25 multiple-choice questions for the OSHA Electrical Safety (Subpart S) Practice Test. Pick an answer to see the rule behind it, quoted from the official source.
1. An unqualified worker is performing non-electrical maintenance work near a premises wiring installation. According to the scope of electrical safety-related work practices, are the provisions of §§ 1910.331 through 1910.335 applicable to this worker?
Answer: Yes, because the provisions cover work performed by unqualified persons on, near, or with the listed installations. The rule states that the safety-related work practices apply to unqualified persons working on, near, or with the covered installations.
29 CFR § 1910.331(b): “The provisions of §§ 1910.331 through 1910.335 also cover: (1) Work performed by unqualified persons on, near, or with the installations listed in paragraphs (c)(1) through (4) of this section”
2. A worker is installing a system to support cables and raceways using a rigid structural system. According to the definition of a 'Cable tray system', which of the following is included as part of this system?
Answer: Associated fittings. The definition specifies that the system includes 'associated fittings' as part of the rigid structural system.
29 CFR § 1910.399: “A unit or assembly of units or sections and associated fittings forming a rigid structural system used to securely fasten or support cables and raceways.”
3. An industrial worker is installing a disconnecting switch for a feeder circuit. The switch is located in a crowded electrical room where its purpose is not immediately evident from its location or arrangement. What is required for this disconnecting means?
Answer: It must be legibly marked to indicate its purpose. Since the purpose is not evident from the arrangement, the regulation requires the disconnecting means to be legibly marked to identify what circuit it controls.
29 CFR § 1910.303(f): “Each service, feeder, and branch circuit, at its disconnecting means or overcurrent device, shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident.”
4. An industrial worker needs to change a lamp in a working space about electric equipment. How must the lighting outlets be arranged to ensure safety during this task?
Answer: They must be arranged so that persons changing lamps will not be endangered by live parts or other equipment. The rule requires the physical arrangement of outlets to prevent endangerment from live parts during lamp changes.
29 CFR § 1910.303(h): “The lighting outlets shall be arranged so that persons changing lamps or making repairs on the lighting system will not be endangered by live parts or other equipment.”
5. An electrician is installing temporary wiring for a remodeling project. They are using a 240-volt, three-phase receptacle that is not part of the permanent building wiring. GFCI protection is not available for this specific receptacle type. What must the employer establish and implement to allow employees to use this receptacle?
Answer: An assured equipment grounding conductor program covering cord sets, receptacles, and equipment connected by cord and plug. When GFCI protection is unavailable for non-standard temporary receptacles, the regulation mandates an assured equipment grounding conductor program.
29 CFR § 1910.304(b): “Where the ground-fault circuit-interrupter protection required by paragraph (b)(3)(ii)(B) of this section is not available for receptacles other than 125-volt, single-phase, 15-, 20-, and 30-ampere, the employer shall establish and implement an assured equipment grounding conductor program covering cord sets, receptacles that are not a part of the building or structure, and equipment connected by cord and plug that are available for use or used by employees on those receptacles.”
6. Which of the following statements correctly describes the requirement for metal raceways and enclosures in general use wiring?
Answer: They shall be metallically joined together into a continuous electric conductor. Metal raceways and enclosures must be metallically joined to provide effective electrical continuity, ensuring they act as a continuous conductor.
29 CFR § 1926.405(a): “Metal raceways, cable armor, and other metal enclosures for conductors shall be metallically joined together into a continuous electric conductor and shall be so connected to all boxes, fittings, and cabinets as to provide effective electrical continuity.”
7. An electrician is installing fused cutouts inside a transformer vault. What characteristic must these cutouts possess?
Answer: They must be of a type identified for the purpose and readily accessible for fuse replacement. The rule specifically requires fused cutouts in these locations to be identified for the purpose and readily accessible for fuse replacement, distinguishing them from the locking requirements for general energized part enclosures.
29 CFR § 1926.408(a): “Fused cutouts installed in buildings or transformer vaults shall be of a type identified for the purpose. They shall be readily accessible for fuse replacement.”
8. A vehicle near energized overhead lines is intentionally grounded. What precaution must ground workers take regarding the grounding location?
Answer: Ground workers may not stand at the grounding location whenever there is a possibility of overhead line contact. Workers must avoid standing at the grounding point if there is any risk of the vehicle contacting the overhead lines to prevent exposure to hazardous ground potentials.
