OSHA 1926 Extension Cords: Ratings, GFCI, and Penalties

OSHA extension cord requirements for construction sites live in 29 CFR Part 1926, Subpart K. In short: use a three-wire cord rated for hard or extra-hard service, use it only for temporary connections to portable equipment, keep it out of walls and off staples, back it up with either GFCIs or a written Assured Equipment Grounding Conductor Program, inspect it daily, and remove any cord that shows damage.

Cord Type, Gauge, and Markings

Every extension cord used with portable tools or appliances on a construction site must be a three-wire type designed for hard or extra-hard usage.¹ The third wire is the equipment grounding conductor. The hard-usage jacket is what lets the cord survive rough handling.

The type designation is printed on the cord itself. Hard service cords are marked S, ST, SO, or STO. Junior hard service cords are marked SJ, SJO, SJT, or SJTO. A cord cannot be used unless it is durably marked with the type designation, the conductor size, and the number of conductors.² If the marking is worn off, the cord is out.

Gauge matters too. A 16 AWG three-conductor cord handles up to about 10 amps, 14 AWG handles 15 amps, 12 AWG handles 20 amps, and 10 AWG handles 25 amps. Running a high-draw tool on an undersized cord builds heat, melts insulation, and starts fires. When in doubt, go heavier.

Where Cords Can and Can’t Be Used

Flexible cords are allowed for connecting portable lamps and appliances, wiring fixtures, connecting stationary equipment that gets moved frequently, and a handful of other specific purposes.³ Everything else is off limits.

The prohibited uses are where most sites get in trouble. Extension cords cannot:

Serve as a substitute for the fixed wiring of a structure
Run through holes in walls, ceilings, or floors
Run through doorways or windows, except as temporary wiring during construction under 1926.405(a)(2)(ii)(I), and even then the cord must be protected from damage at the opening
Be attached to building surfaces
Be concealed behind walls, ceilings, or floors

If the project needs power on the other side of a wall for more than a short window, the answer is a proper outlet, not a cord threaded through drywall.

Protecting Cords from Physical Damage

Walkways and work areas must be kept clear of cords to prevent trip hazards and to keep them from being stepped on or crushed.⁴ Where cords cross vehicle routes, use a cable ramp. A cord run over by a loader has damaged conductors even when the jacket looks intact.

How the cord is secured is also regulated. Extension cords cannot be fastened with staples, hung from nails, or suspended by wire.⁴ All three methods can crush or nick the internal conductors while leaving the outer jacket looking normal.

Cords must be connected to devices and fittings in a way that keeps tension off joints and terminal screws.⁵ A cord dangling from an overhead receptacle with its own weight pulling on the plug connection is a textbook violation. Use strain-relief connectors or cord grips at every connection.

Ground-Fault Protection: GFCI or AEGCP

Every employer on a construction site must provide ground-fault protection for employees using cord-and-plug-connected equipment. There are two paths: Ground-Fault Circuit Interrupters or an Assured Equipment Grounding Conductor Program.⁶ You can use one, the other, or both, but at least one must be in place.

GFCI Protection

All 120-volt, single-phase, 15- and 20-ampere receptacle outlets on a construction site that are not part of the building’s permanent wiring must be protected by approved GFCIs.⁶ A GFCI trips the circuit in milliseconds when it detects current leaking to ground. That speed is what prevents electrocution.

The broader ground-fault protection requirement in 1926.404(b)(1)(i) is not limited to 120-volt outlets. It applies at all voltages. The GFCI sub-rule singles out 120-volt, 15- and 20-amp outlets because that’s where listed GFCI devices are readily available. For 208-volt or 240-volt equipment, the AEGCP is usually the practical option.⁷

The Assured Equipment Grounding Conductor Program

The AEGCP is a testing-based alternative that verifies grounding integrity through regular inspection rather than relying on a device to trip. It takes more paperwork but covers cord-and-plug equipment at any voltage. The program must include:

A written description of the program and its procedures, kept at the jobsite and available to OSHA or any affected employee
A designated competent person capable of identifying electrical hazards and authorized to take corrective action⁸
Daily visual inspections of every cord set, plug, receptacle, and cord-connected piece of equipment before use, checking for deformed or missing grounding pins, insulation damage, and signs of possible internal damage⁶
Continuity and terminal connection tests on the schedule described below

The grounding path from equipment through the cord to the receptacle ground terminal must be permanent and continuous.⁹ Any break in that path means the equipment frame can become energized without tripping a breaker.

