Overview
Extension cords are not restricted to temporary use, or multi-plug adapters are used as a substitute for permanent wiring or receptacles.
Temporary wiring, e.g., extension cord, is supposed to be just that – temporary. So, how is “temporary” defined? Usually that means that it is in position for less than 90 days. Why 90 days? Regulatory agencies recognize temporary power needs such as for holiday lights. But, even when used on a “temporary” basis, the set-up has to meet all other electrical safety conditions.
Exhibit A depicts use of a multi-plug adapter.
In Exhibit B, not only was the extension cord being used as permanent wiring from the wall outlet originally designed for a clothes dryer to a foreign-wired piece of lab equipment but it was incorrectly configured resulting in an overload to the electrical panel.
Multi-plug adapters should not be used. They do not provide any protection and present high risk of circuit overload, which could result in fire. Rather, more outlets should be installed to accommodate needs.