Need new switch for TS after converting to 240?

[Mike Hoyt]

Hi guys I pose this question to the guys who have converted their TS to 240v, did you need to change out the switch when you made the conversion? I have a Delta 36-979 contractors saw and I have been thinking about making the switch. Any insight would be greatly appreciated.

Thanks,
Mike

[Chris Padilla]

"No" you do not need to change it. In fact, you will be drawing about half the current when wired for 120 V (double the voltage, half the current...power draw remains about the same). The switch could care less how the motor of the saw is wired...it only opens one leg to stop current flow.

[Wade Lippman]

240v uses double pole switches, 120v uses single pole switches; since 240v has two hots and 120v has only one. Sometimes you will find double pole switches on 120v, but it is unusual.

If you don't change the switch there will be voltage on the motor and wiring (to ground) at all times. As long as you never touch it, it shouldn't much matter; but if you do...

So, it will "work" with the single pole switch, but it isn't a good idea. Your choice.

[Jim O'Dell]

I recently changed my Ridgid 3612 over to 220. The switch it had on it was a double pole double throw. The wiring schematic makes the 2 poles break the hot leads, and leaves the ground intact. My guess is that if your saw came with a motor that would wourk on 110 or 220, then the switch is a double pole double throw that will be safe on 220. Easy to tell when you open the switch up. A single pole unit will have 2 wires attached, 1 power in, 1 power out to the motor. A double pole will have exactly twice that many. When wired for 110 volt, it runs the hot and neutral wires through the switch, and makes or breaks contact with both wires. Your owner's manual should have the wiring schmatic in it. The motor plate may also show it. Hope this helps. Jim.

[Chris Padilla]

Now that I think about it, I guess it is a good idea to have a both hots disconnected...my bad.

[Steven Wilson]

The switch on your saw is probably double throw and you won't need to rewire to use 220v.

[Matt Meiser]

I agree that it is probably ready to go. Mine was. The manual probably has instructions for converting it, but it probably just involves replacing the plug and switching a few leads in the motor.

[Art Mann]

240v uses double pole switches, 120v uses single pole switches; since 240v has two hots and 120v has only one. Sometimes you will find double pole switches on 120v, but it is unusual.

If you don't change the switch there will be voltage on the motor and wiring (to ground) at all times. As long as you never touch it, it shouldn't much matter; but if you do...

So, it will "work" with the single pole switch, but it isn't a good idea. Your choice.

I don't understand what you mean. What is it you should never touch? Both the hot wire and the neutral wire are electrically isolated in the 120V configuration. When the configuration is changed from 120V to 240V, both of those wires are still electrically isolated. There is nothing there for you to touch with voltage on it or if there is, your motor has something seriously wrong with it and it shouldn't be used at either voltage. The motor chassis is grounded by the safety ground connection.

I swapped over my dust collector from 120V to 240V and used the original SPST switch. Obviously, I am still alive. All you need to do is break the connection between the two legs going through the motor.

[Dale Lesak]

There's a lot of poles and throws going on here. Poles = how many circuits that can be run through the switch A 220 must use a double pole switch. (Two hot wires) Throws = is how many positions the switch has. a single throw switch is a on/off switch a double throw could be off in the middle and on one way and momentary on the other. or it could be off/ on/ on or off / mon / on. a double throw double pole could be used as a single throw with the other throw not being used. Or could be a off in the middle and on either way. Dale

[Chris Padilla]

I'll see your two throws and up you a couple of switches.... ;)

[Rick Christopherson]

Because the switch is integral to the tool, it is not necessary (e.g. required) to switch both legs. If you like your existing switch, then reuse it. If you don't like the switch, then get a new one.

There are no safety issues with doing this. There are live parts inside the saw regardless what type of switch it has, so anyone that opens up the junction box without unplugging the saw first is simply thinning the herd.

[Rob Russell]

Poles = how many circuits that can be run through the switch A 220 must use a double pole switch. (Two hot wires)

Sorry Dale, but that's not true. You only need a single pole switch to stop/start a 240v circuit.

Current flows back and forth between the 2 current-carrying conductors in either a 120v or 240v circuit. Interrupting the current flow on either conductor will break the circuit. That's true whether the circuit is 120v or 240v.

There are some reasons that I personally consider 2-pole switches to be safer for 240v circuits, but that's a different story.

Rob

[Chuck Lenz]

Hi guys I pose this question to the guys who have converted their TS to 240v, did you need to change out the switch when you made the conversion? I have a Delta 36-979 contractors saw and I have been thinking about making the switch. Any insight would be greatly appreciated.

