Hand-held circuit tester with lens arrangement for viewing indicator lamps housed within the tester

A hand-held electrical tester for checking the wiring of a wall receptacle. The blades of an electrical terminal protrude from one end of a housing which contains indicator lamps and electrical connecting means between the lamps and blades. Thus, the lightining of each lamp or combination of lamps indicates a predetermined wiring condition of a wall receptacle in which the terminal blades may be inserted. The housing is shaped to provide oppositely disposed push/pull surfaces to facilitate insertion and removal of the tester into and from a wall receptacle. The housing further includes compartments at one end thereof, each having a three-sided opening with a generally U-shaped lens disposed therein. Each of the compartments contains a lamp which can be viewed from the top, bottom and end of the tester.

SUMMARY OF THE INVENTION 
This invention relates in general to electrical testing equipment and more 
particularly to a hand-held tester for checking the wiring of a wall 
receptacle. 
A hand-held receptacle wiring tester is provided which includes a housing 
having first laterally opposite surfaces which spread increasingly apart 
toward one end of the tester and second laterally opposite surfaces which 
spread increasingly apart toward the other end of the tester to provide 
bearing surfaces for respectively pushing the tester into a receptacle and 
pulling it out. A set of electrical terminal blades protrude from one end 
of the housing in order to be plugged into a wall receptacle. The housing 
contains indicator lamps and electrical connecting means between the lamps 
and respective pairs of the terminal blades so that the lighting of a lamp 
and various combinations of lamps indicates respective predetermined 
wiring conditions of the wall receptacle. 
Variations of the basic tester include separate enclosed compartments 
within the housing for each lamp and semi-recessed protective lenses over 
the lamps. The first and second laterally opposite surface may be on the 
same or different sides of the housing and may be provided with a surface 
treatment to prevent slippage as the tester is pushed into or out of a 
wall receptacle. The housing may be longitudinally split so that the 
tester can be substantially assembled in one half before closing it with 
the other. 
A primary object of the present invention is a hand-held receptacle wiring 
tester which is provided with non-slip push/pull surfaces to facilitate 
insertion of the tester into a wall receptacle and its removal therefrom. 
A related object is a hand-held receptacle wiring tester having a housing 
with push/pull surfaces which may be utilized with a single grip of the 
tester. 
Another object is a hand-held receptacle wiring tester in which the 
terminal blades are held by the housing at two points spaced substantially 
apart, thereby affording a holding leverage which protects the housing and 
maintains the blades in their fixed positional relationship. 
Another object is a hand-held receptacle wiring tester which is 
substantially flat so that it may be easily carried in an electrician's 
pocket or pouch. 
Another object is a hand-held receptacle wiring tester in which the legend 
which indicates the wiring condition of the receptacle is placed on a 
single, generally flat surface so as to be entirely visible at a glance. 
Another object is a hand-held receptacle wiring tester in which the 
indicator lamps are protected by semi-recessed lenses which are thus 
visible from various angles and yet protected laterally by the walls of 
the tester housing. 
Another object is a hand-held receptacle wiring tester having separate 
internal compartments for the indicator lamps to prevent diffusion of 
light from one lamp through the lens of another. 
Another object is a hand-held receptacle wiring tester in which the 
terminal blades, lamps and electrical connector means may be assembled in 
a casing portion of the housing and be entirely visible for inspection 
prior to closing and sealing the housing with the cover portion. 
Another object is a hand-held receptacle wiring tester which is durable, 
light-weight and somewhat fitted to the hand of an electrician to 
facilitate the testing of wall receptacles. 
Other objects will become apparent in the ensuing specification, drawings 
and claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A hand-held electrical tester 10 for checking the wiring of wall 
receptacles is shown in FIGS. 1-6. The tester includes a housing 12 having 
a set of electrical terminal blades protruding from one end 14. The 
terminal blades include two parallel flat blades 16 (hot) and 18 (neutral) 
and a generally U-shaped ground blade 20. The terminal blades, which are 
arranged in the conventional fixed positional relationship for insertion 
into a wall receptacle, are mounted within the housing in a manner 
described in further detail below. Referring to FIGS. 5 and 6, the housing 
also contains three indicator lamps 22, 24 and 26, and electrical 
connecting means between each lamp and a respective pair of the terminal 
blades so that the lighting of each lamp and each combination of lamps 
indicates a predetermined wiring condition of a wall receptacle into which 
the terminal blades may be inserted. 
