OK, this might be a stupid question, but then again I’ve been known to be stupid at times –
I just purchased a Jet 18″ bandsaw – it came pre-wired for 110v with a 1 3/4hp motor. It can be rewired for 220v – I have plenty of 220v wiring throughout the shop – even have 3phase – so it wouldn’t be a problem for me to use this machine on 220v – but what is the advantage?? As far as I can tell the cost would be the same – I’m charged by the kilowatt, which should be the same for either wiring configuration so it won’t save me any money. The wiring is heavy enough to handle the amperage from the 110v configuration so what’s the advantage??
Should I be lazy and just leave things the way they are or spend the 20 min to reconfigure the motor and put on a new plug?
Replies
Haines, do yourself a favor and use the 220 volt connection. You will have more power to the blade and less motor heating. I suspect you will not be able to bog your machine either. Generally on tools like these, the low power setting is for use where there isnt enough power available to run the machine but it does diminish the quality of use. aloha, mike
Mike, since we are old chinas, could you please tell me why you guys in the States are still using all these strange voltages and all. Is ther a similar foncopulation when it comes to 3 phase equipment?
And dare I ask if those black telephones with the two bells on are in use too?
Hopefully Direct Current has been phased out for every thing except the electric chair.Philip Marcou
Phillip, USA voltage choices are based on a conspiracy between Westinghouse and the other competitors in the emerging electric industry over the creation of standards. We ended up with AC when we could have been DC. I use 3 phase for most things but home shop craftsman use 110-220 single phase. Small tools are okay with the lower voltage but most larger machines need at least the 220 voltage. The electric chair is mostly over but DC is still used for street tolleys and subway systems in cities.
My phone is black but has custom ring tones aloha, mike
Thanks Mike-was just funning you all. As long as the distinction between AC and DC is upheld all will be well.Philip Marcou
Actually, there is an interesting history about this. Thomas Edison favored DC current, and his company which is now General Electric, pushed its implementation. The trouble is, line losses are more of a problem for DC than for AC which can be transmitted over long distances at high values (volts) by the use of transformers. AC was promoted by, among others, George Westinghouse, Edison's arch rival. In a bid to boost the pr for his DC plan, Edison promoted AC for use in the electric chair, reasoning that it would appear too dangerous for home use. Unfortuantely for Tom, physics won the day and AC was the adopted standard.It is interesting that in many applications, AC is converted to DC by the appliance or instrument itself, usually in a switching power supply. Radios, televisions and all digital electronics use DC for their internal circuitry. Heating elements and electric motors can use either AC or DC. Early transformer/capacitor power supplies that supported tube radios were designed to replace heavy lead acid batteries and were called "battery eliminators".As for 110 vs 220, I'm not sure why the standard in the U.S. evolved differently from ex-U.S.: 110 is safer, as there is less chance of electrocution, and for many applications, it is more than adequate. In the U.S. 220 is reserved for heating, AC, cooking ranges and clothes dryers. For most WWing tools where power requirements approach or exceed 3 hp, 220 is preferrred, because current draw on a 110 line will exceed 20 amps (3 hp x 746 watts/hp = 2238 watts. 2238 watts is 20.3 amps at 110 V), which is the standard heavier gauge wiring found in most non-commercial construction. Since a 3 hp motor will usually surge above its rated power at start up, you can trip a breaker fairly easily. At 220, such a motor would draw 10 amps. Even allowing for the overstatement of power by many equipment manufacturers, at 2 1/2 to 3 hp, you are bumping into a real limit at 110.As for 3 phase, it is more efficient than single phase, but it is also more expensive and not as readily available in non-commercial settings. It's probably overkill for most woodworking outside of production shops using commercially scaled and powered equipment.Just my 2p,
Glaucon
If you don't think too good, then don't think too much...
