Museum of Plugs and Sockets logo, small Classic US outlets
based on Edison screw lamp sockets
navigation iconUS plug
navigation icon navigation iconclassic


Harvey Hubbell's pioneering work on designing a separable attachment plug to connect electrical appliances to mains, is described in detail on the page about history and early models of US plugs and sockets. Attachment plugs fit in Edison screw lamp sockets.
In addition to separable attachment plugs, lamp sockets have been designed with a single or dual,
integrated outlet. Examples of both a Hubbell attachment plug and integrated outlets are shown below.

The museum is grateful for the donation of the lamp sockets from the collection of  Samuel Schuman z"l, who made his living as an electrician.


Hemco lamo outlet and Hubbell attachment plug

Arrow lamp socket with plug outet CM lamp socket with twio plug outlets

1 Dual Edison screw lamp socket. It has the standard North American 26 mm tread size, measured across the peaks of the thread of a matching incandescent light bulb or separable attachment plug. One of both sockets can be used for an attachment plug.
Manufacturer: Hemco Electrical Manufacturing Company, New York. Tach-Lite was a trade name used by Hemco.
Hemco Plastics division was acquired by Bryant Electric Co. in 1928.   {Sch}
2 Original Hubbell separable attachment plug. The outlet accepts polarized parallel blade plugs. The Hubbell patent for polarized plugs was granted in 1916. Because of the Bakelite outlet it is likely that attachment plug has been made not before 1920.
3 Early model of a standard E26 lamp socket with pull chain switch and outlet for parallel and tandem blade plugs. Hubbell designed tandem plugs in 1904. His parallel blade plugs were introduced in 1910. Electrical accessories have been made with either tandem or parallel plug application cords. For many years it was convenient to have outlets that accept both types of plugs.
Manufacturer: Arrow Electric Manufacturing Co.   {Sch}
Dating: the Arrow 1923 catatog shows an identical "Brass shell pull socket with current tap" (Cat. No. 8236, list price $ 1.00).
4 Bakelite E26 lamp socket with two outlets for polarized parallel blade plugs.
Manufacturer: unknown company that used logo with a large C and small capital M.   {Sch}


Each of the items shown above is rated at 660 Watt - 250 Volt, which corresponds to 2.64A-250V, or 6A-110V.

It is remarkable that separable attachment plugs and dual outlet lamp sockets, essentially identical to nos. 2 and 4, are still for sale; see page about classic plugs for examples.


Navigation icon D i g i t a l   M u s e u m   o f Navigation icon P l u g s   a n d   S o c k e t s Navigation icon