Thanks,
Mike
What does the manual say Mike ? My 13 year old Delta 34-445 manual doesn't mention anything about changeing or rewireing the switch. I just says to reconnect the motor leads in the motor junction box, by following the instructions givein on the motor name plate. It is also necessary to replace the 115 Volt plug, supplied with the motor, with a 230 Volt plug that has two flat, current carrying prongs in tandem, and one round or "U" shaped longer ground prong. This is used only with the proper mating 3 conductor grounding receptacle. You need to check your manual. I'm not sure which switch is in your saw. It should have 4 posts on it if it's 230 Volt.

[Steve Clardy]

My Jet [sander] came wired 110.

I changed it over to 220.


Switch was already a double pole switch. So I had to change nothing there.

Just a couple of leads under the motor cover, and a 220 plug on the cord.

[Mike Hoyt]

In the manual it says that it "may" need to be replaced and it does not come with a wiring schematic. I will go to the delta website and see if they have one there. Thanks for all the quick replies,
Mike

[Wade Lippman]

I swapped over my dust collector from 120V to 240V and used the original SPST switch. Obviously, I am still alive. All you need to do is break the connection between the two legs going through the motor.

So anything that doesn't kill you immediately is okay? Interesting approach to life.

Just for a moment try to imagine why 240v machines come with double pole switches.

[Greg Funk]

So anything that doesn't kill you immediately is okay? Interesting approach to life.

Just for a moment try to imagine why 240v machines come with double pole switches.
What are you worried about Wade? If you take apart your 240v machine with double pole switch it will still be energized. No different really than a single pole switch on one of the legs. If it was in any way unsafe it would not be allowed by the NEC.

Greg

[Dale Lesak]

Hi Rob, Let me reword that A two pole switch should be used with 220. That will kill all power to the motor. I don't like having one side hot with the switch off. Dale

[Art Mann]

So anything that doesn't kill you immediately is okay? Interesting approach to life.

Just for a moment try to imagine why 240v machines come with double pole switches.

Not all of them do. The instructions supplied with the aforementioned dust collector did not illustrate a DPST switch and did not suggest replacing the existing switch with one.

Having the voltage on one of the two power wires going to the saw motor is exactly the same situation (and risk) as leaving an extension cord plugged into a wall outlet going to a hand drill or circular saw. Do you always unplug all your extension cords before leaving the shop for the day?

[glenn bradley]

240v switches are normally double pole single throw. My hybrid came with a DPST switch even though it is supplied wired for 110v. It makes the change easy and I believe Grizzly does the same on some tools; I would check to see if yours is already capable as well.

As some will point out you can just open one leg with a SPST switch but it is not advised by any manufacturer I have had to ask. It may just be CYA for them or there is a real reason. An electrician, I'm not. Any "real" Sparkys out there that can chime in?

[Wade Lippman]

Having the voltage on one of the two power wires going to the saw motor is exactly the same situation (and risk) as leaving an extension cord plugged into a wall outlet going to a hand drill or circular saw.

What is exactly like is putting the switch to your ceiling light on the neutral. It will work just fine, you can even change the light bulb without problems; odds are no one would ever notice the difference. But for some odd reason it is a code violation.
It is fine that it doesn't bother you, but you shouldn't advise others to do it.

[Bob Feeser]

The climate is a little tepid so I hesitate to go swimming but I have to get my 2 cents in.
I converted my old Sears 1hp 110 volt to 220 volt according to the schematic on the motor plate. Then I did the simple yet less convenient method of replacing the plug with a 20 amp 220 volt, and just plug it in when I want to use it. I have a new saw that I normally use, so the old Sears saw does not get very much use anymore.
Anyhow, wiring the outlet is taking 2 hot leads from the box, and one ground. The 2 hots go into each leg of the 220, so if you stuck your feet in water, and grabbed either one of these wires, well you know. So both lines are hot, even though a 220 volt motor will not run unless both legs are connected. As someone mentioned, each line is isolated, and as long as you are using a plug properly, with the ground, and each hot in the right spot, you would not get electrocuted by touching the saw.
I grew up in a house with double bladed plugs, and remember what it was like playing with the band, playing the guitar, and having the microphone, connected to the PA system with the plug in the other way around, and getting a shock on the lips that is hard to forget. So I am sensitive to any risk issue with electricity.
I'm not an electrician so please ask a pro for real advice.
I think both opinions here are correct. The internal hot leads are isolated, and the ground is grounding the case so it should be safe. As a backup safety measure I like having a double pole switch, thereby completely removing any hot lines from within the motor. Both ways work, both ways are safe, but I think the double pole switch is an extra measure. If someone was working on the inside of the motor, they would be unplugging it anyhow, so once again both ways work.
My first experience of only breaking the one leg of a 220 line was when I was installing a heat pump system, and under the direction of a professional installer, he told me to only attach the one leg to the cut off switch on the internal band heater, whereas the other leg would not matter, since you need 2 attached for it to work.
I am not an electrician, so please seek the advice of a qualified professional, instead of doing anything based on my rantings. I thought we had some electrical pros here at SMC. They will probably chime in if they haven't already.

