Wise move to power done the compressor when leaving the shop. A friend lost his shop and all tools to fire when a failure caused his big compressor to run continuously while he was out. He had left the compressor on for decades with no problem. Some years later a different failure caused the (new) compressor to run continuously but he had only gone to the house for a short iime.

The same thing happened to my 5hp compressor when the pressure switch contacts stuck and the motor didn’t turn off after it cycled. I had left the shop to feed the llamas and when I walked back I could barely hear it running from outside since the compressor is in a sound insulated closet. The switch contacts were welded together and the compressor had been running for, at most, an hour. Very hot.

Another time I was in the shop when I heard the compressor cycle when I wasn’t using it. In the closet I heard a hiss from a leak in a connection.

I have a motor disconnect toggle switch outside the closet in the main shop. i put a bright flag on it so I can see at a glance if the switch is on when I leave the ship. My plan is to to wire in a bright indicator light outside the shop door to show the state.

BTW, on the thread topic: There is a circumstance where the tank can accumulate more water than it would otherwise. The air in and leaving the tank is heated by the compression and hot air can hold more moisture than cool air.. As the air cools water can condense in the line. If the hose or piping from the compressor is long enough and positioned just “right” this water can run back down the line and drain into the tank. Some advise a long initial line running straight up then sloping down so condensed water will run away from the tank. I’ve read suggestions of at least 25’ of copper line with a water trap at the low end with a valve for draining. This length before the normal in-line water separator and desiccant dryer will help keep moisture out of the air, helpful for plasma cutting, spraying paint/finishes, etc. This, of course, may not be practical for a portable compressor.

JKJ

Quote Originally Posted by David Walser View Post
The reason I try to remember to shut off my compressor when leaving the shop is because of a bad experience I had several years ago. While I was out of town on vacation, a connected air hose split. I returned home to find that my air compressor had been running non-stop for about five days. I turned it off and, once cooled off, it would not run again.