Wiring an Ungrounded, Polarized Outlet This is an older version of the receptacle in the first diagram. The slots are different sizes to accept polarized plugs but it lacks a grounding slot. This outlet does not make use of a ground wire and there is no protection against electrocution as provide by the grounded receptacle above. When replacing an ungrounded, polarized receptacle use this type.. Clear, easy-to-read wiring diagrams and instructions to add a new wall outlet to an existing outlet or a light fixture and switch circuit.
The NEMA 6-20 Outlets and Receptacles A NEMA 6-20 receptacle is a 20A - 250V (often called 240V) outlet designed primarily for single-phase, 2-pole, 3-wire grounding circuits. It differs from a standard 120V outlet by having two hot slots for blades and one ground pin instead of one hot, one neutral, and one ground pin.. Outlet ground connection diagram is shown separately. Switched (Split) Outlet Wiring Diagram In this diagram, a 2-wire NM cable supplies a line from the electrical panel to the switch outlet box. The black wire (line) connects to a switch terminal and the black wire of a 3-wire NM cable that travels to the split outlet box.