29 CFR § 1910.333(c): “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.”
9. An electrician is installing communications wires and cables on a pole that also supports electric light and power conductors. To comply with OSHA requirements for in-span parallel runs, what is the required positioning of the communications wires relative to the power conductors?
Answer: Communications wires must be located below the electric light or power conductors where practicable. The regulation requires communications wires to be placed below power conductors on shared poles when it is practicable to do so.
29 CFR § 1910.308(e): “Where practicable, communication wires and cables on poles shall be located below the electric light or power conductors”
10. An electrician is installing a screw-shell lampholder in a wet location. Which of the following conditions must be met for this installation?
Answer: The lampholder shall be of the weatherproof type. The rule specifically requires lampholders in wet or damp locations to be weatherproof to prevent electrical hazards.
29 CFR § 1910.305(j): “Lampholders installed in wet or damp locations shall be of the weatherproof type.”
11. A worker is using a 120-volt, single-phase, 20-ampere receptacle outlet on a construction site that is not part of the permanent building wiring. What protection is required for personnel safety?
Answer: Approved ground-fault circuit interrupters. Temporary 120V, 15- or 20-amp receptacles on construction sites must be protected by approved GFCIs for personnel safety.
29 CFR § 1926.404(b): “All 120-volt, single-phase, 15- and 20-ampere receptacle outlets on construction sites, which are not a part of the permanent wiring of the building or structure and which are in use by employees, shall have approved ground-fault circuit interrupters for personnel protection.”
12. An electrician is inspecting a panel to determine if it is safe to work on without additional shielding. According to OSHA definitions, which condition describes a 'Dead front' configuration?
Answer: There are no live parts exposed to a person on the operating side of the equipment. A dead front specifically means that from the operator's perspective, no live parts are exposed, ensuring safety during operation.
29 CFR § 1910.399: “Dead front. Without live parts exposed to a person on the operating side of the equipment”
13. For a ride or concession at a fair, where must the fused disconnect switch or circuit breaker be located relative to the operator's station?
Answer: Within sight and within 6 feet of the operator's station. OSHA requires the disconnect to be both visible to the operator and physically close (within 6 feet) to allow for rapid emergency shutdown.
29 CFR § 1910.306(k): “Each ride and concession shall be provided with a fused disconnect switch or circuit breaker located within sight and within 1.83 m (6 ft) of the operator's station.”
14. Regarding the grounding path for circuits, equipment, and enclosures, what characteristic must the path to ground possess according to the standard?
Answer: Permanent and continuous. The rule mandates that the grounding path must be both permanent and continuous, ruling out temporary or intermittent paths.
29 CFR § 1926.404(f): “The path to ground from circuits, equipment, and enclosures shall be permanent and continuous.”
15. A worker is routing lead-in conductors from an outdoor radio transmitter near a building equipped with lightning protection conductors. What is the minimum required clearance between the lead-in conductors and the lightning protection conductors?
Answer: 6 feet (1.83 m). The rule mandates a minimum clearance of 6 feet to prevent accidental contact or interference.
29 CFR § 1926.408(c): “The clearance between lead-in conductors and any lightning protection conductors shall not be less than 6 feet (1.83 m).”
16. An industrial worker is evaluating a water feature constructed in the ground that is primarily for aesthetic value, cannot be readily disassembled for storage, and is not intended for swimming. How is this facility classified for electrical safety purposes?
Answer: Permanently installed decorative fountain. The rule defines permanently installed decorative fountains as units constructed in the ground, not readily disassembled, and primarily for aesthetic value rather than swimming.
29 CFR § 1910.399: “Permanently installed decorative fountains and reflection pools. Pools that are constructed in the ground, on the ground, or in a building in such a manner that the fountain or pool cannot be readily disassembled for storage, whether or not served by electrical circuits of any nature. These units are primarily constructed for their aesthetic value and are not intended for swimming or wading.”
17. An electrician is installing a single receptacle on an individual branch circuit. What is the minimum ampere rating required for this receptacle?
Answer: Not less than that of the branch circuit. The rule specifies that a single receptacle on an individual branch circuit must have an ampere rating equal to or greater than the branch circuit's rating.
29 CFR § 1926.404(b): “A single receptacle installed on an individual branch circuit shall have an ampere rating of not less than that of the branch circuit.”
