US2041250A

US2041250A - Switch

Info

Publication number: US2041250A
Application number: US670430A
Authority: US
Inventors: Herman C Kalwitz
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-05-11
Filing date: 1933-05-11
Publication date: 1936-05-19
Anticipated expiration: 1953-05-19

Description

W W3@ H. c. KALWITZ SWITCH Originalv Filed Aug. 26, 1951 4 Sheets-Sheet l May W, W36- H. c. KALWITZ Mmm swiTcH original Filed Aug. 26, 1951 4` Sheets-Sheet 2 Wil/5f 2 4 vSheets-Silea?I 3 Original Filed Aug. 26, 1931 NLE H. c. KALWITZ r SWITCH Original Filed Aug. 26, 1931 4 Sheets-Sheet 4 @u y V Patented May ,19, 1936 UNITED STATES PATENT OFFICE Rei-lied for forfeited application Serial No. 559,358, August 26, 1931. This application May 11,1933,

Serial No. 670,430

11 Claims. (Cl. 200-48) This application is a continuation in part of my copending application that has now issued as Patent No. 1,944,661, and a substitute for my application, Serial No. 559,358, filed August 26, 1931.

'I'he present invention relates to electric switches in general and more particularly to such switches as are used on high, or moderately high, voltage systems and are contained in a suitable housing. While the present invention is particularly applicable to enclosed type disconnect switches it is not limited thereto, being also applicable to other types of disconnect switches, or to high voltage switches in general, such as circuit breakers or the like.

It is one of the objects of the present invention to provide a switch which will aord a high degree of safety to people working on apparatus connected therewith. I accomplish this end by providing a grounded barrier which is arranged to move between the two switch terminals when the switch is opened. By this arrangement the switch contacts may be placed closer together without sacrificing on the safety factor.

In disconnect switches of the type enclosed in a suitable housing or casing the barrier may be utilized to give a visual indication of the open or closed position of the switch. It is a familiar rule with power operating companies that no man shall work on an oil circuit breaker unless he can actually see the disconnect switch in such position as to interrupt the continuity of the proper line conductor. When such switches are placed in a housing or casing the workman can never feel sure that the switch is in such position as to guarantee safety, notwithstanding the fact that the usual indicating means external of the casing indicates such position. The more mechanism there is interposed between the indicator and the switch blade or member that actually closes the gap between the terminals of the switch the greater is the probability that a false indication may be given due to some of the interposed apparatus failing to function properly. This has always constituted a source of danger to operating men. In accordance with the teachings of the present invention this danger is eliminated by mounting the barrier directly on the switch blade support within the casing so that the barrier moves with the switch blade. Two aligned windows are provided in the switch housing and the arrangement is such that the grounded barrier obstructs light from passing through both windows when the switch is moved to its closed position, whereas it permits light to pass through both windows when the switch is moved to its open position. If the barrier is in the way between the two windows, no light can shine through and the attendant therefore knows that the disconnect switch is closed. If light does shine through, the attendant thereby knows that the barrier is out of the way and the disconnect switch is open so that the oil circuit breaker is disconnected. If the disconnect switch is immersed in a bath of insulating oil which is relatively discolored or otherwise not clear, an electric light may be placed on the outside of and adjacent to o-ne of the windows.

In accordance with the teachings of my invention opening of the switch results not only in an interruption in the electrical continuity of the conductor but also in a division of the oil chamber into two compartments wherein any potential above ground that may exist in one of the compartments cannot possibly be carried over to the other compartment. The grounding barrier that is interposed between the two terminals provides a physical separation of the continuity of the sheath or casing within which the switch is located. At points where a grounding barrier cannot be maintained I interpose an insulating barrier. By this arrangement I positively preclude any possibility of a workman inadvertently poking a screw driver or other object beyond the confines of the portion of the sheath or housing within which he is working, and toward the other portion. In addition, I provide means for positively placing ground potential on the contact bar when the switch is open. Thus the contact bar, which extends between the two portions of the switch casing, cannot possibly be at any potential other than ground potential when the switch is open.

