Testing and test facilities

This section applies only to testing that involves interim measurements using high voltage, high power, or combinations of high voltage and high power, not routine continuous measurements. For the rule text, see Application in 1926.963(a).

• Examples covered: short-duration, high-voltage/high-power test procedures performed in labs, shops, substations, or in the field.
• Examples excluded: routine metering, relaying, and normal line work that involve continuous measurements (these are considered routine line work).

Cited requirement: 1926.963(a).

The employer must establish work practices that, at minimum, cover test area safeguarding, grounding, safe use of measuring and control circuits, and periodic safety checks of field test areas. See Safe work practices in 1926.963(b)(1).

• Test area safeguarding: control access and prevent accidental contact with energized parts.
• Grounding: implement and maintain safe grounding practices (see more in 1926.963(d)).
• Measuring/control circuits: ensure safe wiring, isolation of instruments, and protective terminations.
• Periodic safety checks: routine verification of test area conditions before tests.

Cited requirement: 1926.963(b)(1).

Each employee must receive training in the safe work practices for the test area upon initial assignment, with retraining as required by [1926.950(b)]. See Training requirement in 1926.963(b)(2).

• Initial training: instruction on the employer's established test-area work practices (safeguarding, grounding, control circuits, safety checks).
• Retraining: follow the refresher/training requirements found in 1926.950(b).

Cited requirements: 1926.963(b)(2) and 1926.950(b).

Employers must provide safeguarding within test areas to control access to test equipment or apparatus that could become energized, preventing accidental employee contact with energized parts. See Safeguarding requirement in 1926.963(c)(1).

• Safeguarding methods may include barriers, enclosures, fences, guarded compartments, or other means that physically separate personnel from energized parts.
• Ensure safeguards account for both direct and inductive coupling that could energize parts.

Cited requirement: 1926.963(c)(1).

Permanent test areas must be guarded with walls, fences, or other barriers; temporary test areas must use colored safety tape with signs, an equivalent barrier, or test observers to control access. See Permanent test areas in 1926.963(c)(2) and Temporary test areas in 1926.963(c)(3).

• Permanent: solid physical barriers (walls, fences) designed to keep employees out.
• Temporary (field sites): one of the following must be used:
  • Distinctively colored waist-high safety tape with warning signs (1926.963(c)(3)(i)).
  • Equivalent physical/visual barrier (1926.963(c)(3)(ii)).
  • One or more test observers covering the entire area (1926.963(c)(3)(iii)).

Cited requirements: 1926.963(c)(2) and 1926.963(c)(3).

Safeguards required for temporary test areas must be removed when employees no longer need the protection they provide. See Removal rule in 1926.963(c)(4).

• The employer should verify test operations or site conditions have changed such that hazards are eliminated or no longer present before removing safeguards.

Cited requirement: 1926.963(c)(4).

Employers must establish and implement safe grounding practices and keep all conductive parts accessible to the test operator at ground potential while equipment operates at high voltage. See Grounding practices in 1926.963(d)(1).

• Treat any ungrounded terminals as energized until tests show they are deenergized (1926.963(d)(1)(ii)).
• Maintain visible, reliable grounds connected to the test equipment and apparatus under test.

Cited requirement: 1926.963(d)(1).

An isolated ground-return conductor is required for high-power testing to prevent current and voltage rise in the earth unless the employer demonstrates the conductor cannot be provided due to site distance and that employees are protected from hazardous step and touch potentials. See Isolated ground-return in 1926.963(d)(3).

• Required: provide isolated ground-return conductor system for high-power testing to avoid intentional current returning through the ground grid or earth.
• Exceptions (both must be true):
  • The distance from the electric energy source makes providing an isolated conductor infeasible (1926.963(d)(3)(i)).
  • The employer protects employees from hazardous step and touch potentials that may develop (1926.963(d)(3)(ii)).

Cited requirement: 1926.963(d)(3).

Before any employee enters a deenergized test area, a ground must be placed on the high-voltage terminal and any other exposed terminals, and high-capacitance equipment must first be discharged through a resistor rated for the available energy. See Grounding after tests in 1926.963(d)(5).

• Discharge stored energy through a suitable resistor before applying a direct ground (1926.963(d)(5)(i)).
• Apply a direct ground only after stored energy has dropped to a safe level (1926.963(d)(5)(ii)).

Cited requirement: 1926.963(d)(5).

The chassis of a test trailer or vehicle must be grounded, and the employer must protect employees from hazardous touch potentials on vehicle panels and other conductive parts using bonding, insulation, or isolation. See Grounding test vehicles in 1926.963(d)(6).

• Ground the chassis to prevent dangerous potential differences.
• Protect accessible conductive parts (instrument panels, chassis) with bonding, insulation, or isolation so employees are not exposed to hazardous touch potentials.

Cited requirement: 1926.963(d)(6).

Control wiring, meter connections, test leads, and cables may not be run from a test area unless they are contained in a grounded metallic sheath terminated in a grounded metallic enclosure or equivalent protective measures are used. Instruments with accessible terminals must be isolated from personnel, temporary wiring must be protected and routed to avoid damage, and a test observer must be present if anyone is in the test area. See Control and measuring circuits in 1926.963(e).

• Control wiring: use grounded metallic sheath or an equivalent safety demonstration (1926.963(e)(1)).
• Instruments: isolate instruments with accessible terminals, or locate them in metal compartments with interlocks (1926.963(e)(2)).
• Temporary wiring: protect against damage and separate signal, ground, and power cables to the maximum extent possible (1926.963(e)(3)).
• Test observer: required if any employee is present during testing and must be able to deenergize test circuits immediately (1926.963(e)(4)).

