4 prong to 3 prong plug for disc sander

[mharris2007]

Hi,

I bought a 220v disc sander at auction and it came with a 4 prong plug. My 220v outlet is 3 prong. Is it ok to cut off the four prong plug and put on a three prong plug to fit my existing 220v outlet or do I need to put in a different outlet/rewire to match. I was reading that four prong is two hot neutral and ground, and three prong is two hot and ground. Here are pictures of what I'm talking about.





I'm not trying to start a fire!! Thanks for the advice.

 

[Stuart in MN]

Are you sure the sander isn't three phase?

(Also, it would help to know what state or country you're in - I assume you're in the US but other countries have different electric utility configurations.)

 

[mharris2007]

Are you sure the sander isn't three phase?

(Also, it would help to know what state or country you're in - I assume you're in the US but other countries have different electric utility configurations.)

I'm in Southern California.

I am not sure if it is three phase or not. I will have to take a closer look at the motor assembly and do some reading on three phase to try and figure that out. Thanks for the help.

 

[Sal Bandini]

It says 3 phase on the plug.

 

[mike93lx]

Considering it is a 3 phase plug, you probably have your answer.

That will mean one of three options, assuming you don't have access to 3 phase (unlikely) :
1. Rotary phase conveter
2.VFD
3. Replace with single phase motor

 

[mharris2007]

Considering it is a 3 phase plug, you probably have your answer.

That will mean one of three options, assuming you don't have access to 3 phase (unlikely) :
1. Rotary phase conveter
2.VFD
3. Replace with single phase motor

Yup, I think you're right. Wish I was smarter than that before I bought it. I think it's going to be more trouble than it's worth and will probably sell it on Craigslist. Dang it.

You guys are great. Thanks for your help with my electrical ignorance.

 

[mike93lx]

Yup, I think you're right. Wish I was smarter than that before I bought it. I think it's going to be more trouble than it's worth and will probably sell it on Craigslist. Dang it.

You guys are great. Thanks for your help with my electrical ignorance.

No problem.

For future reference, if you find 240v tools/appliamces with 4 prong plug, it will generally mean that they have electronics which require 120v. Think of an oven. But tools that run solely on 240v don't need the neutral, like a welder.

At least check Craigslist for a phase converter. You might find one for short money.

 

[mharris2007]

No problem.

For future reference, if you find 240v tools/appliamces with 4 prong plug, it will generally mean that they have electronics which require 120v. Think of an oven. But tools that run solely on 240v don't need the neutral, like a welder.

At least check Craigslist for a phase converter. You might find one for short money.

Makes perfect sense. The 120V on an oven is to service the electronics on the screen, etc. And a four prong tool that runs solely on 220V is 3 phase!

I'll look at craigslist now. Thanks again.

 

[mharris2007]

No problem.

For future reference, if you find 240v tools/appliamces with 4 prong plug, it will generally mean that they have electronics which require 120v. Think of an oven. But tools that run solely on 240v don't need the neutral, like a welder.

At least check Craigslist for a phase converter. You might find one for short money.

Cheapest one I could find used was $300. I only paid $100 for the disc sander! Onto craigslist it goes.

 

[mike93lx]

Cheapest one I could find used was $300. I only paid $100 for the disc sander! Onto craigslist it goes.

Depending on how big the motor is, you could get a vfd for $100-200 and that would give you variable speed as well. Might be a useful feature

 

[Dick in Wisconsin]

For future reference, if you find 240v tools/appliamces with 4 prong plug, it will generally mean that they have electronics which require 120v. Think of an oven. But tools that run solely on 240v don't need the neutral, like a welder.

This explains a TON to me.

Our motorhome has a 50amp, 240volt, four prong plug. I see 240volt welders plugged into three prong receptacles all the time. My 240 volt South Bend lathe has only a three prong plug.

Mike93lx's explanation explains in simple terms why the RV is four prong (with both neutral and ground) as there is lots of 120 volt stuff in the motorhome!

Thanks much mike93lx!!!!!

 

[mharris2007]

Depending on how big the motor is, you could get a vfd for $100-200 and that would give you variable speed as well. Might be a useful feature

Hi Mike,

Let me get home and look at the motor and get back to you. I'll look at VFD's as well. I'm not that electrically sophisticated. I can do anything low volt, but the high volt stuff I haven't had much experience with.

Thanks so much.

Matt

 

[wyliesdiesels]

Post a pic of the nameplate.

 

[mharris2007]

This explains a TON to me.

Our motorhome has a 50amp, 240volt, four prong plug. I see 240volt welders plugged into three prong receptacles all the time. My 240 volt South Bend lathe has only a three prong plug.

Mike93lx's explanation explains in simple terms why the RV is four prong (with both neutral and ground) as there is lots of 120 volt stuff in the motorhome!

Thanks much mike93lx!!!!!

I totally agree. I've never seen it put so simply. Makes me understand exactly why and what's going on. Agreed much thanks to Mike.

 

[mharris2007]

Post a pic of the nameplate.

Will do when I get home from work.

 

[mharris2007]

Post a pic of the nameplate.

Here's a picture of the name plate.