Actually, it doesn't need to be a switching power supply, it's changed to DC in most devices when it goes through the bridge rectifier(either half wave or full wave, depending on the need) and then the ripple is removed with capacitors. Switching power supplies, also called pulse or PWM (Pulse Width Modulation) power supplies, convert the AC to square or triangle and waveform and use an oscillator as a reference. The supply then sends pulses out which switch on/off and stay on longer during heavier demand. Much more efficient than the normal power supplies, too. You probably know this, though. Poor Tom, as much as he wanted DC to win, he just couldn't beat the laws of physics. I wonder how he proposed to transmit DC over long distances. We would probably have run out of copper if DC had been adopted.
"I cut this piece four times and it's still too short."
Actually, it doesn't need to be a switching power supply...You're right. Most inexpensive appliances (portable radios with optional AC adaptors, for example) use transformers/caps- switching power supplies are generally favored for more expensive applications. It seems that prices for the latter have declined in recent years, as I see them more and more in less expensive applications.Glaucon
If you don't think too good, then don't think too much...
You brought up one thing I didn't consider - motor heating. I'm not sure if Jet prewires these machines for 120v to make them more appealing for folks that have smaller home shops with limited wiring possibilities. I think I'll switch over to 220v - it will be relatively simple to do. Thanks for the advise.
If you can change out a socket & rewire the motor/plug in 20 minutes, I would like to watch this speed demonstration. Higher operating voltage has the advantage of delivering twice the current through the same wire diameter. If you are cutting the maximum depth at the maximum feed rate with your saw, you may notice a difference. Small but probably undetectable differences will be a slightly cooler running motor, which should have a longer life, as well as less chance of slowing the blade.Cadiddlehopper
<<"Higher operating voltage has the advantage of delivering twice the current through the same wire diameter">>Not sure what you mean here... At higher potential (volts), the current through the "wire diameter" would be less to develop the same power- e.g for a 3 hp motor it would be 20 amps at 110V and 10 amps at 220V.The advantage is that the same power can be delivered while drawing less current through an existing circuit (the breaker and receptable would be changed out for 220, but the copper wire between the mains and the tool could be used if adequate to code).Glaucon
If you don't think too good, then don't think too much...
I stand corrected. It would be power, not current.Cadid
Um... not sure about a bandsaw, but I definitely noticed an improvement on my Jet 10" contractors saw.Start up is much faster, and it seems to be harder to slow the blade down. I also think I was getting a little bit of a vibration as the motor was getting taxed.I even switched over my Jet 650 dust collector, and it also seems to run better.Another benefit (for those of us at home with companions), is that the lights in the house don't dim whenever I turn the saw on! BillPS. I've heard the same argument for/against 110/220... I've heard that 110 is just the right voltage to 'freeze' your muscles if you grab ahold of a live wire, where 220 will make you 'jump back'. But 220... being that most appliances require less amperage.. will create less heat (in your wiring) and be less of a fire hazard (which is why I put 12 gauge wire thru-out my house. I've neglected arguments FOR 110v, but the point is moot.. since we are stuck with what is code in our respective locale.
The freezing effect you refer to is called muscular tetanization and it is a function of current rather than voltage. You can place your hand on a Van de Graaf generator at 100,000 volts or more with no ill effects beyond a bad hair day.
For power frequencies (50 - 60 Hz) the current requirement for involuntary tetanization is 6 - 10 milliamperes (0.006 - 0.010 amperes) depending on body mass (They used to believe is was gender based with men having higher tolerance). For DC the current requirements for tetanization are higher. Interestingly, as frequency increases the body can withstand higher current values as well (up to 19 mA) but this is due to the skin effect at elevated frequency (kHz range and above) the current travels increasingly toward the outer surface of a conductor (you) so internal musculature and organs are not so damaged. Topical burning is still an issue though.
The "jump back" effect is an involuntary startling reaction to exposure to current levels around 1 milliampere (as I recall) and greater. This is referred to as the reaction current level.
Power mains frequencys (50 - 60Hz) at common current levels 10 or more Amperes is extremely dangerous. I do not believe the difference between 110 and 220 volts would be significant.
