Electrical Safety in Construction for Workers

Know where the power is before you start

You must not be put to work so close to any part of an electric power circuit that you could contact it, unless you are protected in one of two ways:

Before work begins

Your employer must find out, by asking, looking or using instruments, whether any energized circuit, exposed or concealed, is located where the work could bring a person, a tool or a machine into contact with it. Where such a circuit exists, your employer must post warning signs and tell you where the lines are, the hazards, and the protective measures to take.

Reference: 29 CFR 1926.416(a)(1) · 29 CFR 1926.416(a)(3) · 29 CFR 1926.416(a)(2)

Guarded areas are for qualified persons

Live parts of electric equipment operating at 50 volts or more must be guarded against accidental contact, for example by cabinets or other enclosures.

Entrances to rooms and other guarded locations with exposed live parts must be marked with warning signs forbidding unqualified persons to enter. A qualified person is one familiar with the construction and operation of the equipment and the hazards involved. If that is not you, stay out.

Open panels

When energized parts of electrical equipment are exposed, barriers or other guarding must keep the workspace in front of that equipment from being used as a passageway. Do not cut through it, and do not move the barrier to get by.

Reference: 29 CFR 1926.403(i)(2)(i) · 29 CFR 1926.403(i)(2)(iii) · 29 CFR 1926.449 "Qualified person" · 29 CFR 1926.416(b)(1)

GFCIs on temporary power

On a construction site your employer must protect you with one of two systems: ground-fault circuit interrupters (GFCIs) or an assured equipment grounding conductor program.

Where GFCIs are used

All 120-volt, single-phase, 15- and 20-ampere receptacle outlets on the site that are not part of the permanent wiring of the building or structure, and that workers are using, must have approved GFCIs for personnel protection. Think spider boxes, temporary power panels and similar setups.

Wet and conductive spaces

Portable lighting used in wet or conductive locations, such as drums, tanks and vessels, must run at 12 volts or less. 120-volt lights may be used there only if protected by a GFCI.

Reference: 29 CFR 1926.404(b)(1)(i) · 29 CFR 1926.404(b)(1)(ii) · 29 CFR 1926.405(a)(2)(ii)(G)

The assured grounding program: your daily look

If your site uses an assured equipment grounding conductor program instead of GFCIs, cords and cord-and-plug tools are covered by inspections and tests.

Before each day's use

Each cord set, plug, receptacle of a cord set, and cord-and-plug tool must be visually inspected before each day's use (except cord sets and receptacles that are fixed and not exposed to damage). Look for:

• Deformed or missing pins
• Insulation damage
• Signs of possible internal damage

Anything found damaged or defective must not be used until repaired.

Tests and records

Required tests are done before first use, before equipment goes back into service after repairs, before equipment is used after an incident that may have caused damage (for example, when a cord set is run over), and at intervals not to exceed 3 months (6 months for cord sets and receptacles that are fixed and not exposed to damage). Tests must be recorded, and the record must be kept by logs, color coding, or other effective means until it is replaced by a more current record. Your employer must not make available, or let you use, equipment that has not met the program's requirements. Learn how your site marks equipment that has passed.

Reference: 29 CFR 1926.404(b)(1)(iii)(C) · 29 CFR 1926.404(b)(1)(iii)(E)(1) · 29 CFR 1926.404(b)(1)(iii)(E)(2) · 29 CFR 1926.404(b)(1)(iii)(E)(3) · 29 CFR 1926.404(b)(1)(iii)(E)(4) · 29 CFR 1926.404(b)(1)(iii)(F) · 29 CFR 1926.404(b)(1)(iii)(G)

Pick the right cord and run it right

Choose

Extension cords used with portable electric tools must be three-wire type and designed for hard or extra-hard usage.

Check

• Worn or frayed cords must not be used.
• Cords are used only in continuous lengths without splice or tap. The only repair allowed: hard service cords No. 12 or larger, spliced so the splice keeps the insulation, outer sheath properties and usage characteristics of the cord.

Run

• Protect cords from damage and avoid sharp corners and projections. A cord may pass through a doorway or other pinch point only if protection is provided to avoid damage.
• Never fasten an extension cord with staples, hang it from nails, or suspend it by wire.
• Keep working spaces and walkways clear of cords so they do not create a hazard.
• Do not hang temporary lights by their cords unless the cords and lights are designed to be hung that way.

Reference: 29 CFR 1926.405(a)(2)(ii)(J) · 29 CFR 1926.416(e)(1) · 29 CFR 1926.405(g)(2)(iii) · 29 CFR 1926.405(a)(2)(ii)(I) · 29 CFR 1926.416(e)(2) · 29 CFR 1926.416(b)(2) · 29 CFR 1926.405(a)(2)(ii)(F)

Tools and the path to ground

The path to ground from circuits, equipment and enclosures must be permanent and continuous. On a cord-and-plug tool, the third (grounding) pin is part of that path.

Exposed metal parts of cord-and-plug equipment that may become energized must be grounded on hand-held motor-operated tools, among other types.

So if a hand-held power tool has a two-prong plug, check that it is marked as double insulated. If a three-prong tool or cord has had its ground pin cut off, its path to ground is no longer continuous. Do not use it; report it.

Reference: 29 CFR 1926.404(f)(6) · 29 CFR 1926.404(f)(7)(iv) · 29 CFR 1926.404(f)(7)(iv)(C)(1) · 29 CFR 1926.404(f)(7)(iv)(C)(6)

A tag means someone is working on it

When equipment or circuits are being worked on, the rules require tags:

• Controls that are deactivated during the work must be tagged.
• Equipment or circuits that are deenergized must be rendered inoperative and tagged at all points where they can be energized.
• Tags must be placed to identify plainly the equipment or circuits being worked on.

Reference: 29 CFR 1926.417(a) · 29 CFR 1926.417(b) · 29 CFR 1926.417(c)