OSHA general industry electrical safety practice questions
20 free practice questions from 29 CFR 1910 Subpart S. Each answer is explained and linked to the rule it comes from.
OSHA Electrical safety
20 questions across 8 topics. After each answer you see why it is right, with a link to the official source.
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Prefer to read? Here is every question in the OSHA Electrical safety set, grouped by topic. Open a question to see the answer, why it is right and the official source.
Working space and guarding
1. Apart from its width, what must the working space in front of electric equipment of 600 volts or less that is likely to be serviced while energized permit, under 1910.303(g)(1)(i)(B)?
- A. An opening of equipment doors of no more than 45 degrees, so the doors do not block the aisle
- B. At least a 90-degree opening of equipment doors or hinged panels
- C. Storage of spare parts beside the equipment
- D. Removal of the equipment without disconnecting it
Show answer
Answer: B. At least a 90-degree opening of equipment doors or hinged panels
After setting the width, the rule says "In all cases, the working space shall permit at least a 90-degree opening of equipment doors or hinged panels."
2. What does 1910.303(g)(1)(v) say about controlling the illumination in electric equipment rooms?
- A. It must be controlled by motion sensors only
- B. It must be switched from outside the building
- C. It must be on a timer that turns the lights off after 10 minutes
- D. It may not be controlled by automatic means only
Show answer
Answer: D. It may not be controlled by automatic means only
Illumination must be provided for working spaces about service equipment, switchboards, panelboards, and motor control centers installed indoors, and "In electric equipment rooms, the illumination may not be controlled by automatic means only."
3. Under 1910.303(g)(2)(i)(A), live parts operating at 50 volts or more can be guarded by location in a room, vault, or similar enclosure that is accessible only to whom?
- A. Qualified persons
- B. Employees who have worked at the site for at least one year
- C. Any employee who is wearing rubber gloves
- D. Employees on the day shift
Show answer
Answer: A. Qualified persons
One of the listed means of guarding live parts is "By location in a room, vault, or similar enclosure that is accessible only to qualified persons."
Approval, examination and marking
4. For electrical installations made after August 13, 2007, 1910.303(f)(4) requires disconnecting means required by Subpart S to be capable of being locked in which position?
- A. The closed position
- B. The test position
- C. The open position
- D. Any position chosen by the operator
Show answer
Answer: C. The open position
Disconnecting means required by this subpart "shall be capable of being locked in the open position." Section 1910.302 lists this requirement among those that "apply only to electrical installations and utilization equipment installed after August 13, 2007."
Grounding and GFCI protection
5. No grounding means exists in a receptacle enclosure, and a nongrounding-type receptacle is replaced with a grounding-type receptacle supplied through a ground-fault circuit-interrupter. How must the replacement receptacle be marked under 1910.304(b)(2)(iv)(C)(3)?
- A. "GFCI Protected" and "No Equipment Ground"
- B. "Grounded Outlet"
- C. "Temporary Use Only"
- D. No marking is required
Show answer
Answer: A. "GFCI Protected" and "No Equipment Ground"
Such a receptacle may be used "where supplied through a ground-fault circuit-interrupter; the replacement receptacle shall be marked “GFCI Protected” and “No Equipment Ground;”" and an equipment grounding conductor may not be connected to it.
Source: eCFR: 29 CFR 1910.304, Wiring design and protection (as of Nov 3, 2026)
6. How long must the test record of an assured equipment grounding conductor program under 1910.304(b)(3)(ii)(C)(6) be maintained?
- A. 5 years
- B. Until replaced by a more current record
- C. For the life of the equipment
- D. 30 days after the last test
Show answer
Answer: B. Until replaced by a more current record
The record "shall be kept by means of logs, color coding, or other effective means and shall be maintained until replaced by a more current record."
Source: eCFR: 29 CFR 1910.304, Wiring design and protection (as of Nov 3, 2026)
Portable equipment and PPE
7. Before an attachment plug is connected to a receptacle, what does 1910.334(a)(2)(iii) require to be checked first?
- A. That the circuit is rated over 30 amperes
- B. That the cord is at least 25 feet long
- C. That the receptacle cover has been painted orange
- D. That the plug and receptacle contacts are of proper mating configurations
Show answer
Answer: D. That the plug and receptacle contacts are of proper mating configurations
When an attachment plug is to be connected to a receptacle, "the relationship of the plug and receptacle contacts shall first be checked to ensure that they are of proper mating configurations."