[Chuck Lenz]

In the manual it says that it "may" need to be replaced and it does not come with a wiring schematic. I will go to the delta website and see if they have one there. Thanks for all the quick replies,
Mike
I just looked in ServiceNet at the manual, odd they don't know which switch is in it. Maybe the back of the switch will tell you.

[Art Mann]

The dust collector I switched from 120V to 240V was a Delta. That particular manual did not mention replacing the SPST switch with a DPST. It only illustrated how to wire up the SPST switch. I find it hard to believe they would instruct the owner to do something that is dangerous.

It makes sense to switch the hot side of a light socket because it is easy to stick your finger in it and provide a path to ground through your body. I can't say the same thing for an electric motor, particularly a TEFC. You would really have to work at it. As Rick said, that would be "thinning the herd". I don't advocate anyone doing anything that violates the owner's manual or the NEC. If either source of information says use a DPST switch, then that is what you should do. Recommendations from people on this board are a different story.

[Loren Hedahl]

Since the motor would be a squirrel cage type motor, the current is just applied to the field coils. So an SPST type switch would work for either 120 or 240 VAC.

If a fault should develop, such as a breakdown of the insulation in the field coil to ground, the ground wire that's also connected to the motor frame would carry the current. The motor frame would remain at approximately zero volts.

Just be sure your ground wire is properly connected and you'll be OK.

[Rick Christopherson]

..... But for some odd reason it is a code violation. ....... but you shouldn't advise others to do it.It is not a code violation to leave an ungrounded conductor unswitched at a motor, so you really should not tell people that it is.

First off, NEC does not cover machine code. Secondly, there is only one condition where a 2-pole switch is required in the NEC anyway.

I don't like fear-mongering, but that's what you have attempted here. The only risk in this situation is if someone opened the junction box on the motor without disconnecting the power. Depending on the tool's design, some tools use the motor's junction box as the main distribution point of power, so power will be present regardless what type of switch is used. Moreover, there are many more tools that have more complex circuitry than simple On/Off controls, where 240 volt power is used throughout the equipment without breaking all non-grounded conductors. My widebelt sander is a prime example, where a single retaining screw will open the hinged panel into the control electronics where 240 volts is present even when the sander is E-stopped.

As I said in my original posting, if you like the original switch, keep it. If you don't like it, then replace it. The choice is up to the user, but don't tell them they will be in peril when you cannot substantiate it.

[Rod Sheridan]

My concern with using a single pole switch for a 240 volt application would be whether the switch is rated for 240 volts.

If you use a double pole switch, the two contacts will share the applied voltage when they open (possibly not evenly, however they will share the voltage).

Using a single pole switch requires that it be capable of extinguishing the arc at 240 volts, not 120 volts.

If the switch is HP rated, and has the appropriate voltage rating, you're fine with interrupting the one line.

I really laughed when I read Rick's comment about "thinning the herd". I'd never considered a single pole switch as a Darwinian selection device before.

Regards, Rod.

[Wade Lippman]

It is not a code violation to leave an ungrounded conductor unswitched at a motor, so you really should not tell people that it is.


I didn't. You really have to start reading posts before you contradict them. (but if code covered such things, it would be a code violation...)

But if fear mongering (better known as the truth) prevents an injury, then it is worthwhile.

[Greg Funk]

I didn't. You really have to start reading posts before you contradict them. (but if code covered such things, it would be a code violation...)

But if fear mongering (better known as the truth) prevents an injury, then it is worthwhile.
Wade,

You've made repeated statements that this is unsafe but have been unable to explain under what conditions one would be at risk. I use a SPST switch to control my dust collector and I would like to understand any potential dangers.

Bear in mind that the NEC does require that 240V circuits have a circuit breaker that disconnects both legs and that this would be the proper way of removing power prior to exposing any electrical components. I would never rely on a switch.

