HVAC Glossary

Motor Nameplate

Last updated: March 11, 2026

The motor nameplate is the permanent label affixed to electric motors displaying electrical specifications, performance ratings, and manufacturing information. This label contains critical data required for proper installation, operation, and maintenance. Nameplate information ensures correct motor selection and helps technicians identify motors for replacement or repair.

Required Nameplate Information

Standard nameplates include horsepower rating, voltage requirements (120V, 240V, 480V), full-load amperage (FLA), frequency (50/60 Hz), phase (single or three-phase), frame size (56, 143T, 184T), and service factor (1.0-1.25). Manufacturer name, model number, serial number, and manufacturing date facilitate identification. Efficiency ratings and thermal protection type provide operational guidance.

Practical Usage

Technicians verify nameplate specifications before installation to confirm compatibility with electrical supply and HVAC equipment. Nameplate horsepower determines appropriate circuit breaker and wire gauge sizing. FLA rating establishes maximum current capacity; oversizing by 25 percent prevents nuisance breaker trips during startup.

Maintenance Applications

Nameplate data enables proper motor replacement with electrically equivalent units. Service factor indicates acceptable overload conditions; 1.15 service factor permits 15 percent continuous overload. Regular nameplate inspection identifies corrosion or damage indicating environmental stress or electrical problems requiring motor replacement.

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