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OSHA Elec test topic: lockout/Tagout

19 test-style questions with the answer and the exact rule.

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1. A worker needs to isolate equipment for inspection, but the isolating means is not designed to interrupt the load current. What must be provided to ensure safety?A sign warning against opening them under load. If the isolator cannot interrupt load current, it must be interlocked or have a warning sign against opening it under load.
   29 CFR § 1926.408(a): “Isolating means which are not designed to interrupt the load current of the circuit shall be either interlocked with a circuit interrupter or provided with a sign warning against opening them under load.”
2. An electrician is preparing to remove a capacitor bank from service on a circuit operating at more than 600 volts. According to OSHA requirements, what specific feature must the isolating means provide to ensure safe isolation from all sources of voltage?A visible gap in the electric circuit adequate for the operating voltage. The regulation mandates that the isolating means must provide a visible gap in the circuit appropriate for the voltage level when removing capacitors from service.
   29 CFR § 1910.305(j): “A means shall be installed to isolate from all sources of voltage each capacitor, capacitor bank, or capacitor installation that will be removed from service as a unit. The isolating means shall provide a visible gap in the electric circuit adequate for the operating voltage;”
3. An electrician is installing a metal raceway that supplies an equipment enclosure where reduction of electrical noise is necessary. How may the enclosure be isolated from the raceway while maintaining a proper ground path?By using listed nonmetallic raceway fittings and supplementing with an internal insulated equipment grounding conductor. To reduce electrical noise, the enclosure can be isolated using nonmetallic fittings, provided an internal insulated equipment grounding conductor is added to ground the enclosure.
   29 CFR § 1910.305(a): “an equipment enclosure supplied by a branch circuit may be isolated from a raceway containing circuits supplying only that equipment by one or more listed nonmetallic raceway fittings located at the point of attachment of the raceway to the equipment enclosure. The metal raceway shall be supplemented by an internal insulated equipment grounding conductor installed to ground the equipment enclosure.”
4. An electrician is preparing to service a disconnecting means required by the subpart. What specific capability must this disconnecting means possess to ensure safe lockout procedures?It must be capable of being locked in the open position. The regulation requires that disconnecting means be lockable in the open position to facilitate safe isolation of the circuit.
   29 CFR § 1910.303(f): “Disconnecting means required by this subpart shall be capable of being locked in the open position.”
5. An electrician is installing a piece of equipment that produces arcs and sparks during ordinary operation. To prevent fire hazards, what must be done regarding the surrounding environment?The arcing parts must be enclosed or separated and isolated from all combustible material. The rule requires that sources of ignition like arcs and sparks be physically separated or enclosed to keep them away from any combustible materials.
   29 CFR § 1910.303(d): “Parts of electric equipment that in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from all combustible material.”
6. An electrician is wiring a resistance welder and its control equipment to the supply circuit. What type of device must be provided to allow the welder and its control equipment to be isolated from the supply circuit?A switch or circuit breaker. The regulation specifies that a switch or circuit breaker is the required device for isolating resistance welders and their control equipment from the power supply.
   29 CFR § 1926.406(c): “A switch or circuit breaker shall be provided by which each resistance welder and its control equipment can be isolated from the supply circuit.”
7. 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?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.”
8. An electrician is evaluating the dedicated space for an indoor motor control center. The space extends from the floor to a height of 1.83 m (6.0 ft) above the equipment. Which foreign items are permitted in this specific lower dedicated space if not isolated by height or physical enclosures?None; piping, ducts, or equipment foreign to the electrical installation may not be located in this area. In the lower dedicated space (up to 1.83 m above equipment), foreign piping, ducts, or equipment are generally prohibited unless specific isolation measures are taken.
   29 CFR § 1910.303(g): “Unless isolated from equipment by height or physical enclosures or covers that will afford adequate mechanical protection from vehicular traffic or accidental contact by unauthorized personnel or that complies with paragraph (g)(1)(vii)(A)(2) of this section, piping, ducts, or equipment foreign to the electrical installation may not be located in this area;”
9. An electrician is working on a high-voltage installation where equipment is guarded by location and isolated from ground. Under what condition is this equipment exempt from grounding requirements?When the equipment is pole-mounted distribution apparatus at a height exceeding 2.44 m (8.0 ft) above ground or grade level. The rule states that pole-mounted distribution apparatus exceeding 8.0 feet in height does not need to be grounded, whereas the other options are not listed as exemptions in this context.
   29 CFR § 1910.304(g): “Additionally, pole-mounted distribution apparatus at a height exceeding 2.44 m (8.0 ft) above ground or grade level need not be grounded.”
