Electrical hazards pose serious risks like electric shock, electrocution, fires and explosions which can cause fatalities or injuries. Proper grounding, use of protective equipment like GFCIs, insulating tools and wires, and training can help protect workers. Subpart K of OSHA regulations addresses electrical safety through requirements for installation, work practices, maintenance, and special equipment to prevent exposures and ensure worker safety.

1. Subpart K Electrical
• Long recognized as a
serious hazard.
• Exposes workers to;
– electrical shock.
– electrocution.
– fires/explosions.
– fatalities and serious
injuries.
– NEC TO OSHA Standard.

2. OHM’S LAW
I= E/R
E= Voltage I= Current R= Resistance
(volts) (amperes) (OHMS)

3. Fatalities have occurred at 50
volts or less!
I= E/R .05 amps 50V
(50 mA) = 1,000 OHM
.11 amps 110V
(110 mA) = 1,000 OHM

4. Effects of Current
8-15 mA= Pain.
15-20 mA = Pain & muscle contraction.
30-100 mA= Severe pain and paralysis of
breathing muscles.
100-1,000 mA= Ventricular fibrillation.
(may cause death)
> 1,000 mA = Heart normally stops.

5. Human Resistance
Body Area Resistance (OHMS)
Dry Skin 100,000 to 600,000
Wet Skin 1,000
Internal Body 400-600
Ear to Ear 100

6. So How Do We Protect
Ourselves?
• Effective Grounding.
• Electrical Protective
Devices.
• Insulation and
Guarding of Live Parts.
• Inspection &
Maintenance.
• Training.

7. PROTECTIVE MEASURES
• Equipment Grounding.
• Fuses and Circuit Breakers.
• Ground Fault Circuit Interrupters (GFCI).
• Double Insulated Tools.
• Wire Insulation.

8. FLEXIBLE CORDS
“Extension Cords”
• A must on a construction site.
• Must be “industrial grade”.
• Must be grounded.
• Can have no breaks.
• Are for temporary use only.

9. Subpart K - Four Major Groups
• Installation Safety Requirements:
– Approval
– Examination, Installation & Use of Equipment
– Guarding
– Overcurrent Protection
– Grounding of Equipment Connected by Cord
and plug

10. Groups, continued
• Safety Related Work Practices:
– Protection of Employees
– Passageways and Open Spaces
– Lockout and Tagging of Circuits

11. Groups, continued
• Safety Related Maintenance and
Environmental Considerations:
– Maintenance of Equipment
– Environmental Deterioration of Equipment

12. Groups, continued
• Safety Requirements for Special
Equipment:
– Batteries
– Battery Charging

13. Other Considerations
• Temporary Lights-
– 405(a)(2)(ii)(E)
– 405(a)(2)(ii)(F)
– 405(a)(2)(ii)(G)
– 405(a)(2)(ii)(J)