CA1125856A - Test structure for ground fault circuit interrupters - Google Patents

Abstract

48,020 ABSTRACT OF THE DISCLOSURE
A test structure for a ground fault circuit interrupter characterized by a circuit breaker, a ground fault detector, an insulating housing, and a manual test button in the housing. The insulating housing includes a load terminal structure and a groove leading from the load terminal structure to the test button, and a conductor press-fitted within the groove and extending from the load terminal structure to the test button.

Description

1 48,020 TEST STRI)CTURE FOR GROUND ~AULT
CIRCUIT INTERRUPTERS
BACKGROUND OF THE INVE~TION
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Field of the Invention:
This invention relates to a ground fault circuit interrupter and, more particular-]y, to a simplified test circuit con-Eiguration.
Description of the Prior Art:
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Essentially the basic condition for which known types of ground fault interrupters of the differential - transformer type are intended to be effective is that in ~which there is a ground fault between the hot or line `conductor and ground. A ground fault between the neu~tral conductor of a multi-wire A.C. system on the load side of the differential transformer and ground does not itself present a safety hazard of the type for which protection is required. However~ such a grounded neutral condition has the effect of rendering the apparatus inoperable, particu-larly in the absence of a load on the circuit.
In the past, most ground fault circuit breaker manufacturers chose to connect their test circuit function with small flexible leads, in which the connection to the ungrounded load side of the ground fault circuit breaker .~ . . , . , ~ .

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2 ll~t020 <:Incl the i.nput line ne~lt:ral were connecte~ to two contact tesl c:l.ips. D:isa(lvant:ages of that type o~ connection involved numerous welds or soklered joints from the under-ground loac] circuit term-inal to the res.Llient contact melnber as we:L1 as probl.ems of circuit concl~lctor insulation.
Ground fault ci.rcuit interruplers of the type involved are disclosed ill IJ.S. Pat.ent Nos. 3,7~5,414; 3,930,189;

3,959,693; 3,999,103; 4,015,169; and 4,081,852.
SUMM~R~' OF THE INVENTION
0 lt has been found in accordance with this inven-tion that some disaclvantages of ground fault circuit breakers of prior construction may be overcome by providing a ground fault circuit interrupter for use in a load center and comprising a circuit breaker, a ground fault detector, and an i.nsulation housing therefor; the circuit breaker comprising a pair of cooperable contacts operahle between open and closed positions, an operating mechanism for operating the contacts and comprising a latched pivotally supported trip member, trip mèans for latching the~ trip 2u member, a load terminal structure, a line terminal struc-ture, a line conductor of an AC electrical distribution system connec~.ing the trip means to the load terminal structure; the ground fault detector comprising a current monitoring core, a plurality of primary windings on the core, each being one of the line and a neutral conductor of the AC electrical distribution system, a secondary winding sensing current imbalance between currents in the primary windings, means responsive to a predetermined sensing signal OIl said sensing winding to open said line conductors;
test means to test the ability of the apparatus to trip .

3 ~,020 u~on occurrence of either line to ground :Eault conclitions or neutral to ground ~ault conditions, said test means comprising a circùi~ branch connecled from a first point on a line conductor on the load side of said di~fe~ential current transfor~er an(l a seconcl point electricall,y proxi-mate to the neutral conductor on the supply side of said differential current transformer, said circuit branch including a normally open test switch that is closable to cause unbalanced currents in said primary windings, said 0 circuit branch connected from said first point on a line conductor comprising a wire-like conductor extending from said first point to said test switch, said insulating housing having groove means in which the wire-like conduc-tor is secured by a pressure fit, the wi.re-like conductor being in a pressure-fit connection with a load circuit terminal, and said wire-like conductor having a portion in line with the path of movement of the test switch.
. The advantage of the ground fault circuit inter-.
rupter of` this invention is that it eliminates welded or 2u soldered joints from ungrounded load circuit terminals to resilient contact members, reduces the chance of failure due to mass incompatibility in which small gauge wire used for flexibility is connected to conductor gauge wire of a larger size, and enables the use of pressure-fit connec-tions for retaining a conductor in place'as well as provid-ing good electrical contact with associated electrical conductors.
BRIEF DESCRIPTION OF THF DRAWINGS
Figure 1 is a perspective view of the ground fault circuit breaker structure of this invention;

