Test Switch Features


  • Non-ferrous materials – highest quality copper (blade), phosphor-bronze (jaw, hinge, spring washer, shorting element, test jack,) and brass (terminal studs, rivets, assembly nuts and screws) are used for all current-carrying metal parts.
  • Nickel plating protects all current-carrying components including hardware. This corrosion-resistant nickel finish ensures good electrical contact and smooth operation of moving parts even after years of inactivity.
  • Stainless steel is used for mounting ears and mounting hardware.
  • Self-extinguishing flame-retardant thermoplastics rated at Underwriters Laboratories’ best rating (V-O) are used in all non-metal components.

1. Safety-Knob Handle: No more risk of electrical shock. The operator’s fingers stay out of reach of current-carrying components by using a standard 5/16 inch nut driver to open and close the test switch. Just fit the nut driver over our patented safety knob and pull up to open or down to close. Of course, the W3TS Test Switch can always be operated by hand. (See Safety Knob Instructions.)

2. Thermoplastic Mounting Plate: The right-angle foot of our patented barrier wraps around each test switch to form a fail-safe nonconductive backing for the test switch block – no metal mounting plate or potting is needed. The backing serves as a thermoplastic mounting plate requiring no additional insulation. This assures a safer, more reliable test switch. The footed barriers are extra high and permanently mounted to provide maximum circuit isolation. The thermoplastic mounting plate is reinforced by a rod mount which supports the weight of the block.

3. Special Blade Shape: The copper knife blade is shaped so that the edge of the blade enters at a right angle to the jaw. This keeps the full width of the blade in contact with the jaw as it enters or exits, making a better connection.

4. One-Piece Hinge Jaw: One piece construction of the hinge jaw eliminates unnecessary multiple connection points.

5. Contact Jaw: The contact jaw, a spring in itself, assures a low resistance contact and no overheating.

6. Fixed Terminal Studs: The #10-32 stud terminals on which wiring connections are made are squared against the test switch base and cannot be turned or backed out.

7. Short-Circuit Element: The short-circuiting test switch has a rugged make-before-break element to short the secondary of a current transformer. Its positive stop prevents the blade from lifting out of contact with the element. A brass common bar completes the circuit to the adjoining pole.

8. Test Jack: The test jack eliminates the possibility of opening current transformer secondaries. It provides easy measurements in current circuits without disturbing permanent wiring. The test jack only carries current when making a measurement because it is shunted by a standard test switch blade that stays closed except when the test jack is used. A dual-circuit test plug inserted into the test jack puts the measuring instrument in series with the current circuit.

9. 5/8 Inch Centers: The W3TS Test Switch is compact and space-saving.

10. Ganged Handles: test switches can be operated independently, or insulated yoking bars can gang any number of test switch handles together for simultaneous operation.

11. Rod Mount: The rod mount supports the weight of the test switch block and reinforces the nonconductive mounting plate formed by the footed barriers.

12. Stainless Steel Mounting Ears: At each end of the test switch block, triple-slotted mounting ears securely mount the block to panel-board, switchboard or other surface .

13. Color-Coded Handles: Standard colors are red for potential elements and black for current elements. Other colors are available by special order.

14. Marker Tag: Each safety-knob handle is slotted for insertion of a tag to mark or color-code individual poles. A specification drawing for customer-supplied marker tags is available here.

15. Standards Compliance:

  • The Testswitch LLC W3TS knife blade miniature test switch has qualified under IEEE Standard C37.90 — Standard for Relay and Relay Systems Associated with Electric Power Apparatus.
  • Underwriters Laboratories, Inc. qualifies the Testswitch LLC W3TS knife blade miniature test switch at 600 Volts, 30 Amps in the United States and Canada under UL Standard 414 (7th Edition) and Standard C 22.2 No. 115-M1989 — Standards for Meter Socket Bases and Associated Assemblies, Meter Switches. Refer to file No. E189531.
  • The Testswitch LLC W3TS knife blade miniature test switch is compliant with ANSI C 33.31 — Standard for Knife Switches
  • The Testswitch LLC manufacturing process is ISO 9001:2008 registered.
  • SVHC under REACH Compliant as per June 2012 Revision
  • RoHS Compliant as per EU Directive 2002/95/EC

16. Tamperproof Covers: Covers are attached to two thermoplastic studs with captive knobs. The studs have holes for wire seals. All back-connected switches come with covers. Covers are also available for front connected switches.

17. 1 to 52 Poles in a Single Block: Unit construction allows unlimited arrangements of up to 52 poles in a single block.

18. Front connected switches have an option of DIN Rail Mounting. Plated steel clips mount to standard 35mm Din Rails.