#Solar mooc 2009 nabcep study guide solutions 1-29

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SolPowerPeople #SolarMOOC explanation of problems 1-29 of the 04/2009 NABCEP Study Guide.

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#Solar mooc 2009 nabcep study guide solutions 1-29

  1. 1. April 2009 NABCEP Study Guide Questions 1-29 SolPowerPeople, Inc. Austin, TX March 8, 2012
  2. 2. Problem 1
  3. 3. Problem 1­  1. b. “as required by OSHA Subpart E.”­  Seems to be an error in this answer. NABCEP indicates subpart “E”. OSHA indicates subpart “M”.­  1926.501(b)(1) ­  "Unprotected sides and edges." Each employee on a walking/working surface (horizontal and vertical surface) with an unprotected side or edge which is 6 feet (1.8 m) or more above a lower level shall be protected from falling by the use of guardrail systems, safety net systems, or personal fall arrest systems.
  4. 4. Problem 1
  5. 5. Problem 2
  6. 6. Problem 2­  2. b. reference OSHA Subpart E.
  7. 7. Problem 3
  8. 8. Problem 3­  3. A. “See section 3.1.2” (of NABCEP Study Guide)­  “The severity of the shock depends on the path of current flow through the body, the amount of current, and the duration of the exposure”
  9. 9. Problem 4
  10. 10. Problem 4­  4. A. “See section 3.1.2” (of NABCEP Study Guide)­  “Currents above 10 mA can paralyze or “freeze” muscles.”
  11. 11. Problem 5
  12. 12. Problem 5­  5. D. “See section 3.1.2” (of NABCEP Study Guide)­  “Currents of more than 75 mA ac can cause a rapid, ineffective heartbeat, and can result in death in minutes unless a defibrillator is used.”
  13. 13. Problem 6
  14. 14. Problem 6­  6. A. “See section 3.1.2”­  “Lockout and tagging is used to prevent unknowing individuals from energizing electrical circuits while they are being serviced or maintained.”
  15. 15. Problem 7
  16. 16. Problem 7­  7. B. “See section 3.1.3” (of NABCEP Study Guide)­  “Consequently, OSHA requires that fall protection be used for walkways and ramps, holes and excavations, roofs, and wall openings where an employee or worker can fall 6 feet or more.”
  17. 17. Problem 8
  18. 18. Problem 8­  8. D. “See section 3.1.3” (of NABCEP Study Guide)­  “Guardrails used to protect open-sided floors and platforms must have top rails between 39 and 45 inches tall, a mid rail, and toeboards at least 3-1/2 inches high.”
  19. 19. Problem 9
  20. 20. Problem 9­  9. B. “See section 3.1.3”­  “Guardrails used to protect open-sided floors and platforms must have top rails between 39 and 45 inches tall, a mid rail, and toeboards at least 3-1/2 inches high.”
  21. 21. Problem 10
  22. 22. Problem 10­  10. D. “See section 3.1.3”­  “Safety nets must be deployed no further than 30 feet below where work is performed, preferably closer.”
  23. 23. Problem 11
  24. 24. Problem 11­  11. C. “See section 3.1.4”­  “OSHA requires that a stairway or ladder be used at points of access where there is an elevation break of 19 inches or more on a jobsite.”
  25. 25. Problem 12
  26. 26. Problem 12­  12. A. “See section 3.1.4”­  “Stairways with four or more risers, or higher than 30 inches, must be equipped with at least one handrail, capable of withstanding a force of 200 pounds.”
  27. 27. Problem 13
  28. 28. Problem 13­  13. B. “See section 3.1.4”­  “Stairways with four or more risers, or higher than 30 inches, must be equipped with at least one handrail, capable of withstanding a force of 200 pounds.”
  29. 29. Problem 14
  30. 30. Problem 14­  14. D. “See section 3.1.4”­  “Stairs must be installed between 30 and 50 degrees, must have uniform riser height and tread depth, with less than a 1/4-inch variation.”
  31. 31. Problem 15
  32. 32. Problem 15­  15. B. “See section 3.1.4”­  “Stairways landings must be at least 30 inches deep and 22 inches wide at every 12 feet or less of vertical rise.”
  33. 33. Problem 16
  34. 34. Problem 16­  16. B. “See section 3.1.4”­  “Non-self-supporting ladders (those that lean against a wall or other support) must be positioned at an angle where the horizontal distance from the top support to the foot of the ladder is 1/4 the working length of the ladder.”­  The working height is 20 feet. 1/4th of 20 is 5 feet.
  35. 35. Problem 17
  36. 36. Problem 17L = (12)2 + (3)2 + 3L = 144 + 9 + 3L = 153 + 3L = 12.4 + 3L = 15.4 feet
  37. 37. Problem 17 3.1.4 “When using a portable ladder for access to an upper landing surface, the side rails must extend at least 3 feet as 3 feet above the upper landing surface.” required by OSHA 2 2L = (12) + (3) + 3 UnknownL = 144 + 9 + 3 length 12 feetL = 153 + 3L = 12.4 + 3 3 feet (i.e. ¼ of 12 as required byL = 15.4 feet OSHA)
  38. 38. Problem 18
  39. 39. Problem 18­  18. D. “See section 3.1.4” If using ladders where the employee or the ladder could contact exposed energized electrical equipment, such as transformers or overhead services, ladders must have nonconductive side rails such as wood or fiberglass.
  40. 40. Problem 19
  41. 41. Problem 19­  19. D. “See section 3.1.6”­  “Class B hardhats are intended for electrical and utility work, and protect against falling objects, as well as high- voltage shock and burns.” from NABCEP Study Guide.