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4 48,020 Eig. 2 is a vertical sectional view taken on the line Il-II of Fig. 1 and showing the circuit breaker side of the inventio~ and in the closecl position;
Fig. 3 is a view similar to Fig. 2 with the breaker shown in the tripped position;
Fig. 4 is a vertical sectiorlal view taken on the line IV-IV of Fig. 1 showing the ground fault detector side of the invention;
Fig. 5 is a sectional view taken along the line O V-V of Fig. 4;
Fig. S is a sectional view taken on the line - VI-VI of Fig. 4;
Fig. 7 is a diagram showing th~e electrical cir-~` cuit of the invention; and ; Fig. 8 is an isometric view of the conductor ' mounted within the housing.
- DESCRIPTION OF THE PREFERRED EMBODIMENT
; ~ In Fig. 1 a ground fault circuit breaker struc-ture~is generally indicated a~ 3 and it comprises a housing ~2~ 5 which is composed of electrically insulating material such as a thermosetting resin. The housing 5 includes a - pair of tray portions 7 and 9 and a side cover 11, which- are secured-in place by suitable means such as rivets 12 in ; a conventional manner. The tray portion 7 (Fig. 5) com-~prises a back wall 8 and the tray portion 9 comprises a back wall 13 that serves as a partition wall which extends ~- ~ between compartments 15 and 17 formed between the back .
walls 8 and 13 and the side cover 11.
In Figs. 2 and 4 a circuit breaker mechanism is disposed within the compartment 15 (Fig. 2) and a ground .:; i . , .

