Safety twist lock connector for an extension power cord

The twist lock connector of the invention includes an UL approved conventional twist to connect male and female mating ends of a pair of extension power cords for temporary supplying AC power to a work site or the like from a remote power source. The mating plugs of the first embodiment are triangular in cross-section and when connected one of the flat side surfaces rests on the support surface. In a second embodiment the mating plugs when connected have a semi-circular cross-section with the flat surface resting on the support surface. In a third embodiment, the mating plugs when connected form a rectangular cross-section. One of the larger surfaces rests on the support surface when the power cords are in use. In each of the three embodiments, the mating plugs taper or down scale in dimension toward their respective extension power cords.

BACKGROUND OF THE INVENTION 
This invention is directed to extension cords and more particulary to the 
attachment means for interconnecting lengths of heavy duty extension power 
cords for temporary use in building construction and the like where the 
power source is distant from the work site. 
Typical connectors for this use can be found in U.S. Pat. Nos. 3,023,394; 
3,148,930; 3,183,474; 3,945,702 and 4,173,383. As can be readily 
understood, all of the noted connectors are cylindrical in configuration 
with a generally circular cross-section. 
U.S. Pat. Nos. 3,605,059 and 4,199,207 generally teach the interconnecting 
of the typical connectors discussed above and the specific similarly 
configured connectors of the referenced patents. 
There is no doubt that this general type of power cord interconnector has 
found great acceptance in the electrical art as a safe means electrically 
to interconnect extension power cords and the like. 
The safety of personnel working in the generally area of an extension cord 
using the prior art inter-connectors although protected from electrical 
injury are not protected from tripping and falling or the like when 
inadvertently stepping on a cylindrical power cord interconnect which is 
caused to rotate throwing that person off balance. A power cord 
interconnect that will not rotate when inadvertently stepped on should 
find wide acceptance in the building trades and other arts. 
SUMMARY OF THE INVENTION 
The preferred embodiments of the power cord connectors of the present 
invention take three forms, namely, triangular, semi-circular and 
rectangular. As can be readily understood, when a work person steps on one 
of the connectors of the present invention the connector will not rotate 
and the work person will not loose his or her balance as normally expected 
when stepping on the conventional cylindrical connectors that are 
presently available. Also the configuration of the connectors of the 
present invention prevent them from catching on objects that they may be 
drug over for placement in position for use. The connectors of the three 
preferred embodiments have the largest dimension at the male and female 
plug interconnect end and scale downward in dimension in a linearly smooth 
manner while maintaining the same configuration in a direction toward the 
power cord to which they are connected. 
An object of this invention is to provide a electrical power cord 
interconnect which is safe for a worker to inadvertent step on. 
Another object of this invention is to provide interconnecting twist to 
lock connectors for heavy duty AC extension cords that do not rotate when 
stepped upon. 
Still another object of this invention is to provide a power cord that can 
be drug into position and will not catch on objects that it may be drug 
over. 
Other objects and advantages of the invention will become apparent and will 
be more clearly understood from the following description when read in 
connection with the accompanying drawing figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
Referring now specifically to the prior art showing of FIG. 1, In this 
Figure a pair of twist lock male and female connectors A and B 
respectfully, shown separated, which are used to provide an extension D to 
the length of the AC power cord C. As can be noted the connectors A and B 
are cylindrical with a circular cross-sectional configuration greater in 
cross-sectional area than the power cords C and D. It should be obvious 
that on a support surface 10, such as wood, cement, or the like, the 
connectors A and B will rotate when stepped upon. This rotation has been 
the clause of many industrial accidents to workers carrying loads of 
material or the like inadvertently stepping on the connectors which rotate 
causing the worker to possibly fall. The present invention eliminates this 
cause of industrial accidents. 
Referring now specifically to drawing FIGS. 2 and 3 wherein a first 
embodiment of the AC power cord connectors 12 and 14 of the present 
invention is shown. The first embodiment and the embodiments to follow are 
shown utilizing a twist to lock mating male and female interconnect as 
taught by the prior art or otherwise. It should be understood that any 
convenient type of connector may be used to practice this invention. As 
shown in the drawing FIGS. 2 and 3 the connectors are configured 
triangular in cross-section so that when they mate each connector appears 
to be a continuation of the other. The distal end of each of the 
connectors 12 and 14 have the greatest cross-sectional dimension. This 
cross-sectional dimension uniformly tapers downwardly in cross-section 
toward the AC power cord to which they are attached and at the power cord 
are substantially the same dimension as the power cord. 
It should be apparent that when the connector is resting on one of its flat 
sides it is difficult to rotate the connector and the connector will not 
rotate when a worker steps thereon. 
The embodiment as shown in drawing FIG. 4 comprises mating connectors 16 as 
above described which have a semi-circular cross-section which linearly 
scales down in the same manner. As mentioned above, the connector will not 
rotate when stepped on by a worker when the connector is resting on it 
flat surface 18. 
The embodiment as shown in drawing FIG. 5 comprises connectors 20 that are 
rectilinear in cross-section with the larger surfaces 22 of the connectors 
being the resting surface. As mentioned above, the connector will not 
rotate when stepped on by a worker. 
In addition, all of the configurations of the above embodiments are 
designed such that when the workers drag these extension cords into 
position for temporary use they do not catch on objects that they may be 
drug over. 
The various connectors of the invention may be assembled as shown in FIG. 2 
or in any other conventional manner. 
While three preferred embodiments of the invention have been illustrated 
and described, it will be understood that various changes and 
modifications may be made therein by persons skilled in the art without 
departing from the scope or spirit of the invention disclosed.