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 electrician is working on a wheelchair lift and needs to ensure the disconnecting means is properly located relative to the motor controller. What is the required location?
Answer: Within sight of the motor controller. For wheelchair lifts and stairway chair lifts, the standard mandates that the disconnecting means be located within sight of the motor controller.
29 CFR § 1910.306(c): “On wheelchair lifts and stairway chair lifts, the disconnecting means shall be located within sight of the motor controller.”
2. An electrician is terminating open conductors smaller than No. 8 at a dead-end connection to a lampholder. What is the maximum distance allowed between the connection and the nearest support?
Answer: 305 mm (12 in.). For dead-end connections to lampholders or receptacles, the support must be within 12 inches of the connection.
29 CFR § 1910.305(a): “(B) Within 305 mm (12 in.) of a dead-end connection to a lampholder or receptacle;”
3. An electrician is working on a portable cable system over 600 volts and needs to make a splice. Under what condition is this splice permitted?
Answer: The splice is of the permanent molded, vulcanized, or other approved type. Splices in portable cables over 600 volts are only allowed if they are permanent molded, vulcanized, or otherwise approved types.
29 CFR § 1910.305(h): “Portable cables may not be operated with splices unless the splices are of the permanent molded, vulcanized, or other approved type.”
4. An electrician is installing service conductors as open conductors near a building. What is the minimum clearance required from windows that are designed to be opened?
Answer: 914 mm (3.0 ft). The regulation requires a minimum clearance of 3.0 feet from openable windows for service conductors installed as open conductors.
29 CFR § 1910.304(c): “Service conductors installed as open conductors or multiconductor cable without an overall outer jacket shall have a clearance of not less than 914 mm (3.0 ft) from windows that are designed to be opened, doors, porches, balconies, ladders, stairs, fire escapes, and similar locations.”
5. An electrician is installing cord-and-plug-connected lighting fixtures near a permanently installed pool. To comply with OSHA requirements, what is the maximum allowable length for the flexible cord?
Answer: 0.9 m (3 ft). The regulation limits the flexible cord length to 0.9 meters (3 feet) for this specific application.
29 CFR § 1910.306(j): “Flexible cords used with the following equipment may not exceed 0.9 m (3 ft) in length and shall have a copper equipment grounding conductor with a grounding-type attachment plug:”
6. An electrician is installing receptacles near a swimming pool. The receptacles are located 4.0 m (approx. 13 ft) from the inside walls of the pool. What protection is required for these receptacles?
Answer: Ground-fault circuit interrupter protection. Since 4.0 m is within the 4.57 m (15 ft) threshold specified for GFCI protection, the receptacles must be GFCI protected.
29 CFR § 1910.306(j): “Receptacles that are located within 4.57 m (15 ft), or 6.08 m (20 ft) if the installation was built after August 13, 2007, of the inside walls of the pool shall be protected by ground-fault circuit interrupters.”
7. An electrician is installing outdoor electrical equipment that will be accessible to unqualified employees. The bottom of the enclosure is located 2.0 meters (6.5 feet) above the grade level. According to OSHA rules for this specific situation, what is the required condition for the enclosure door or hinged cover?
Answer: It must be kept locked. Since the enclosure bottom is below the 8-foot threshold and accessible to the public, the regulation requires the door or cover to be kept locked.
29 CFR § 1910.303(h): “Where nonmetallic or metal-enclosed equipment is accessible to the general public and the bottom of the enclosure is less than 2.44 m (8.0 ft) above the floor or grade level, the enclosure door or hinged cover shall be kept locked;”
8. A worker is identifying a single panel containing buses and automatic overcurrent devices, designed to be placed in a cabinet against a wall and accessible only from the front. Based on the definitions, what is this equipment called?
Answer: Panelboard. The definition of Panelboard matches the description of a single panel with buses and overcurrent devices, placed in a cabinet against a wall and accessible only from the front.
29 CFR § 1910.399: “Panelboard. A single panel or group of panel units designed for assembly in the form of a single panel; including buses, automatic overcurrent devices, and with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front.”
9. An electrician is using circuit breakers as switches in 120-volt fluorescent lighting circuits. What specific marking must appear on the breakers?
