Whether to Leave Equipment Running

Here's a discussion of the cost, efficiency, and safety aspects of leaving equipment running for periods of time, versus shutting machinery down the moment it's not being actively used. September 15, 2011

I have always wondered what is best for big equipment (slider, shaper, cutoff saw) - leave them run for long periods of time, or keep turning them off and on all day? Typically, if we have a lot of cutting to do, I leave all the machines running. But what about the days where you have to make a cut here and there? Is it still best to leave the 3 phase converter and saws running with long breaks in between? I am not necessarily concerned about the electric bill, just trying to do what's best for the life of the machines. Just wondering if anyone follows any sort of "rule of thumb" for leaving equipment on.

Forum Responses
(Cabinetmaking Forum)
From contributor Z:
What about safety? Leave a machine running when not in use? Thatís penny wise dollar foolish and just plain crazy. You will not increase the life of the machinery by any noticeable amount by leaving it on. You can however greatly reduce the chance of losing a limb by turning them off.

From contributor P:
Tools are never left running - I leave the phase converter running if I'm going to be making a cut in the next ten minutes or so.

From contributor O:
Good practice says a worker must never leave a machine unattended, and turn off the machine and let it stop completely before leaving the area. EU regulations mandate brakes on all equipment due to the same safe practice. With a good shaper taking 60 seconds or more to wind down, the brakes make for a more efficient shop, without having an unattended machine still spinning. But no mater what, an operator needs to stay with it until it is stopped and safe. If hearing protection is worn, it is difficult to tell sometimes if a machine is running at first approach.

From contributor M:
I agree with the others. The first thing that came to my mind was safety. The guards are only part of a safe shop. If your shop is like mine you canít even hear when the panel saw is running or not. We all wear hearing protection, but even if we didn't noise from the other machines drowns out machines like a saw or a shaper.

You will definitely use a lot more electricity running the machines idle for even five minutes than the inrush current to start the machine would ever use. These machines all use motors that are not worn down by starting and stopping them. That leaves the electronics. A quality machine's electronics will last many years of on-and-off use without fail. The motor starters are specifically designed for that purpose. If we leave a machine running it is to save the labor of turning it back on again. For example our panel saw stays running while the next panel is loaded because the switch is not accessible once the panel is loaded. But machines are not left running unattended. Now that I think about it I should add that to the list of things not to do.

From contributor Y:
Three phase motors have fewer start up parts than single phase. It is not a big deal at all to start and stop them often. If you get into big 3ph motors, 40hp or larger, then startup costs can add up in a hurry if you are metered by demand charges.

From the original questioner:
Maybe it's my fault for the way I worded the original post, but this post has really been taken the wrong way. I am not careless when it comes to safety. I use guards on all machines - alway's wear hearing protection, using respirators and spray suits in the finish room, and etc. When I was asking about leaving a machine run I never once said "unattendedĒ, I would never do that. I simply meant if you are trying to put a complicated piece together, and standing two feet from your saw and need to make a cut every minute or so.

From contributor J:
Let me put it this way because I considered what you are thinking. If for some reason you are handling a big piece, say a plywood sheet and you trip and let go of the sheet to hold yourself up and it just so happen you put your hand on your running equipment, what would happen? I know it is a pain to be turning on and off the equipment, but somehow it gave me a bad feeling to leave it running, and in these cases I usually go with my intuition. The fact that you are asking makes me think you feel the same way.

From contributor U:
I think your question was taken way out of context. I too have a two to three man shop and I know exactly what you are talking about. The same thing has run through my mind before. If I'm going back and forth between table saw and the table that the cabs are built on then I let the thing run until I'm done with it. I have one guy that I'm helping build the cabinet and another guy that is sanding doors then I'm not worried about either one of them sticking their hand into that saw, heck I can see both of them. Having said that, I wear ear plugs and it is obvious to me what machines are running, so there is no mistaking that.

To answer your question, I don't think it will make much difference in the life of the tool whether we let them run or turn them off. The bigger equipment is made to hum all day long. If I have to step away from a machine more than 30 seconds I turn it off mainly because I'm already tired of hearing it run so if I catch a break for a minute or so I turn it off and I can hear myself think.

From contributor Y:
Here's away to take the safety aspect out of the equation. I ask myself multiple times a day, "should I shut the 15 hp dust collector off or not?" How dangerous is that to leave running." If I am going to use it again in a few minutes or fewer I will leave it running. If itís longer than that I will turn it off. I agree that it won't make much difference in the life of the tool. I just do what I'm comfortable with, both for safety and convenience.