Safety switch test

[Bill Dufour]

I see machines sold with pushbutton switches, paddle switches and safety switches that are not. A easy test is to turn on the machine and leave it running. Then flip the breaker off, wait five seconds and flip the breaker back on.
If the machine continues to run you do not have a safety switch with contactor or overloads to protect you or the motor. If the machine continues to coast to a stop you probably have some motor protection in the switchgear.
Bill D.

[Jerry Bruette]

The term "safety switch" seams vague to me. Do mean an E-stop? Or a switch that has magnetic contacts that would prevent the machine from restarting after a power interruption?

[Edward Weber]

"safety switch' is a generic term.
Bill's method will work for power interrupt switches like magnetic.

For those little yellow "keys" and lockouts, they're just nonsense. They do nothing other than to let you know they're there. I know of no ono who has ever actually used one of those little plastic keys as they're intended. They break easily, get lost easily, they are just the manufacturers way of covering their backside.
An actual metal key/switch or magnetic switch are far safer options.

A switch lock out and a power interrupt are really two different animals and provide two different functions.

[Rod Sheridan]

Bill, I’m sure it’s a typo on your part however having motor overload protection has nothing to do with having a magnetic starter.

Motors can have built in thermal protection, and manual motor starters can have thermal overload protection.

That said it’s nice to have a magnetic starter to eliminate auto restart after a power failure.

Regards, Rod

[Lee Schierer]

For those little yellow "keys" and lockouts, they're just nonsense. They do nothing other than to let you know they're there. I know of no ono who has ever actually used one of those little plastic keys as they're intended. They break easily, get lost easily, they are just the manufacturers way of covering their backside.

Allow me to introduce myself. When Our children lived at home and even when our grandchildren were younger, I always removed the yellow plastic safety plug from my Table saw and Radial Arm saw. Since both of our children are adults and our grand children are all teen aged or adults, I no longer pull the yellow safety plug. I have all the original yellow plugs that came with the two saws, none have broken.

[Richard Coers]

How often has anyone had a power failure and then have a machine start up again to put them in danger? It hasn't happened to me in my 52 years of woodworking. I don't stay in the shop when power is out anyway, so not a major safety hazard to me.

[Edward Weber]

Allow me to introduce myself. When Our children lived at home and even when our grandchildren were younger, I always removed the yellow plastic safety plug from my Table saw and Radial Arm saw. Since both of our children are adults and our grand children are all teen aged or adults, I no longer pull the yellow safety plug. I have all the original yellow plugs that came with the two saws, none have broken.

Ah children, I understand

[Doug Garson]

How often has anyone had a power failure and then have a machine start up again to put them in danger? It hasn't happened to me in my 52 years of woodworking. I don't stay in the shop when power is out anyway, so not a major safety hazard to me.
Power failure no, but trip a circuit breaker and forget to shut off the switch and have the table saw restart when the breaker was reset. No injury but the potential is there.

[Lisa Starr]

I, like Lee, always removed the yellow "locks" when our children were young. I also always turned off the breakers for equipment that didn't have those little keys. If we're ever blessed with grandchildren, I'll do the same.

[Edward Weber]

Power failure no, but trip a circuit breaker and forget to shut off the switch and have the table saw restart when the breaker was reset. No injury but the potential is there.
I have had momentary (less than ten seconds) power glitches. It gets your attention.
I have a mag power switch on my TS and RAS, the lathe VFD resets electronically, the other tools just have the little yellow (child-safety) key.

[Jimmy Harris]

What do you guys do when the power suddenly goes off? Do you climb on your table saw or grip your bandsaw blades? Do you completely lose your mind without power? Who cares if a tool suddenly starts up? You should be acting like you're tools are going to do that anyway, until you've personally verified that they're unplugged.

Mag switches just seem like another gimmick that's sold as a way to make tools seem safer, while actually making them more dangerous. Practice good safety habits. Don't rely on doo-dads and gizmos to do the thinking for you.