Answer: SWD. Breakers used as switches in this specific application must be marked SWD.
29 CFR § 1926.404(e): “If used as switches in 120-volt, fluorescent lighting circuits, circuit breakers shall be marked “SWD.””
10. Regarding the scope of temporary wiring provisions, when must temporary wiring be removed?
Answer: Immediately upon completion of construction or the purpose for which the wiring was installed. The rule requires immediate removal of temporary wiring once the construction phase or specific purpose is complete.
29 CFR § 1926.405(a): “Temporary wiring shall be removed immediately upon completion of construction or the purpose for which the wiring was installed.”
11. An electrician is grounding a metal mast that supports an outdoor antenna. What is the specific requirement for the grounding conductor connection?
Answer: It must be permanently and effectively grounded without splice or connection in the grounding conductor. The rule requires a continuous, unspliced grounding conductor for antenna masts to ensure effective grounding.
29 CFR § 1926.408(c): “Masts and metal structures supporting antennas shall be permanently and effectively grounded without splice or connection in the grounding conductor.”
12. An electrician is installing a metal-sheathed aerial cable entering a building where it is exposed to contact with electric light and power conductors. What must be done to the metal sheath?
Answer: It shall be grounded or interrupted by an insulating joint. The regulation requires the metal sheath to be either grounded or interrupted by an insulating joint to prevent accidental contact hazards.
29 CFR § 1910.308(e): “If exposed to contact with electric light and power conductors, the metal sheath of aerial cables entering buildings shall be grounded or shall be interrupted close to the entrance to the building by an insulating joint or equivalent device.”
13. An electrician is installing open-wire service-entrance conductors for a service over 600 volts. Who must be the only ones able to access these conductors?
Answer: Qualified persons only. Open wires for services over 600 volts must be guarded to restrict access to qualified persons.
29 CFR § 1926.404(d): “Service-entrance conductors installed as open wires shall be guarded to make them accessible only to qualified persons.”
14. During the reenergizing procedure, who is primarily responsible for removing the lock and tag from the circuit?
Answer: The employee who applied it or under his or her direct supervision. The standard mandates that the lock and tag be removed by the specific employee who applied them, or under their direct supervision, unless specific absence conditions are met.
29 CFR § 1910.333(b): “Each lock and tag shall be removed by the employee who applied it or under his or her direct supervision.”
15. An electrician is placing nonpower-limited fire alarm (NPLFA) circuits and Class 1 circuits in the same enclosure. What is the primary requirement for the conductors in this shared space?
Answer: All conductors must be insulated for the maximum voltage of any conductor within the enclosure. NPLFA and Class 1 circuits may share an enclosure only if every conductor is insulated to withstand the highest voltage present in that enclosure.
29 CFR § 1910.308(d): “provided all conductors are insulated for maximum voltage of any conductor within the enclosure, cable, or raceway”
16. An electrician is installing fixed general-purpose equipment (other than lighting fixtures) in a Class I location that is acceptable for use in Class I, Division 2. According to the marking requirements, what is this equipment exempt from having marked on it?
Answer: The class, group, division, or operating temperature. The regulation states that this specific type of equipment does not require markings for class, group, division, or operating temperature.
29 CFR § 1926.407(b): “Fixed general-purpose equipment in Class I locations, other than lighting fixtures, which is acceptable for use in Class I, Division 2 locations need not be marked with the class, group, division, or operating temperature.”
17. A worker is resetting a circuit breaker located inside a locked metal cabinet. How must the operating means be arranged to allow this without opening the door?
Answer: The operating means must project through the metal cabinet or enclosure. To maintain safety and security, the operating mechanism must extend through the enclosure so authorized personnel can reset the breaker without exposing themselves to energized parts by opening the locked door.
29 CFR § 1926.408(a): “Circuit breakers and protective equipment shall have the operating means projecting through the metal cabinet or enclosure so these units can be reset without locked doors being opened.”
18. Under which specific condition is an electrician permitted to place a lock on a disconnecting means without also attaching a tag?
Answer: When only one circuit or piece of equipment is deenergized, the lockout period does not extend beyond the work shift, and employees are familiar with the procedure. A lock without a tag is allowed only when three specific conditions are met: single circuit/equipment, same-shift duration, and employee familiarity with the procedure.
