Electricians face multiple overlapping hazards on every job. Understanding the mechanisms of electrical injury and OSHA's working clearance requirements helps you identify risk before it becomes an incident.

Types of Electrical Injuries

• Burns — most common electrical injury; includes contact burns at entry/exit points, arc burns from radiant heat, and thermal burns from ignited clothing
• Shock — current through the body. At 50–100 mA ventricular fibrillation is possible; at 100–200 mA it is likely and can be fatal. Actual current depends on body resistance and the contact path.
• Arc Flash — pressure wave, intense UV/IR radiation, molten metal splatter, sound blast (up to 165 dB), toxic copper vapor
• Falls — electric shock can cause a worker to fall from a ladder or elevated surface

Body Resistance & Current Path

• Dry skin resistance: 100,000–600,000 Ω. Wet or sweaty skin: as low as 1,000 Ω
• Hand-to-hand current path crosses the heart — most dangerous route
• Hand-to-foot also crosses the heart region and is equally dangerous
• Low resistance (wet conditions) dramatically increases current at the same voltage

GFCI Requirements (NEC 210.8)

• GFCI protection required at: bathrooms, kitchens (within 6 ft of sink), garages, outdoors, crawl spaces, unfinished basements, rooftops, and boat hoists
• OSHA 1926.404 requires GFCI or an Assured Equipment Grounding Conductor Program at all construction sites
• GFCIs trip at 4–6 mA — well below the ventricular fibrillation threshold

Working Clearance (NEC 110.26)

• Minimum 30-inch-wide, 36-inch-deep (Condition 1, up to 150V to ground) working space required in front of electrical equipment
• At 151–600V: 42 inches (Condition 2 — grounded surfaces opposite); 48 inches (Condition 3 — live parts on both sides)
• Nothing may be stored in the working space — not even temporarily
• Minimum 6.5-foot headroom above the working surface is required

De-energize First

• OSHA's preferred approach: always de-energize before working on or near electrical equipment
• Energized work requires written justification: de-energizing creates a greater hazard, or it is infeasible due to equipment design or operational continuity requirements
• Apply LOTO before servicing — see the Lockout/Tagout module

Key References

• OSHA 1910.303 — General electrical safety requirements
• OSHA 1910.333 — Selection and use of work practices
• NEC 110.26 — Spaces about electrical equipment
• NEC 210.8 — GFCI protection for personnel
• NFPA 70E — Electrical safety in the workplace