Which rebar caps should I use?
In an effort to curb worksite injury, OSHA (the Occupational Safety and Health Administration) and Washington's own state-wide standards require all rebar be capped.
There are two types of standard rebar cap. Vaughn Pugh, President of Integrity Safety Services, explains: "One is a saddle cap. This cap has a metal plate inside of it...they're typically four inches long by four inches wide." A saddle cap is most often used with a row of vertical rebar. Once capped, workers can place a two-by-four plank atop the row to guard against impalement.
"The second is called a mushroom cap or bump cap. They're small and don't have any metal inside." Bump caps are best used on horizontal rebar to keep workers from accidentally brushing against the sharp, uncovered ends.
According to Pugh, any material similar to rebar should be capped. "As a rule of thumb, if a cap will fit on top of it, then you need to cap it."
Excerpt from Mushroom Style Plastic Rebar Covers Used For Impalement Protection - OSHA Standards Interpretation and Compliance Letter 05/29/1997
"Tests designed by California OSHA were conducted that entailed dropping sand-filled canvas bags onto rebar protected by standard mushroom caps. Weights of the bags ranged from 140 to 160 pounds, and the bags were dropped from three, five and seven feet. The mushroom caps provided absolutely NO protection."
"Manufacturers of the mushroom caps agree that those caps were designed to provide SCRATCH PROTECTION ONLY and were never intended to prevent impalement, even at grade."
"Considering the serious nature of the hazard, the standard mushroom-style plastic rebar caps should not be used for protection against impalement. Protective devices capable of withstanding at least 250 pounds dropped from a height of ten feet should be used. Although there are no 'approved' mushroom caps on the market, steel reinforced covers and wooden troughs are available, and have been approved by California OSHA and recognized by the California AGC to meet the design criteria."
Bear in mind that, where possible, fall protection is still the best solution. A fall from 6 (six) feet or more on to a wooden trough or steel reinforced cap, even if it doesn't result in impalement, is still likely to produce serious injury.
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