does plugging in a tool that is already on damage it?

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Forum topic by HokieMojo posted 01-02-2011 12:12 AM 1460 views 0 times favorited 12 replies Add to Favorites Watch
View HokieMojo's profile


2104 posts in 3903 days

01-02-2011 12:12 AM

This is probably a really dumb question, but does plugging in a tool that is already switched on cause any damage? For example, is it any different if I
1) plug in a shop vac and then switch it on
2) leave it switched on, and then plug it it

The reason I ask, is I’m thinking about setting up a drilling/miter station with a shop vac. Because neither tool creates a HUGE amount of dust, I want to put the shop vac high on a wall, put a seperator at mid level, and then have the drill/miter saw at normal height. Rather than have an automatic switch that comes on whenever I turn on a saw, I’d rather plug it into a socket and have that socket be switched.

Does this question make any sense? I don’t think my idea would be a problem, but I’d like to hear a thought or two on this idea of mine.

12 replies so far

View ajosephg's profile


1880 posts in 3736 days

#1 posted 01-02-2011 12:20 AM

No problem. There is no difference between using the tools power switch, or using a switched outlet as you described.

I don’t think it’s a good idea to turn a tool on by plugging and unplugging the power cord. It doesn’t hurt the tool, but depending on the current draw of the tool the blades of the power cord may over time be damaged due to the arcing that occurs.

-- Joe

View Gregn's profile


1642 posts in 3158 days

#2 posted 01-02-2011 12:29 AM

I use power strips all the time for this type of application of using more than one thing at a time.
Like Joe said just plugging and unplugging with the cord alone can cause damage to the outlet and plug due to arcing.

-- I don't make mistakes, I have great learning lessons, Greg

View richgreer's profile


4541 posts in 3249 days

#3 posted 01-02-2011 12:31 AM

Some tools have a soft start feature. It’s possible (I’m not certain) that starting the tool by plugging it in may not allow the tool to start with a soft start.

Also, a Sawstop goes through an electronic “booting up” process when started to check all its electronic circuitry. It may not be possible or advisable to start that saw by plugging it in.

Otherwise, I see no problem.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View PurpLev's profile


8541 posts in 3823 days

#4 posted 01-02-2011 02:07 AM

FYI, all those dual power outlet that let you start the shop vac when you start your other tool, or those remote switches to start the DC/shopvac all rely on the fact that the DC/shopvac is always on and all they do is disconnect the power to it on the outlet – just like you are planning to do. so I’m pretty sure you’re safe to proceed with your plan.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View thiel's profile


392 posts in 3467 days

#5 posted 01-02-2011 02:16 AM

Something else to consider… With the newer electrical codes, arc-fault breakers are becoming standard… which means that if you get a little spark (pretty common) when plugging in an “on” tool, you’ll blow the breaker every time.

-- Laziness minus Apathy equals Efficiency

View Knothead62's profile


2598 posts in 3136 days

#6 posted 01-02-2011 03:18 AM

I suggest that you get into the habit of turning off any power tool or electric item in the shop when not in use. You might forget and plug in something that is already on that might create a safety issue. I have one outlet that is on a switch but I’m going to convert it to a four plug outlet.

View Gator's profile


383 posts in 3851 days

#7 posted 01-02-2011 04:07 AM

Not to mention if it is a router or some other hand held tool, you could lose a finger or do serious damage to a project by plugging it in while it is still on..


-- Master designer of precision sawdust and one of a kind slivers.

View Lochlainn1066's profile


138 posts in 2952 days

#8 posted 01-02-2011 05:57 AM

I have a air compressor I control by plugging it in. I’m going to convert it to a switch. The arcing in a switch won’t hurt it, but arcing in a plug will burn it out and eat the prongs up. I know because I’ve had to change them once. Other than that, it won’t hurt the motor.

-- Nate,

View BurtC's profile


103 posts in 3305 days

#9 posted 01-03-2011 05:01 AM

I got my small DC on a switched outlet. It is located outside in a cabinet. No problems at all.
The circuit is GFI protected.

View DaleM's profile


958 posts in 3559 days

#10 posted 01-03-2011 05:19 AM

No problem, even with a soft start. My router is a soft start and when I use it the table, I leave it turned on as it is plugged in to another switched outlet that is built into the table. The only damage I know of is when you accidentally leave something on and plug it in. I did that with a belt sander once. I would leave it permanently on and clamp it upside down on the workbench to use it that way. I unplugged it, forgot I left it switched on, then plugged it in while it was sitting on the workbench right side up. It launched itself right of the bench, similar to a snowmobile. Great fun.

-- Dale Manning, Carthage, NY

View HokieMojo's profile


2104 posts in 3903 days

#11 posted 01-04-2011 08:59 PM

I wanted to post a thank you to everyone for responding. I don’t think I worded my original question very well, yet I think everyone got the meaning of my post. Sounds like I’ll be just fine to leave a shop vac switched on (since the switch won’t be reachable without a ladder) and then just add an outlet style switch lower down to turn the vac on and off. Thanks everyone!

View TopamaxSurvivor's profile


18380 posts in 3851 days

#12 posted 01-05-2011 10:26 AM

You got it, it doesn’t matter where the switch is on most equipment other than for computer type electronic shut down procedures.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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