I was watching an old movie ("The Five Pennies"), and at one point while on stage surrounded by audio gear Danny Kaye reaches down and takes a plug out of a receptacle on a box clearly labeled "110V AC" and plugs into into another labeled "220V DC," with the expected flash and bang.

Is this a case of Hollywood taking license for dramatic effect, or were the same recepts. used for 110 and 220 at one time? Just when did the various NEMA plug configuration in use today originate?

Paul;
I do remember watching Danny K, and i have never been told, or read of any other commonly accepted residential voltage than 120V nominal.
There is a historical section @ NEMA , however it seems to be looking back due to a 75th aniversary......

Paul says - "or were the same recepts. used for 110 and 220 at one time?" I have a photo of a Bryant 15A 125v/10A 250v recep just recently removed from a residence. Has the 125v blade configuration and can be wired 250v....so at one time there was at least this type of configuration...anyone could have plugged their 110 appliance into this 250v recep....I'd post the photo here 'cept I don't know how to post photos.

Thanks. That does seem to confirm that 120 and 240 did once share a configuration.

Steve,
I couldn't find anything on the NEMA site, but interesting nonetheless.

The part of the film where this happens is in a radio studio rather than a home, so I would guess the presence of 220V wouldn't be uncommon. Whether it would have been usual to have both AC and DC supplies at that time, I wouldn't know -- Maybe that part was Hollywood just emphasizing the difference.

The side-by-side "110-" and "220-volt" outlets were identical on construction sites in some places during the sixties/early seventies. They were both wired with a common 3-wire 125/250-volt Twist-Lock receptacle, so if you saw an extension cord to plug into with your trusty wye adapter, you had to ask someone or follow the cord(s) back to the temporary power pole. At least they were usually plainly marked back there. {One guy’s Skilsaw worked with phenomenal torque until it burst into flames.} The ensuing ‘cutover’ enforcement [change to unique cords and receptacles] kept state DIS {pre-OSHA} inspectors busy for about a year.


[This message has been edited by Bjarney (edited 05-11-2002).]

I've not looked into all the industrial Twist-Lock devices in much detail, but I see there are still one or two of these which appear to have multiple uses, e.g. Leviton #3764-C & 3765-C, 4-wire rated 250V DC, 600V AC.

Re the Skilsaw incident, you might be interested to know that although 240V is standard here we do use a 110V safety supply for portable tools on building sites as a requirement of the HSE (Health & Safety Executive). It's fed from a center-grounded 55-0-55V xfmr, or on large sites 3-ph 63/110V.