Source: eCFR: 29 CFR 1910.334, Use of equipment (as of Nov 3, 2026)
8. When does 1910.335(a)(1)(iv) require employees to wear nonconductive head protection?
- A. Only when working more than 10 feet above the floor
- B. Only on circuits over 600 volts
- C. Only when working outdoors
- D. Wherever there is a danger of head injury from electric shock or burns due to contact with exposed energized parts
Show answer
Answer: D. Wherever there is a danger of head injury from electric shock or burns due to contact with exposed energized parts
"Employees shall wear nonconductive head protection wherever there is a danger of head injury from electric shock or burns due to contact with exposed energized parts."
Source: eCFR: 29 CFR 1910.335, Safeguards for personnel protection (as of Nov 3, 2026)
9. What does 1910.334(a)(3)(iii) say about adapters that interrupt the continuity of the equipment grounding connection?
- A. They are allowed on 125-volt circuits only
- B. They may not be used
- C. They are allowed if a ground-fault circuit-interrupter is present
- D. They are allowed on extension cords shorter than 25 feet
Show answer
Answer: B. They may not be used
The rule says "Adapters which interrupt the continuity of the equipment grounding connection may not be used."
Source: eCFR: 29 CFR 1910.334, Use of equipment (as of Nov 3, 2026)
Flexible cords and temporary wiring
10. How does 1910.305(g)(2)(iii) require flexible cords and cables to be connected to devices and fittings?
- A. With the outer jacket removed at the point of connection
- B. By twisting the conductors together and wrapping them with tape
- C. So that strain relief is provided that will prevent pull from being directly transmitted to joints or terminal screws
- D. So that the terminal screws carry the weight of the cord
Show answer
Answer: C. So that strain relief is provided that will prevent pull from being directly transmitted to joints or terminal screws
The rule says "Flexible cords and cables shall be connected to devices and fittings so that strain relief is provided that will prevent pull from being directly transmitted to joints or terminal screws."
Source: eCFR: 29 CFR 1910.305, Wiring methods, components, and equipment for general use (as of Nov 3, 2026)
11. When does 1910.305(a)(2)(ii) require temporary wiring to be removed?
- A. Immediately upon completion of the project or purpose for which the wiring was installed
- B. Within 30 days after the project ends
- C. At the next annual electrical inspection
- D. Only when the wiring is damaged
Show answer
Answer: A. Immediately upon completion of the project or purpose for which the wiring was installed
The rule says "Temporary wiring shall be removed immediately upon completion of the project or purpose for which the wiring was installed."
Source: eCFR: 29 CFR 1910.305, Wiring methods, components, and equipment for general use (as of Nov 3, 2026)
12. Under 1910.305(a)(2)(ix), how must lamps for general illumination on temporary wiring be protected?
- A. By hanging them at least 6 feet above the floor, with no other protection
- B. By painting the bulbs with a protective coating
- C. By using only LED lamps
- D. By a suitable fixture or lampholder with a guard, against accidental contact or breakage
Show answer
Answer: D. By a suitable fixture or lampholder with a guard, against accidental contact or breakage
The rule says "All lamps for general illumination shall be protected from accidental contact or breakage by a suitable fixture or lampholder with a guard."
Source: eCFR: 29 CFR 1910.305, Wiring methods, components, and equipment for general use (as of Nov 3, 2026)
Qualified persons and training
13. What type of training does 1910.332(c) require for electrical safety-related work practices?
- A. Online training only
- B. Classroom or on-the-job training
- C. A course certified by the equipment manufacturer
- D. A state electrician's license
Show answer
Answer: B. Classroom or on-the-job training
"The training required by this section shall be of the classroom or on-the-job type. The degree of training provided shall be determined by the risk to the employee."
