Credits from en.wikipedia.org:

I took this picture of an L21–30P that goes to our portable breaker panel for our brainwave controlled lighting.

I bought the plug at Paul Wolf Electric, for approximately $50 Canadian.

The plug is connected to a 10 gauge cord. It is resting on a cement block, which provides a nice neutral grey background against which both the white and the black portions of the plug stand out nicely. One can also read the letters on the plug that say "L2130P". The "P" stands for "plug", to designate that this is a male (plug) connector; conversely L2130R (officially L21–30R) denotes receptacle (female connector also known as a socket).

The middle prong is ground, and the prong closest to the L2130P text is neutral.

I license this picture for use in Wikipedia.

What are the dimensions of this plug? Chameleon 19:20, 19 Sep 2004 (UTC)

A NEMA connector type Twist-locking 4-Pole 5-Wire Plug. See NEMA_connector#NEMA_L21. To be used in 3-Phase mains electricity, thich is not typical in north american households. National Electrical Manufacturers Association (NEMA) --1-1111 (talk) 10:48, 20 November 2009 (UTC)