Which of the following is NOT a common type of receptacle?

A programmable receptacle is not a common type of receptacle typically found in household and commercial electrical installations. Standard duplex receptacles, isolated ground types, and GFCI receptacles are all widely recognized types of receptacles that serve specific purposes.

Standard duplex receptacles are the most basic and common type used in homes, allowing for two devices to be plugged in simultaneously. Isolated ground receptacles are designed to reduce electrical noise and provide a better ground path for sensitive equipment, often used in commercial settings. GFCI (Ground Fault Circuit Interrupter) receptacles are essential for safety in damp locations, as they protect against electrical shock by quickly cutting off power if a ground fault is detected.

In contrast, a programmable receptacle, which typically allows users to control the power supplied to connected devices through scheduling or remote access, is less common and often more specialized. These are more likely to be found in smart home technology or energy management systems but do not fit the traditional categories of electrical receptacles commonly encountered. This distinction makes "programmable receptacle" the correct choice for the item that is not a typical type of receptacle.