To avoid exceeding 1,800 pounds of impact force during a fall, which equipment must be used with a harness?

Using a deceleration unit with a harness is crucial for limiting the impact force during a fall to no more than 1,800 pounds. A deceleration unit, often in the form of a shock-absorbing lanyard or a self-retracting lifeline, is designed to gradually absorb the energy generated during a fall. This helps to slow the fall and reduce the forces that would otherwise be transmitted to the body upon stopping.

In contrast, while other options might play a role in overall safety, they do not directly address the need to control the impact force during a fall. A safety latch is important for ensuring secure attachment points but does not affect the fall dynamics. A fall restraint system is designed to keep workers from reaching a fall hazard, while a secondary lifeline provides backup protection but does not function to mitigate the forces experienced in a fall. Therefore, the deceleration unit is the key component specifically tasked with keeping the impact forces within safe limits during fall events.