Some people believe that 220v is more dangerous because the striking distance of an arc or discharge is double that of 110v. It is! It goes from .001 inches to .002 inches!
Don't get me started on High Voltage! (My business).
David C.
<<"Power mains frequencys (50 - 60Hz) at common current levels 10 or more Amperes is extremely dangerous. I do not believe the difference between 110 and 220 volts would be significant.">>I would disagree. Burning and muscle tetany are unpleasant and dangerous, but ventricular fibrillation (VF) is lethal. At 110V or 220V, this is what kills people. AC is much more effective than DC in inducing VF. The human body is a complex, heterogeneous conductor, but it still obeys Ohmn's Law. The effective resistance across the thorax is about 700-1100 ohms; capacitive losses are minimal at 60 Hz. If you use 1,000 ohms as nominal, than the current developed at 220 V is twice that at 110V (220mA vs 110mA). The risk of VF increases with the potential, and is affected by other things such as geometry, the size of the heart, the presence of preexisting disease, use of certian medications, etc.Nonetheless, at higher potential the risk of VF increases significantly.Glaucon
If you don't think too good, then don't think too much...
Glaucon,
You are correct, when I said I didn't expect there would be much difference between 100v and 220v, I was specifically referring to the effects of voltage on muscle tetanization, which was the specific point I was responding to. I was not trying to suggest that there was no difference in terms of general shock hazard. I should have been clearer.
Voltage is a factor in ventricular fibrillation.
Best Regards,
David C.
Re: electrocution.
Very interesting - and helpful. I have heard that humans are more resistant to electrocution than most animals. Can you verify that and if so why?
Hmmmmm. If electrocution means dying from a cardiac arrhythmia (VF)- as opposed to being cooked- then it would depend on the animal that you compare humans to. Small animals have small hearts- whcih are more resistant to VF. Cows and horses are more easily fibrillated, but their greater mass likely means that the field strength required is greater.Not sure if we'll ever see a scientific study ("A comparison of AC electrical current requirements for ventricular fibrillation in large mammals and death row inmates: a randomized trial")- funding could be a problem...Glaucon
If you don't think too good, then don't think too much...
Oh, I was hoping it would be more simple. Thanks for the response.
If you grab one leg of 220 or 110 and your body is grounded at another point you get 110v to ground either way. Across both legs - give me 110v every time.
Hello: For a line cord that guarantees no voltage drop see pictures at 6997.1
DukeKenneth Duke Masters
The Bill of Rights December 15 1791 NRA Endowment Member
LEAA Life Member
CRPA Member
>> You will have more power to the blade and less motor heating.
Neither one of the above statements is correct. All dual voltage motors have two coils that run on 120 volts each. All you do when you re-wire for 240 is change the wiring from parallel to series. The voltage in each coil remains the same. Similarly, the amperage in each coil is the same. It's amperage that causes heating so if the coils have the same amperage with either wiring, the heat is the same. The motor neither knows or cares whether it is using an input voltage of 120 or 240.
As long as your wiring from the panel is sufficient for the amperage, there is no benefit to converting to 240 volts. Howie.........
Howie, I have used motors wired for low voltage that were both. At low voltage they suck but work. I always convert them back when its possible to do so or appropriate. Loaded motors in particular (air compressors, etc) respond better when both coils are heated up. I am not an electrician or engineer but as a user I prefer the 208-220 mode. aloha, mike
Mike: Howie is correct, both coils are used no matter what voltage the motor is setup for. If the circuit has sufficient wire size (all the way though; feeder, branch and cordset) and no other device is pulling down the voltage you should get the same performance at 120 or 208/240. There are some smaller issues such as weak connections in the cord cap (plug) or bad contacts in a cheap or worn receptacles causing voltage drop which would be halved at 220v. In a wood shop or anyplace where cords are plugged in and removed frequently and the loads are on the heavier side better quality plugs and receptacles would be worth the cost.
Duke the electricianKenneth Duke Masters
The Bill of Rights December 15 1791 NRA Endowment Member
LEAA Life Member
CRPA Member
If your wiring from the panel is sufficient for the amperage, there is no benefit of converting to 240 volts.
