Transfer Switch Inspection


Wheeler Power Systems employs more than 12 field technicians to serve our customers 24/7 and quick response and quality service is our number one goal. With employee safety being the most important aspect of our business and yours, Wheeler Machinery has taken the initiative to make sure our technicians are properly trained to work on many makes and models of automatic transfer switches (ATS) to include CAT, Zenith, ASCO, Onan and others. Technicians have completed Arc Flash training and are required to wear the appropriate PPE for each inspection and repair. This ensures that when Wheeler Machinery arrives on site we are providing electrical safety practices that are standard in our industry.

Wheeler Power Systems will perform the following inspection points below and take corrective action if any, as needed. Where applicable and when permitted by the customer, we will inspect the following items:


  • Check all terminal connections for tightness.
  • Re-torque connections, TS mounting, contact mounting and terminal strips.


  • Record utility voltage
  • Record utility amperage
  • Record peak amperage
  • Check for proper operation of the transfer switch,timers, relays, remote start contacts, exercisers,phase monitors and record settings.
  • Check for excessive heat build-up with infraredthermometer.
  • Record emergency voltage.7. Record emergency frequency.
  • Inspect all optional accessories.


  • Inspect all insulation for degradation.
  • Inspect barriers for arc chutes.
  • Inspect Transfer Switch coil, rectifier andresistors
  • Inspect the coil and/or circuit cards andprotective devices.
  • All other accessory relays
  • Inspect all timers
  • Inspect and infrared arcing contacts wherepossible.
  • Inspect and infrared main contacts wherepossible.
  • Inspect linkage and lubricate as necessary.
  • Clean the exposed Transfer Switch coil coreand lubricate.
  • Clean and vacuum Transfer Switch enclosureand controls.
  • Inspect transfer switch & enclosure forcorrosion, moisture and/or chemicals.
  • Inspect and lubricate cabinet hardware forproper operation.
  • Re-lubricate the transfer switch operator andpivot points.
  • Replace defective switch indicator bulbs.


  • Inspect arcing contacts.
  • Inspect main contacts.
  • Inspect barrier and arc chutes.
  • Inspect linkage and lubricate as necessary.
  • Check engine start bypass contacts for properoperation.
  • Inspect all safety interlocks.


  • Check closed transition Bypass operation.
  • Check alarm time delay settings.


  • Replace ATS Batteries as needed.
  • Customer authorized Load Transfer.
  • Place all switches in proper operation mode.
  • Provide customer with written documentationof service procedures, any findings, suggestedrepairs and recommend corrective actionsas needed.
Transfer Switch Inspection

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4901 West 2100 South
Salt Lake City, UT 84120
5300 West Wheeler Way
Hurricane, UT 84737


24 Hour Emergency Service 801-978-1581

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