[Edward Weber]

What do you guys do when the power suddenly goes off? Do you climb on your table saw or grip your bandsaw blades? Do you completely lose your mind without power? Who cares if a tool suddenly starts up? You should be acting like you're tools are going to do that anyway, until you've personally verified that they're unplugged.

Mag switches just seem like another gimmick that's sold as a way to make tools seem safer, while actually making them more dangerous. Practice good safety habits. Don't rely on doo-dads and gizmos to do the thinking for you.

With all due respect, this is not personal.
I think you're way off the mark.
I don't know how long or what kind of machinery you've been exposed to but your answer seems a little naive IMO

If a tool stops, fine, you're usually safe but not always.
When the power is restored, which you don't know when that will happen, you need to have your tools and material in a safe condition.
Switch off and nothing engaging the blade or bits. A sudden start with a blade or bit engaged in the wood can be extremely dangerous and can also damage the tool.

Mag switches are not Doo-Dads, they are tried and true power interrupt devices.
A tool can not be turned on until the switch gets power and then the operator intentionally presses the start button. This eliminates the dangers I mentioned above.

[Rod Sheridan]

What do you guys do when the power suddenly goes off? Do you climb on your table saw or grip your bandsaw blades? Do you completely lose your mind without power? Who cares if a tool suddenly starts up? You should be acting like you're tools are going to do that anyway, until you've personally verified that they're unplugged.

Mag switches just seem like another gimmick that's sold as a way to make tools seem safer, while actually making them more dangerous. Practice good safety habits. Don't rely on doo-dads and gizmos to do the thinking for you.

Jimmy, when I lose power in the shop, I lose lighting.

I don't really want auto start on my machinery, and all of my larger machines have safety interlocks for covers and guards so they need a magnetic starter.

I'm not really sure where your comment was headed.

Regards, Rod.

[William Hodge]

Plugging in a machine or power tool with a manual switch in the on position will wake you up.

I worked in a shop where there were a lot of people with 4 x 24 Porter Cable belt sanders in one department. People would lock an unplugged belt sander on, so that it would charge off the bench when someone plugged it it. Fun and games.

[Jimmy Harris]

With all due respect, this is not personal.
I think you're way off the mark.
I don't know how long or what kind of machinery you've been exposed to but your answer seems a little naive IMO

If a tool stops, fine, you're usually safe but not always.
When the power is restored, which you don't know when that will happen, you need to have your tools and material in a safe condition.
Switch off and nothing engaging the blade or bits. A sudden start with a blade or bit engaged in the wood can be extremely dangerous and can also damage the tool.

Mag switches are not Doo-Dads, they are tried and true power interrupt devices.
A tool can not be turned on until the switch gets power and then the operator intentionally presses the start button. This eliminates the dangers I mentioned above.

I work with industrial machinery for a living and we lose power all of the time. So I have plenty of experience. When the power goes out, or anything happens that you didn't expect, you stop the machine immediately. You don't try to figure it out. You stop it before you figure out what happened or what that sound was. That's what I've always done with any power tool. You don't rely on gizmos to keep you from thinking about safety. Gizmos can and do fail. You have to always keep safety at the front of your mind. Safety is YOUR responsibility. You don't pass that off to a doo-dad or anyone else. That's how people get hurt. I know. I've seen safety devices fail and people get seriously hurt because they relied on safety devices to keep them safe instead of focus and good habits. One of them will never speak, walk, or feed or dress themselves again. That incident still haunts my dreams. You don't ever forget something like that.

Now, I'm not saying I wouldn't buy a tool with a mag switch. It's fine if it has one. I just wouldn't treat it any differently if it had a mag switch or not. If the power goes out, I'm immediately turning the machine off so I know it's off. So the mag switch doesn't offer me anything because I'm not willing to risk my health and well being on a convenience.

[Warren Lake]

if power went out and a machine was running it would not start when the power came back on. The switches take care of that when the coil disengages when the power went off. Anyone running a roto then its even more so as there are other things supplying the power that are not going to start.

