I'm looking at adding magnetic starters to some of my woodworking tools to provide low-voltage protection because the power here isn't that stable.

I need to purchase control wiring. Are there standard wire colors for a 3 wire control scheme / what are they / dictated by NEC / which article, etc..

And, same as above for wiring from starter to motor. Tools are 120V single phase.

Only neutral must be white, and equipment ground must be green, other than that control wires can be any color. Red is popular. I have seen huge control cabinets with 500 red control wires. Of course each one is labeled with a number.

The recommended, traditional colors for 120 volt is black, red, blue, and white for neutral, green for ground.

Simply adding mag starters will not protect from undervoltage. Mag starters are designed to contain overload protection devices. You may find undervoltage detection that can be added as an option.

While 120 volt motors may use a mag starter, most 120 volt single phase motors have thermal protection built in.

Explain more detail about your situation and why you think mag starters will protect from undervoltage.

My understanding is the coils are designed to drop out at 85% nominal voltage. I've run into instances where the power goes out for a few seconds while I'm using a tool. I don't want it to start back up when the power comes back. If the coil drops out, the device shouldn't resume operation until you press the start button again?

Low voltage protection may have been the wrong term. I'm not meaning undervoltage protection as it applies to larger industrial 3 phase situations to protect the motor.

Motors with built-in thermal protection was going to be another question. I have some motors with a little button that pops out, but many are ones I've acquired over the years from industrial surplus sales. Are there any that have internal self-resetting overload protection with no external reset?

The 85% value is about right. And your right, tools are much safer if they drop out. I think your term of "low voltage protection" is "about right". "Dropout protection" might be a better term.

For your second question. Thermal protection. In most cases you don't want the motor to start back up, so in general self-resetting thermals are out. Some of the better motor protection schemes actually have a thermal switch in the motor. This is wired to the motor starter.

Motor starters are the best way to protect motors, but I've only used them on three phase systems. The "heaters" are sized for the motors. There are electronic controls out there that you just set the Full load amps and go. Single phase motor starters are out there.
It's usually one box, all pre-wired and ready to go.

I've also seen what looks like a wall switch with overloads in there as well.

Since this is a woodworking shop, consider integrating the controls to operate a central dust collecting system. An AUX contact installed in the motor starter can become a low voltage contact closure to a central panel. In that panel parallel all of the aux contacts together (use DIN rail and terminal blocks w/jumpers to do it professionally). Mount a control transformer and a fuse and a motor starter for your dust collecting system.

Sounds like you have undervoltage relays, or the option to a motor starter, if the open at 85% undervoltage.

What make and part number do you have? I can look at the specs and advice you further if necessary.

Motors that drive machinery should never start automatically. You will be hard pressed to find one that does. A relay should always need manual resetting, unless the motor is under qualified supervision ,and is for something benign such as a pump, or some critical operation.

All but mechanically held and magnetic latching relays have this property. Here is a contactor spec sheet: http://www.automationdirect.com/stat...contactors.pdf

Note that in this datasheet the drop out voltage is 20-75% of the rated voltage.

OK, this is the standard operating characteristics of standard coils in mag starters. This is not intended to protect from undervoltage for the device being controlled by the contactor.

Standard undervoltage devices will be listed as an undervoltage protection device and have a setting that will be a much tighter tolerance. Most equipment will run poorly or be damaged if the nominal voltage varies greater than 10%.

So, Scleros, if the contactor you have or planning on using is similar to the one Kiss offered, your motor will be affected by the undervoltage, and not protected by the contactor.

Here is a separate component that is designed for such protection:

http://web5.automationdirect.com/sta...lestarters.pdf

My concern that prompted all of this is protecting ME from the tool restarting when the power blips. I do not care (well maybe a little) if the MOTOR is damaged when the power blips.

I've already purchased a WEG Enclosed Starter (WEG Electric Motors) for one of my saws. It has an IEC contactor with an overload relay you adjust a dial on to set FLA. I think I'm just going to wire it up and see what happens next power blip. Can't be any worse than the toggle switch that's controlling the motor now.