AIt is further object of my present invention to provide an improved switch wherein electrical connection may be made with great facility and wherein the line circuit extending from the switch may be by-passed when the switch is open for inspection or repair purposes.

The attainment of the above and other objects of the present invention will be apparent from the following specification taken in conjunction with the accompanying drawings forming a part thereof.

In the drawings:

Figure 1 is a transverse sectional view through one bay of a switching station wherein my improved switches are employed;

Figure 2 is an enlarged vertical transverse section through the switch;

Figure V3 is a horizontal section taken along the line 3-3 of Figure 2 and looln'ng in the direction of the arrows;

Figure 4 is a vertical transverse sectional view through a modified form of switch embodying the principles of my invention;

Figure 5 is a sectional view taken along the line 5-5 of Figure 4;

Figure 6 is a fragmentary sectional view illustrating another embodiment of my invention;

Figure 7 is a fragmentary view of a portion of the top of the switch shown in Figure 6; and

Figure 8 is a fragmentary view illustrating the application of a photoelectric cell to a switch of my invention.

In the following detailed specification like reference numerals refer to like parts throughout.

Reference may be had rst to Figure 1. A main bus is indicated at I and a transfer bus at 2, both of the buses consisting of longitudinal conductors extending lengthwise of the station. 'Ihese buses vare adapted to be connected to a power conductor 3 which may be an incoming 0r an. outgoing line. The main Ybus I is adapted to Vbe connected to the conductor 3 by means of a pair of disconnect switches, one of which is indicated at 4, and an oil circuit breaker 5. The transfer bus is adapted to be connected to the line 3,by means of an oil circuit breaker 6 and a. pairof disconnect switches, one of which is indicated at 1, and connects one pole of the circuit breaker Vto the line 3. The particular way in which the connections are established will be morefully set forth as this description. proceeds. For a further description reference may be had tothe parent patent as set forth above. The three conductors comprising the main bus and the three conductors comprising the transfer bus are disposed each in a separate metallic tubular sheath, each sheath being provided with 'a metallic junction box such as is indicated at I0, at the Vpoint where the connection is to be made to the conductor within. `'l'he tubular sheaths within which the conductors are disposed are preferably thin copper pipes or the like, and the boxes 0.are preferably thin cast iron boxes. They may beof anyfform of sheet metal or of cast metal such as bronze, aluminum, non-magnetic iron, or any suitable medium, preferably of a non-magnetic character.

The junction box I0 for the bus I rests upon a. similar box or casing there being'a metallic wall I2 common to the two boxes. A bushing type insulator I3 extends through this wall and provides insulation for the tap which extends from the conductor, through the bushing, to a stationary terminal I4 of the disconnect switch 4. VThe terminal I4 is mounted upon a block I6 of insulation, `and a similar terminal I8 is likewise mounted upon a block of insulation I8 within the casing Il, these insulating blocks preferably beingsupported upon the bottom wall of the casing II. The casing II has an upwardly projecting extension 20, which is more clearly shown in Figure 2 and which will be more fully described as this description proceeds.

The casing has a flange at 25 to which an oil circuit breaker terminal box 26 is adapted to be clamped by a cooperating ange. This box 26 is generally rectangular, although the form of the same is optional. At its bottom it hasa clamping Viange 21 to which a ange of a suitable collar 28 is clamped. Suitable cap screws or the like are employed for joining these two fianges. The bottom of the collar 28 likewise has a clamping ange which is coupled to a flange forming a part of the circuit breaker frame. This last mentioned ange is formed on a sleeve 29, the lower end of which forms a part of the top frame of the circuit rbeaker.

The sleeve 28 surrounds a terminal bushing 30 of the circuit breaker, the terminal bushing being a permanent part of the circuit breaker structure. 'I'he bushing extends upwardly into the box 26 and supports a terminal 3| which is a permanent part of the circuit breaker. To the terminal 3| a conductor 32 is connected, thereby establishing a connection between the terminal I8 of the disconnect switch 4 and one side of the circuit breaker.