18. Under an assured equipment grounding conductor program, how often must a cord set that is fixed and not exposed to damage be tested?
Answer: At intervals not exceeding 6 months. While most cord sets require testing every 3 months, those that are fixed and not exposed to damage have an extended testing interval of 6 months.
29 CFR § 1926.404(b): “At intervals not to exceed 3 months, except that cord sets and receptacles which are fixed and not exposed to damage shall be tested at intervals not exceeding 6 months.”
19. An unqualified worker is on the ground near energized overhead lines. What restriction applies to the worker regarding conductive objects?
Answer: The worker may not bring any conductive object closer to unguarded, energized overhead lines than the distances given in paragraph (c)(3)(i)(A). Unqualified persons on the ground are strictly prohibited from bringing conductive objects closer than the specified minimum approach distances.
29 CFR § 1910.333(c): “When an unqualified person is working on the ground in the vicinity of overhead lines, the person may not bring any conductive object closer to unguarded, energized overhead lines than the distances given in paragraph (c)(3)(i)(A) of this section.”
20. An electrician is inspecting a transformer vault to ensure it complies with OSHA construction standards regarding access and safety. Which condition must be met regarding the vault door locks and latches?
Answer: Locks and latches shall be so arranged that a vault door can be readily opened from the inside. The regulation requires that vault doors be operable from the inside to ensure workers can exit safely.
29 CFR § 1926.405(j): “Locks and latches shall be so arranged that a vault door can be readily opened from the inside.”
21. A worker is identifying the type of service-entrance cable used for an underground installation. According to the definition of 'Service-entrance cable,' what characterizes Type USE cable?
Answer: It is identified for underground use and has a moisture-resistant covering, but is not required to have a flame-retardant covering. The rule specifies that Type USE is for underground use with a moisture-resistant covering but does not require a flame-retardant covering, unlike Type SE.
29 CFR § 1910.399: “Type USE. Type USE, identified for underground use, having a moisture-resistant covering, but not required to have a flame-retardant covering.”
22. A technician is servicing a hoisting mechanism and needs to ensure the load block does not exceed its safe travel limit. What specific device is required to prevent the load block from passing the safe upper limit of travel?
Answer: A limit switch or other device. The rule mandates the installation of a limit switch or equivalent device to automatically stop the hoist before the load block exceeds its safe upper travel limit.
29 CFR § 1926.406(a): “A limit switch or other device shall be provided to prevent the load block from passing the safe upper limit of travel of any hoisting mechanism.”
23. A worker is inspecting a metal enclosure for an electrical panel. According to the definition of a 'Cabinet', which feature distinguishes it from a simple box or enclosure?
Answer: It is provided with a frame, mat, or trim in which a swinging door or doors are or can be hung. The definition requires the presence of a frame, mat, or trim specifically for hanging a swinging door, which differentiates a cabinet from other enclosures.
29 CFR § 1910.399: “Cabinet. An enclosure designed either for surface or flush mounting, and provided with a frame, mat, or trim in which a swinging door or doors are or can be hung.”
24. An industrial worker is installing new machinery after January 2, 1990. In addition to the requirements in §§ 1910.303 through 1910.308 regarding disconnecting means, which additional requirement applies to the energy isolating devices for this new equipment?
Answer: They must be capable of accepting a lockout device. The rule specifies that for new machines installed after January 2, 1990, energy isolating devices must be capable of accepting a lockout device, in addition to other disconnecting means requirements.
29 CFR § 1910.302(c): “The requirement in § 1910.147(c)(2)(iii) that energy isolating devices be capable of accepting a lockout device whenever replacement or major repair, renovation or modification of a machine or equipment is performed, and whenever new machines or equipment are installed after January 2, 1990, applies in addition to any requirements in §§ 1910.303 through 1910.308 that disconnecting means be capable of being locked in the open position under certain conditions.”
25. A worker is routing communication lead-in conductors on a utility pole where light and power conductors are also present. To comply with safety rules regarding pole placement, what is the required positioning of the communication conductors relative to the power conductors?
Answer: Communication conductors shall be located below the light or power conductors and not attached to a crossarm carrying them. The rule mandates that communication conductors be placed below power conductors and prohibits sharing a crossarm with them.
29 CFR § 1926.408(c): “Where practicable, communication conductors on poles shall be located below the light or power conductors. Communications conductors shall not be attached to a crossarm that carries light or power conductors.”