Inspector Safety: Three-Point Control for Climbing Ladders
by Nick Gromicko, CMI® and Ben Gromicko
When it comes to ladder safety, there’s a difference between three-point control and the traditional three-point contact rule. Three-point control is a climbing method that involves always using three or four limbs distributed over three or four locations for reliable support. Three-point contact involves simply coming into contact with the ladder at three points without necessarily requiring a reliable hand grip for support. Three-point contact is sometimes referred to as the three-point stance, an American football term used to describe the stance of a lineman with two feet planted in and one hand in contact with the ground.
Critical to three-point control is grasping the ladder so that one hand can bear the full weight of the body, if needed, and distributing the climber’s weight among three or four rungs. The three-point control method distributes the climber’s weight among three or four rungs, which is safest. If one foot slips during a foot transition, two hands should be grasping the ladder rungs to support the body weight. If either foot slips during a hand transition, the climber’s weight can be supported with a hand and a foot. If both feet slip during a hand transition, the climber’s weight is transferred to one or both hands.
Demonstration
The images below show the safe climbing method: grasping the rungs, rather than the side rails; having only one limb on one rung at a time; and moving only one limb at a time. The image at the left shows the climber using both hands to grasp, with both feet in contact with the ladder rungs. The image in the center shows him using both hands to grasp and one foot to transition. The image on the right shows him making contact with one hand to transition while both feet are in contact with the ladder rungs.
Whenever there's a risk of a serious fall, three-point control should be used because it helps decrease the likelihood that a person will lose control when an unexpected slip or loss of balance occurs.
Traditional Method
The traditional method of climbing a ladder consists of:
- keeping the belly button between the two side rails;
- two hands holding a ladder rung or side rail; and
- one foot on a ladder rung.
The main problem with the traditional method for climbing a ladder is that the hand grip strength is inadequate to hold onto a side rail to support the entire body weight in order to prevent a fall (Young, Wooley, Armstrong, et al., 2009). It is safer for an inspector to grab a horizontal rung rather than a vertical side rail.
Horizontal Power Grip
Holding a ladder rung or horizontal bar is referred to as a horizontal power grip (Barnett & Poczynok, 2000). To help prevent an uncontrolled fall, one hand must grasp a horizontal support using a horizontal power grip at all times. Grip control in contrast with contact is critical. Side rails or vertical holds provide a contact hand grip based mostly on friction. The horizontal power grip has a 75% to 94% larger breakaway force than when gripping a vertical rail (Young, Wooley, Ashton-Miller, et al., 2012).
Vertical Side Rail
Based on a recent study at the University of Michigan funded by the Center for Construction Research and Training/NIOSH, neither men nor women can support their full body weight through the use of only one hand gripping a vertical side rail (Young, Wooley, Ashton-Miller, et al., 2012).
The hand that is gripping the ladder side rail will, in a fall, slide down and hit the next ladder rung 12 inches below in a quarter of a second. It takes about a third of a second for a human hand to respond and fully grasp an object. Therefore, the climber’s hand will hit and pass the ladder rung before the climber has the muscle response to fully grasp and attempt to stop the fall (Robinovitch, Normandin, Stotz, et al., 2005; Thelen, Schultz, Ashton-Miller, et al., 1996).
Conclusion
Three-point control is not three-point contact. Ladder users may increase their personal safety by using the three-point control method in addition to following the other accepted ladders safety standards.
Consider the following when climbing a ladder:
• Properly stage the ladder according to standards.
• Grasp the horizontal ladder rungs and not the vertical rails.
• Use the horizontal power hand grip.
• Grasp, rather than simply make contact.
• Distribute your weight among three or four locations.
Sources:
- Barnett, R.L. & Poczynok, P.J. (2000). Ladder rung vs. siderail hand grip strategies. Triodyne Safety Brief, 16(4), 1-15.
- Robinovitch, R.N., Normandin, S.C., Stotz, P., et al. (2005). Time requirement for young and elderly women to move into a position for breaking a fall with outstretched hands. Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 60(12), 1553-1557.
- Thelen, D.G., Schultz, A.B. & Ashton-Miller, J.A. (1996). Effects of age on rapid ankle torque development. Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 51(5), M226-M232.
- Young, J.G., Woolley, C.B. & Armstrong, T.J. (2010). Effect of handhold orientation, size and wearing gloves on the ability to hang on. Presentation at the International Conference on Fall Protection and Prevention, Morgantown, WV, USA.
- Young, J.G., Woolley, C., Armstrong, T.J., et al. (2009). Hand/handhold coupling: Effect of handle shape, orientation and friction on breakaway strength. Human Factors, 51(5), 705-717.
- Young, J.G., Wooley, C.B., Ashton-Miller, J.A., et al. (2012). The effect of handle orientation, size and wearing gloves on hand/handhold breakaway strength. Human Factors, 54(3), 316-333.
Read InterNACHI's article on Ladder Safety.
Read InterNACHI's article on Attic Pull-Down Ladders.
Read InterNACHI's article on Fall-Arrest Systems.
Take InterNACHI's free "Safe Practices for the Home Inspector" online course.
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