The circuit breaker 5 has, of course, two terminals, as is well known to those skilled in the art, mounted upon the top frame of the same. The second terminal is identical to that above described and is located immediately in the back of the bushing 38. This terminal is connected, through a disconnect switch similar to the switch 4 and located immediately in back of the same, to the conductor 3. The connections between this side of the circuit breaker and the conductor 3 are identical to the connections between the circuit breaker 6 and the conductor 3, as illustrated at the left hand side of Figure l.

The bushing 3D' of the oil circuit breaker 6 affords a connection to the terminal I8 of the disconnect switch 'Ihis connection is identical to the connection through the bushing 30 to the terminal I8, as previously described, and similar parts have been indicated by similar reference numerals which, in connection with the circuit breaker 6, are primed.

A conductor 35 extends the circuit from the terminal |4 of the disconnect switch 1, said conductor extending through an opening in the end wall of the casing II', through an oil barrier 36 and a tube 3l into a box or casing 38 which forms a junction between the conductor 35, extending from one side of the circuit breaker 6, and a corresponding conductor correspondingly extending from the side of thecircuit breaker 5 opposite to that illustrated in Figure 1.

The conductor 35 is connected to the line conductor 3 at 40 where the line conductor passes through an insulating bushing 4|. The bottom of the junction box 38 has a short flanged nipple 42 bolted thereto with the upper end of the bushing 3| projecting into the casing 38. The other end of the flanged nipple 42 is bolted to the top of a current transformer casing 43 and the lower end of the bushing 4| projects thereinto. A current transformer 44 of the removable type, that is, it has a main conductor, the end of which may be clamped to the adjacent conducting parts so that the entire transformer may be readily removed, is mounted in the casing 43. The current transformer conductor extends through a suitable bushing 46 into a terminal box 41 where connection is established to the line 3.

The disconnect switches 4 and are of identical construction and are illustrated more particularly in Figures 2 and 3.

The Vextension 20 which is mounted upon the terminal box forms a liquid-tight seal therewith and constitutes a continuation of the box to provide a housing for an operating rod 58 and a barrier 5|. The extension 2U extends the full width of the casing II and is provided with a cover 52 having a collar 53 constituting a bushing through which the operating shaft 50 may move while maintaining a liquid-tight seal.

The rod or operating link supports at its lower end, a switch link or bar carrying contacts 56 and 5'I at its ends adapted to cooperate with the spring contact lingers I4 and I8 mounted upon the terminals that are supported by the insulators I5 and I9, as previously set forth. The switch bar 55 is a conducting link which is removable from the contacts I 4 and I 8 to physically and electrically interrupt the continuity of the circuit extending between them.

The disconnect switch bar 55 is adapted to be thrust downwardly into the position shown in Figures 2 and 3 to disconnect the circuit extending to the corresponding pole of the circuit breaker 5 shown in Figure 1. The opposite pole of the `circuit breaker 5 is provided with a disconnect switch corresponding to the disconnect switch I of Figure 1 and similarly connected for opening that side of the circuit breaker.

The barrier 5I comprises a metallic plate 60 preferably, but not necessarily, completely covered with insulation except at its edges by an envelope 6| of insulation, and this metal plate 60 is guided in suitable guideways 63 and 04 formed at the sides of the casing. This is clearly shown in Figure 3. The barrier 5| is intended to interpose between the disconnect terminals a grounded metallic barrier for insuring workmen against injury during any work upon the oil circuit breakers or in connecting or disconnecting them. The lowering of the disconnect bar 55 is accompanied by the interposition of the grounded barrier between the terminals I4 and I8,'this barrier being grounded through the casing and the guideways such as 63 and 64. In fact, the metallic plate 46 may be connected by a flexible lead to the grounded casing so as to insure not only that the disconnect switch is open but also that a grounded barrier is interposed between the live parts and the parts which are intended to be rendered dead by the opening of the disconnect switch.

