Extension cords that we use on the job have to be 3 wired cords with a ground plug, and a minimum of 12 gauge wire is required. Three wire cords are used for outdoor appliances & electrical tools. A construction site requires extension cords which are specified by the National Electric Code for hard usage will have the word OUTDOOR or the letters WA on the jacket.
-Portable Light Strings-
NEVER use an ordinary light string in an area that could contain flammable vapors. When used within an enclosed or confined space, the space must be certified as SAFE FOR HOT WORK if a conventional string is used. Keep in mind any time you place lighting in an area where flammable vapors are present you are introducing an ignition source.
Correct ground-fault protection requires the use of either GFCIs or an Assured Equipment Grounding Conductor Program. There are 2 types of tests required by OSHA to assure good grounding, one is a continuity test and the other is a test done on receptacles & plugs to ensure that the grounding terminal is connected properly.