Motor Drain Plugs: Open or Closed?
#MotorTalkMonday is back with another common question we hear: should motor drain plugs be open or closed?
The answer is simple: it depends.
Motor drain plugs (or drain fittings) are easy to overlook, but they play an important role in protecting your motor from moisture damage. Using the correct drain plug configuration can improve reliability, extend motor life, and help prevent unnecessary maintenance issues.
What are motor drain plugs?
As temperatures fluctuate, condensation can form inside a motor housing. Drain plugs provide a path for that moisture to escape when installed in the correct location for the motor’s mounting position.
Should drain plugs be open or closed?
There isn’t a universal answer. The correct drain plug configuration depends on the motor’s mounting position, operating environment, and the manufacturer’s recommendations.
In general:
- The designated drain location should be configured to allow condensation to escape when specified for the installation.
- The remaining drain plugs should stay closed to help maintain the motor’s intended level of protection.
- In washdown, dusty, or other harsh environments, following the manufacturer’s instructions is especially important to help prevent water or contaminants from entering the motor.
Why does it matter?
An incorrectly configured drain plug can reduce the protection the motor was designed to provide. Over time, trapped moisture or contaminant ingress can contribute to corrosion, insulation damage, bearing problems, and premature motor failure.
ABB also notes that failing to follow the recommended drain plug configuration may affect warranty coverage. That’s why it’s important to consult the installation instructions for your specific motor before making any changes.
The bottom line
Motor drain plugs may be small, but they serve an important purpose. There is no one-size-fits-all answer—the correct configuration depends on the motor and the application.
When in doubt, follow the manufacturer’s installation instructions or reach out to your local ABB Baldor-Reliance team. A few minutes spent verifying the proper drain plug configuration can help protect your motor for years to come.