The barrier5l is adapted to enter the housing 20 when the disconnect switch is closed. Aligned

sight openings

65 and 66 are provided upon opposite sides of casing 20. These sight openings have

glass windows

61 and 68 held in place by clamping rings 59 with suitable interposed gaskets to seal the sight openings. The barrier 5| performs the additional function of providing an indicator for indicating the open or closed position of the disconnect switch. That is tosay,when the barrier is lowered, an operator or an attendant can look through the two windows and see that the switch is open. If the oil is relatively discolored or otherwise not clear, an electric light may be placed on the outside of and adjacent to one of the windows to determine whether or not the barrier is located between the two Windows. If the barrier is in the way no light can shine through and the attendant therefore knows that the oil circuit breaker is not-fully open, or is closed. If the light shines through and may be seen from the opposite window the attendant is thereby apprised of the fact that the barrier is out of the way and the disconnect switch is open, so that the oil circuit breaker may be physically removed or worked upon.

Where it is desired to employ the disconnect switch of my inventionfor sectionalizing cable, the two ends of the casing II are provided with glands for wiping joints to the sheath of the cable. I do' not wish to be limited to putting the cable connections at the ends, as the casing II may be provided with suitable openings for the connection of the cable vends at eitherthe sides or the ends of the housing II. The cable may be a single phase or multi-phase cable, and where multi-phase cable, such as three-phase cable, is to be sectionalized, the housing I I may be a unitary housing for a number of disconnects, suitably separated by barriers, and the operating mechanism for all three phases may be suitably connected together. Such disconnect switches may be placed under ground or. in fact, in any position in which cable or other apparatus may be located, 'without danger of the same becoming grounded through moisture or the like, and with the assurance of safety for the workmen. Instead of employing the packing gland 53 for the stem' 50 of the disconnecting switch, a metal expansible bellows may be employed for maintaining at all times hermetically sealed joints.

The switch shown in Figure 4 is mounted within a casing |00 to the opposite end of which are welded terminal boxes I 0I and |02. The current carrying conductors extend into the casing `IIlIl by way of bushings |03 and |04 which are bolted to the end walls of the casing |00 and form liquidtight seals therewith. The terminal boxes IIJI and |02 have circular openings in their tops, bottoms and sides for extending circuit connections. In the case of the terminal box |0I the bottom and side openings are closed by plates |06 and |01 that are suitably gasketed and bolted to form a liquid-tight seal. A pot-head body |08 is secured to the upper opening in the terminal box IDI and extends a line conductor |09 to the terminal of the bushing |03. In alike manner, plates IIO and III are suitably bolted to the top and bottom openings of the terminal box |02, and a pot-head body I I2 is secured to the side opening of this box and extends a conductor I I4 to the bushing |04. The various openings in the terminal boxes IDI and |02 are of the same sizes, so that the pot-head body may be used to extend the circuit to the switch through any of the openings, depending upon the direction of the incoming oroutgoing line conductors. The conductor |09 extends the circuit through the bushing |03 to a terminal I5 from which a male plug type contact I6 extends upwardly. A exible lead conductor III is clamped to the terminal I I5 and extends the circuit to a switch contact I I8 mounted on an insulator I9 that is mounted on the under side of a cover plate |20 of the casing |00. The cover plate |20 is bolted in place by means of a number of bolts and wing nuts indicated at |20a.

The conductor I I4 extends the circuit to a terminal II5 and to a switch contact II8' which is mounted on an insulator ||9 that is bolted or otherwise secured to the under side of the cover |20. The leads I and I I1 may be removed from the terminals ||5 and H5 by loosening the respective nuts that hold them in place.

The cover |20 is provided with openings immediately above the respective male plug type contacts I I6 and I I6', said openings being closed by removable closure members |2I and I2I that are suitably gasketed toy form liquid-tight seals.