Cited requirement: 1926.963(e).

A test observer must be present when any employee is in the test area and must be capable of immediately deenergizing test circuits for safety. See Test observer in 1926.963(e)(4).

• The observer monitors the entire area and must know how to interrupt power or initiate an emergency shutdown without delay.
• Employers should ensure the observer is trained and familiar with test disconnects, signaling procedures, and emergency response actions.

Cited requirement: 1926.963(e)(4).

Before each series of tests, the test operator in charge must verify barriers and safeguards, system test status signals, clearly marked test-power disconnects, identifiable ground connections, required personal protective equipment, and proper separation of signal, ground, and power cables. See Safety check items in 1926.963(f)(2).

• Specific items to verify include:
  • Barriers and safeguards are in workable condition and properly placed (1926.963(f)(2)(i)).
  • System test status signals are operable (1926.963(f)(2)(ii)).
  • Test-power disconnects are clearly marked and readily available (1926.963(f)(2)(iii)).
  • Ground connections are clearly identifiable (1926.963(f)(2)(iv)).
  • PPE is provided and used as required by Subpart E and this subpart (1926.963(f)(2)(v)).
  • Proper separation of signal, ground, and power cables (1926.963(f)(2)(vi)).

Cited requirement: 1926.963(f)(2).

1926.963 requires that personal protective equipment be provided and used as required by Subpart E of Part 1926 and by the testing subpart itself, so employers should follow [1926 Subpart E] and 1926.963(f)(2)(v).

• Consult 1926 Subpart E for construction PPE rules (eye, face, head, body protection, insulating gloves, etc.).
• Ensure PPE selections come from a hazard assessment; see OSHA's PPE hazard assessment guidance in the Letter of Interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28 for requirements on assessing hazards and providing written certification when PPE is required.

Cited requirements: 1926.963(f)(2)(v) and 1926 Subpart E. Also see PPE hazard assessment guidance at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28.

Yes — an employer may use a ground clearly indicated in the test set-up instead of the equipment grounding conductor if they can demonstrate that this ground provides equivalent protection to the grounding conductor in the power supply cord. See Alternative grounding allowance in 1926.963(d)(5).

• The employer must be able to demonstrate equivalence in employee protection to the standard equipment grounding conductor.
• Document and verify that the alternate ground prevents hazardous potentials and maintains operator-accessible conductive parts at ground potential.

Cited requirement: 1926.963(d)(5).

If instruments are placed in metal compartments with viewing windows to isolate accessible terminals, the employer must provide interlocks that interrupt power when someone opens the compartment cover. See Instrument isolation in 1926.963(e)(2).

• The interlock must deenergize the instrument or test circuit upon opening to prevent worker contact with energized terminals.
• If interlocks are not used, equivalent isolation that prevents employee access to energized parts must be provided.

Cited requirement: 1926.963(e)(2).

If an isolated ground-return conductor cannot be provided, the employer must protect employees from hazardous step and touch potentials by measures such as bonding, insulation, or isolation and must demonstrate those protections are effective. See Exception and protection in 1926.963(d)(3)(ii).

• Practical measures include establishing equipotential bonding zones, insulating walkways or platforms, installing mats, or limiting access during tests.
• Employers can consult Appendix C to Subpart V for information on measures to protect against step and touch potentials.

Cited requirement: 1926.963(d)(3)(ii).

The test operator in charge must perform the routine safety checks before each series of tests and verify the listed safety conditions. See Responsible person in 1926.963(f)(1)–(2).

• The operator in charge should be knowledgeable about the test setup, disconnects, grounds, safeguards, and emergency procedures.
• The operator documents or otherwise confirms completion of the checks before starting a test series.

Cited requirement: 1926.963(f)(2).

Employers must protect temporary wiring and its connections from damage and accidental interruptions, and to the maximum extent possible keep signal, control, ground, and power cables separated. See Routing temporary wiring in 1926.963(e)(3).

• Use cable trays, conduits, elevated supports, or routed pathways to prevent physical damage.
• Mark and segregate different cable types to reduce interference and avoid inadvertent disconnection or grounding faults.

Cited requirement: 1926.963(e)(3).

No — routine inspection and maintenance measurements by qualified employees are considered routine line work and are not covered by 1926.963, provided the hazards require only the normal precautions specified elsewhere in the subpart. See Application note in 1926.963(a).

• If the measurement work involves intrinsic high-voltage or high-power sources but only needs the normal precautions used in routine line work, 1926.963 does not apply.
• Employers should still follow applicable Subpart V and Subpart E safety requirements for routine line work.

Cited requirement: 1926.963(a).

The employer must isolate meters and instruments with accessible terminals from test personnel, either by physical isolation or by locating them in metal compartments with viewing windows and interlocks that interrupt power when opened. See Instruments isolation in 1926.963(e)(2).

• If isolation by enclosure is used, interlocks must cut power when the enclosure is opened to prevent exposure to energized parts.
• Alternative isolation methods are acceptable if they provide equivalent protection.

Cited requirement: 1926.963(e)(2).

Broader PPE requirements for construction are contained in [1926 Subpart E], which employers must follow in conjunction with 1926.963's testing-specific PPE obligations. See 1926 Subpart E and 1926.963(f)(2)(v).

• Use Subpart E for selection, inspection, and use of protective equipment such as insulating gloves, arc-flash protection, face shields, and eye protection.
• Perform hazard assessments as required; OSHA's PPE hazard assessment interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28 explains employer duties for assessing hazards and documenting PPE needs.

Cited requirements: 1926 Subpart E and 1926.963(f)(2)(v).