Housing 12 has first laterally opposite surfaces 28 (FIGS. 2 and 6) which 
spread increasingly apart toward end 14 of the tester and second laterally 
opposite surfaces 30 (FIGS. 1 and 5) which spread increasingly apart 
toward the other end of the tester, which surfaces provide bearing 
surfaces for respectively pushing the tester into a receptacle and pulling 
it out therefrom. The first and second laterally opposite surfaces are 
each shown as a pair of surfaces which are generally symmetrically 
situated with respect to a longitudinally center line through the housing 
12 which would intersect end 14. The first laterally opposite surfaces or 
push surfaces 28 are oppositely disposed on diametrically opposed sides of 
the tester housing 12. The second laterally opposite surfaces or pull 
surfaces 30 are similarly disposed but on different sides of the housing 
from each other and from the push surfaces 28. Although the illustrated 
form is preferred, the push and pull surfaces 28 and 30 might otherwise be 
formed as continuous oval or annular surfaces around the housing 12 or 
discontinuous arcuate surfaces. Likewise, the push and pull surfaces 28 
and 30 could each be formed on all four sides of the housing or on all or 
only some of the sides of any other multi-sided housing. The important 
point is that the surfaces flare outwardly from the surface of the housing 
toward one end or the other to form bearing surfaces against which an 
electrician can push or pull to facilitate using the tester. Again, it is 
preferred that the push surfaces 28 be longitudinally positioned closer to 
the end 14 of the tester than the surfaces 30, but this could be 
otherwise. 
In FIGS. 1, 2 and 4, push surfaces 28 are shown with a plurality of spaced 
ridges 32 formed laterally across each surface. The purpose of these 
ridges is to prevent slippage of the electrician's grip on the connector 
as he pushes it into a wall receptacle. The particular design of the 
ridges is not critical, but rather any non-slip surface treatment could be 
substituted which would increase the frictional contact between the push 
surfaces 28 and the electricians's hand. Thus, the surfaces might be 
knurled, foraminated or otherwise coarsened. The same or different surface 
treatment may be applied to one or both of the first and second sets of 
laterally opposite surfaces 28 and 30. 
The housing 12 is longitudinally split, as best shown in FIGS. 2 and 3, and 
thereby consists of a casing portion 34 and cover portion 36. The front 
wall 37 (FIG. 3) of casing 34 is provided with two parallel slots 38 
adapted to receive and properly position the flat blades 16 and 18. A 
ground support member 40 projects downwardly away from the slots 38 to 
receive and properly position ground blade 20. The terminal end 14 of 
cover 36 is provided with cooperating shoulders 42 for retaining flat 
blades 16 and 18 in their respective slots 38 and a center shoulder 44 for 
retaining the ground blade 20 within ground support member 40. The other 
end of the casing and cover portion is generally open for receiving three 
lenses 46, 48 and 50 which are described in further detail below. 
The internal construction and components of receptacle tester 10 are best 
shown in FIGS. 5 and 6. The terminal blades extend inwardly from the 
terminal end 14 of the tester and through a blade-retainer wall 52. Like 
the front wall 37 of casing 34, wall 52 is slotted to receive flat blades 
16 and 18 and has a downwardly extending ground blade support member 54. 
Ground blade retainer wall 52 serves not only to retain the blades in 
their proper positional relationship, but also as a member through which 
longitudinal forces are applied to the terminal blades to push them into a 
wall receptacle. 