Greg

[Wade Lippman]

Wade,

You've made repeated statements that this is unsafe but have been unable to explain under what conditions one would be at risk. I use a SPST switch to control my dust collector and I would like to understand any potential dangers.


I never once said it was unsafe. In my first post I said "So, it will "work" with the single pole switch, but it isn't a good idea. Your choice."
And it isn't a good idea.
Switches are intended to cut off voltage beyond the switch. It may be neither necessary nor unsafe to use switches improperly in some instances, but it is always a bad idea.
Code is not concerned with what is plugged in, but if it were, code would forbid SP on 240v devices; as code always requires there to be no voltage beyond the switches.

You can do what you want with your equipment, but please don't give bad advice. Just because you are getting away with it, and will probably continue to get away with it does not make it right. I had a 23a water heater hooked up with #12 for 28 years without a problem. Probably would have gone another 28 years, but I still changed it to #10.

[Greg Funk]

I never once said it was unsafe. In my first post I said "So, it will "work" with the single pole switch, but it isn't a good idea. Your choice."
And it isn't a good idea.
Switches are intended to cut off voltage beyond the switch. It may be neither necessary nor unsafe to use switches improperly in some instances, but it is always a bad idea.
Code is not concerned with what is plugged in, but if it were, code would forbid SP on 240v devices; as code always requires there to be no voltage beyond the switches.

You can do what you want with your equipment, but please don't give bad advice. Just because you are getting away with it, and will probably continue to get away with it does not make it right. I had a 23a water heater hooked up with #12 for 28 years without a problem. Probably would have gone another 28 years, but I still changed it to #10.
Wade,

With all due respect you are not making sense. You are saying that it is not unsafe but bad advice and a bad idea.

We are talking about a switch that is meant to control operation of a piece of equipment. It is not intended to disconnect power to allow you to work on the equipment. It is not uncommon to use low voltage switches to control power via a magnetic contactor. Like the SPST switch, a low voltage switch will not remove power from the equipment to allow you to work on it.

Greg

[Steven DeMars]

Sorry Dale, but that's not true. You only need a single pole switch to stop/start a VAC circuit.

Current flows back and forth between the 2 current-carrying conductors in either a VAC or VAC circuit. Interrupting the current flow on either conductor will break the circuit. That's true whether the circuit is VAC or VAC.

There are some reasons that I personally consider 2-pole switches to be safer for VAC circuits, but that's a different story.

Rob
You might want to re-think that! Please feel free to grab either "leg" of a live 220VAC and locate a convenient ground . . . when you get yourself dusted off, if you are that lucky . . .please let me know about the experience . . .

P.S. I have made a living as a Industrial Instrumentation and Electrical Technician for over 20 years and I understand what you are saying. But please for safety sake, do not quote theory to non-electrical trained persons . . . Someone will assume that unless you grab both "legs" of a hot 220VAC at the same time they are safe . . .

Let me be clear . . . REMOVE ALL POWER PRIOR TO DOING ANY WORK . .

In my profession a keyed "LOCKOUT" of power with at least two people were required before service of equipment began . .

[Wade Lippman]

Wade,

With all due respect you are not making sense. You are saying that it is not unsafe but bad advice and a bad idea.

We are talking about a switch that is meant to control operation of a piece of equipment. It is not intended to disconnect power to allow you to work on the equipment. It is not uncommon to use low voltage switches to control power via a magnetic contactor. Like the SPST switch, a low voltage switch will not remove power from the equipment to allow you to work on it.

Greg

I give up. SP switches are just as good, and the universal use of DP switches on 240v is just a silly waste. Got it.

From Delta AP400 Manual
"The Service Center will be able to convert your dust collector

for 240 volts by (a) re-wiring the motor for 240 volts; (b)
installing a 240 volt attachment plug to the power supply
cord; and (c) replacing the single pole on/off switch
shipped with your dust collector with a double pole switch."

You ought to straighten Delta out about (C) not being necessary.

[Greg Funk]

I give up. SP switches are just as good, and the universal use of DP switches on 240v is just a silly waste. Got it.

Wade,

You are wrong. DP switches are not universally used on 240V. My swimming pool motor has a SPST 240V timer switch made by Intermatic. It switches one leg of the supply.

Your use of a smug, sarcastic tone doesn't help your argument. It's better to use fact-based evidence and logic to support your position.

Greg

[Chris Padilla]

C'mon, Folks...TAKE A BREATHER HERE...we are all friends! I'm locking this for a wee bit to allow the cool beverages to flow. :)