Electrical Safety Basics

Electrocution is one of the Focus Four causes of construction deaths. You don’t have to be an electrician to be killed by electricity. Many victims are laborers, painters, roofers and equipment operators.

• Construction
• General Industry

How electricity hurts you

• Shock and electrocution: current passes through your body. A very small current, far less than what trips a standard 15-amp breaker, can stop your heart.
• Burns: deep internal burns along the current path, and burns from arcs.
• Arc flash and arc blast: explosive release of heat, light, pressure and molten metal. See Arc Flash.
• Falls: a shock can make you fall from a ladder or lift.

Most common causes of electrical deaths

1. Contact with overhead power lines (ladders, booms, scaffolds, long tools)
2. Contact with energized parts during work that should have been locked out
3. Damaged cords and tools without ground or GFCI protection
4. Improper or makeshift wiring

Rules for everyone

• Treat every wire and part as energized until it has been tested and locked out by a qualified person.
• Use GFCI protection for all cords and tools on construction sites. See GFCI Protection.
• Inspect cords and tools before each use. Remove damaged ones from service.
• Look up and live: check for overhead lines before moving ladders, scaffolds and equipment.
• Keep panel covers closed and the space in front of panels clear. See Panel Clearance.
• Use fiberglass ladders near electrical work.

• Don’t work on electrical equipment unless you are trained and qualified.
• Don’t remove the ground pin from a plug, or use adapters that defeat grounding.
• Don’t touch someone who is being shocked. Shut off the power first, or use a dry non-conductive object to separate them, then call 911.

How much current is dangerous?

A typical 15-amp breaker trips at 15,000 mA, which is far above the level that kills. Breakers protect wiring and equipment, not people. That’s why GFCIs matter. Wet skin, wet ground and metal ladders all make a shock worse. See Wet Locations.

Qualified vs. unqualified workers

OSHA separates workers into two groups:

• Qualified persons are trained to recognize and avoid electrical hazards on specific equipment. They know how to tell live parts from dead ones, how to find voltages, and the safe approach distances. They are the only people who may work on or near exposed energized parts.
• Unqualified persons (most workers) must be trained in safe practices: staying away from exposed live parts, not opening panels, recognizing damaged equipment, and keeping clear of overhead lines.

See Qualified vs. Unqualified and Test Meters.

Overhead lines: keep your distance

For lines up to 50 kV, keep equipment and materials at least 10 feet away, and farther for higher voltages. Under the crane standard, for example, lines over 50 kV need 20 feet or more, depending on voltage. Assume every overhead line is energized and uninsulated, including service drops to houses. Call the utility to have lines de-energized or covered before working close. See Overhead Power Lines and Downed Power Lines.

Temporary power on jobsites

• Use heavy-duty or extra-hard-usage cords rated for the load. See Extension Cords.
• Keep cords out of water and doorways, and protect them from vehicles and sharp edges.
• Ground portable generators according to the manufacturer’s instructions and use GFCI outlets.
• Keep temporary panels covered and locked, with circuits labeled. See Temporary Power.

Last updated: October 1, 2026