The shape and assembled position of the flat terminal blade 16 is shown 
best in FIG. 6. The other flat terminal blade 18 may be constructed and 
mounted similarly. Basically, the blade has three integral sections: a 
terminal plug portion 56, a center section 58 and an inner wrap-around 
connector section 60. The terminal plug portion 56 is adapted to extend 
longitudinally outwardly from casing 34 through one of the slots 38 for 
the purpose of being plugged into a wall receptable. Thus the dimensions 
of plug portion 56 are conventional. The outer tip 62 may be rounded and 
tapered to further ease insertion into the typically stiff wall 
receptacles found in new construction. The center section 58 is enlarged 
vertically above and below the terminal plug section 56. Thus a shoulder 
64 is provided which is adapted to abut against the front wall 37 of 
casing 34 to prevent the terminal blade from being pulled longitudinally 
out of the housing. The inner end of center section 58 is received within 
a slot 66 in retainer wall 52, which slot provides longitudinal restraint 
to prevent the terminal blade from being pushed into the housing. The 
slots 38 and 66 in casing 34 both provide the lateral restraint necessary 
to maintain the proper and uniform spacing between flat blades 16 and 18. 
Slot 66 is shown as being stepped at 67 to allow the middle section 58 of 
the terminal blade to be seated partially within retainer wall 52 while 
allowing the connector portion 60 to extend completely through the wall 
and further into the housing. Connector section 60 has two vertically 
semi-circular indentations 68 adapted to receive wires for making an 
electrical connection with the terminal blade. The flat blades 16 and 18 
are vertically restrained in the assembled housing in a number of ways. 
First, the cover portion 36 has a front wall 70 with shoulders 42 which 
are adapted to close slots 38 of the casing and restrain the terminal 
blades therein. The center section 58 of the terminal blade is fitted 
between slot 66 in retainer wall 52 and the front wall 37 so that vertical 
rotation is restricted. But to further restrict vertical movement of the 
blade at the retainer wall 52, it is preferred that the blade be staked 
into slot 66 by closing the retainer wall over the slot such as by heat 
staking or ultrasonic staking. 
The shape and installed position of ground blade 20 can likewise be seen in 
FIGS. 5 and 6. Extending longitudinally outwardly from ground support 
member 40 on the front wall 37 of the casing, the ground blade is 
generally U-shaped in the conventional manner for insertion into the 
ground slot of a wall receptacle. Inwardly of front wall 37, the ground 
blade becomes flattened prior to reaching retainer wall 52. The flattened 
middle portion 74 of ground blade 20 is wider (FIG. 5) than the center 
slot 76 in retainer wall 52. Therefore, two laterally opposite 
indentations 78 are formed in the ground blade so that it may be fitted 
into slot 76. Ground blade 20 also has a wrap-around connector section 80 
at its inner end. Longitudinal restraint for the ground blade in its 
assembled position is provided by the edges of the indentations 78 which 
abut against both sides of retainer wall 52. Lateral restraint for the 
ground blade is provided by the sides of the ground support member 40 at 
the front wall 37 and by the sides of slot 76 in retainer wall 52. 
Vertical restraint is provided by shoulder 44 of cover 36 at the front 
wall and by staking the ground blade in position at the retainer wall by 
at least partially closing slot 76 over the ground blade. 
Looking at the other end of the housing in FIGS. 5 and 6, both the casing 
34 and cover 36 are provided with cooperating longitudinal dividing walls 
82 and 84 respectively, which walls are generally equally spaced from the 
sides of the tester and from each other to form three separate 
compartments for lamps 22, 24 and 26. In their assembled positions as 
shown in FIG. 6, walls 82 and 84 abut against one another to prevent the 
diffusion of light from one lamp into the compartment of another. 
To further enclose the lamp compartments, a wall 86 laterally spans the 
cover 36 in engagement with the inner ends of walls 84. Likewise, housing 
34 is provided with a similarly disposed lateral wall 88 which, however, 
is shorter than the longitudinal walls 82 to provide a gap between walls 
86 and 88 through which the terminal portion 90 (FIG. 6) of the lamps may 
extend. The divider walls 82 and 84 also have laterally spaced slots 92 
intermediate their length, which slots are adapted to receive and retain a 
lamp retainer 94. The lamp retainer 94 is a thin, flat member of 
cardboard, plastic or any other suitable material having three laterally 
spaced holes which are adapted to receive the lamps 22, 24 and 26 to 
support them in a generally centralized position within the compartments. 
