A safety padlock is meant to provide a measure of safety beyond that offered by a tag alone. Used properly in conjunction with a well-planned lockout process, the safety padlock helps ensure that employees will not inadvertently energise a piece of equipment while someone else is working on it.
The first rule in choosing a padlock for lockout is to ensure the lock looks different than those used in the facility for locking toolboxes, gates, etc. This often is done by the use of bright colours. The most popular lockout padlocks have a "Danger" label incorporated on them, which includes employee name, photo or both.