Wet and Damp Locations

Portable electric lighting used in wet or conductive locations like drums, tanks, and vessels must operate at 12 volts or less. If protected by a GFCI, 120-volt lighting is permitted.³ Receptacles installed in wet or damp locations must be designed for those conditions, and enclosures in wet locations must be weatherproof.² In practice this means watertight or sealable connectors wherever cords and their connections are exposed to moisture.

Daily Inspection and Removing Defective Cords

Under the AEGCP, every cord set, plug, receptacle, and piece of cord-connected equipment must be visually inspected before each day’s use, except equipment that stays fixed in place and is not exposed to damage.⁶ Even on sites relying solely on GFCIs, 1926.416 independently prohibits worn or frayed cords, so daily checks make sense either way.

During the inspection, look for:

Missing, bent, or loose grounding pins
Cuts, cracks, or abrasion in the outer jacket
Exposed conductors or bare copper
Pinched or crushed sections that suggest internal damage
Discoloration or melting near the plug or receptacle end
Loose or damaged strain-relief fittings

Worn or frayed cords cannot be used.⁴ Pull the cord immediately, and make sure no one plugs it back in. Cutting the plug off is the simplest way to accomplish that. Tagging works if the site culture backs it up, but a cord with no plug can’t hurt anyone.

AEGCP Testing Intervals and Records

The AEGCP requires two electrical tests on all cord sets, non-permanent receptacles, and cord-connected equipment that must be grounded. A continuity test confirms the grounding conductor is unbroken end to end. A terminal connection test confirms that grounding conductor is landed on the correct terminal at each plug and receptacle.

Both tests must be performed:¹⁰

Before first use on the site
Before returning to service after any repair
After any incident that could have caused damage
At least every three months for equipment in regular use
At least every six months for fixed cord sets and receptacles not exposed to damage⁶

The employer must keep written records identifying every piece of equipment that passed and the date of the most recent test, available on the jobsite for OSHA and any affected employee.¹⁰ Equipment that has not passed the required tests cannot be made available to employees. There is no grace period on the interval.⁶

Splices and Repairs

The default rule is that flexible cords must be used in continuous lengths without splice or tap.¹ No wire nuts in the middle of a cord, no taped-together cuts, no inline junction boxes.

One exception: hard-service cords of 12 AWG or larger may be repaired, but only if the splice retains the original insulation, outer sheath, and usage properties of the cord.¹ That means a vulcanized or molded splice done properly, not a field repair with tape and shrink tubing. Portable cables rated above 600 volts require permanent molded, vulcanized, or equivalent splices. After any repair, the cord must pass the AEGCP electrical tests before going back into service.

Power Strips

Standard relocatable power taps, the power strips found in offices, are not intended for construction sites. Under OSHA’s interpretation of the listing and labeling requirements, UL-listed power strips carry manufacturer instructions specifying they are not designed for construction environments.¹¹ Power strips also cannot be daisy-chained or plugged into extension cords. Using listed equipment contrary to its listing violates Subpart K.² When multiple outlets are needed, use a temporary power distribution box rated for the environment.

Penalties for Noncompliance

Electrical citations under Subpart K carry the same penalty structure as any other OSHA violation. As of the adjustment effective January 2025, the maximum penalties are:

Serious or other-than-serious violation: up to $16,550 per violation
Willful or repeated violation: up to $165,514 per violation
Failure to abate: up to $16,550 per day beyond the abatement deadline¹²

These amounts adjust annually for inflation. A single cord with a missing ground pin can draw a serious citation. A site with a pattern of ungrounded cords, no AEGCP documentation, and no GFCIs can face multiple willful citations that stack quickly into six figures.

1
eCFR. 29 CFR 1926.405 – Wiring Methods, Components, and Equipment for General Use
2
eCFR. 29 CFR Part 1926 Subpart K – Electrical
3
Occupational Safety and Health Administration. 1926.405 – Wiring Methods, Components, and Equipment for General Use
4
eCFR. 29 CFR 1926.416 – General Requirements
5
Occupational Safety and Health Administration. eTool – Construction – Electrical Incidents – Flexible Cords
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eCFR. 29 CFR 1926.404 – Wiring Design and Protection
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Occupational Safety and Health Administration. Letter of Interpretation – Requirements of 1926.404(b)(1) Application to 208-Volt Branch Circuits
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Occupational Safety and Health Administration. 1926.32 – Definitions
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Occupational Safety and Health Administration. 1926.404 – Wiring Design and Protection
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Occupational Safety and Health Administration. Electrical – Assured Equipment Grounding Conductor Program
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Occupational Safety and Health Administration. Compliance Requirements for Relocatable Power Taps or Power Strips
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Occupational Safety and Health Administration. OSHA Penalties