An awful big IF. The fact is that there is no perfect conductor. No matter what material or size, however imperceptible the amount, there is always resistance and voltage drop. That drop will be only half as much for 240 volt supply as for the 120 volt supply. And that is why the motor wired to 240 volts runs cooler and has more power than when wired to 120 volts.
He was right, there will be no difference, you just need BIG wires for the 120V supply and your supply losses I^2 R will be a little more but hardly noticeable.
Your motor running cooler, could be a placebo effect.
Wellllll, I dont know if I stand corrected or not. I only use the 110volt (104volts in Hawaii) when 220 (208volts) is not available or too far away. As I no longer do job site work most of my machinery is hard wired and alot is 3 phase. Occaisionally I have to do a spray touch up on something installed and I have used a portable compressor for this. It seems to work better close to loadcenter and on 220 when I can get it. I must admit, the air still feels the same although it seems the charge up to tank is slower. aloha, mike
Negligible at fractional HPs. At higher HPs, long spans and undersized wire, the difference become quite noticeable ie. trying to run multi HP motors on fourteen gauge wire at 110 volt can damage the motor and building.
110 will perform poorly if you have a too-small conductor, or a too-long run. 220 is of course more resistant to this effect. But since you've asserted the connector is of adequate size (for startup current too, I hope), the motor should behave identically either way.
Now since Mike and I are saying opposites, your next best bet is to contact Jet and ask 'em. :)
Haines,
Some comments about all the previous posts.
The voltages are normally 120V and 240V here in the US. You seem to be in an industrial building, so I assume you are receiving a 480V supply and you step down with a transformer?
It is better to use the 240V option, simply as you will have less copper losses due to the lower current and thus be more efficient.
Willie
I'm a little curious about that 1.75hp motor...I looked at the owner's manual for that bandsaw on the Jet website, and for the 120vac configuration it shows a standard 15 amp plug on the end of the power cord.
There wasn't any information in the owner's manual about the full load current rating of the motor, but typically a 1.75hp motor would be at around 22 amps at 120 vac. It makes me wonder if Jet uses some sort of fake 'peak' hp rating for the motor, rather than actual hp.
Ill look at the amperage when Im in my shop tomorrow. It's a pretty heavy duty plug, at least 12gauge, however, I guess this is only good for up to 20amps anyway. I guess the HP could be bs - it usually is anyway.
Actually the 22 Amps you site are peak numbers. That motor probably has a no load amperage of less than 12 amps, with moderate loads raising it a few Amps. I agree that it would be better in a 20 Amp outlet, but the motor would not trip a well wired 15 amp circuit.
Mike
The thing is, power tool manufacturers like to use terms like 'peak current' that don't really mean anything...it's marketing speak, much like how car stereo manufacturers talk about how many watts of 'instant peak power' their equipment generates, instead of using quantifiable numbers that you can compare to other manufacturer's products.
If you look at the nameplate on a motor, or browse through a motor catalog, it's going to list the horsepower, the operating voltage or voltages, the full load amp rating (which is what current the motor will draw at 100% load), the locked rotor amp rating (which is what you'd get if the motor was stalled, and is generally 5 to 7 times the full load rating), and the motor efficiency. That's pretty much it.
Certainly, a motor will draw more or less current depending on the applied load, but that isn't used to size the circuit breaker or power cord.
edited to add: There will be some other information on the motor name plate, like service factor, insulation rating, temperature rise, etc. but they are outside the subject of this discussion.
Edited 4/20/2006 6:19 pm ET by Stuart
But there can be a few variables - breakers for one. I have a 3 HP PM66. I think it should be about 18 amps, but it kept blowing a 30 amp breaker. I have known a 20 amp Federal Pacific breaker to carry, in excess of, 200 amps without blowing. I would guess that the rated amperage is a much more accurate rating than what some brands rate their HP ratings i.e. the motor might draw the 22 amps without exceeding the acceptable temperature rise on a continuous basis. A good 20 amp circuit breaker should blow at that load.