I wont be putting a mag starter on my belt sander though, more weight if I enter the sander into belt sander races.

Can a mag starter fail and stay engaged. Yeah it can but its rare. Ive had one in over 30 machines do that when my compressor would not shut off cause the coil had arced in the engaged position. It was 37 years old and its mounted on the compressor so its had its ass rattled off for many years.

[Bill Dufour]

If I am ripping a long heavy board and it starts to bind then the lights and power go off I do not want to have to fumble around to stop the saw while staying out of the path of any kickback in case it restarts.
I was surprised to find my jointer push button switch was just off/on and no way to tell which before I plugged it in after changing the knives. I must have touched the switch because it was on as soon as I plugged it in.
Bill D

[Warren Lake]

ripped tons of 10 foot solid, if a board started to close and some amount did I just lifted them off.

[Edward Weber]

I
Now, I'm not saying I wouldn't buy a tool with a mag switch. It's fine if it has one. I just wouldn't treat it any differently if it had a mag switch or not. If the power goes out, I'm immediately turning the machine off so I know it's off. So the mag switch doesn't offer me anything because I'm not willing to risk my health and well being on a convenience.

If the power goes off, a machine with a mag switch is physically disconnected from the power source. There is no "turning it off" it's already off.
It's off as soon as the power is gone. You can press the switch all day long, it won't do anything once the power is cut.
I also didn't imply that they were a substitute for good safety practices, I just said they're not doo-dads or gizmos. They're probably one of, if not the best, safety systems out there. A bit more than a convenience.

You can choose to use them as you like but not everyone on the forum knows what they are or how they work. Simply dismissing them out of hand doesn't inform or help those members.

[Warren Lake]

Switches are a part of machines.

Gizmos are all those plastic and other things with wheels and. No use for most of them but a mag switch yes for sure. A number of machines came with no starter and ive had to source and instal and on some machines, now over time replaced some of them. One brand not around anymore had a number of failures in time.

I had the best luck with Danfoss and likely one of them is 60 years old or very close. They got cheaper than the originals over time metal cases became plastic then made in Poland and those were still fine. Danfoss stopped making those switches and ive been able to find some old stock.

[Rollie Meyers]

A safety switch is a enclosed switch, either fusible, or non fusible, general duty, (240V max), and heavy duty, (240V & 600V), available in NEMA type 1, or 3R, for general duty, & heavy duty, plus NEMA type 4, watertight, 4X watertight corrosion resistant usually stainless steel, NEMA 12 dust & oil tight, which the NEMA type 12 is what I prefer for wood & metalworking machines. What is described as a "safety switch" by the OP is simply 3-wire control with two push buttons with one with NO, normally open contacts, and a NC, normally closed contact, wired with a magnetic starter, or if overload protection is not desired a magnetic contactor.

[Ken Flesher]

"safety switch' is a generic term.
For those little yellow "keys" and lockouts, they're just nonsense. They do nothing other than to let you know they're there. I know of no ono who has ever actually used one of those little plastic keys as they're intended. They break easily, get lost easily, they are just the manufacturers way of covering their backside.


Well now you do.

Much of my career at a University was overseeing a shop space used by students in various coursework. Woodworking, welding, metal fab, etc. If a tool had one of those keyed switches, you better believe the yellow key was pulled out and locked away when classes were not using them. I never had one break, and I never lost one.

[Edward Weber]

Well now you do.

Much of my career at a University was overseeing a shop space used by students in various coursework. Woodworking, welding, metal fab, etc. If a tool had one of those keyed switches, you better believe the yellow key was pulled out and locked away when classes were not using them. I never had one break, and I never lost one.

I never lost one either because I leave them in place and don't have children or students or anyone who would/could possible lose one on me.

I do think I may have Jinxed myself, after my post I had to buy one of those (4 pack actually) for a saw I'm rehabbing. Karma set me straight.