Combined pilot light and ground testing assembly

A combined pilot light and ground testing assembly for conventional 120 volt A.C. circuits is secured in the front panel of an electric console, secured to the male A.C. plug at the end of a cable, or secured to other appropriate equipment. It includes a pair of lamp chambers spaced from a third lamp in rectilinear alignment. When both of the juxtaposed pair of chambers are lit as a dual pilot light a perfect condition exists. Any other combination of lighted lamp chambers indicates an unsafe condition in the circuitry.

BACKGROUND OF THE INVENTION 
It has heretofore been proposed in U.S. Pat. No. 3,317,825 to Huff of May 
2, 1967 and in U.S. Pat. No. 3,383,588 to Stoll of May 14, 1968 to provide 
a portable, three prong, circuit tester for electric sockets in which 
three lamps are triangularly arranged in side by side chambers. 
In U.S. Pat. No. 2,598,775 to Fischer of June 3, 1952, a similar portable 
ground tester is disclosed in which the three test lamps are rectilinearly 
arranged in side by side relationship. 
SUMMARY OF THE INVENTION 
In this invention, a ground tester is disclosed in which a molded casing in 
permanently affixed to an electric apparatus having power, neutral and 
ground conductors, for example to the front panel of an electric console, 
or to a male electric plug at the end of a cable. The ground tester has 
three rectilinearly aligned chambers, each with a lamp therein, but two of 
the chambers are juxtaposed, and side by side to indicate a perfect 
circuit when energized and to serve as a pilot light. The third chamber is 
spaced from the dual, or pair of, chambers so that when it is energized, 
or when any lamps other than the pair only, are energized, an unsafe 
condition is indicated.

DESCRIPTION OF A PREFERRED EMBODIMENT 
As shown in FIGS. 1-11, in a combined pilot light and ground testing 
assembly 20 of the invention is secured, or affixed permanently to the 
front panel 21, or to some other suitable panel of an electric apparatus 
22 having the usual power conductor 23, neutral conductor 24 and ground 
conductor 25. 
Testing assembly 20 includes a molded case 26, of plastic or the like, 
having integral, unitary front wall 27, top wall 28, bottom wall 29, and 
opposite side walls 31 and 32. The elongated molded case 26 also includes 
a plurality of transverse, integral partitions 33, 34 and 35 which form a 
pair of juxtaposed, side by side lamp chambers 36 and 37, longitudinally 
spaced a substantial distance apart from the third lamp chamber 38 but 
rectilinearly aligned therewith. The front wall of each chamber is formed 
by a concave-convex, radially grooved, or fluted, lens such as at 39, 41 
and 42, and there is a visual signalling, electrically energizable element 
43, 44, or 45 such as a neon lamp, in each chamber. 
The neon lamps 43, 44 and 45 are mounted by suitable terminals 46, 47 and 
48 in the elongated circuit board 49, as best shown in FIGS. 5, 8 and 11, 
and are preferably of the high intensity type. Because the molded case 26, 
its front, top and bottom walls and partitions are of transparent plastic 
30, to permit passage of light through the lenses 39, 41 and 42, a 
cylindrical sleeve 50, 51 or 52, of opaque, plastic tubing 40 lines each 
chamber 36, 37 or 38 to shield each chamber from the other as at 53, 54 
and 55. 
The circuit board 49 of the combined pilot light and ground testing 
assembly 20 is connected to the appropriate conductors of the apparatus 22 
by the hot, or power, conductor 23 (black), the neutral conductor 24 
(white) and the ground conductor 25 (green) or other suitable conductors. 
A printed circuit 56, having conductors 57, 58, 59, 61, 62 and 63, on the 
rear face 64 of the board together with resistors 60, 65 and 66 on the 
front face of the board, completes the circuitry in a manner well known 
and similar to that shown and described in U.S. Pat. No. 3,383,588 to 
Stoll in FIG. 10, thereof, or in FIGS. 1-5 of U.S. Pat. No. 3,317,825 to 
Huff, both mentioned above. As in U.S. Pat. No. 3,383,588, when the two 
lamps 22 and 23 are lit, correct wiring is indicated, and as in U.S. Pat. 
No. 3,317,825 when lamps 1 and 2 are lit correct wiring is indicated, in 
the tester of this invention, when juxtaposed lamps 43 and 44 are lit, 
correct wiring is indicated and any other combination of lamps indicates 
an unsafe condition. 
The partitions 33, 34 and 35 are of less depth than the depth of the walls 
28, 29, 31 and 32 to form a circuit board compartment 50 at the rear of 
the hollow insulating case 26. The elongated circuit board 49, as shown in 
FIG. 11 is located in the circuit board compartment 50 between the 
transverse partitions 33, 34 and 35 and cover means 67, within the molded 
case 26. The case 26 includes an integral upper extension 68 to front wall 
27 and an integral lower extension 69 to front wall 27 to prevent fall 
through of the assembly 20 on the aperture 71 in the front panel 21. 
Cover means 67 includes the rear wall 72, with a flange 73 fitting within 
the rear opening of the case 26 to form a press fit closure therefore. 
Preferably molded case 26 also includes an upper, integral, resilient 
prong 74 and a lower integral resilient prong 75, for insertion of the 
case in aperture 71 to then snap outwardly so that the free tips 76 and 77 
lock against the rear face of panel 21. If desired the prongs 74 and 75 
may be integral with cover means 67 rather than with case 26. Preferably 
the tips 76 and 77 are serrated as shown at 78 and 79 for a more firm 
frictional grip. 
As shown in FIG. 12 the combined pilot light and ground testing assembly 20 
may be permanently affixed to a male plug 80, having the usual blades 81, 
82 and 83, and carried at the end of cable 84. The assembly 20 is provided 
with rounded edges and may be molded integrally with the male plug 80 of 
rubber, plastic or the like or may be affixed to the plug by suitable 
screws. 
In FIG. 13 a circuit diagram of a normal installation is shown in which the 
tester 20 acts as a pilot light and line fault monitor when the electric 
equipment 22 is operating with off-on switch 79 closed. 
An alternative installation is shown in FIG. 14 wherein the tester 20 acts 
as a pilot light and functions as a ground fault tester when momentary 
push button switch 80 is pressed. 
Another alternative installation is shown in FIG. 15 wherein the tester 20 
acts as line fault tester when the apparatus 22 is plugged into an A.C. 
receptacle and the power switch 81 is off. When power switch 81 is turned 
on, the equipment 22 is connected to the line and the tester 20 is 
disabled.