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#152316 07/09/04 11:22 PM
Joined: Oct 2000
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Quote
Has anyone here ever seen a receptacle like this one? Its rated for 120V 15A just like regular NEMA 5-15 recepts but looks much different. It accepts NEMA 1-15 plugs and the top pin is the ground.

-MattE
[Linked Image]

#152317 07/10/04 03:27 AM
Joined: Feb 2004
Posts: 1,437
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I've never come across a combo unit like this one... Coincidentally, I do have a couple old Hubbell duplexes that are a T-slot outlet combo with a configuration for the other outlet that looks similar to this one... Hubbell had all kinds of odd stuff back in the day!

-Randy

#152318 07/10/04 02:00 PM
Joined: May 2004
Posts: 22
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I don't know why Hubbell would make something like this with a...
/ \
|
...slot configuration rated at 120V and 15A when there was already an accepted NEMA standard established for this. I found it at my old cottage in the boathouse. Maybe it was once used for some strange appliance. Anyone have any ideas?

[This message has been edited by MattE (edited 07-10-2004).]

#152319 07/10/04 03:12 PM
Joined: Feb 2004
Posts: 1,437
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Matt,
I've found these in some odd places... The Hubbell duplexes I described above were in an old 1900's house we razed the old system out of... Most common place I seem to find the single ones were in the FAU closet of old 1940's & 50's houses. My old elementary school I went to had some really strange stuff (Sierra Nema 5-15/6-15 duplexes in the bathrooms!) But each classroom had a single 5-15 recept & one of the style above in a 2G box.. always right next to the door.. & one step up of the same in the cafeteria.. I've no clue what the purpose of alot of things in that place was for!

-Randy

Here's the one of the Hubbell duplex's

[Linked Image from pstr-g01.ygpweb.aol.com]

edited to add image..

[This message has been edited by Lostazhell (edited 07-10-2004).]

#152320 07/11/04 11:07 AM
Joined: Apr 2002
Posts: 2,527
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Moderator
MattE, that's quite a find. The “crowfoot”/parallel-blade all-in-one combination is curious, and as NEMA wiring devices go these days, looks like a combination of NEMA 1-15R and 10-20R, but these days, the 10-20R configuration is for ‘non-grounded’ 3-pole 3-wire 125/250V 20A service. Maybe a 1940s mutation for earlier 120V-grounded portable equipment? I think NEMA 5-15R and other “U-ground” devices were a mid-/late-1950s iteration.

The “small crowfoot” (NEMA 10-20R) illustration is…
[Linked Image from 6l6.net]
At that time, differentiation between a current-carrying neutral and an equipment-ground conductor did not exist in wiring devices. Out west, 10-20R was the predecesor to 3-pin NEMA 6-15R/6-20R for grounded 240V, cord-connected window air conditioners starting in the mid 1950s. 240V {up to 3.8kW} portable electric heaters [probably as early as 1930-40s] typcailly used a NEMA 2-20R 2-pin 2-wire, NO-equipment-ground configuration, and occasionally 2-30R {up to 5.7kW.}




[This message has been edited by Bjarney (edited 07-11-2004).]

#152321 07/11/04 05:44 PM
Joined: Nov 2002
Posts: 456
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Had those on the farm. They were used in the barn where a standard 5-15 U-grounded recepticle would have been installed.
The farm was wired in 1952.

I have a collection of those, and have been using them for speaker connections at one time, and as 12VDC power.
Also, the plates for that particular one are identicle to the NEMA sigle recepticle.

#152322 07/11/04 09:12 PM
Joined: May 2004
Posts: 22
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Member
Originally posted by Bjarney...

Quote
Maybe a 1940s mutation for earlier 120V-grounded portable equipment? I think NEMA 5-15R and other “U-ground” devices were a mid-/late-1950s iteration.

Now that you mention it, I think it might have been used for an older water pump that needed grounding. The boathouse where this was found is also where the pump has always been located. The cottage was wired in the late 40's. I guess this was some early design by Hubbell for equipment that needed grounding, but was forgotten once grounding became standard in the 60's.

Thanks to everyone who posted!

#152323 07/12/04 05:32 PM
Joined: Aug 2001
Posts: 7,520
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The "How & Why" of the different receptacle configurations is something I find quite fascinating.

On the pics elsewhere of receptacles with two T-slots (look like they'll accept a 1-15 or 2-15 plug), in what sort of locations and during what time period were these installed?

Scott,
In your posted diagram of the 10-20R specifications, what's that reference to an "Optional notch" all about?

#152324 07/12/04 06:15 PM
Joined: Feb 2004
Posts: 1,437
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Paul,
I've come across the T slot outlets more or less anyplace you could put an outlet in older homes dating from the late 1800's to about the early 1960's.. The house I grew up in was built in 1958, & peculiarly, all the switch controlled outlets were T slot, while the rest were standard Nema 1-15.. I've personally never come across one of the T-slots wired to 240V, even though some of them show a dual 120/240V rating.. I've also come across old 1-15 outlets which show 250V ratings!

Then there's the really odd versions that basically function the way a T-slot would...

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

I've only come across a handful of these..

-Randy

#152325 07/12/04 06:48 PM
Joined: Apr 2002
Posts: 2,527
B
Moderator
Paul, apparently it mates with the "10-20P" plug, but I have no idea what purpose it serves.

[Linked Image from 6l6.net]

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