Changing the motor voltage to 220 V AC

rock_breaker

H-M Supporter - Sustaining Member
H-M Platinum Supporter
Joined
Dec 31, 2010
Messages
756
I have a Enco 105 111? mill/drill and am considering changing the power in put from 110 V AC to 220 V AC . Is there any thing more to change than the 2 jumper bars in the power box on the back of the machine? It does have a reverse switch and will run counter clockwise when the switch is thrown. All help will be appreciated.
Ray
 

mksj

Active User
H-M Supporter Gold Member
Joined
Jun 12, 2014
Messages
2,640
This was reviewed in a previous thread:
 

markba633csi

Registered
Registered
Joined
Apr 30, 2015
Messages
4,702
Hi Ray, take a look at that other thread, let us know if you need more info or it doesn't match your machine
Mark
 

stioc

Registered
Registered
Joined
Feb 22, 2017
Messages
589
Is there an advantage to switching to 220v vs 110v? I'm asking because I have the same mill currently wired for 110v. I would love to have speed control via a VFD but that requires a 3-phase motor.
 

Karl_T

H-M Supporter - Sustaining Member
H-M Platinum Supporter
Joined
Oct 14, 2014
Messages
1,385
1 hp and under 110 is fine.
2 or 3 hp 110 will work, not advised.
over 3, you need 220.

Current is 1/2 as much on 220.
 

stioc

Registered
Registered
Joined
Feb 22, 2017
Messages
589
@Karl_T thanks, I'm just trying to understand the whys. So why is it that 2-3hp are not advised on 110v? :)

True the current is half on 220 but the watts consumed are the same. So is the advantage just that you can run bigger motors without running heavy gauge wiring and breakers as would be required for 110v to handle the amperage?
 

Latinrascalrg1

Registered
Registered
Joined
Dec 9, 2016
Messages
1,130
Running on 220v instead of 110v will pull less amperage which means less heat which is easier on the electrical components along with more cash in your pocket because it is a bit cheaper to run.
 

stioc

Registered
Registered
Joined
Feb 22, 2017
Messages
589
Running on 220v instead of 110v will pull less amperage which means less heat which is easier on the electrical components along with more cash in your pocket because it is a bit cheaper to run.
OK the less heat part (from fewer amps) makes sense. However, 220v being cheaper I believe is a myth because as I mentioned earlier the wattage is the same. My power company charges by KWh.
 

Latinrascalrg1

Registered
Registered
Joined
Dec 9, 2016
Messages
1,130
Less energy lost through the extra heat is proof of the savings if you really think about it. Its not a huge amount thats hardly worth mentioning and personally I believe the true value to be in the long run aspect of it being easier on many of the electrical components......at least thats what I have deciphered thru my learning process......
 
Last edited:

WCraig

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 10, 2018
Messages
328
I am not an electrician, but...

In round numbers, and many motors are different:

a 1 HP motor requires 15 amps at full load on 120 volts or 7.5 amps on 240 volts
a 2 HP motor requires 30 amps at full load on 120 volts or 15 amps on 240 volts
...

A standard household 120 volt circuit is sized for a max 15 amp load. But electrical motors briefly suck up much more current when starting. Therefore it is recommended to ensure that the circuit can supply 20 to 25% more amps than the full load requirement for the motor. So, right there, a standard household circuit is inadequate for a 1 HP motor. Do people run 1 HP motors on 15 amp circuits? Yes. But it is cutting into the safety margins. You should always assume that your wiring was done by some kid who was hung over from last night's party. All too often, that's literally true. Overheated wiring can lead to a fire and that is generally not a desirable outcome.

Can you put in higher amperage household circuits? Sure, but the wire in the wall has to be a sufficient gauge to carry the current. Note that the same wire gauge can carry the same amount of amperage regardless of the voltage. Thus, if you are going to run wire through the walls to power a motor, you can safely use smaller gauge wire to power the motor at 240 volts. That saves money.

Craig
PS I don't believe that electric motors are generally more efficient on 240 v. 120 volts. But that is even further from my field of expertise.
 

markba633csi

Registered
Registered
Joined
Apr 30, 2015
Messages
4,702
They are a bit more efficient on 240 because of things like copper loss, eddy current losses and stuff like that. It's a small amount, around 3% I think
Because the resistivity of copper is a constant, when you double the voltage and halve the current the whole system gets more efficient, the wiring in the wall, the motor, everything. Less voltage drop means more power delivered to the load
This is why automotive electrical systems went from 6 volt to 12, less copper required, less weight, etc.
 
Last edited:

stioc

Registered
Registered
Joined
Feb 22, 2017
Messages
589
Well said Craig. I'm not an electrician either but that doesn't stop me from playing one :D Just added two 20 amp breakers to the panel and ran 12ga wiring for 12 outlets. And I'm in the middle of running a 220v line too.

1563816743472.png

But the reason I asked if there's an advantage is because my mill's 2HP motor is rated for 16A at 110v and 8A at 220v which I'm assuming are peak amps -because my 15A breaker has never tripped. Of course it's possible I have a bad breaker, I need to put my Kill-A-Watt plug on it.
 

Karl_T

H-M Supporter - Sustaining Member
H-M Platinum Supporter
Joined
Oct 14, 2014
Messages
1,385
All horses aren't the same. Sears came out with a supposedly 4hp air compressor 20 years ago. it ran on 110. that's when I coined the terms "sears horses". They are just ponies.

A true 1 hp should draw 750 watt with a 2:1 temporary overload.