  42. 42. Problem 19­  WRONG!: Hard hats are classified based on ANSI Z89.1. The 1986 revision had a Class B classification for high voltage. This classification changed in 1997 to Classes G & E.
  43. 43. Problem 19
  44. 44. Problem 20
  45. 45. Problem 20­  20. D. “See section 3.1.6” (of NABCEP Study Guide)­  “Employee responsibilities include using PPE in accordance with training received and other instructions, and inspecting daily and maintaining in a clean and reliable condition.”
  46. 46. Problem 21
  47. 47. Problem 21­  21. D. “See section 3.1.6”­  “Eye protection must be provided to protect against hazards such as dust and other flying particles, corrosive gases, vapors, and liquids, and welding operations.”
  48. 48. Problem 22Note: NABCEP loves this question!
  49. 49. Problem 22­  22. C.­  C is the best answer because (a) is not at the level of the workers, (b) may be distracted, and d is not at the level of the workers and not in communication with them while they work.
  50. 50. Problem 22"Safety monitoring systems." Safety monitoring systems [See 1926.501(b)(10) and 1926.502(k)] and their useshall comply with the following provisions:1926.502(h)(1)The employer shall designate a competent person to monitor the safety of other employees and the employershall ensure that the safety monitor complies with the following requirements:1926.502(h)(1)(i)The safety monitor shall be competent to recognize fall hazards;..1926.502(h)(1)(ii)1926.502(h)(1)(ii)The safety monitor shall warn the employee when it appears that the employee is unaware of a fall hazard or isacting in an unsafe manner;1926.502(h)(1)(iii)The safety monitor shall be on the same walking/working surface and within visual sighting distance of theemployee being monitored;1926.502(h)(1)(iv)The safety monitor shall be close enough to communicate orally with the employee; and1926.502(h)(1)(v)The safety monitor shall not have other responsibilities which could take the monitors attention from themonitoring function.
  51. 51. Problem 23
  52. 52. Problem 23­  23. B. The module and wiring can withstand short-circuit current of the module, even if modules are connected in series or parallel. (Wiring must be sized accordingly.)
  53. 53. Problem 23­  Consider this. Modules have a nameplate rating for Isc (short-circuit current) under STC (standard test conditions) which is an irradiance of 1,000 watts per square meter
  54. 54. Problem 23 ­  Now consider that all modules have a “series fuse rating” which is an indication of the ampacity of the device, as in how much current the device can handle.
  55. 55. Problem 23 ­  This implies that in order for the module 2Isc@1, 000watts / m = 6.25 to produce current greater than the20amps / 6.25amps = 3.2 ampacity of the module itself, it would3.2 ×1, 000W / m 2 = 3, 200W / m 2 been to be exposed to an irradiance level of 3,200 watts per square meter which you would never see with terrestrial irradiation.
  56. 56. Problem 24
  57. 57. Problem 24­  24. C. Multiply the open-circuit voltage by 1.18. B­  Be sure to use the −20°C correction factor from NEC Table 690.7.
  58. 58. Problem 24
  59. 59. Problem 25
  60. 60. Problem 25­  25. B. The GFP is designed to provide fire protection. The GFCI protects people from shock.
  61. 61. Problem 25­ From 3.5.4.1: The 2008 NEC, in article 690.5 requires that all grounded PV arrays must incorporate a ground-fault protection device to reduce fire hazards.
  62. 62. Problem 26
  63. 63. Problem 26­  26. C. The module maximum power voltage decreases at the rate of -0.5%/°C (rule of thumb) for module temperatures above 25°C.­  Hence, at 60°C, the module voltage will have decreased by 0.5×(60−25) = 17.5%, resulting in Vmp = 14.1 V.
  64. 64. Problem 27
  65. 65. Problem 27­  27. A. See NEC 480.9(A). Note that option (c) represents an implementation of (a), but is not exact NEC wording.
  66. 66. Problem 27
  67. 67. Problem 28
  68. 68. Problem 28­  28. C. “See instructions from equipment and battery manufacturers.” ­  “When vented lead-acid batteries are used, they should not be located beneath any electronic components. The corrosive vapors from the batteries can degrade the circuitry in the electronic equipment causing premature failures.” ­  The answer implies all of the other battery types listed produced outgassing that can damage electronic equipment.
  69. 69. Problem 29
  70. 70. Problem 29­  29. B. See any instructions from manufacturers of storage batteries or equipment that uses storage batteries.­  From section 3.1.9: “If batteries are used outdoors in cold climates, the electrolyte freezing temperature increases as the batteries discharge. If the electrolyte freezes, DO NOT CHARGE THE BATTERY. Let it thaw slowly in a place where, if it should rupture, the electrolyte will be contained. Do not attempt to accelerate the thawing process with anything that might be capable of igniting any gases that may be liberated.”

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