29 CFR § 1910.333(b): “A lock may be placed without a tag only under the following conditions: (1) Only one circuit or piece of equipment is deenergized, and (2) The lockout period does not extend beyond the work shift, and (3) Employees exposed to the hazards associated with reenergizing the circuit or equipment are familiar with this procedure.”
19. An electrician is installing a surface-mounted enclosure where a nonmetallic sheath cable enters through a nonflexible raceway. To qualify for the exception that allows the cable not to be secured to the enclosure, what is the required length range for the raceway?
Answer: Not less than 457 mm (18 in.) or more than 3.05 m (10.0 ft). The exception for not securing the cable applies only if the raceway length is between 18 inches and 10 feet.
29 CFR § 1910.305(b): “However, where cable with an entirely nonmetallic sheath enters the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 457 mm (18 in.) or more than 3.05 m (10.0 ft) in length, the cable need not be secured to the cabinet, box, or enclosure provided all of the following conditions are met:”
20. An electrician is connecting a grounding electrode conductor in a grounded system. Where must both the equipment grounding conductor and the grounding electrode conductor be connected to the grounded circuit conductor?
Answer: On the supply side of the service disconnecting means. For a grounded system, the connection point for these conductors to the grounded circuit conductor must be on the supply side of the service disconnecting means.
29 CFR § 1926.404(f): “Both the equipment grounding conductor and the grounding electrode conductor shall be connected to the grounded circuit conductor on the supply side of the service disconnecting means, or on the supply side of the system disconnecting means or overcurrent devices if the system is separately derived.”
21. An electrician is installing a series combination system using circuit breakers applied in compliance with manufacturer ratings. What marking is required on the equipment enclosure in the field?
Answer: It shall state “Caution—Series Combination System Rated __ Amperes. Identified Replacement Component Required.”. Field-installed series combination systems require a specific cautionary label indicating the amperage rating and the need for identified replacement components.
29 CFR § 1910.303(f): “The marking required by paragraph (f)(5)(i) of this section shall be readily visible and shall state “Caution—Series Combination System Rated __ Amperes. Identified Replacement Component Required.””
22. An electrician is identifying a conductor that is encased within material of composition and thickness that is recognized as electrical insulation. How should this conductor be classified?
Answer: Insulated. The rule defines 'Insulated' as a conductor encased within material of composition and thickness that is recognized as electrical insulation.
29 CFR § 1926.449: “Insulated. A conductor encased within material of composition and thickness that is recognized as electrical insulation.”
23. An electrician is working on a panelboard in a location accessible only to qualified persons. Which configuration of the panelboard is permitted under these specific conditions?
Answer: A panelboard other than the dead front externally-operable type. While panelboards generally must be dead front, the rule permits non-dead front types if they are accessible only to qualified persons.
29 CFR § 1926.405(d): “However, panelboards other than the dead front externally-operable type are permitted where accessible only to qualified persons.”
24. An industrial worker is evaluating a piece of equipment to determine if it is 'bonded.' Which condition must be met for the metallic parts to be considered properly bonded?
Answer: The metallic parts must be permanently joined to form an electrically conductive path that assures electrical continuity. Bonding is defined as the permanent joining of metallic parts to create a conductive path ensuring electrical continuity.
29 CFR § 1926.449: “Bonding. The permanent joining of metallic parts to form an electrically conductive path which will assure electrical continuity and the capacity to conduct safely any current likely to be imposed.”
25. An electrician is installing motor controllers for an escalator and wishes to place them outside the standard required spaces. Under what condition is this permitted?
Answer: Provided they are in enclosures with doors or removable panels capable of being locked closed and the disconnecting means is adjacent or integral. Relocation of motor controllers is allowed only if they are in lockable enclosures and the disconnecting means is either adjacent to or part of the controller itself.
29 CFR § 1910.306(c): “Motor controllers may be located outside the spaces otherwise required by paragraph (c) of this section, provided they are in enclosures with doors or removable panels capable of being locked closed and the disconnecting means is located adjacent to or is an integral part of the motor controller.”