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#152191 04/08/04 12:58 PM
Joined: Oct 2000
Posts: 3,682
Likes: 3
Admin Offline OP
Heres something for the nostalgia....

two pics which show different manufacturer names on identical recepts I've come across....
Who came first &/or bought who out?? Or Why the name change?

Arrow Hart Vs. Mohican Rely-On

Hubbell Vs. Acorn

Maybe some of the senior members will know! =)

-Randy (aka Lostazhell)
[Linked Image]

[Linked Image]

#152192 12/17/04 12:10 AM
Joined: Nov 2004
Posts: 56
i'm only 22 but i know that hubbel is still around! =) everything else is greek to me!

#152193 12/17/04 05:56 AM
Joined: Jan 2002
Posts: 1,457
They all look different to me.

#152194 12/21/04 10:07 AM
Joined: Aug 2002
Posts: 1,691
I have a couple of identical electrical plugs at home in my collection. One is labelled Leviton on the pins. The other is labelled Snap It.

I believe Snap-it used to be a separate company. Now it's a Leviton trade name. They still label their round rubber plugs with the Snap-it "S" on the front cover.

#152195 12/21/04 02:28 PM
Joined: Sep 2003
Posts: 114
I have a brown bakelite version of the Arrow-Hart one, original to a house built in 1950. It has a lot of paint on it- yellow, lime green, pink, blue, white, and yellow again. You can still see the design, though. As for the others, no idea.

Thanks Sven, I always wondered what that "S" stood for.

#152196 10/28/06 11:43 AM
Joined: Jan 2005
Posts: 59
I've heard of Hubbell....the others don't ring a bell....

I take it back in the old days it was common to put a design on the receptacles?

Any idea what years those receptacles are from? Also what type of plug fits into the horizontal slots of that t-slot receptacle?

#152197 10/28/06 07:01 PM
Joined: Apr 2005
Posts: 200
some early appliances (lamps, fans, etc) often used the tandem blade (flat) slots. these outlets were made to accomodate both parallel and tandem blade plugs. On my desk is an ancient porcelain Hubbell tap, with two of these T-Slot receptacles (non polarized), and a tandem blade plug, which would mate with the flat blades on these outlets.

#152198 10/28/06 08:55 PM
Joined: Jan 2005
Posts: 59
Were the ungrounded tandem blade plugs solely for 240 volts? Or was that just another plug used on the 120 volt appliances? And if so was the tandem blade receptacle/outlet designed to carry 20 amps as opposed to 15?

#152199 10/28/06 10:37 PM
Joined: Feb 2003
Posts: 288

In the early days, nothing was standardized as we are accustomed to today. Now we have just one medium base (Edison) for the vast majority of incandescent lamps, but in 1900, there were at least four. Each base was patented, so a new company wanting to manufacture bulbs had to come up with a new base. (Think of the five different flash card standards used in digital photography, for a modern comparison.) By 1910, the Edison base had won out, and the others were disappearing.

Frequencies weren't fully standardized, either. Although 60Hz AC had become very common in most of North America by 1900 or so, many urban centers already had DC service and would continue to have it until well into the '30s. And most of Southern California had 50Hz AC service until the late '30s. The conversion of California to 60Hz was a monumental undertaking. Then there was 25Hz service, used mostly for industrial motive power and for rotary conversion to DC for railroad applications. I think this is mostly gone by now.

So it is with the perennially confusing t-slot receptacle. I can date my interest in electricity to age 6, when I stared at a t-slot receptacle in my family's 1951 split-level and wondered what sort of weird plug was supposed to fit into that! Obviously, a standard parallel plug would fit just fine, but what other kind was there, and why?

In the early days, there were few appliances, and if you wanted to plug one in, it had a plug that looked like a bulb base. You would unscrew a bulb, and screw in the appliance plug. This was inconvenient, because the cord would twist into knots while you screwed the plug in. At least one company came out with a swivel plug that would turn freely without twisting the cord, but most offered "cap and base" solutions. The "base" screwed into the lampholder, and the "cap", which was attached to the appliance cord, plugged into the base. (This is why American electricians still call it a "cord cap".)

Again, each "cap and base" design was patented, so there were several out there. The two most common ones were parallel and tandem. At some point before 1930, the electrical industry decided to standardize on the parallel design (today's NEMA 1-15). Since there were still many tandem plugs out there, the t-slot receptacle was developed to accept both plugs.

The dual voltage rating, which confuses so many people today, had nothing to do with the difference between tandem and parallel. Originally, all lighting circuits were to be fused at 10A, because lampholders were only rated at 660W. This requirement was dropped sometime before 1920, I believe, and fusing set at 15A because that is the ampacity of rubber-insulated 14 AWG copper, which was already in standard use. It was uncommon, though not unheard of, to have 220V lighting circuits at this time (say, in a building with 3-wire delta service), and there was nothing to prohibit the use of standard devices on these systems if listed for the voltage, as most were. However, the 10A fusing requirement was retained for lighting circuits over 150V, hence the split rating: 125V 15A / 250V 10A.

When the NEC first became serious about phasing in grounding-type devices in the '50s, this is when each device configuration was assigned a specific nominal voltage. From the 1951 NEC Handbook:

For use on circuits of voltages higher than 125 volts, a duplex receptacle and attachment plug has been developed which is exactly the same as the design shown in Fig. 28, except that the current-carrying blades of the plug and contacts of the receptacle have the tandem arrangement instead of being parallel. These devices are rated 15 amp, 250 volts. It is expected that a change will be made in the Underwriter's Laboratories' Standard to require a rating of 250 volts only for 10-amp attachment-plug receptacles of the tandem type. (italics mine)

[This message has been edited by yaktx (edited 10-28-2006).]

[This message has been edited by yaktx (edited 10-28-2006).]

#152200 10/28/06 10:46 PM
Joined: Feb 2003
Posts: 288
Incidentally, very early in the history of "u-ground" devices, there was a grounding t-slot receptacle manufactured! I have a picture of one in a 1952 catalog. I call it a NEMA 5.5-15R. I've never seen one of these. I bet very few of them were ever made. I'd just about give my eyeteeth for one. One of these days, I'll get my scanner hooked up and post the picture.

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