What is a Safety Harness & How Does it Work?

A safety harness is an essential part of a fall protection system. It is a form of protective equipment designed to protect you from sustaining injuries during a fall.

The harness itself is an attachment between a stationary object, such as a building, and non-stationary object, such as you, the wearer. Most often harnesses are fabricated from rope, cable or webbing and locking hardware.

Most safety harnesses fit into one of the four safety equipment classes:

Class 1 – Body Belts  

Body belts are designed to be worn around your waist, like a belt. They are usually equipped with D-rings in the front or back that can be attached to a carabiner. They can also be attached to escape ropes, ladders, and other safety equipment. Although body belts are adjustable to accommodate different waist sizes, they still have their limitations. Body belts should be used for position or restraint only.

Class 2 – Seat Harnesses

A seat harness is designed to fit the body much like an actual seat would. Seat harnesses consist of a belt that goes around the waist and two smaller belts that loop around each thigh. These smaller leg belts are attached to the waist belt with straps, and each component is adjustable.

Seat harnesses keep your body in a slightly seated position, while allowing your legs to move vertically up or down a tree, pole, rock face, or other surface.

Class 3 – Full Body Harnesses

A full body harness looks much like a seat harnesses with suspenders. The harness wraps over your shoulders, around your waist, and also around your upper legs for full-body support. They are equipped with multiple D-rings, allowing them to be secured to a line at various angles. 

Full body harnesses are designed to arrest the most severe free falls. They are designed to provide the maximum amount fall protection because they offer full body support and have no risk of sliding out when being inverted.

Class 4 – Suspension Belts

Suspension belts are designed to be independent work supports, and are used to suspend a rescuer or worker. They may also be used for work seats or to raise or lower a harness.

Suspension belts are not designed to be used for fall arrest systems. They are only to be used to provide comfort and allow for long periods of suspension without the risk of cutting off circulation.

When comparing rescue and safety harnesses, make sure to get a size and weight limit that fits your body or the needs of your application. Also make sure that it fits you properly and comfortably.

How Does a Safety Harness Work?

OSHA requirements state that fall arrest systems must limit the maximum arresting force on the wearer to 1800 pounds when used with a body harness.

The harness then takes these forces and, through its system of straps and buckles, distributes them to the parts of your body best suited to absorb force and support your weight. This includes the large muscles of your upper thighs, chest and shoulders, as well as the bony mass of your pelvis. 

This also diverts the forces from the more vulnerable parts of your body like your groin, stomach and neck. 

However, the same technology used to distribute force throughout your body could cut off circulation, leading to suspension trauma.

Along with distributing force, the design of a full body harness helps to keep your body upright in a fall. The purpose of this feature is to keep your spine in a vertical position, which is the best position for it to absorb the compressive forces of a fall.  This is also the optimal position when it comes to rescuing or lowering someone to a safe location.