Personal fall arrest systems: anchorage, body support and connectors

A personal fall arrest system lets a worker fall but stops them before they hit the level below, and does so with forces the body can survive. It is the most widely used form of personal fall protection and also the most demanding: every part must be right, and the parts must work together. This lesson introduces the system as a whole using the familiar ABC of fall arrest, then looks in detail at harnesses and connectors. Lesson 7 covers lanyards and self-retracting devices, lesson 8 covers anchors and lesson 9 covers clearance and swing falls.

The ABCs of fall arrest

Trainers often describe a personal fall arrest system with three letters, sometimes extended to five or six:

• A for anchorage: a secure point of attachment, strong enough for the forces of a fall, in the right place;
• B for body support: a full body harness that distributes the arrest forces across the thighs, pelvis, chest and shoulders;
• C for connectors: the lanyard, self-retracting device, lifeline, snap hooks, carabiners and anchorage connectors that link the harness to the anchor and absorb energy;
• D for descent and rescue: a plan and equipment to bring a fallen worker down quickly;
• E for education: training in selection, inspection, use and rescue;
• F for fall clearance: enough space below the worker that they stop before hitting anything.

Every letter must be right. A perfect harness clipped to a weak anchor is no protection. A perfect anchor with too little clearance below is no protection. A system that catches the worker but leaves them hanging for an hour can still kill them.

Full body harnesses

A full body harness is the only body support permitted for fall arrest. It holds the worker by straps over the shoulders, around the thighs and under the buttocks, so that the arrest force is spread across the strongest parts of the body and the worker stays upright, or nearly so, after the fall. Body belts, which wrap only around the waist, were once common for fall arrest but concentrate force on the abdomen and spine and allow the worker to slip out or hang jackknifed. They are no longer permitted for fall arrest, although some rules allow them for positioning or restraint.

Key parts of a harness include:

• the dorsal D-ring between the shoulder blades, the main attachment point for fall arrest;
• shoulder straps and a chest strap that keep the shoulder straps in place;
• leg straps and a sub-pelvic strap that carry most of the load in a fall;
• buckles, which may be pass-through, tongue or quick-connect types;
• optional attachment points: a sternal or front D-ring for ladder climbing systems and some rescue applications, side D-rings for positioning, and shoulder D-rings for confined space retrieval;
• labels that show the standard, class, capacity, size, serial number, date of manufacture and inspection record.

CSA Z259.10 classifies harnesses by use with letters. Class A harnesses have a dorsal attachment for fall arrest and are the basic requirement. Additional classes add capabilities: D for suspension and controlled descent, E for limited access such as confined space retrieval, L for ladder climbing, and P for work positioning. A harness can carry several letters, for example Class AP or Class ADP.

Capacity

Harnesses and the rest of a fall arrest system are rated for a range of user weights, including clothing, tools and equipment. Older standards assumed a worker of about 100 kg (220 lb). Modern standards and products cover a wider range, commonly up to about 140 kg (310 lb), and some products are rated higher. A heavier worker in a system rated for less may experience higher forces, longer deceleration and less clearance than the system was designed for.

Fitting a harness

A harness that fits badly can injure the worker in a fall, let them slip out, or leave them hanging in a dangerous position. Fit it every time:

• hold the harness by the dorsal D-ring and shake it so the straps fall into place;
• put on the shoulder straps like a jacket, with the D-ring at the back;
• connect the leg straps and adjust them so that you can fit a flat hand, but not a fist, between the strap and the leg;
• connect the chest strap and position it in the middle of the chest, roughly at armpit level, not at the throat or the stomach;
• adjust the shoulder straps so the dorsal D-ring sits between the shoulder blades;
• tuck loose strap ends into keepers so they do not snag.

Leg straps that are too loose are the most common fit problem. In a fall, a loose strap can slide toward the groin and cause serious injury, and the worker may slip partly out. Harnesses come in sizes and in designs for different body shapes, including models designed for women. Shared, one-size harnesses that are rarely adjusted are a recurring factor in poor fit.

Inspecting a harness

Inspect your harness before each use and have it inspected formally by a competent person at regular intervals, usually at least once a year, or more often in harsh conditions as the manufacturer directs. Before each use, check:

• webbing for cuts, fraying, burns, melted fibres, chemical damage, mould, broken stitching and excessive wear;
• hardware for cracks, sharp edges, deformation, corrosion and buckles that do not close properly;
• labels, which must be present and readable, showing the standard and the inspection record;
• fall indicators, which are stitches or tags that tear or deploy when the harness has arrested a fall.

Remove a harness from service if it fails any check, if it has arrested a fall, or if the manufacturer's service life has been reached. Most regulations require equipment that has arrested a fall to be removed from service until it is inspected and recertified by the manufacturer or a competent person, and many manufacturers require harnesses to be destroyed after a fall. Store harnesses clean, dry, out of sunlight and away from chemicals and heat.

Connectors

Connectors join the harness to the lanyard or self-retracting device and the lanyard to the anchor. They include snap hooks, carabiners, D-rings, O-rings and anchorage connectors such as beam clamps, cross-arm straps and roof anchors. Modern snap hooks and carabiners must be self-closing and self-locking, so that the gate cannot open unless the user deliberately unlocks it. Older non-locking snap hooks are no longer permitted for fall protection.

Connectors can fail in surprising ways:

• rollout: a snap hook connected to a ring or bar that is too small can rotate so that the ring presses the gate open and slips out;
• gate loading: a carabiner loaded across its gate, rather than along its spine, is much weaker;
• incompatibility: a large rebar hook connected to a small D-ring, or two snap hooks connected to each other, can load in ways the manufacturer never tested;
• tie-back misuse: wrapping a lanyard around a beam and hooking it back onto itself is permitted only with lanyards specifically designed for tie-back use;
• side loading: hooks loaded sideways over an edge can bend or open.

Use only connectors that the manufacturer says are compatible, connect each hook to a suitable attachment point, never clip two hooks together unless the manufacturer allows it, and never connect more than one snap hook to a single D-ring unless both the hook and the ring are designed for it.

CSA Z259.12 sets the requirements for connecting components in Canada, including gate strength and locking requirements.

Putting the system together

A fall arrest system is only as good as its weakest link and its worst mismatch. Before work begins, the competent person planning the work should check that the harness, connectors, lanyard or self-retracting device and anchor are compatible, rated for the worker's total mass, suitable for the anchor position, and able to stop the worker within the available clearance. Lessons 7 to 9 explain those checks in detail.

Harnesses for special conditions

Standard polyester or nylon webbing can melt or burn, so workers doing hot work such as welding, cutting or grinding at height need harnesses with webbing designed for heat and sparks, such as aramid fibres, and lanyards with heat-resistant covers. Electrical workers exposed to arc flash need harnesses tested for arc flash, with dielectric or coated hardware where required. Workers in cold climates need harnesses that can be adjusted over bulky winter clothing and rechecked when layers are removed. High-visibility harnesses help in traffic and on construction sites. In each case, choose equipment certified for the condition and follow the manufacturer's limits.

Comfort and acceptance

Workers wear harnesses that are comfortable and take off harnesses that are not. Padded shoulder and leg straps, quick-connect buckles, lighter materials, sizes that fit and designs for different body shapes all increase the chance that workers will wear and adjust their harnesses properly for a whole shift. Issuing harnesses to individuals, rather than sharing them, also improves fit and care. The cost of a better harness is small compared with the cost of one fall.