Between the terminal blade retainer wall 52 and lamp compartments, the 
casing 34 and cover 36 are generally open to accommodate the electrical 
connecting means between the lamps and terminal blades. The only 
interference within this area is the peg and sleeve connections between 
the cover 36 and casing portion 34 of the housing. The cover is provided 
with a pair of spaced apart vertically directed pegs 96 which are adapted 
to be received within cooperating sleeves 98 of casing 34 to fix the 
lateral and longitudinal positional relationship between the cover and 
casing in the assembled receptacle tester. The peg and sleeve connections 
are further advantageous for separating the various electrical connecting 
means between the lamps and terminal blades. 
The aforementioned electrical connecting means includes the wires, 
resistors and insulative tubing necessary to complete the electrical 
connections between each lamp and a respective pair of the terminal 
blades. Preferably, resistor attached glow lamps which may be utilized 
have a resistor 100 pre-connected along one of the lead wire 102 of each 
lamp. Thus, the only assembly required as insulating certain crossover 
wires and electrically connecting each lead wire to a terminal blade. In 
the preferred embodiment, a 0.25 watt lamp is used having an attached 22K 
Ohm resister. Referring to FIG. 5, the resister attached lead 102 and 
plain lead 104 of lamp 22 are connected respectively to the hot blade 16 
and ground blade 20. Likewise, the leads of lamp 24 are connected 
respectively to ground blade 20 and neutral blade 18. Finally, the leads 
of lamp 26 are connected respectively to neutral blade 18 and hot blade 16 
to complete a parallel circuit between the lamps and blades. In the 
crossover area of the casing between sleeves 98 an insulative tubing 106 
may be used to cover the plain lead of lamp 26 to insulate it from and 
separate the leads of the center lamp 24. 
The actual connection to each terminal blade is accomplished by wrapping an 
end of a wire about the wrap-around connector portion of the blade as at 
60 in FIG. 6 with respect to the hot blade 16. The wire is held in the 
semi-circular indentation 68 to prevent it from slipping longitudinally 
off the blade. It is preferred that the wires also be soldered to their 
respective blades to insure a strong mechanical and electrical connection 
to the blades. 
To complete the receptacle tester assembly, a set of generally three-sided 
lenses 46, 48 and 50, are fitted onto the open ends of the lamp 
compartments to close the same and protect the lamps therein. A 
cross-section of lens 46 is shown in FIG. 6. 
Each lens has a generally flat outer surface 108 with side walls 110 which 
taper vertically into the housing 12 at an angle conforming to the tapered 
ends 112 of the housing sidewalls shown in FIG. 2. The side walls 110 are 
formed with a shoulder 113 which is adapted to abut against the end of the 
casing 34 or cover 36. Extending into the housing from shoulders 113 are 
legs 114 having vertically directed feet 116 which are adapted to engage 
lips 118 formed in the casing 34 and cover 36 to rigidly secure the lenses 
over the lamp compartments. In FIGS. 1 and 2, it can be seen that the open 
sides of lenses 46 and 50 are protected by the sidewalls of housing 12 and 
that the lenses protrude longitudinally beyond the housing by a distance 
approximating the thickness of the lens. The other sides of the lenses are 
protected by divider walls 82 and 84. It is preferred that the lenses be 
constructed of translucent plastic and each of a different color to aid in 
identifying the particular lamp or combination of lamps which light up 
when the tester is plugged into a wall receptacle. Thus lenses 46, 48 and 
50 may be clear, red and amber respectively. Accordingly, it is the 
lighting of the clear and amber lamps which indicates that the wiring of a 
receptacle is corret. The other combinations are as follows: 
______________________________________ 
Color Wiring Condition 
______________________________________ 
Amber only Open 
Amber and red Reversed polarity 
None Open hot 
Clear only Open neutral 
Red and clear Hot and ground reversed 
Red only Hot on neutral with hot open 
______________________________________ 
To identify which wiring condition is designated by which combination of 
lamps, an appropriate label may be attached to a flat surfce 120 on the 
housing adjacent the lenses between the pull surfaces 30. Surface 120 may 
be slightly recessed into the housing as shown in FIG. 6 to protect the 
edges of the label. A laminated label with a pressure-sensitive adhesive 
backing may then be applied to surface 120, which label would generally 
fill the recess of surface 120 and be flush with the housing surface. 
