1.5.2 Factor of safety (FOS)

Good practice requires that any lifting equipment shall have an adequate factor of safety incorporated in its design. Where appropriate in each of the separate sections, a minimum factor of safety for the specific item is recommended and this should not be reduced.

The purposes of a factor of safety are numerous, including allowance for wear, impact, dynamic loading and accidental overloading. For example, chain slings are more robust and defects can be more apparent than textile slings and therefore tend to have a lower factor of safety. However, it cannot be too highly stressed that such allowances are a contingency only and must never be purposely eroded. Care should always be taken to avoid circumstances which can overload (e.g. impact, shock) and care should also be taken in circumstances where inadvertent overload can occur (e.g. multi point lifts. See section 1.9 SAFE USE OF LIFTING EQUIPMENT). In extreme cases, multiple adverse circumstances may cause failure even if the nominal load does not exceed the SWL. If such circumstances are likely to occur, reference should be made to a Competent Person who will advise whether it is necessary to use higher rated equipment to achieve a higher factor of safety.