Electricity is an important part of building houses today, but it can also be a deadly part. Many workers believe a little "house power” won’t hurt anyone. The fact is that workers can be and have been electrocuted, burned, or shocked by simple house power. Add in any standing water or a concrete floor that is made up mostly of water and you have a conductor for electricity.
Extension and Flexible Cords
The normal wear and tear on extension and flexible cords at your site can loosen or expose wires, creating hazardous conditions. OSHA permits only 3-wire (so they may be grounded and to permit grounding of any tools or equipment connected to them) hard or junior hard service extension cords to be used on construction sites. These cords will be marked with the following letters: S, ST, SO, and STO for hard service, and SJ, SJO, SJT, and SJTO for junior hard service. Extension cords must be kept in good condition and protected when run through doors, windows and floor holes. Use GFCIs to protect extension cords and any other connectors, even if the cords are plugged into the permanent wiring of the house.
Ground-fault Circuit Interrupters, or GFCIs, are life-saving devices that protect people from electrocution. Under normal conditions, electrical current moving through a circuit flows at the same rate (amperage) all along the circuit; amperage flowing away from the electrical source should be the same amperage returning to the source. GFCIs sense imbalances or differences along the electrical circuit and shut it down when needed. All temporary 120-volt, single-phase, 15- and 20-ampere receptacle outlets (i.e., generators, extension cords, temporary power poles) must be protected with approved GFCIs.
Overhead Power Lines
It is critical to the safety and health of all workers that a safe distance be maintained between the scaffolds and materials on scaffolds, ladders, cranes, motorized equipment and vehicles and the overhead power lines. Unless power lines are de-energized or guarded in some manner (ask the power company for help), workers must maintain a 10-foot distance between scaffolds, any materials on the scaffolds, ladders, and all other equipment and the overhead power line. For cranes, the operator must maintain a minimum 20-foot distance between the crane, load or load line. Also, the minimum clearance distance requirements increase as the voltage increases. Other precautions may also be required, such as having an observer/spotter if there is a chance that the crane operator cannot accurately judge the distance between the crane/boom and the overhead power lines, and warnings/alarms that prevent encroachment.
Underground Power Lines and Other Utilities
Knowing where underground utility lines are buried before each digging project begins helps protect you from injury, expense and penalties. The depth of utility lines varies and there may be multiple utility lines in the same area. Even simple digging projects can damage utility lines and can disrupt vital services to an entire neighborhood, harm diggers and potentially result in expensive fines and repair costs. Marked lines show diggers the approximate location of underground lines and help prevent undesired consequences.
Calling 811 will help save lives and protect infrastructure. “Call Before You Dig”: One easy phone call to 811 quickly and easily begins the process of getting underground utility lines marked. Local One Call Center personnel will then notify affected utility companies, who will continue to mark underground lines for free.
Lockout/tagout refers to specific practices and procedures to safeguard employees from the unexpected energization or startup of machinery and equipment, or the release of hazardous energy during service or maintenance activities. A lockout/tagout system must be implemented to prevent electrocution. OSHA’s standard on the Control of Hazardous Energy (Lockout/Tagout) spells out the steps employers must take to prevent accidents associated with hazardous energy.
Download electrical safety resources:
- OSHA eTool: Electrical Safety
- OSHA Fact Sheet: Working Safely with Electricity (PDF)
- OSHA Fact Sheet: Using Portable Generators Safely (PDF)
- OSHA Quick Card: Portable Generator Safety (PDF)
- OSHA Ground-Fault Protection on Construction Sites (PDF)
- OSHA Fact Sheet: Lockout/Tagout (PDF)