To assemble receptacle tester 10, casing 34 is laid open-side-up as seen in 
FIG. 5. Insulative tubing 106 is slid onto the plain lead of lamp 26 after 
which the leads of all the lamps are electrically connected to their 
respective terminal blades. Flat blades 16 and 18 are then pressed into 
position within slots 38 of front wall 37 and slots 66 of terminal blade 
retainer wall 52. Ground blade 20 may then be inserted so that its 
generally U-shaped outer portion is supported within the ground blade 
support 40 (FIG. 3) and so that the indentations 78 of the inner flat 
portion of the blade are fitted over the ground blade support portions 54 
of retainer wall 52. Lamp retainer 94 may then be inserted over lamps 22, 
24 and 26, to properly space them for insertion into the lamp compartments 
of the casing 34. Lamp retainer 94 is pressed into slots 92 in the divider 
walls 82 of the casing 34. The resistors 100 and lead wires 102 and 104 
for each of the lamps may then be pressed into the casing about sleeves 
98. The lead wires are sufficiently bent to allow each lamp to be 
longitudinally positioned so that its terminal portion 90 overlies the 
inner lateral wall 88 which partially closes each lamp compartment in 
casing 34. 
To rigidly secure the terminal blades in their fixed positional 
relationship, it is preferred that the blades be staked securely at 
retainer wall 52. This may be accomplished by heat staking, ultrasonic 
staking or any other mechanical means for closing slots 66 over flat 
blades 16 and 18 (FIG. 5) and at least partially closing slot 76 over 
ground blade 20. 
With the blades, lamps and electrical connecting means thus assembled in 
the casing portion 34 of housing 12, the lenses 46, 48 and 50 and cover 36 
may then be added to complete the receptacle tester assembly. The lenses 
are inserted between the casing 34 and cover 36 so that the lips 118 of 
both portions of the housing will engage the small inner feet 116 of the 
lens as the housing is closed to thereby securely retain the lenses at the 
end of the housing. To properly align cover 36 over casing 34, both 
laterally and londitudinally, it is simply necessary to insert pegs 96 
properly into sleeves 98. The housing portions are then pressed together 
to close and seal the housing. It is preferred that the housing portions 
be permanently sealed together to rigidify the tester unit so that it may 
best withstand the abuse it is likely to incur in use in the field. It is 
preferred that the housing sections 34 and 36 be ultrasonically joined 
together, although a heat-seal, adhesive or other suitable means may be 
otherwise used. To ultrasonically join the housing sections, six so-called 
energy directors 122 (FIG. 5) are formed along the edges of casing 34 
which will contact the cover 36. Two of the energy directors 122 are 
formed on the divider walls 82 between the lamp compartments. The energy 
directors 122 are simply thin raised integral portions of the casing 
material which preferably rise to a point. As the housing portions are 
joined, the material of the energy directors 122 is fused to that of the 
cover 36 to form a unitary enclosed housing. 
The use, operation and function of the invention are as follows: 
The present invention is useful for quickly and easily checking the 
polarity or wiring condition of a conventional three-prong electrical wall 
receptacle. To do this, the terminal blades of the receptacle tester are 
inserted into the wall receptacle in the same manner as the plug of any 
electrical appliance. As a result, a lamp or combination of lamps which 
corresponds to the wiring condition of the receptacle will light up to 
indicate this information to the electrician or inspector using the 
device. If no lamp lights up, either the hot terminal of the receptacle is 
open or no power is being supplied to the receptacle. 
Checking receptacles with the tester device of the present invention has 
several significant advantages. First, checking may be accomplished 
quickly since the receptacle plate need not be removed nor the receptacle 
itself pulled away from the wall for visual inspection. As a result, all 
of the receptacles of a particular construction job may be tested in the 
time it may previously have taken to spot-check only a portion of them. 