Aswitch blade |25 is mounted on an insulating rod |26, which is bifurcated and through which extends a metallic grounding plate |21 the lower edge of which terminates at a safe distance from the blade |25. An insulating plate |28 extends from the lower edge of the plate |2'| into proximity with the blade |25. When the switch is open the blade |25 rests upon spring contacts |30 and |3I Which maintain ground potential upon the blade. To close the switch the grounding plate |21 is drawn upwardly, thereby bringing the switch blade into contacting relation with the switch contacts II8 and |I8. Actuation ofthe switch is accomplished through a rotary shaft |35, a crank I 36 and a link |31 which connects the crank with the plate |21. The grounding plate |21 moves within an extension |39 that is welded to and extends the full width of the casing |08, forming a liquid-tight seal therewith. This corresponds to the extension 20 of Figure 2.

In this switch, as in the switch shown in Figure 2, the grounding plate |21 terminates between the lower edges of two aligned windows |4| and |42 when the switch is open. When the switch is closed the plate moves between the windows.

If it is desired to remove the cover, for inspection or repair purposes, the closure caps I2 I-I 2 I are removed togain access to the leads |I1 and i I1', and these leads are removed from the plugs |I6 and ||6. Thereafter, upon loosening of the wing nuts |28a, the entire cover |20 may be removed, said cover carrying with it the insulators |9| i6', the terminals |I8-I I8', and the switch blade and the supporting means therefor.

The switch shown in Figure 4 may be a single phase switch, as is the switch shown in Figures 2 and 3, or it may be a polyphase switch. In the present embodiment I'have illustrated the same as a polyphase switch, comprising four separate side by side switches. This is illustrated in Figure 5. The respective switch rods are all mounted upon the same barrier plate |21. The switch units are separated from one another by barrier plates Ilil that extend across the casing |00 at right angles to the barrier |21 and are slotted to extend on the opposite side of the barrier |21.

When the switch is opened the springs |30 and |3I constitute rebound springs for breaking the fall of the switch blades and associated parts. r'hese' springs also constitute ground contacts for the switch blades.

If it is desired to extend a circuit connection to or from the plug I I6 or I6', it is merely necessary to remove the corresponding closure cap |2| or |2I and establish connection with the plug. This may be accomplished by inserting, into the opening above the plug, an insulating bushing which carries at its lower end a female contact that establishes electrical connection with the plug II6 or with the plug |I6. Thus, if the conductor 89 constitutes an outgoing line it is possible to maintain service on this line even when the switch is open, this being accomplished by plugging a line connection to the male plug |I6. The left hand half of the disconnect switch is ien alive, whereas the right hand half is at ground potential and may be worked upon with safety. This same' procedure may, of course, be followed for extending a circuit to the conductor Elfi by way of the plug II6.

Reference may now be had to Figures 6 and '7, wherein I sho-w a modified form of switch structure. In this embodiment of my invention the circuit from the conductor extending through the bushing |63 is brought to the switch terminal I8 by means of a switch blade |50 that is carried at the end of the bushing I 83 and cooperates with pronged contacts I5| that are carried by a proper bracket |52 at the bottom of the insulator IIS. Similar connections are established from the conductor that extends through the bushing |84 to the right hand switch terminal I I8. This arrangement eliminates the necessity of the flexible leads ||1 and ||'I. In this arrangement when the cover is removedV it may be lifted bodily upward without previously disconnecting leads such as ||1 and ||1. When the cover of this switch housing is lifted the insulators ||9 and |I9' carry the brackets |52 and |52 upward whereby the pronged contacts I5I and I5I are `moved out of engagement with the respective knife terminals |50 and |50.

In the switch shown in Figure 6 the side wall |60 constitutes a portion of the cover, said side wall being bent over to form the portion I 6|. Likewise, the opposite side |62 of the switch is also integral with a portion of the cover as indicated at |63. 'Ihe portions I6I and |63 are provided with circular holes above the respective male plugs ||6 and |I6', which circular holes are closed by suitable closure plates |64 and |64. The inner peripheries of the openings above the plugs ||6 and |I6 are upwardly flanged, as indicated at |65, and the inner edges of the top portions |62 and |63 are also upwardly flanged, as indicated at |68. The removable cover |20 extends between the upwardly flanged portions I 68|68 and beads over those ilanges to form a liquid-tight seal. Suitable bolts I 'I0-|10 serve to lock the cover plate IEM-|64 in place and likewise serve to hold the cover |20 in place.

