Electrical receptacles come in which two basic varieties?

Electrical receptacles indeed come in two basic varieties: straight blade and locking. Straight blade receptacles are the most common type found in residential and commercial settings. They accept straight-blade plugs and are defined by their configuration that allows easy connection and disconnection without extra effort. These receptacles come in various designs, voltages, and currents to accommodate different electrical needs.

Locking receptacles, in contrast, are designed to prevent accidental disconnection from the power source by incorporating a locking mechanism. This is especially important in environments where a secure connection is critical, like in industrial settings or outdoor applications. The locking feature involves a twist mechanism that keeps the plug secured in the outlet, ensuring safe and reliable electrical service.

The other options don't accurately describe the fundamental types of electrical receptacles. Standard and heavy-duty refer more to the capacity or usage level of receptacles rather than their basic design types. Plug and socket describe the components of electrical systems but do not represent the categories of receptacles. Portable and fixed relate to placement or mobility rather than to the design of the receptacles themselves. Thus, the categorization of electrical receptacles into straight blade and locking captures the primary distinctions that influence their application and safety considerations.