14. Which item is on the minimum training list for qualified persons in 1910.332(b)(3)?
- A. Designing a building's service entrance
- B. Operating powered industrial trucks
- C. The skills and techniques necessary to determine the nominal voltage of exposed live parts
- D. Writing the employer's hazard communication program
Show answer
Answer: C. The skills and techniques necessary to determine the nominal voltage of exposed live parts
Qualified persons must at a minimum be trained in "The skills and techniques necessary to determine the nominal voltage of exposed live parts," along with distinguishing exposed live parts and the clearance distances in 1910.333(c).
Deenergizing and lockout
15. Under the first sentence of 1910.333(a)(1), when may live parts that an employee may be exposed to stay energized while the employee works on or near them?
- A. When the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations
- B. When the job will take less than 30 minutes
- C. When the employee prefers to work on them energized
- D. Whenever the circuit is 600 volts or less
Show answer
Answer: A. When the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations
Live parts "shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations."
Source: eCFR: 29 CFR 1910.333, Selection and use of work practices (as of Nov 3, 2026)
16. What does 1910.333(b)(2)(ii)(B) say about push buttons, selector switches and interlocks when deenergizing circuits?
- A. They are the preferred way to deenergize circuits
- B. They may be used alone if a tag is attached
- C. They may not be used as the sole means for deenergizing circuits or equipment
- D. They may replace lockout for one shift
Show answer
Answer: C. They may not be used as the sole means for deenergizing circuits or equipment
"Control circuit devices, such as push buttons, selector switches, and interlocks, may not be used as the sole means for deenergizing circuits or equipment."
Source: eCFR: 29 CFR 1910.333, Selection and use of work practices (as of Nov 3, 2026)
17. Under 1910.333(b)(2)(iii)(E), one of the conditions for placing a lock without a tag is that:
- A. More than one circuit is deenergized
- B. The lockout period does not extend beyond the work shift
- C. The lock is painted a safety color
- D. The lockout lasts at least 24 hours
Show answer
Answer: B. The lockout period does not extend beyond the work shift
A lock may be placed without a tag only if only one circuit or piece of equipment is deenergized, "The lockout period does not extend beyond the work shift," and exposed employees are familiar with the procedure.
Source: eCFR: 29 CFR 1910.333, Selection and use of work practices (as of Nov 3, 2026)
Work near energized parts and overhead lines
18. Under the note to 1910.333(c)(3)(i)(B), how are objects that do not have an insulating rating for the voltage involved treated near overhead power lines?
- A. They are considered to be conductive
- B. They are considered insulating if they are made of wood
- C. They are considered insulating if they are dry
- D. They are disregarded if they are shorter than 10 feet
Show answer
Answer: A. They are considered to be conductive
The note says "For voltages normally encountered with overhead power lines, objects which do not have an insulating rating for the voltage involved are considered to be conductive."
Source: eCFR: 29 CFR 1910.333, Selection and use of work practices (as of Nov 3, 2026)
19. A vehicle with a boom that can be raised near energized overhead lines is intentionally grounded. Under 1910.333(c)(3)(iii)(C), where may employees working on the ground not stand whenever there is a possibility of overhead line contact?
- A. More than 50 feet from the vehicle
- B. Upwind of the vehicle
- C. On the far side of the vehicle's cab
- D. At the grounding location
Show answer
Answer: D. At the grounding location
In that case "employees working on the ground near the point of grounding may not stand at the grounding location whenever there is a possibility of overhead line contact." Additional precautions such as barricades or insulation are also required to protect against hazardous ground potentials.
Source: eCFR: 29 CFR 1910.333, Selection and use of work practices (as of Nov 3, 2026)
20. An employee wearing a metal watch band will work where the band might contact exposed energized parts. What does 1910.333(c)(8) allow?
- A. Wearing it if the band is less than 1 inch wide
- B. Wearing it if the circuit is 600 volts or less
- C. Wearing it only if it is rendered nonconductive by covering, wrapping, or other insulating means
- D. Wearing it if the employee also wears leather work gloves
Show answer
Answer: C. Wearing it only if it is rendered nonconductive by covering, wrapping, or other insulating means
Conductive articles of jewelry and clothing such as watch bands "may not be worn if they might contact exposed energized parts. However, such articles may be worn if they are rendered nonconductive by covering, wrapping, or other insulating means."
Source: eCFR: 29 CFR 1910.333, Selection and use of work practices (as of Nov 3, 2026)