From my above description it is apparent that I have invented an improved switch having a degree of safety and exibility which is highly desirable. Should an operator be unable to look through the windows on the opposite sides of the upwardly projecting extension 20 or I 39, he is thereby warned that it is not safe to work upon the switch. If the oil becomes foggy, this will indicate danger, rather than safety-a highly i desirable characteristic. Also, the barrier plate is so located that if ity is not between the two windows, as is evidenced by light shining between the windows, it can be nowhere else than between the switch contacts, and the operator is thereby apprised with certainty that the switch 1s open.

In Figure 8 I have shown the application of a photoelectric cell to a switch such as is shown in Figure 2, it being obvious, from Figure 8, that the same is applicable to the switch shown in Figure 4. A housing 80, pivoted at 8|, contains an incandescent electric lamp 82, which may be supplied with energy from any suitable source. Light from the incandescent lamp 82 shines through the window 61 and, if the barrier 60 is in its lowered position, through the window 68, and strikes a photoelectric cell 84. The photoelectric cell 84 is mounted in a housing 85 pivoted at 86. The circuit of the photoelectric cell 84 includes a signal 81 which may be either a visual or audible signal, that is, either an electric light or a buzzer, or the like. A short circuiting switch 88 is provided for the signal 81. 'Ihe circuit for the photoelectric cell 84 extends by way of the conductors 89 and 90 to a source of electrical energy and to a signal which may be mounted on a switch board at some remote point. When the disconnect switch is in its open position the signal 81 will be energized and thereby give a continuous indication of the switch open position. Should the light 82 fail, or should any defect develop in the signaling circuit, the resulting deenefrgization of the signal 81 will indicate danger. Therefore, as long as the signal 81 is operative the attendant knows that the disconnect switch must be in its open position and that it is safe to work upon the circuit.

In compliance with the requirements of the patent statutes I have herein shown and described alfew preferred 'forms of my invention.

It is, however, to be understood that the inven-l tion is not limited to the precise construction herein shown, the same being merely illustrative of the principles of the invention.

What I consider new and desire to secure byA terminals mounted. in insulated relation, a hous` ing for the switch enclosing said terminals, a connecting bar for Vthe terminals, a supporting member for the bar, and a grounded barrier carried by the supporting member between the terminals, said disconnect switch housing having an extension into which the barrier moves when the switch is closed, said extensionfincluding a pair of aligned openingsthrough which light may pass only when the barrier is in substantially its full open position, said barrier in its other positions obstructing the light path between said openings.

2. In a switch mounted in a switch housing, means for indicating the open and closed position of the switch, said means comprising a pair of aligned windows for permitting light to be directed through the housing, and a barrier in the housing obstructing said light and moved out of obstructing position as the switch reaches its open position, the edge of the barrier being adjacent the line of sight between the windows when the switch is open whereby the sight path is obstructed responsive to the initiation of the switch closing movement.

3. A switch comprising a casing having top, bottom and side walls defining an oil tank, insulators within the casing, contacts mounted on the insulators, bridging means movable into and out of bridging relation to the contacts, a grounding plate carried by the bridging means and insulated therefrom, the casing having a slit-like opening within which the plate moves as the bridging means is moved between its switch closed and its switch open positions,rand, separate from the casing, an enclosure surrounding the slit-like opening and secured to the casing and forming a liquid tight seal therewith and open at the side facing the slit of the casing, said enclosure having a pair of aligned windows between which the grounding plate moves, said plate being adjacent to but vclearing the line of sight between said windows when the bridge member reaches substantially its full open position and said plate moving into vision obstruction position between the windows upon the initial movement of the bridge member from its full open position towards its closed position.

