GFCI protection is required by OSHA any time you are plugging a power tool into an extension cord, whether in a construction or shop setting. The protection is also required in wet or damp locations, outside, on rooftops or within 6 feet of running water.
Protection can also be provided by GFCI receptacles, GFCI circuit breakers or portable GFCIs. GFCIs should be tested using manufacturer’s directions after installation and at least once per month. Any electrical installation must be cone by a qualified electrician.
A portable GFCI should be used out-of -doors with various electrical power tools (i.e., drills, mowers,
trimmers) and should be tested before each use. Never use a GFCI that has any obvious damage.