One of the difficulties of checking the wiring of wall receptacles in new 
construction, even with a hand-held receptacle tester, is that the new 
receptacles commonly are very stiff and resist the insertion of a plug or 
tester device such as the present invention. To overcome this difficulty, 
the present invention is provided with laterally opposed push-pull 
surfaces to strengthen the grip of the electrician on the tester and 
thereby facilitate its insertion into a receptacle. The push surfaces 28 
are somewhat steep and provided with a surface treatment such as the 
ridges 32 to prevent slippage of the electrician's hand while inserting 
the tester. Since the force required to remove the tester from a 
receptacle is generally less than that needed for insertion, the pull 
surfaces 30 may be gently sloped outwardly from the surface of the housing 
so as to comfortably conform to the grip of the electrician using the 
device. Primarily for this purpose of somewhat fitting the tester to an 
electrician's hand, it is preferred to have the push surfaces 28 located 
closer to the terminal end 14 of the housing and on different sides of the 
housing from the pull surfaces 30. With such a construction, the push and 
pull surfaces are both effective to assist an electrician using a single 
grip on the tester to both insert and remove the tester from a wall 
receptacle in one motion, which is all that is necessary to precisely 
check the wiring of the receptacle. 
It is also preferred that the push and pull surfaces be formed on different 
sides of the housing so that neither interferes with the use of the other. 
Whereas it is desirable to minimize the size of the housing and yet 
accommodate the different sizes of hands and styles of grips of many 
individuals, segregating the bearing surfaces on different sides of the 
housing accommodates every user. Furthermore, since that portion of the 
housing behind each bearing surface is narrower than the bearing surface 
itself, the operator's hand comes naturally to rest against the 
appropriate bearing surface when using the tester device. In FIG. 1, it 
can be seen that the terminal end 14 of the housing is somewhat narrow and 
widens smoothly and gradually toward the other end to a point where the 
slope is increased to form each bearing surface 30. Similarly, turning the 
device 90.degree. as seen in FIG. 2, the lamp end of the housing is flared 
as at 112 and maintains a somewhat narrow flat thickness toward the 
terminal end of the housing to the point where the push surfaces spread 
increasingly apart to provide bearing surfaces for inserting the tester 
device. 
The housing 12 is constructed with several features to increase its useful 
life as well as facilitate the use of the device. By securely holding the 
terminal blades both at the front wall of the housing and at the terminal 
blade retainer wall 52, a definite holding leverage is provided which 
increases the force necessary to divert the terminals out of their fixed 
positional relationship. 
Each terminal blade may be viewed as a lever mounted between front walls 37 
and 70 which serve as a fulcrum. Thus, the further apart the front wall 37 
and terminal blade retaining wall 52 are, the less the force is that will 
be applied to the housing in response to forces acting externally of the 
housing on the terminal blades. This is because of the greater leverage 
within the housing. As a result, deformation of the plastic housing is 
less likely because of the lower forces and the useful life of the tester 
device is increased. 
The lamp lenses 46, 48 and 50 are constructed to both improve the 
visibility of the lamps of the test device and protect them from 
mechanical impact. Since the lenses are semi-recessed longitudinally 
outwardly from housing 12, they can be seen from all four sides and the 
visible end of the tester when it is inserted into a wall receptacle. 
Thus, regardless of the orientation of the receptacle on the wall, the 
electrician can simply look down from a comfortable position above the 
tester to see which lamps are lit. But the lenses are not recessed so far 
as to form an external bulb which itself is subject to fracturing. Rather, 
the lenses protrude longitudinally beyond the housing by a distance 
approximating the thickness of the lens so that only solid bodies of the 
lens material are exposed. Otherwise, the entire sides of all three lenses 
are completely shielded and protected by the flared ends 112 and divider 
walls 82 and 84 of the housing. 
Assembly of the tester device of the present invention is greatly 
facilitated by providing a longitudinally split housing comprised of a 
separate casing 34 and cover 36. First, the casing is completely open so 
that each of the lamps, blades and electrical connecting means can be 
directly placed into their fixed positions within the casing as opposed to 
fishing them in from one end or the other. Secondly, because the casing is 
completely open before closing it with cover 36, all of the assembled 
elements can be visually inspected prior to closing and sealing the 
housing. 
Finally, the wiring condition of a given receptacle can be immediately 
apparent, even to one unfamiliar with the receptacle tester since a label 
indentifying the respective wiring conditions may be prominently displayed 
on the single large flat surface 120 formed into housing 12. The entire 
label is visible at a glance and the tester body need not be rotated or 
turned to read any portion of the label. 
Whereas the preferred form of the invention has been described herein, it 
should be realized that there may be many modifications, substitutions and 
alterations thereto.