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fault circuit interrupter is disposed within the compar-t-ment 17 (Fig. 4). The circuit breaker s~ructure is of the type disclosed in Pa-tent No. 3,566,318, to which reference is made for a complete description of the structure an~
operation. Briefly, the circuit breaker mechanism COM-prises a stationary contact ~1, a movable contact 23s a supporting metal frame ~5, an operating mechanism 27, and a trip device 29. The stationary contact 21 is welded, or otherwise secured to a line terminal 31.
10The stationary contact 21 (Figs. 2 and 3) cooper-ates with the movable contact 23 that is welded or other-wise secured to a small flange portion 33 of a flat metal-lic generally C-shaped contact arm 41. M~ans for operating the contact arm 41 to the open and closed positions com-prises an operating member indicated generally at 43 having a V-shaped opening 45 therein, which opening receives a projection 47 of the stationary metallic frame 25.. The operating member 43 is biased outwardly or upwardly (~igs.
- 2 and 3) to a position wherein the lower edges of the projection 47 pivotally engage the lower side walls of the V-shaped opening 45. The contact arm 41 is bent over at its upper end at 48, and a slot is provided in the part 48.
Depressions 51 are formed in the part 48 on opposite sides of the slot.
When the parts are in operating position, a molded projection integral with the operating member 43 extends into the slot of the contact arm 41 to position the operating member 43 relative to the contact arm 41, and pivoting portions 55 on opposite sides of the projection 3 pivotally engage in the depressions 51 of the con~act arm . . .
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' 6 48,020 41. The operating member 43 has a handle portion 57 molded integral therewith which extends through an opening 61 in the housing, whereby the mechanism may be manually operated to open and close the breaker. Arcuate surfaces 63 on opposite sicles of the handle 57 substantially close the opening 61 in all positions of the operating member 43.
Motion is transmitted from the operating member 43 to the contact arm 41 when the breaker is manually operated and from the contact arm 41 to the operating member 43 when the breaker is automatically tripped.
The frame 25 supports an insulating pivot 65. A
releasable member 67 is pivotally supported at one end thereof on the pivot 65. The other end ~69 of the releas-able member 67 is latched by the trip device 29 in a manner to be hereinafter specifically described. Except for the trip device 29, the operating mechanism is more specific-ally described in the Patent No. 3,~54,176.
As is more specifically described in said Patent No. 3,254,176, the ends of the releasable member 67 are offset and disposed along a plane which is parallel to a plane in which the main body portion of the releasable member 67 is disposed. A spring 71 is connected under tension at one end in a slot 73 in contact arm 41, and at the other end in a slot in a projection 75 that extends from the main body portion of the releasable member 67.
The contact arm 41 is electrically connected to the lower end of a bimetal 77 by means of a flexible con-ductor 79. The bimetal 77 is part of the trip device 29.
A flexible conductor 81 connects the upper end of the ~ 30 bimetal 77 with a terminal strap 83 that extends th~owgh an . ~ .
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7 ~8,020 opening l83 in the end wall o~ the housing. A terminal connector 85 is connected to the external end of the term-inal strap 83 to permit connection o~ the circuit brealcer in a circuit in a manner well known in he ar~. The closed circuit through ~he circuit breaker 9 extends from t`he terminal 31 through the stationary contact 21, movable contact 23, contact arm 41, flexible conductor 79, current-carrying bimetal 77, flexible conductor 81, to the terminal strap 83 by means of the terminal connector 8S. Since the movable contact arm 41 extends downwardly from lts pivot, the arc is established adjacent the bottom of the housing in an arc chamber 87 which is connected by a vent passage 89 to an opening in the end of the ho~sing beneath the terminal comlector 85.
When the releasable member 67 is in the latched position (Fig. 2), the circuit breaker may be manually operated by operation of the operating member 43. Movement of the operating member 43 in a clockwise direction (Fig.
3) from the "on" (closed position) to the "of" (open position). The spring 71 biases the contact arm 41 upward into engagement with the operating member 43 to bias the operating member 43 against the lower edges of the projec-tion 47 about which the operating member 43 pivots. Move-ment of the operating member 43 in a counterclockwise direction from "off" to "on" moves the upper end of the switch arm to the right of the line of action of the spring 71 to move the contact arm 41 to the closed position.
The trip device 29 comprises the elongated bi-metal 77~ The bimetal 77 is a flat member that is secured - 3 at the upper end thereof to a projection 93 of the sta-..
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8 48,020 tionary frame 25. The frame 25 is a flat member that is ~ecured in place in the housing between proje~tions of the molded insulating housing, and the projection 93 over to extend and in a direction generally normal to the plane o the flat supporting plate 25. An elongated rigid magne~ic armature or latch member 95 is mounted on a spring 97 that is welded to the high expansion side of the bimetal 77.
The armature 95 extends upward along the high expansion side of the bimetal 77 in a parallel relationship with the bimetal 77 when the bimetal is in the cold or straightened condition. The armature 95 has an opening 99 therein to form a latch surface 101 at the base of the opening.
The latch end 69 of the releas~able member 67 is formed with a latch surface 103 thereon and a stop surface or fulcrum part 105 thereon. The armat~re 95 serves as a stop to engage the fulcrum part 105 of the releasable member 67 in the latched position of the releasable member.
A U-shaped magnetic member 109 is mounted on the bimetal 77 with opposite legs being posi-tioned on opposite sides of the bimetal.
The circuit breaker is in the reset position (Fig. 2) wherein the releasable member 67 is latched on the armature 95. The circuit breaker can be manually operated only when the releasable member 67 is in the reset or latched position. In the reset position (Fig. 2)~ the bimetal 77 is biased toward the releasable member 67 and engages the fulcrum part 105 of the rigid releasable member 67. In this position, the latch surface 103 of the releas-able member 67 rests on the latch surface 101 of the arma--~ 30 ture 95 to latch the releasable member~67~ thereby prevent-. - :

