Getting in and out of maintenance holes is a daily task, especially for contractors who work in urban environments where a large percentage of electrical equipment is kept underground. Hazards include oxygen deficiency, electric contacts, arc flashes and falls. When developing a safety strategy, the primary objective is to eliminate as many hazards as possible and control those remaining.
Work Area Protection
Generally, maintenance holes sit in the middle of the street or sidewalk and require additional protective measures. Depending on the jurisdiction, this could involve signs and cones, lane closures or blocking the street completely. Contractors should assess the risks their workers face and develop traffic control plans. Consider how the work area will be affected by traffic flow. Build in a margin for error: increase buffers and tapers, use parked vehicles as barricades and additional lighting or signage. Engage traffic control professionals when necessary.
Fires and Explosions
In some areas, multiple entities share the maintenance hole, which may contain a mix of electrical, natural gas, steam and communication equipment. These installations pose little risk to the public and the electrical worker under normal circumstances. But what happens when there’s a problem? An electrical fire could occur, with the resulting potential for burns, inhalation hazards or an explosion. This is especially true if combustible gas is present, such as in a natural gas leak. Natural gas can migrate through duct banks when a leak occurs, making it difficult to find the source. When combined with an electrical fire, the results can be devastating. Such explosions have resulted in property damage, injury and death. Reports of covers traveling hundreds of feet away from their original location are not uncommon.
Workers should determine whether it is safe before removing a maintenance hole cover. Conducting a good visual inspection, checking to see if the cover is hot and testing for combustible gas can go a long way in preventing an incident.
Strains and Sprains
Even before entering the maintenance hole, a worker can be injured by removing the cover. A cover is typically made of thick cast iron and can weigh up to 250 pounds, or more if covered with concrete or asphalt. The heavy design prevents it from becoming dislodged inadvertently. A study by one electrical contractor found the force required to remove a cover can be as high as 340 pounds.
Selecting the right tool and using the proper techniques will go a long way in preventing strains and sprains when moving a maintenance hole cover. A wide variety of tools and equipment is available for this task, ranging from simple steel bars and hooks to complex magnetic systems that attach to a truck. There is no one-size-fits-all solution, but contractors should select a tool that minimizes the amount of force required to remove the cover, allows for good ergonomic techniques and keeps the worker out of the line of fire. If this is a tool that you haven’t paid much attention to, take another look.