Thanks for the prompt responses. I wouldn't have thought about using an AUX on each device for the DC... hmmm, more work... :)

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Originally Posted by Scleros

I'm looking at adding magnetic starters to some of my woodworking tools to provide low-voltage protection because the power here isn't that stable.

I need to purchase control wiring. Are there standard wire colors for a 3 wire control scheme / what are they / dictated by NEC / which article, etc..?

And, same as above for wiring from starter to motor. Tools are 120V single phase.

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Just a very quick thought and a couple of questions.

Check the web pages of the manufacturers of the tools to see if you can do that. If the tools can't take a magnetic start conversion about the colors of the wiring is moot.

Questions:

1) When you say the electricity is not stable in your area, what do you mean?

A) Please define your service to your home, including your total "Rated" amperage.
B) Please define how you are wired from the house panel to the your shop.
C) Do the lights in the shop dim when you use high torque tools like a bench table saw?

2) Magnetic start components, do they connect directly to circuit components or to the
Tools themselves?

3) Have you considered Capacitor Start motors for the larger tools?

Observations:

I have two concerns here, One is that you are trying to draw more amperage off the panel than you should. And two, that you are not wired properly. Have you considered calling in an electrical inspector to approve the existing wiring from the main panel to the shop and then get a permit for the new work.

Safe is a lot better than sorry. If you are causing an overload situation, you may also cause a fire!

Tk:

I disagree somewhat with your answer. All his motors are single phase. The undervoltage protection system you identified is for 3 phase. I quote from the document: "Phase loss protection is integral to the MSP overload protection system. Phase loss protection works by detecting unequal current in each of the phases."

Here is a product for single phase undervoltage protection: http://www.ssac.com/catalog/HLV02B01.pdf

I know he has single phase, just using the same source to show that the coil specs is one thing , and that there is a separate component for undervoltage.

Under voltage monitors each phase indivdually.

Why bring up phase loss ? That is even another issue, that I did not mention.

And I brought something up based on the ifo you provided, while waitng for the poster to provide his info on the contactors he has, which he finally did,

Oh and by the way, the poster then changes his reason for asking.

SSAC is an excellent source, use them often. Was stepping through this based on info provided.

I think the poster has enough info to move forward and decide how to proceed, so I am done with this.

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Originally Posted by donf

Check the web pages of the manufacturers...

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Doesn't really apply as most of my tools are old as the hills and the manufacturers are no longer in business. Rockwell, Duro, Southbend, etc...

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Originally Posted by donf

When you say the electricity is not stable...

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I have power brownouts where the lights dim and flicker for a few seconds or it goes out completely as much as a few minutes. Reset your clocks and vcr type stuff.

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Originally Posted by donf

A) Please define your service to your home, including your total "Rated" amperage.

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New main panel and service entrance to 200A from 60A in 2003.

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Originally Posted by donf

B) Please define how you are wired from the house panel to the your shop.

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Shop is the basement. Circuits are direct run into main panel.

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Originally Posted by donf

C) Do the lights in the shop dim when you use high torque tools like a bench table saw?

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Nope.

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Originally Posted by donf

Magnetic start components...

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Best example I could quickly find is this G0454 20" Planer. The start button enclosure houses a magnetic starter. The starter and associated pilot devices (start & stop momentary pushbuttons) replace the normal inline switch on the motor's power wiring.

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Originally Posted by donf

Have you considered Capacitor Start..

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Not specifically to address my issue as some of my tools already have capacitor start motors.

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Originally Posted by donf

Have you considered calling in an electrical inspector...

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He approved the main panel upgrade, and quite frankly I found him to be a total @#$% as he rejected for weeks the dual meter base I had the electrician and the utility put in until I asked where the NEC said I couldn't put in a dual meter base. He and I are only meeting again when it is absolutely necessary.