As for that 2hp mill on 110, you just need to be aware not to push your mill to the limit. easier said than done - something will go harder than you expect sooner or later. if you ever rewire, move etc. upgrade it to 220.
 

mksj

Active User
H-M Supporter Gold Member
Joined
Jun 12, 2014
Messages
2,640
So a few things to clarify, it is one thing change the wiring on the machine from 120 to 240V single phase if designed to do so. But a whole different proposition changing out the motor to 3 phase and adding a VFD. There are a multitude of factors that determine the load requirements and electrical sizing of the socket, and the requirements of the equipment you plan to use. Looking at the Hp alone, well that can be anything depending on the actual current being drawn at the rated voltage, what load it is operated under, and for how long. You often see vacuums rated 4-5Hp, but plug into 120VAC 15A sockets, the real continuous Hp/current is much lower. A VFD on the other hand can draw upwards of 200% of the motor amperage for up to a minute, so the maximum size 120VAC VFD is around 1.5 Hp and this requires a 20A plug/breaker. As other's mentioned, most 120VAC sockets are 15A, so trying to run a 2 Hp motor off of that is not wise. The running Hp/current under no load is less, but current and resistance is what cause heating in the wire. Use a smaller wire at a higher current = more heat and eventually damage and possibly fire.

Breakers are designed to protect the wiring, but the assumption is you are not overloading them based on the socket/plug rating. Breakers are also designed with different trip curves, depending on the age and wiring, it may not be working at 100% of spec. Wiring in a house and also appliances have a safety margin built but there may be some de-rating based on the the wire ratings and associated equipment. A breaker is usually designed to trip based on current over time, so you can pull higher peak currents over a specified time. The motors with very high starting currents to not trip the breaker, as long as the current quickly declines.

If you plan to go to a VFD, then you need to replace the motor and for the most part you would not be using any of the current machine controls/wiring, so a complete rebuild. The only available VFD's for 2 Hp are 240VAC, the VFD manual will usually specify a 30A breaker, it may run off of a 20A breaker if you dial down some of the VFD load parameters or have light duty use. It will run, and may be fine, but for continuous use with load I would use a 30A breaker. The circuit breaker is supposed to be sized to ~125% of the VFD full load rated input current, does not matter what the VFD is connected to.
 

Attachments

stioc

Registered
Registered
Joined
Feb 22, 2017
Messages
589
@mksj thank you for the informative post. I agree, if I upgrade it to a 3 phase motor (and a vfd) I will be running it off of single phase 220v and at least dual pole 30amp breakers with 10ga wiring. The original question was out of my curiosity if there's any benefit to converting a 110v wired motor to 220v.

Speaking of converting to a 3 phase motor I found this article helpful...even though it specifies Automation Direct's products but I learned about the NEMA frame sizing which I didn't know. This will certainly help finding a motor that fits with minimal modifications.

 

WCraig

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 10, 2018
Messages
328
the reason I asked if there's an advantage is because my mill's 2HP motor is rated for 16A at 110v and 8A at 220v which I'm assuming are peak amps -because my 15A breaker has never tripped.
We as the operators of machines like a mill, lathe, table saw or whatnot control how much load we put on the motor. If you push the mill quickly through a long, deep and wide cut, you could well trip the breaker. Most of us recognize the stress we're putting on our machines and don't push them to their limits. On the other hand, things like a water pump or air compressor face pretty much the same load every time they run.

Ideally, if you were to continue running the mill on 120 volts, you'd want to put it on a 20 amp circuit so you have some headroom over the 16 amp full load draw. I agree that 240 volts makes sense if adding the circuit isn't prohibitive.

Craig
 

rock_breaker

H-M Supporter - Sustaining Member
H-M Platinum Supporter
Joined
Dec 31, 2010
Messages
756
I have a 220 volt air compressor at the far end of the shop from the breaker box and a 220 volt Enco lathe within 8 feet of the mill and they are both within 8 feet of the breakers, it is an opportunity to reduce the heat potential. My band saw is is close to the compressor outlet so I installed a 220 volt switch, a polarized plug and changed the motor connections. Again this is about reducing heat in the wiring.
Have a good day
Ray

P.S. Mark thanks for the info.
 
Last edited:

RockingJ

Registered
Registered
Joined
Jun 7, 2018
Messages
21
I had problems with my RF mill when running on 115 V. The centrifugal switch burned up the contacts. The centrifugal switch is what turns off the start windings in the motor when it comes up to full speed. I had to replace the switch.

If your wire is properly sized for the rtotal load on it, the wiring should not heat up, if it is getting warm then the wire size is too small and needs to be addressed!

I have learned not to use the horsepower ratings of motors now days, go by the amp draw or Kw rating. If you look at the HP on my RF mill it is rated at 2 HP but the amp draw is closer to 1 1/4 HP. Obviously Chinese HP isn’t the same as the rest of the world!

The mill may run better on 204V since the voltage drop through the wiring will not be as big of a factor.
 

FOMOGO

Active User
H-M Platinum Supporter
Joined
Sep 2, 2013
Messages
2,241
Not by any means an electrical guru, but it has been my experience that on dual voltage motors, running on 240 will always feel like you have more available power. I have an ancient Craftsman radial arm saw that had a tough time ripping 2x material. Rewired it for 240 and it was night and day difference. Same story with my old Buffalo 8" grinder. Mike
 
It can take up to an hour for ads to appear on the page. See our code implementation guide for more details. If you already have Auto ad code on your pages there's no need to replace it with this code
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock