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Re: Odd Receptacle #152326 07/12/04 07:32 PM
Joined: May 2004
Posts: 33
DetroiterRob Offline

those tandem-paralell recepticles, do you know what they would have been used for, ive got one up here in my room/office below a window cut into the baseboard, and it reads 240v, i was thinking it was for an old window ac or somthing along those lines, but the only dp breakers in my panel is for the range and dryer, and neither of those are tapped off anywhere along their run, or in the panel


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Re: Odd Receptacle #152327 07/12/04 11:06 PM
Joined: May 2004
Posts: 22
MattE Offline
Randy, I also have many old NEMA 1-15 recepts with a 240V rating, and one of those really odd ones which function just like the T-slot type. Something interesting about all of these old recepts with a dual rating is that they are rated for only 10A at 240V. So if one of these were wired for 240V then wouldn't it need a 10 amp fuse or breaker? [Linked Image] Has anyone ever seen a 10 amp fuse in an old panel? (...most likely in a fuse block with 2 of these 10A fuses for the 240V.)

Re: Odd Receptacle #152328 07/12/04 11:13 PM
Joined: May 2004
Posts: 22
MattE Offline
Another thought...

Maybe an old version of the NEC would solve the mysteries surrounding these old recepts, blade configurations and ratings. I know someone must have an old version of the NEC of Canadian electric code book.

Re: Odd Receptacle #152329 07/13/04 08:38 PM
Joined: Jun 2001
Posts: 5
Kilokat7 Offline
Junior Member
Here’s a really strange old current tap. I found this in an antique mall last weekend here in Michigan and couldn’t resist it for $2.00! I collect pre-1900 light bulbs and other turn of the century electrical items and thought this would make a neat addition to the collection. If anyone could shed some light on the funky 4 prong pattern I would be interested in learning more about this thing. I thought it was the same pattern as the plugs shown elsewhere in this thread but I now see it’s a little different…

Tim Tromp

[Linked Image from]
[Linked Image from]

Tim Tromp
Re: Odd Receptacle #152330 07/13/04 09:15 PM
Joined: Apr 2002
Posts: 2,527
Bjarney Offline

30 seconds with an ohmmeter would answer a lot.

[Notice the tandem-blade pair is not aligned too well.]

Re: Odd Receptacle #152331 07/13/04 09:16 PM
Joined: Feb 2004
Posts: 1,432
Lostazhell Offline
Nice find there [Linked Image] I see what you're referring to as far as the slots not being aligned straight... but my guess would be it was intended to function at the outlets I posted earlier... As far as what that function would be, I'm guessing code wise, they weren't too particular about a 120V plug fitting a 240V outlet & vice versa.. & these outlets could be used for either! Is there any markings on this regarding manufacturer, ratings, etc?

Even though you don't have a 2 pole breaker for the outlet, doesn't mean someone didn't connect it to both phases via 2 - 120V circuits someplace.. I'd test it with a meter to see what voltage is present..
The left outlet in the pic I posted is labeled "Magnus" "10A 250V" on the face.. but it was connected to 120V (the original service that I changed out was 30A 120V in that house!) Under a window in the baseboard, I'd make a wild assumption that it was an original general use outlet, since the baseboard is where they seemed to put all the outlets back in these days.. As far as for an A/C unit... I'd bet the extinction of this outlet style was likely some time before A/C was around...

Matt E.
We quite frequently use Nema 5-15 outlets rated for 15A 120V on circuits using 20A breakers.. Code allows this as long as there are more than 1 outlet.. (A duplex satisfies this) If you're only installing one single outlet on a 20A 120V circuit.. It must be Nema 5-20 per NEC 210.21(B)(1)
I'd love to get my hands on a wiring guide or some type of electrical code book from back in the era this stuff came from.. To think the code book back then was probably no thicker than an average magazine!


Re: Odd Receptacle #152332 07/13/04 10:09 PM
Joined: Nov 2003
Posts: 127
Sir Arcsalot Offline

I'd love to get my hands on a wiring guide or some type of electrical code book from back in the era this stuff came from.

Me too! I bet the codes were extremely simple, e.g.:

"Wire, for circuit conductors, shall be used."

"Fuses, for circuit protection, shall be permitted." [Linked Image]

I could think of other ersatz codese but I'll spare the rest of the world.

No wire bias here- I'm standing on neutral ground.
Re: Odd Receptacle #152333 07/15/04 01:19 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline
There are some old configurations over this side of the Big Pond that might confuse current generations as well.

Here's an old adapter, or line-tap as you might call it:

[Linked Image]

Re: Odd Receptacle #152334 07/16/04 08:19 PM
Joined: Feb 2004
Posts: 1,432
Lostazhell Offline
How many different configurations are in that thing??? I'm guessing 3?


Re: Odd Receptacle #152335 07/17/04 03:42 AM
Joined: Jun 2004
Posts: 202
32VAC Offline
A lot of the 'T' plugs & sockets similar to the NEMA 2-20 pattern have found their way onto caravans & campervans for 12VDC power. The packet for the plugs rates them as "32V @ 15A". These plugs are also rated for 110VDC. The words 'extra low voltage' are marked on the plugs, matching extension cord sockets & surface sockets.
There are a couple of other plugs that are a mystery to me. In Australia, one manufacturer (Clipsal) offers a 2 pin parallel plug the same as a NEMA 1-15P configuration. It is rated at 250VAC @ 10A. I guess this was for electric clocks that were connected onto lighting circuits. This plug does fit into a NEMA 5-15R socket.
The second mystery plug/socket combination are the 3 pin plugs with two round pins (for active & neutral) & a flat earth pin. These are rated at 110V @ 10A. These are also an Australian made device. How much 110V gear made it into Australian homes to warrant manufacture this pattern of connector?. (I can get photos if people are curious on these connectors)
Finally, I have measured a three pin socket to see if the ones used in Australia, New Zealand, New Guinea & other South Pacific countries are the same dimensions as the NEMA 10-20R shown in this post. The one pictured is bigger that our sockets in distance between pins & pin size.

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