Ampere Selector Switch 20A LW28 | Accurate Current Measurement

Ampere Selector Switch 20A — LW28 Series Cam Switch

The LW28-20 ammeter selector switch lets you read current across all three phases from a single panel-mounted ammeter. Rotate the knob to switch between L1, L2, L3, and OFF positions — no need for three separate ammeters on your distribution board.

This is the standard cam-type selector switch used by electricians across Pakistan in 3-phase DB boxes, industrial panels, and generator control boards. Pair it with a CT (current transformer) and a panel ammeter for accurate per-phase current monitoring.

Specifications

Where It's Used

• 3-phase distribution boards — rotate to check amps on each phase without opening the panel
• Generator control panels — monitor load balance across phases
• Industrial motor control centers — quick phase-by-phase current check
• Solar on-grid DB boxes — verify export current per phase

Wiring Setup

Wire the selector switch between your 3 CTs (one per phase) and the panel ammeter. In the OFF position, the ammeter circuit is open. Rotate to L1, L2, or L3 to route that phase's CT secondary through the ammeter. Standard wiring diagram included in the box.

Why Electricians Prefer the LW28

• Solid cam mechanism — no loose contacts after years of daily switching
• Silver alloy contacts — low resistance, accurate readings
• Compact 22mm panel hole — fits standard DB cutouts
• Clear position markings — readable even in dim panel enclosures

What's in the Box

• 1x LW28-20 ammeter selector switch
• 1x mounting nut and hardware
• Wiring diagram

Note: This switch handles the ammeter signal circuit only — it does not carry the main load current. Always use appropriately rated CTs for your system. For voltage selection between phases, see our Volt-Ampere Selector Switches.