I believe this receptacle was the forerunner to the T slot:

[Linked Image from pstr-g02.ygpweb.aol.com]

Notice how there are 4 sets of slots. Two of the slots could accomodate your typical 120 volt 15 amp plug. The other two slots look like they would accomodate a 15 amp 240 volt plug (like you would find on a window air conditioner) with the grounding prong removed of course.

These are very odd looking may I say the least.

I've seen alot of t-slot receptacles in older homes. My grandfather had a ranch house he bought in the late 50's/early 60's and it had them in it.

Thanks.


[This message has been edited by Dawg (edited 01-10-2005).]