I advise using a fall harness in an aerial lift at all times. At least in the U.S., this is absolutely required. OSHA’s general requirement to provide fall protection kicks in at six feet for construction activity and four feet for general industry activity (some state OSHA plans go with four feet for all activities to simply things). However, a harness is required in aerial lifts at all times.
OSHA’s six and four foot treatment is a “general purpose” requirement that applies when there isn’t a more specific standard. For example, fall protection on scaffolds isn’t required until 10 feet from the ground. And, we can go even higher in some steel erection applications without fall protection being mandatory. But, fall protection should be used whenever possible. After all, we don’t work safely just to be in compliance with administrative laws, we work safely to reduce injuries and loss events.
Fortunately for our understanding of aerial lift fall protection, we don’t need to remember numbers; we provide fall protection at all times. Aerial lifts include any devices that employ extensible or articulating members. If there’s a telescoping boom, then it’s an aerial lift. A scissor lift is not considered an aerial lift, which is why so many models aren’t equipped with anchorage points on the deck to attach to.
I recommend that the personal fall arrest system (PFAS) be attached to an anchorage point on the deck if possible, and not the boom, railing, or anything else higher up. In the event of a fall from the plat
form, the total fall distance prior to the arrest will be minimized. OSHA allows up to a six foot drop in a PFAS, though this should always be minimized since an arrested fall can cause back or other injuries.
Let’s say the total length of our PFAS components will arrest a fall at six feet exactly. If we attach to the boom or the top of the platform or bucket, then the fall arrest distance will be approximately six feet. But, if the attachment is on the deck, then the fall arrest distance is reduced because the fall will be limited to the length of material that goes beyond the top of the platform, and not its total length.
Maybe we can even do better than that. If the deck anchorage point and our chosen PFAS components are such that we can’t physically go over the edge, then there is no fall arrest situation at all. In fact, in such situations OSHA even allows the use of body belts, and not a full body harness, since there is no fall potential. OSHA allows fall restraint (body belts) when no fall is possible, though this has mostly fallen out of popular use.
There is one scenario when not wearing a harness in an aerial lift is allowed and may well be advisable: when working over water and the drowning hazard trumps the fall hazard. If the lift platform is a few feet above water and a fall occurs in a harness, then there could be a considerable drowning hazard. When drowning is deemed the greater hazard, ensure that personnel are wearing an approved personal flotation device and that means are available to get them out of the water ASAP, such as a small boat.