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9 48,020 ing clockwise movement of the releasable member 67 about the pivot 6S. The high expansion side of the bimetal 77 is on the left as seen in Fig. 2. Upon the occur-rence of a sustained lesser overload current above a first predeter-mined value, the bimetal 77, which is heated by the cwrrent flowing therethrough, deflects from the position (Fig. 2 to a thermally-tripped position.
The bias of the complete bimetal 77 toward the left maintains the armature 95 against the fulcrum part lOS
during the deflection of the bimetal 77 to a thermally-tripped position. The bimetal 77 deflects to a curvature such as that during movement when the rigid armature 95 is angled to the position with the lower end of the ridig armature 95 being carried by the lower end of the bimetal 77, and the armature 95 moves about the fulcrum part 105 with a levering action to move the latch surface 101 of the armature 95 free of the latch 103 of the releasable member 67 to thereby release the releasable member 67.
When the releasable member 67 is released, the spring 71 rotates the releasable member 67 in a clockwise direction about the pivot 65 until the releasable member 67 is stopped by engagement thereof with a molded projection : 177 on the housing part 13. During this movement, the line - of action of the spring 71 is to the right on the pivot 55, 51, whereupon the spring 71 biases the contact arm 41 in ~the opening direction and moves the contac~ arm 41 so that the line of action of the force exerted by the spring on the oerating member 43 shifts across the pivot 45, 47 and - actuates~ the operating Inember h3 to the tripped position : 30 ~Fig 3). The tripped position of the operating member 43 .
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~8,020 is intermediate the "on" and "off" positions. The operat-ing member 73 is stopped in the intermediate or tripped position (Fig. 3) when an insulating projection 119 thereon engages the projection 75 on the releasa'b~e member 67. The contact arm 41 is stopped in the open position (Fig. 3) when it engages an insulating projection 121 molded inte-gral with the partition wall 13. Positive separation of the contacts is provided during a tripping operation by means of a projection 123 extending from the releasable member 67. If the contacts are slow in opening due to sticking, drag or other reasons, the projection 123 engages the inner edge of the contact arm 41 to start the contact arm in the opening direction. The circuit breaker is trip-free in that the breaker will automatically -trip open even if the handle 57 is held in the closed position.
Following a tripping operation, it is necessary to reset the brea'ker 'before the breaker can be operated.
This is accomplished by moving the operating member 43 from the tripped position (Fig. 3) slightly beyond the full "off" position. During this movement, the projection 119 on the operating member 43 operates against the projection of the releasable member 67 to move the releasable member 67 counterclockwise to a position, wherein the latch surface 103 of the releasable member 67 is just above the latch surface lOl of the armature 95. 'The spring 91 then moves the bimetal 77, which cools and straightens when in non-current carrying tripped condition, and armature 95 toward the releasable member to latch the trip member in an initial 0perating position With the releasable member 67 reset in the operating position, the circuit breaker can be ~: ,' , ' ,:
, ~ 8,0~0 manually operated in the same manner as was hereinbefore described.
The circuit breaker is instantaneou~ly tripped upon the occurrence of a short circuit or 5evere overload current above a second predetermined value, higher the the first predetermined value, by operation of the magrletic trip of the trip means 29. The current passing through the bimetal 77 (Fig. 2) generates magnetic flux which operates through the armature 95, the air gaps between the armature 95 and the magnetic member 109, and through the stationary magnetic member 109. When the current reaches the second predetermined value, this magnetic flux is strong enough to attract the armature 95 toward the st~ationary magnetic member 109, and the spring 97 flexes permitting the arma-ture 95 and bimetal 77 to move as a unit to the magneti-cally-tripped position (Fig. 3) wherein the releasable member 67 is releasable to trip the breaker in the same manner as was hereinbefore described.
Following a magnetic tripping operation, the circuit breaker is reset and relatched in the same manner as was hereinbefore set forth with regard to the time-delay thermal tripping operation. The bimetal 77 and armature 95 are shown in the attached position in Fig. 3. It can be understood that when the circuit is interrupted the arma-ture 95 will no longer be atracted to the stationary magne-tic member lQ9 and returns the bimetal 77 and armature 95 to the unattracted position.
The ground fault de-tec-tor or actuator in compart-ment 17 tis generally indicated at 127 in Fig. 4 and is em-ployed to avoid the adverse effects of the grounded neutral . ~ . .

