10 Best Overload Relays

Buying Guide

Overload relays are the silent guardians of electric motors and compressors. When current draw exceeds safe thermal limits, these devices interrupt power before insulation damage or fire risk escalates. Selecting the best overload relay for your application requires more than matching a part number; you need to align current range, trip class, reset behavior, and physical termination with the actual workload and environment.

Sizing and Current Capacity

The first step in choosing an overload relay is confirming the full-load amperage (FLA) of the motor or compressor you intend to protect. Thermal overload relays are adjustable across a specific amperage window—common ranges include 7–10 A, 16–24 A, and 23–32 A. Always select a relay whose adjustment dial brackets your motor’s FLA. If the FLA sits at the extreme top or bottom of the range, consider moving to the next size up or down for finer calibration and faster response.

For large industrial motors, you may encounter Class 20 or Class 10 trip curves. Class 20 is standard for general-purpose motors, allowing a brief inrush period before tripping, while Class 10 offers faster protection for motors with lower inertia or sensitive windings. Refrigerator and mini-fridge compressors, on the other hand, rely on PTC starter relays paired with overload protectors. These are not dial-adjustable; instead, you match the ohm rating—typically 4.7 ohms—to the compressor’s start winding specifications.

Feature Tradeoffs

Industrial thermal overload relays differ mainly in reset method and terminal style. Manual reset models require a technician to press a button after a trip, which is ideal for remote pumps or unattended machinery where automatic restarting could damage equipment or endanger personnel. Automatic reset units restore power once the bimetallic strip cools, making them convenient for HVAC systems inside occupied buildings where brief downtime is acceptable.

Screw-clamp terminals, such as those found on Schneider Electric Easy TeSys units, accept ring or fork lugs and resist loosening under vibration. Spring-clamp or push-in alternatives speed installation but may need periodic torque checks in high-vibration environments. For refrigerator repair kits, the tradeoff is between one-pin and three-pin PTC relays. One-pin designs are common in LG and Kenmore-style compressors, while three-pin variants fit a broader cross-section of mini fridges, wine coolers, and deep freezers.

Installation and Setup Considerations

Before mounting any overload relay, verify that your contactor or compressor terminal layout matches the relay’s physical dimensions and pin arrangement. Industrial units typically mount beneath a magnetic contactor; the relay’s current transformers sense heater current through the power circuit. Ensure adequate clearance for airflow and reset access, and always de-energize both control and power circuits before wiring.

Refrigerator overload protectors and PTC starters install directly on the compressor hermetic terminal. Take a photo before removing the old part, because terminal orientation matters. If the overload protector feels loose or shows burn marks, replace both the relay and the protector simultaneously; pairing a new PTC starter with a fatigued overload can lead to repeat failures.

Maintenance and Reliability Signals

Overload relays are generally low-maintenance, but periodic inspection extends their service life. In industrial settings, check screw-clamp torque annually and look for dust accumulation that can insulate the bimetallic element, altering trip points. If a relay trips repeatedly without an obvious motor fault, use a clamp meter to verify actual running current; nuisance tripping often indicates bearing wear, voltage imbalance, or an undersized conductor.

For appliance repair kits, reliability is harder to inspect visually. Instead, rely on review patterns. Products with hundreds or thousands of reviews mentioning successful compressor restarts after years of dormancy indicate consistent manufacturing tolerances. Be cautious of listings with very few reviews or sporadic complaints about fitment; compressor terminal boxes vary slightly by OEM, and a millimeter of pin misalignment can cause arcing.

How to Compare Reviews

When reading feedback, distinguish between installation errors and product defects. Reviews that mention “trips immediately” on an industrial relay often trace back to incorrect heater-element sizing, not a faulty unit. Look for comments that reference longevity: “still running after six months” or “survived summer peak loads.” For refrigerator kits, prioritize reviews that name specific brands and model numbers; generic praise is less useful than a verified match to your LG, Whirlpool, or Danby unit.

Final Recommendation

If you are protecting commercial motors, pumps, or HVAC compressors, prioritize a Schneider Electric TeSys or Easy TeSys thermal overload relay with a current range that comfortably covers your motor’s FLA. The manual/auto reset flexibility and screw-clamp terminals found in our top-ranked industrial models offer the best balance of safety and serviceability. For facility maintenance teams managing multiple motor sizes, stocking a 16–24 A and a 23–32 A variant covers the majority of fractional to mid-horsepower loads.

If your task is refrigerator or freezer repair, choose a PTC starter and overload protector kit that matches your compressor’s pin count and ohm rating. The highest-scored refrigerator kits in our ranking combine strong review volume with high recent purchase rates, suggesting technicians trust them for repeat service calls. When in doubt, buy the matched pair—replacing only one half of the start circuit often leads to callbacks.

Ultimately, the best overload relay is the one that fits precisely, trips at the right current, and resets in a way that matches your operational needs. Use the ranked list above to narrow the field, then confirm your motor or compressor specifications before ordering.