: Check the insulation for cracks, cuts, or breaks. Look for insulation damage and for bent or weakened conductors. Are connections at the plug ends frayed? Check the plug attachment. Are male plug ends damaged or bent? Extension cords should have ground continuity testing at least every 90 days.

Question 64

64. What about GFCIs on extension cords?

Answer 64

With a GFCI extension cord, when defects in isolation or grounding happen, the GFCI can shut down the current in the extension cord before a shock. A GFCI extension cord reduces the possibility of false shutdowns caused by normal current loss in a circuit - as often happens when GFCIs are located father away in outlets or in circuit boxes.