4. A switch comprising a casing having top, bottom and side walls defining an oil tank, insulators within the casing, contacts mounted on the insulators, bridging means movable into and out of bridging relation to the contacts, an insulating actuating rod connected to the bridging means, a grounding plate carried by the rod and insulated from the bridging means, the top of the casing having a slit-like opening within which the rod and the plate move as the rod is moved between its switch closed and its switch open positions, an open bottomed enclosure surrounding the slit-like opening and secured to the casing and forming a liquid-tight seal therewith, the top of said enclosure being closed, and said rod extending through said enclosure and moving within an opening in the top and filling said u opening, said enclosure having a pair of aligned windows between which the grounding plate the line of sight between said windows when the bridge member reaches substantially its full open position and said plate moving linto vision obstruction position between the windows upon the initial movement of the bridge member from its full open position towards its closed position.

`5.'A switch comprising a casing having'a removable cover, a switch structure supported therefrom and including insulators, switch terminals mounted on the insulators, a switchblade for establishing connections between the terminals, a barrier plate conjointly movable with said blade into a vertical plane between the terminals, conductors, insulators projecting normal to` said rst named insulator for extending the conductors into the casing, terminals terminating the conductors at points spacedV from said switch terminals and switch means operable upon closure of said cover oversaid casing for establishing electrical connection `between said last mentioned terminals and the switch terminals.

6. A switch comprising a casing having a removable cover, a switch structure supported therefrom and including insulators, switch terminals mounted on the insulators, a switch blade for establishing connections between the terminals, conductors, insulators extending the conductors into the casing independently of said `removable cover,` terminals terminating the conductors, and switching means including portions connected to the switch terminals and portions connected to the last mentioned terminals and, closed by closure of the cover for establishing an electrical connection between said last mentioned terminals and the switch terminals.

7. A switch including a casing, insulated con-` ing the cover carried terminals to the rst mentioned terminals upon closure of the cover on the casing.

8. A switch comprising a casing, a terminal box at each end thereof, conductors extending into the casing through insulators providing a liquidtight seal, terminals mounted on the respective conductors within the casing, openings in the casing wall opposite the terminals for extending circuit connections to the terminals, closures for the respective openings, switch terminals in the casing and connected to the first mentioned terminals by a removable connection., separate insulators supporting the last mentioned terminals, and a switch blade movable into and out of circuit closing position between the two last mentioned terminals.

9. A disconnect switch comprising a casing, conductors extending into the casing from the opposite ends thereof said conductors terminating in said casing substantially in longitudinal alignment, a pair of insulators mounted in said casing and extending laterally of the conductors, terminals on the insulators spaced from and substantially in alignment with the conductors, means for connecting said conductors to said terninals, a switch blade bridging the terminals and substantially in alignment with the conductors, said blade being gravity biased to the switch open position, a grounded barrier plate connected to the blade but insulated therefrom and movable moves, said plate being adjacent tobut clearing ltsjswltch open'position, guides at the opposite sides of 'the' casing for guiding the'plate, and grounding contacts' engaging the switch blade 5- whenI the blade isin its'open position, said grounding contacts being mountedon leaf spring means constituting cushioning springs for the blade.

- A10.*In combination,l a switch housing, a pair of conductors extending into said housing, con-V 10 tact' blades carried'by and projecting from said conductors, a detachable cover for said housing, insulators carried by said cover, a pair of oiset spaced'contact clips carried by each of said insulatorsgone of each of said pair of clips engaging 15` said contact blades when said cover is positioned upon said housing, a' switch bar for bridging across 'said other'contact clips, and operating means for said bar including a grounded barrier plate member'within'said housing movable in a 20i vertical plane into position between said insulators for dividing said housing between said insul between the terminals when'the blade 'moves toV lators when said switch bar is in switch-open position.

11. A switch structure comprising a housingV disposed between the adjacent ends of two conductor sections, insulators extending the conductors into the opposite ends of vsaid housing;

switching terminals on the ends of said conduc-V