The Original ZENGTAI H-1122 3-Pin Heavy-Duty ON-OFF-ON Toggle Switch (15A 250VAC / 20A 125VAC) is an industrial-grade single-pole double-throw with center-off (SPDT Center-OFF / 3-Position) panel-mount mechanical switch engineered for bidirectional control, dual-source selection, and AC/DC circuit switching. Constructed with a heavy-duty solid nickel-plated metal bat lever, a high-dielectric phenolic/bakelite insulating base, and arc-resistant silver alloy contacts, it provides positive mechanical detent action with low contact resistance across all three positions. Featuring three heavy-duty brass screw clamp terminals and standard 12mm threaded mounting hardware with an anti-rotation locating ring, the ZENGTAI H-1122 is widely utilized in industrial machinery, reversible motor controls (Forward-Stop-Reverse), generator/mains transfer switches, automotive dashboards, winches, inverters, and custom electrical control panels.

Specifications

• Brand / Manufacturer: ZENGTAI (Original Heavy-Duty Switch Series)
• Model / Part Number: H-1122 (H1122)
• Switch Type: Heavy-Duty Industrial Bat Lever Toggle Switch
• Circuit / Pole Configuration: SPDT with Center-OFF (Single Pole, Double Throw - 3 Pins / 3 Positions)
• Switching Function / Operation: 3-Position Maintained / Latching (ON - OFF - ON)
• Electrical Contact Ratings:
  • AC Rating: 15A @ 250V AC / 20A @ 125V AC
  • DC Rating: 15A @ 12V–30V DC (General inductive/resistive switching)
• Contact Material: Silver Alloy Contacts (High electrical conductivity and arc resistance)
• Contact Resistance: ≤ 50 mΩ (Initial at 1A DC)
• Insulation Resistance: ≥ 100 MΩ (at 500V DC)
• Dielectric / Breakdown Voltage: 1500V AC (50/60 Hz for 1 minute between non-connected parts)
• Mechanical Life Expectancy: ≥ 50,000 Cycles
• Electrical Life Expectancy: ≥ 10,000 Operations (at full rated load)
• Actuator Style: Heavy-Duty Nickel-Plated Solid Metal Bat Lever
• Body / Housing Material: High-Dielectric Heat-Resistant Phenolic / Bakelite Casing
• Termination / Connection Type: 3x Heavy-Duty M3.5 Brass Screw Clamp Terminals (Accepts spade lugs, ring terminals, or bare wire)
• Mounting Method: Panel Mount via Threaded Bushing
• Mounting Hole / Cutout Diameter: 12.0 mm to 12.2 mm (Standard 1/2-inch panel hole)
• Bushing Thread: M12 × 0.75 mm
• Operating Ambient Temperature: -25°C to +85°C
• Included Hardware: 2x Hex Nuts, 1x Internal Tooth Lock Washer, 1x ON-OFF-ON Legend Faceplate Nameplate
• Dimensions: Approx. 29 mm × 19 mm × 17 mm (Body only, excluding lever and terminals; Total height approx. 54 mm)
• Weight: Approx. 31 g

Features

• High 15A / 250VAC Heavy-Current Capacity: Engineered to handle high-power AC loads, motor reversing currents, and heating elements without contact pitting or welding.
• 3-Position Center-OFF Functionality (ON-OFF-ON): Features a dedicated central neutral/disconnect state, allowing complete circuit isolation between switching active states.
• Solid All-Metal Bat Lever: Delivers crisp tactile feedback and distinct mechanical detent snap in all three positions, ensuring positive engagement in demanding environments.
• Heavy-Duty Screw Terminals: High-torque brass screw terminals with captive washers accommodate direct wire clamping or secure fastening with M3.5 ring/fork crimp lugs without soldering.
• Durable Phenolic Housing: High-temperature, flame-retardant insulating base offers superior dielectric strength and high vibration resistance under continuous duty.
• Complete Panel Mounting Kit: Includes dual locking hex nuts, lock washer, and an aluminum "ON-OFF-ON" indicator nameplate with an anti-rotation locating tab.

Common Applications

• Motor Forward / Stop / Reverse Control: Direction control for AC/DC linear actuators, winches, hoist cranes, and conveyor drives.
• Dual-Source Power Transfer: Manual selector switching between Mains Grid, OFF, and Generator/Inverter backup power lines.
• Industrial Machinery & Automation: 3-way mode selectors (Manual - OFF - Auto), dual-speed fan/pump selectors, and heating stage controls.
• Automotive, Marine & 4x4 Rigs: Winch in/out controls, dual-battery selector setups (Battery 1 - OFF - Battery 2), and electric trim tab controls.
• Laboratory & DIY Test Benches: Dual-rail voltage routing, test circuit isolation, and polarity reversal switching in custom power supplies.

Usage Tips

• Terminal Connections (SPDT Center-OFF Pinout): The center screw terminal is the **Common (COM)** contact. In the center lever position, COM is completely disconnected (OFF). Flipping the lever up connects COM to the bottom terminal (Position 1), and flipping down connects COM to the top terminal (Position 2).
• Motor Polarity Reversing Circuit: When using this switch for DC motor direction reversal (Forward-Stop-Reverse), wire the supply (+/-) to the center terminal and cross-connect the outer terminals to invert motor polarity safely with a positive stop in the center position.
• Secure Terminal Fastening: For high-vibration automotive or industrial machinery environments, crimp stranded wires with **M3.5 fork (spade) or ring terminals** before tightening down the brass screw clamps to ensure low contact resistance and prevent loose wire fraying.
• Panel Anti-Rotation Alignment: Use the included keyed ON-OFF-ON legend nameplate and ensure the locating tab sits inside the panel notch to prevent the switch body from twisting during operation.
• Inductive Load De-rating: When switching heavy inductive loads (transformers, AC induction motors, large solenoids), de-rate the continuous operating current to **50%–60% of rated capacity (approx. 8A–10A)** to handle turn-off voltage transients and inrush currents.
• Optional Weatherproof Boot: For outdoor, marine, or dusty workshop installations, an optional M12 threaded silicone/rubber toggle boot seal can be screwed over the metal lever to achieve an IP65 splash-proof seal.