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12 48,020condition. In Fig. 7, the ground fault detector 127 of thedifferential transformer type is shown schematicall.y where-in a differential transformer 129 having a toroidal core 131 is provided with conductors including a line condwctor 81 and a neutral conductor 135. The conductors 81 and 135 extend through the core 131 as primary windings, each pre-ferably of a single turn although multiple turn windings may be used if desired. The .illustration of the conductors is merely schematic and in accordance with a preferred 10form. The conductors 81 and 135 are in coaxial arrangement as they pass through the core 131 as disclosed in U.S.
Patent No. 3,736,463.
A sensing winding or sensor 137, usually of a plurality of turns, is provided on the core 131 for sensing an imbalance in the conduction current levels of the pri-mary conductors. Such an imbalance produces a sensed current in the winding 137 which, if of sufficient magni-tude and occurring for a sufficient time, actuates a trip circuit 139 in order to actuate the circuit breaker on the 20conductors 81 and 135 on the input side of the differential transformer 129. The trip circuit 139 may be of various known types including, for example, those disclosed in -the above-mentioned U.S. Patent No. 3,73~,468. The ground fault circuit interrupter 127, the trip circuit 139, and the circuit breaker are shown in ~.S. Patent No. 3J745,414.
The circuit illustrated is merely exemplary. The invention may also be embodied in a circuit having more than two conductors, such as a single phase, three wire system or a three phase, four wire system. Terminals 141 3and 143 on the input side are for connection to a power , .
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13 48,020 source or supply. One or more loads to be energized by the system may be connected to terminals 145 and 147 on the output side.
If a ground fault occurs on the line condwctor 133 in the load circuit, without a grownded newtral condi~
tion, the operation of the apparatus is essent.ially straightforward in accordance with past practice. If a leakage path to the ground occurs from the neutral conduc-tor on the load side of the transformer, as indicated by the path 149 to ground, which may have some impedance, the apparatus so far described would no-t be sensitive to line conductor grounds and would prevent an unknown hazard to those relying on the protection of the apparatus. The problems resulting from a grounded neutral condition are particularly serious when a load is not connected in the system. - -As shown in U.S. Patent NQ. 3,736,468, an ou-tput transformer 151 of the current sensing type is provided on the load side of the sensor or differential transformer 129. The output transformer 151 has a core 153 on which a primary winding 155 is provided. The winding 155 is a conductor connected between the line and neutral conductors 81 and 135 of the system. To minimize the losses in the primary winding 155 and to enable use of a small cross-section conductor, a current limiting means, such as a resistance 157, is interposed in series with ~he primary on the side of the line conductor 81. In most applications a resistance of 10~000 to 35,000 ohms is suitable.
~ In operation~ in the absence of any load on the output terminals and also in the absence of any ground on 14 48,~20 the neutral condllctor, a current path with minor losses is completed ~hrough the l-in~ concluctor 81, the primar~ wind-ing 155, and the neutral conductor 135. The polarities of the windings of the output transformer 151 are not signifi-cant and -the benefits are obtained whether or not they are the same as the primary windings of the transformer 129.
Structurally the ground Eault detector 127 is shown in Fig. 4. The several parts including the differen- i tial transformer 129, the trip circuit 139, and the output transformer 151 are mounted within spaced formed projec-tions comprising integral parts of the intermediate portion 7 of the housing on the side of the compartment 17 Accord-ingly, the several elements are retain~ed in place upon attachment of the cover 11 More particularly, the -trip circuit 139 includes a solenoid 159 having a plunger with an outer end 161. A
lever 163 is mounted on a pivot pin 165 which is a molded portion of the back wall 8. The lever 163 has a notch 167 (Fig. 5) which engages the solenoid plunger adjacent the outer end 161 thereof. The lower end of the lever 163 includes an integral projection or prong 169 (Fig. 5) which extends through an opening 171 in the partition wall 13.
The end of the projection 169 is contiguous to the bimetal 77 of the circuit breaker in the compartment 15 (Fig. 2).
When the solenoid 159 is actuated, the lever 163 rotates slightly cownterclockwise, whereupon the projection 169 moves the bimetal 77 a .suf-ficient distance to trip the circuit breaker.
. The lever 163 is free from any binding forces and 3~ suitable for easy assembly. Moreover, tbe lever being com-.

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48,020 posed of insulating material preven-ts electrical currents from 1Owing from the solenoid to the bimetal 77. The grounded neutral conductor 135 is ho-used withLn the restric-ted con~ines of the molded housing so that essentially a suitable mechanical insulation is achieved, The adapter 173 is constructed to enhance electrical a~taehment and to provide for strain relief of the assembled members. The test circuit means is arranged to exclude the need for a separate housing. By providing molded housing members adapted to confine the various parts in place a restricted movement of the parts including the transformer coils, the trip circuit, and the associated resistor enhanee reliabil-ity and positional individuality.
The portion of the neutral conductor 135 extend-ing through the core 153 of the output transformer 151 comprises an adapter 173, the right end of which (Fig. 4) is connected at 175 to the cable portion of the conductor 135. The left end of the adapter 173 is connectecl to a wire-like conductor 177 (Fig. 7). An intermediate portion 20of the adapter 173 includes a U-shaped part 179 which extends through the core 153 as the secondary winding thereof -and which is connected at 181 to a continuation o~
the cable portion of the conductor 135. As shown in Figs.
4 and 6, the cable portion 135 extends through the core 131 of the transformer 129 and continues to the terminal 147.
As shown in Figs. 2 and 6, the flexible conductor 81 extends through an opening 183 from the upper end of the bimetal 77 and around and through the toroidal core 131 in thè comp~rtment 27 and then through an opening or aperture 3means 183 in the partition wall 13, where it re-enters the . -.

