An “enclosed space” is a phrase referencing a high-risk work environment associated with a corresponding set of safety regulations that the Occupational Safety & Health Administration (OSHA) has defined specifically for the electric power industry. But to work safely in or around any restricted space, workers must also understand OSHA’s stringent safety standards for “confined spaces,” and “permit-required confined spaces.”

First thing to understand is that every “enclosed” space is potentially a “confined” space, governed by tighter OSHA requirements. “Enclosed Space” is an OSHA standard for the electric-power industry. “Confined Space” is a broader OSHA category, with more stringent standards. “Permit-Required Confined Spaces” have even tighter safety rules.

Characteristics of an Enclosed Space

• Large enough to enter and work
• Restricted means of entry and exit
• Designed to allow routine work
• Governed by 29 CFR 1910.269 regulations
• Does not contain atmospheric or physical hazards
• Vented-vault exception

Characteristics of a Confined Space

• Large enough to enter and work
• Restricted means of entry and exit
• Not designed for continuous worker occupancy
• Governed by 29 CFR 1910.146 regulations
• Does not contain atmospheric or physical hazards under normal circumstances

Characteristics of a Permit-Required Confined Space

• Toxic or flammable gases
• Oxygen-deficient air
• Oxygen-enriched air
• Asphyxiation or poisoning
• Weakening or unconsciousness, leading to injury
• A shape that could trap a person
• Mechanical hazards, like rotating parts
• Extreme heat, cold, or noise
• Hazards introduced by working in the space
• Any other “recognized” serious safety or health hazard

Safety and Rescue Terms

• Manhole Access Cover: When closed, the manhole cover prevents anyone or anything from falling into the enclosed space. When it’s open, traffic cones and barriers help protect crew members and the public from the opening.
• Exhaust Ventilation Duct Through Manhole: Workers must eliminate or control any unsafe atmosphere (gas mix). This exhaust ventilation system purges hazardous gases and replaces them with clean air.
• Tripod Extraction Device: Employers must provide equipment for rescuing employees from the enclosed space quickly and safely. This means without injuring the rescuer and without further harming the fallen employee.
• Atmospheric Monitoring Instruments: Prior to entering, and while working in, an enclosed space, you must follow strict atmospheric testing and monitoring procedures.
• Copies of Emergency Action Plan and Pre-Entry Checklist: Employers must maintain an Emergency Action Plan that specifies rescue and escape procedures. Designated rescue personnel must be appropriately trained. Crews should complete a pre-entry checklist before entering the enclosed space.
• Rescue Items: While not required by OSHA’s Enclosed Spaces standard, self-contained breathing apparatuses (SCBAs) and similar respirators/cartridges are required by the Confined Spaces standard. Rescue supplies must be easily accessible to designated rescue personnel, or to other first responders.
• Attendant: An employee with first aid and CPR training must be immediately available, outside the enclosed space, to provide emergency assistance.
• Worker: To work in or around enclosed spaces, employees and attendants must be trained in the hazards for these spaces and in safe work procedures. Training records should indicate the employees’ authorization for entry, and their qualifications to perform rescue.

Safety and Rescue Requirements

• Before anyone enters an enclosed space, work teams must evaluate its hazard level and respond with appropriate precautions. Start with a job briefing. Review the crew’s pre-entry checklist, including emergency and rescue procedures.
• Before entering, inspect apparent conditions associated with the space. Check the cover to see if it is hot. If the cover is fastened in place, loosen it gradually to release any pressure. Test for air hazards—if possible, before opening the cover. Check for bad oxygen levels, or flammable, toxic, or corrosive gases. Workers may not enter any enclosed space while it contains a hazardous gas mix.
• Remove the cover only after teams have eliminated any other hazards that make removal unsafe. Evaluate traffic hazards, and install standard traffic and pedestrian controls. The safety pro must protect crew members, as well as the driving and walking public.
• Install a railing, temporary cover, or other barrier to prevent anyone from falling through the opening. These barriers will also prevent objects from falling onto employees working inside the space.