Relocatable power taps, often called power strips, portable outlets or surge suppressors, are defined by UL as “relocatable multiple outlet extensions of a branch circuit to supply … outlet receptacles for computers, audio and video equipment and other equipment." The need for multiple outlets came about during the arrival of computers and their associated equipment; such as the monitor, printer, scanner, and so on. They were designed for a high concentration of low-powered loads. Underwriter’s Laboratories is one of many Nationally Recognized Testing Laboratories (the OSHA reference is NRTLs) that test and approve products.
OSHA's standard at 29 CFR 1910.303(b)(2), Installation and use, requires that "Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling." Manufacturers and NRTLs determine the proper uses for power strips. For example, the UL Directory contains instructions that require UL-listed RPTs to be directly connected to a permanently installed branch circuit receptacle; they are not to be series-connected to other RPTs or connected to extension cords. UL also specifies that RPTs are not intended for use at construction sites and similar locations.
Power loads are addressed by 29 CFR §1910.304(b)(2), Outlet devices: "Outlet devices shall have an ampere rating not less than the load to be served."
Be sure to read and follow the instructions included with the product and not just the package instructions as these are sometimes geared towards marketing and sales, not safe usage.
RPTs are not designed for high powered leads such as refrigerators, microwaves, coffee pots, portable heaters, hair dryers or other appliances that generate heat or to be used outdoors. Always directly connect the RPT to a permanently installed, grounded receptacle. Avoid physical damage, exposure to water or wet locations, and use low-powered loads only.