All mechanical equipment must be equipped with guards that prevent access to electrical connections or moving parts (such as the belts and pulleys of a vacuum pump). Inspect equipment before use to ensure that the guards are in place and functioning. Careful design of guards is vital. An ineffective guard can be worse than no guard at all, because it may give a false sense of security. Emergency shutoff devices might be necessary, in addition to electrical and mechanical guarding. Contact EHS if you have questions or concerns about guarding. Figure 3.4.