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16 48,020 compartment 15 and is connected to the terminal strap 83 as set forth above. An insulating cover 187 covers the flexi-ble conductor 81 to prevent its electrlcal contact with any portion of the ground fault circuit interrupter such a5 ~he neutral conductor 135 in the core 131 o~ the transformer 129.
To provide a mechanical advantage, the lower portion of the lever 163 is slightly lon~er than the upper portion thereof so that a solenoid 159 of lesser force is required for the desired movement of the lower end of the lever against the bimetal 77. After tripping a conven-tional latch spring on the bimetal 77 automatically reposi-tions the solenoid lever for the next strQke.
The toroidal core 131 (Fig. 6) comprises a stack of laminated rings 189 of an iron base composition which rings are encased within a cover 191 of an electrically in-sulating material. A coil 193-encircles the assembly of the laminated rings 189 and the cover 191 and the assembly of the rings, cover and coil are encased within an outer cover 195. The outer cover 195 has an outwardly ~xtending arm portion 197 in which the two leads of the coil 193 are embedded and extend through the trip circuit 139 (Fig. 7).
To enable periodic verification of the ground fault circuit breaker structure 3, a test circuit 199 (Fig.
7) is provided and excludes the need for a separate housing for the test switch means. The test circuit includes a manual button 201 which closes a circuit between the conduc-tor 177 (Fig. 7) and a wire 203 3 the latter of which leads to the ~eutral conductor 135 ahead of the differential transformer L29 as we:Ll as to the trip circuit 139.
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17 ~8,020 In accordance with this invention, the housing 5 (~ig. 2) comprises a groove 205 that extends from the area of the test button 201 to the terminal 147. The conductor 177 is located in the groove 205 and the ri~id, wi~e-like conductor 177 comprises two end portions 207 and 209 (Fig.
8). The lower end portion 209 is in electrical contact at 211 with the load terminal 147 where said portion 209 is secured by a pressure fit, or clamping connection, between the insulation housin~ 5 and the terminal 147.
10The upper end portion 207 extends across a sur-face of the housing 5 at 213 where said portion 207 is aligned with the test button 201. When the button 201 is pressed, ~he test circuit which includes c~onductors 211 and 213~ is closed between the circui~ 199 and the conductor 177.
Accordingly, the rigid wire-like conductor pro-- vides a mechanical contact surface for completing the electrical connection by using a pressure fit connection to the ungrounded load circuit terminal, thereby eliminating welded or soldered joints with small flexible loads. By imbedding the wire-like conductor in the groove, there is no need for insulation on the conductor.

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Claims (2)

18 48,020 What is claimed is:

1. A ground fault circuit interrupter for use in a load center and comprising a circuit breaker, a ground fault detector, and an insulation housing therefor; the circuit breaker comprising a pair of cooperable contacts operable between open and closed positions, an operating mechanism for operating the contacts and comprising a latched pivotally supported trip member, trip means for latching the trip member, a load terminal structure, a line terminal structure, a line conductor of an AC
electrical distribution system connecting the trip means to the load terminal structure; the ground fault detector comprising a current monitoring core, a plurality of primary windings on the core, each being one of the line and a neutral conductor of the AC electrical distribution system, a secondary winding sensing current imbalance between currents in the primary windings, means responsive to a predetermined sensing signal on said sensing winding to open said line conductors, test means to test the ability of the apparatus to trip upon occurrence of either line to ground fault conditions or neutral to ground fault conditions, said test means comprising a circuit branch connected from a first point one a line conductor on the load side of said differential current transformer and a second point electrically proximate to the neutral conductor on the supply side of said differential 19 48,020 current transformer, said circuit branch including a normally open test switch that is closable to cause unbalanced currents in said primary windings, said circuit branch connected from said first point on a line conductor comprising a wire-like conductor extending from said first point to said test switch, the insulating housing having groove means in which the wire-like conductor is secured by a pressure fit, and the wire-like con-ductor comprising one end portion in a pressure fit connection between the load circuit terminal and the insulating housing.

2. The ground fault circuit interrupter of claim 1 in which said conductor comprises a second end portion in line with the path of movement of the test switch.