- Explain GFCI protection requirements and AEGCP programs for construction sites
- Describe lockout/tagout procedures including energy isolation and re-energizing steps
- Identify arc flash hazards and PPE requirements within the arc flash boundary
- State minimum approach distances for workers near overhead power lines
- Apply OSHA rules for temporary wiring, flexible cords, and double-insulated tools on construction sites
Lección 1
Construction Electrical Standards
Electrocution is one of OSHA's "Focus Four" hazards - the leading causes of death on construction sites. OSHA's electrical standards for construction are found in 29 CFR 1926 Subpart K, covering everything from temporary wiring and ground fault protection to safe work practices near overhead power lines. This lesson covers the specific electrical protection methods every worker on a construction site must understand.
GFCI Protection Requirements
A GFCI (Ground Fault Circuit Interrupter) is a fast-acting device designed to trip when it detects a ground fault current as low as 5 milliamps (+/- 1 mA). That 5 milliamp threshold is critical for the exam - not 1 milliamp, not 15 milliamps, not 30 milliamps. The GFCI continuously monitors the current flowing through the hot and neutral conductors. When it detects an imbalance (meaning current is leaking to ground through a person or faulty equipment), it trips the circuit in approximately 1/40th of a second.
GFCI protection on construction sites is required for all 120-volt, single-phase, 15- and 20-ampere receptacle outlets that are not a part of the permanent wiring of the building or structure. This is the key distinction - the requirement applies to temporary power, not to outlets installed in permanent structures. Outlets connected to generators rated at any capacity still require GFCI protection if they meet the voltage and amperage criteria. The rule is not limited to wet locations only - it covers all temporary receptacle outlets regardless of whether conditions are wet or dry.
Employers on construction sites have two options for protecting workers from ground faults: they can use GFCI devices on all temporary receptacles, or they can implement an Assured Equipment Grounding Conductor Program (AEGCP). Most contractors choose GFCIs because they are simpler to deploy, but an AEGCP is the recognized alternative.
The Assured Equipment Grounding Conductor Program (AEGCP)
An Assured Equipment Grounding Conductor Program - abbreviated AEGCP - requires that all equipment grounding conductors be tested at a specific minimum frequency. The program requires that equipment grounding conductors be tested before first use, after any repair, and at least every 3 months. Not daily, not weekly, not monthly - the standard specifies before first use, after repair, and at least every 3 months as the minimum testing frequency.
The AEGCP must be in writing, must cover all cord sets, receptacles (not part of the permanent wiring of the building or structure), and equipment connected by cord and plug. Each piece of equipment that passes the test must be identified with a color-coded marker or other system indicating it has been tested. The program must designate a competent person to implement it.
Temporary Wiring Rules
Temporary wiring on construction sites is governed by 29 CFR 1926.405. The critical rule is that temporary wiring must be removed immediately upon completion of the construction or the purpose for which it was installed. It does not get 30 days, it does not get 6 months, and it does not remain until the building passes final inspection. The standard is clear: once the construction activity or specific purpose is complete, the temporary wiring must come down immediately.
Temporary wiring is permitted during construction, remodeling, maintenance, repair, or demolition activities. It must originate from an approved power source such as an approved temporary power panel. All connections must be made with approved devices - no bare wire splices or taped connections.
Double-Insulated Tools
Double-insulated tools provide an extra layer of protection against electrical shock. These tools are identified by a symbol of a square within a square on the nameplate - this is the international marking for double insulation. They are not identified by a green ground wire visible at the plug (that indicates a grounded tool), not by a red warning label, and not by a three-prong plug. In fact, double-insulated tools typically have a two-prong plug because they do not require a grounding conductor - the double insulation itself provides the protection.
Flexible Cords
Flexible cords on construction sites must not be run through doorways or windows where they can be pinched - damage to the cord's insulation creates a shock and fire hazard. Flexible cords may absolutely be used with GFCI protection, may be used to power portable tools, and may be connected to approved receptacles. The prohibition is specifically about routing cords through openings where they will be crushed, pinched, or damaged.
Additional rules for flexible cords on construction sites include:
- Cords must be rated for hard or extra-hard usage
- Damaged cords must be removed from service immediately
- Cords must not be fastened with staples, hung from nails, or suspended by wire
- Spliced cords are not permitted unless the splice retains the original insulation, outer sheath, and usage characteristics
Permitted Uses - Flexible Cords
Used with GFCI protection
Used to power portable tools
Connected to approved receptacles
Rated for hard or extra-hard usage
Prohibited Uses - Flexible Cords
Run through doorways or windows where they can be pinched
Used as a substitute for fixed wiring
Fastened with staples or hung from nails
Spliced unless retaining full insulation
Overhead Power Line Safety
One of the most dangerous electrical hazards on construction sites is working near overhead power lines. OSHA establishes strict minimum approach distance requirements. For unqualified workers working near overhead power lines rated up to 50 kV, the minimum approach distance is 10 feet. Not 3 feet, not 5 feet, not 20 feet - the answer is 10 feet for lines rated up to 50 kV.
For power lines rated above 50 kV, the minimum approach distance increases by 4 inches for every 10 kV above 50 kV. Qualified electrical workers have different (closer) approach distances, but those apply only after specific training and safety procedures are followed.
Any equipment, materials, or personnel must maintain this clearance. Cranes, scaffolds, ladders, and material hoists are common sources of power line contact on construction sites.
Overhead Power Line Clearances
The minimum approach distance for unqualified workers near overhead power lines rated up to 50 kV is 10 feet. This applies to workers, equipment, and materials. For lines rated above 50 kV, add 4 inches per 10 kV over 50 kV.
GFCI protection is required for all 120-volt, single-phase, 15- and 20-ampere receptacle outlets on construction sites that are not a part of the permanent wiring. A GFCI is designed to trip at 5 milliamps. The alternative - an AEGCP - requires testing before first use, after repair, and at least every 3 months. Double-insulated tools are identified by the square-within-a-square symbol on the nameplate, and the minimum approach distance for unqualified workers near overhead power lines up to 50 kV is 10 feet.