10. An electrician is working on the back of an enclosed control assembly where rear access is required to work on de-energized parts. What is the minimum horizontal working space that must be provided?30 inches (762 mm). The regulation mandates a 30-inch horizontal clearance for rear access to de-energized parts on enclosed equipment.
    29 CFR § 1926.403(j): “Where rear access is required to work on de-energized parts on the back of enclosed equipment, a minimum working space of 30 inches (762 mm) horizontally shall be provided.”
11. A worker is maintaining a portable high-voltage system supplied by a neutral grounded through an impedance. What specific requirement must be met regarding the grounding electrode for this system?It must be isolated from and separated in the ground by at least 6.1 m (20.0 ft) from any other system or equipment grounding electrode. OSHA requires the grounding electrode for portable high-voltage systems to be physically separated by at least 20 feet from other grounding electrodes and prohibits direct connections like buried pipes or fences.
    29 CFR § 1910.304(g): “The grounding electrode to which the portable equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 6.1 m (20.0 ft) from any other system or equipment grounding electrode, and there shall be no direct connection between the grounding electrodes, such as buried pipe, fence, and so forth.”
12. A worker is accessing internal components of a cubicle containing circuit parts operating at over 1000 volts AC. Which safety measure is required to prevent access until circuit parts are deenergized?Mechanical lockouts with a disconnecting means. For voltages over 1000 volts, the rule requires mechanical lockouts with a disconnecting means (or interlocks plus locks) to ensure deenergization before access.
    29 CFR § 1910.306(g): “Where doors are used giving access to voltages of over 1000 volts ac or dc, either mechanical lockouts with a disconnecting means to prevent access until circuit parts within the cubicle are deenergized, or both door interlocking and mechanical door locks, shall be provided.”
13. An electrician is installing fixed equipment in a wet location that is not isolated. According to OSHA standards, under which condition must the exposed noncurrent-carrying metal parts of this equipment be grounded?If the equipment is located in a wet or damp location and not isolated. The regulation lists being in a wet or damp location and not isolated as a condition requiring grounding for exposed noncurrent-carrying metal parts of fixed equipment.
    29 CFR § 1910.304(g): “If located in a wet or damp location and not isolated;”
14. An industrial worker is evaluating whether a specific piece of equipment requires guarding because it is 'Exposed.' Which scenario fits the definition of exposed live parts?The parts are capable of being inadvertently touched or approached nearer than a safe distance by a person and are not suitably guarded, isolated, or insulated. Live parts are considered exposed if they are not guarded, isolated, or insulated, allowing a person to inadvertently touch them or get too close.
    29 CFR § 1910.399: “Exposed. (As applied to live parts.) Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts not suitably guarded, isolated, or insulated.”
15. An electrician is installing grounding for a portable high-voltage system on a construction site. To ensure safety, how must the grounding electrode for the system neutral impedance be positioned relative to other grounding electrodes?It must be isolated and separated in the ground by at least 20 feet from any other system or equipment grounding electrode. OSHA requires physical isolation and a minimum 20-foot separation for portable high-voltage system grounds to prevent interference and ensure independent grounding.
    29 CFR § 1926.404(f): “The grounding electrode to which the portable or mobile equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 20 feet (6.1 m) from any other system or equipment grounding electrode, and there shall be no direct connection between the grounding electrodes, such as buried pipe, fence or like objects.”
16. When installing resistance welders, what is the minimum ampere rating requirement for the switch or circuit breaker used to isolate the welder and its control equipment from the supply circuit?Not less than the supply conductor ampacity. The disconnecting means for resistance welders must be rated at least as high as the ampacity of the supply conductors feeding it.
    29 CFR § 1926.406(c): “The ampere rating of this disconnecting means shall not be less than the supply conductor ampacity.”
17. A technician is working on a system that uses an isolating transformer and a line isolation monitor with ungrounded circuit conductors. What is the specific term for this type of system?Isolated power system. The definition of 'Isolated power system' matches the components described: an isolating transformer, a line isolation monitor, and ungrounded circuit conductors.
    29 CFR § 1926.449: “Isolated power system. A system comprising an isolating transformer or its equivalent, a line isolation monitor, and its ungrounded circuit conductors.”
18. An electrician is installing a disconnecting means for a motor and its controller. To ensure the motor is safely isolated from the power source, what design feature must the disconnecting means have regarding its poles?It must disconnect the motor from all ungrounded supply conductors and prevent any pole from being operated independently. The regulation requires that all ungrounded conductors be disconnected and that the poles operate together to prevent partial energization.
    29 CFR § 1910.305(j): “The disconnecting means shall disconnect the motor and the controller from all ungrounded supply conductors and shall be so designed that no pole can be operated independently.”
19. Under which specific condition is an electrician permitted to place a lock on a disconnecting means without also attaching a tag?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.”

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