 

[buildyourown]

Thats a reasonably priced motor to just swap out.

 

[American Locomotive]

That's a really boring and standard motor. 1HP 1725 rpm motors are easily attainable for dirt cheap - even new.

 

[Radix2]

Thats a reasonably priced motor to just swap out.

That's a really boring and standard motor. 1HP 1725 rpm motors are easily attainable for dirt cheap - even new.

Maybe if it is a belt driven setup.....but many disk sanders integrate the motor into the housing...which is a whole nother thing...

Op- post up a overall picture of the sander.

 

[mharris2007]

Thats a reasonably priced motor to just swap out.

I could swap it out to a single phase 220v to fit my 3 prong outlet?

That's a really boring and standard motor. 1HP 1725 rpm motors are easily attainable for dirt cheap - even new.

Single phase? What would be a good motor to upgrade?

Maybe if it is a belt driven setup.....but many disk sanders integrate the motor into the housing...which is a whole nother thing...

Op- post up a overall picture of the sander.

Here you go.






Appreciate everyone's input.

 

[Marctrees]

Mharris - That disc is ?12"? or what?

Can you take a few photos from the backside of shroud, and back of disk?

Make sure you check the runout deviation on the sanding face as that thing turns, not to be dissapointed after you invest more time and money.

Don't even need a dial gauge to get some idea, just a pencil or something held firmly to table at 90 from face.

Table is a bit small, and no facility for miter gauge, but good news is it is at level clearly below center, so you could fab a larger table to attach on top of what's there.

Looks tippy on that smallish footprint?

Marc

 

[mharris2007]

Mharris - That disc is ?12"? or what?

Can you take a few photos from the backside of shroud, and back of disk?

Make sure you check the runout deviation on the sanding face as that thing turns, not to be dissapointed after you invest more time and money.

Don't even need a dial gauge to get some idea, just a pencil or something held firmly to table at 90 from face.

Table is a bit small, and no facility for miter gauge, but good news is it is at level clearly below center, so you could fab a larger table to attach on top of what's there.

Looks tippy on that smallish footprint?

Marc

Hi Marc,

Yeah I think you're right. It's more trouble than it's worth at this point for me, plus it's an eyesore. If one of the GJ forum members wants it, I'd give it to them for free if they're in so cal. Thanks again.

 

[American Locomotive]

1 HP single phase motors can be found all day for <$40 used, and around $100-120 new.

If it's direct drive, you just have to find a motor with the same speed, shaft size and frame size - which should be pretty easy since these things are standardized.

 

[Cruzan80]

Not sure where you are finding 1HP motors @ 1725RPM for under $40. I would agree if it was a 3450, or if it were belt driven to change pulleys.

 

[American Locomotive]

I usually buy motors off Craigslist. I even got a 15HP motor for $50 once off CL.

 

[Marctrees]

Mharris - Well, all I mean't was to consider everything before deciding what to do w it.

A large disc is a great addition to any general use shop. Marc

 

[1Garageman]

Look on craigslist for a cheap motor, or cheap drill press and use that motor. That is an awesome disk sander you have.

I would if you could get any money out of selling that 3 phase motor on craigslist?

 

[LS6 Tommy]

...assuming you don't have access to 3 phase (unlikely)

If he's zoned residential it's more likely than not he doesn't. You just about need a Novena to get 3 phase in a residential area most of the time.

Tommy

 

[mike93lx]

If he's zoned residential it's more likely than not he doesn't. You just about need a Novena to get 3 phase in a residential area most of the time.

Tommy

Yeah, i know. It just wasn't clear if this might have been at a commercial property.

 

[mharris2007]

1 HP single phase motors can be found all day for <$40 used, and around $100-120 new.

If it's direct drive, you just have to find a motor with the same speed, shaft size and frame size - which should be pretty easy since these things are standardized.

I'm not sure where you're finding 1HP motors for that price either. I checked all of craigslist around me and there were zero.

Not sure where you are finding 1HP motors @ 1725RPM for under $40. I would agree if it was a 3450, or if it were belt driven to change pulleys.

This.

I usually buy motors off Craigslist. I even got a 15HP motor for $50 once off CL.

Not where I live at least.

Mharris - Well, all I mean't was to consider everything before deciding what to do w it.

A large disc is a great addition to any general use shop. Marc

I know. It's just more HA than it's worth to me at this point. I honestly thought when I bought it it was single phase plug and play with any 220V outlet. Lesson learned, plus I learned something new thanks to you guys. I'd really like to find one I can bolt to my bench top so that it doesn't take up the floor space. I have tons of bench top space.

Look on craigslist for a cheap motor, or cheap drill press and use that motor. That is an awesome disk sander you have.

I would if you could get any money out of selling that 3 phase motor on craigslist?

I'm not sure if there's any value in the motor. I listed the whole thing for sale, but like I said if any GJ member is in so cal and wants it, I'd give it to them for free.

If he's zoned residential it's more likely than not he doesn't. You just about need a Novena to get 3 phase in a residential area most of the time.

Tommy

This is at my house.

Yeah, i know. It just wasn't clear if this might have been at a commercial property.

Not commercial.

Thanks for all the replies guys! You're great.