[quickthrowman]

> This is best practice for anyone who uses three phase power.

No, it’s not. It’s a neat trick that visually reveals when the utility drops a phase, but there are better ways to handle avoiding equipment damage.

Best practice is to use phase monitoring relays that can de-energize a motor when a phase is dropped/reversed to prevent damage. The trip time is adjustable and it’s more reliable than manually hitting an e-stop. It also won’t let a motor with incorrect phasing start up either. You see phase loss relays on a lot of compressor motors and other large motors.

Here’s a flyer for an Eaton product: https://www.eaton.com/content/dam/eaton/products/industrialc...