Plugs, receptacles, and wiring devices make and maintain connections to distribute power from electrical sources to equipment and devices. National Electrical Manufacturers Association (NEMA) is a standard rating that classifies electrical devices and enclosures based on their pin/socket configuration and ability to withstand environmental conditions. Straight-blade plugs and receptacles make quick connections with North American-style wiring devices. Locking-blade plugs and receptacles secure when twisted together to prevent unintentional disconnections. Pin and sleeve devices are sealed connectors that supply safe connections in outdoor and industrial applications. Mechanical interlocks are receptacles that restrict power from flowing until the device is fully engaged to prevent electrical shocks and arcing. High-current single-pole plugs and receptacles make temporary high-amperage connections.