Edited 4/20/2006 11:48 pm ET by tinkerer2
220V is the phase to neutral voltage on a 380 volt three phse system.
110 volts is the phase to neutral voltage on a 3 phase 208 volt system, 208 volts is the phase to phase voltae.
In most residential homes, you have two (2) 120 volt phases. Most Air Considioners, ovens and electric dries use 240 (two 120 volt pahses or 240 volts phase to phase).
The advantage of the higher voltage is that you use less cureent. The power is the same. A 1/3hp or 3hp motor is still 1/3 or 3hp. By using less current for the same power, there is more current available to handle bigger loads. to get the same power out of a 110 Volt line means you are using most of the available current from your circuit to get the required HP out of your motor. Usually, you can do this with a bigger (30 amp circuit) and very (thick) copper wires.
So when ever you get a big motors, higher voltage is the way to go.
Where do you live? The only place I've heard of where 380vac three phase is used is in parts of Europe.
At least in my neck of the woods, the common service voltages are 120/240vac single phase, 120/208vac three phase, and 277/480vac three phase. The three phase services are almost exclusively commercial. There are some other service voltages available like 4160vac, but they are for large facilities outside the scope of this discussion.
120/240 single phase comes from the utility transformer that's either up on the pole out at the street or sitting on a pad out in the yard. It's stepped down from whatever the utility voltage is on the primary side of the transformer, which I believe is typically 12.8kV around here. The 12.8kV may be either single phase or three phase, it just depends on the neighborhood - most residential areas are served with single phase, but if you're in a commercial or industrial zone, or along a main road or highway it's more likely to be three phase.
Going back to the original poster, for a power tool of moderate size 120vac can work fine as long as the wiring (including any extension cords) is adequate. It does give you the freedom to plug your tool in anywhere in the house. If the tool will be stationary in a shop, 240vac is more often the better choice.
Edited to add: You may also find 120/240 three phase delta services in some areas, generally in older areas of town. Around here it's being phased out so it's not very common any more, and the utility companies won't install new 120/240 delta services. That may be different in other parts of the country.
Edited 4/12/2006 9:34 pm ET by Stuart
You are on the money. My point was that the only place I see 220 volts is Europe.
So why do we talk about 22o volts here in the states?
>??? almost every home in US has 220 volt power running to it, to be mostly split to provide 110, but available for uses calling for higher voltage--such as dryers, or my Unisaw. Did you really mean to say you only saw 220 in Europe?
Generally speaking, residential electrical services in the US are actually 120/240v. If you look at the label on the back of an appliance or a power tool, they are more often identified as 115/230 or 110/220. So, it's kind of splitting hairs since everyone knows what a person is talking about when any of these terms are used.
Quite so, but I doubt that was the point being made. And, of course I was speaking about the generic 240/230/220.
I was told by a teacher in electric wiring that the official voltage was 230 but how can I verify that?
I thing you were misinformed, it is officially 120/240 volts. I just measured the voltage in my house and it was 120 volts on one leg and 120.8 volts on the other. I am sure you could verify this using Google. I wish people would not say it is 110/220 volts.
http://encyclopedia.thefreedictionary.com/mains+electricity
Life is what happens to you when you're making other plans .
Edited 4/21/2006 8:39 am ET by JerryPacMan
If you have a voltmeter, read the voltage across the two pins (not ground!)
This will tell you the pahse to phase voltage. If you have three phases, you will see 208. But this is generally a commercial application and not residential. If it is a residence, you should see 240 volts (+/- 5% or so). Then measure from each pin to ground, and you should see half of this, or 120 volts (again +/- 5% or so).
You'll find 3 phase power in a number of different flavors, not just 208. 240, 480, 575, 2300 and 4160 for sure and many ships use 120V 3 phase for lighting (delta-delta xfmrs).
"I was told by a teacher in electric wiring that the official voltage was 230 but how can I verify that?"
1.) Take an Italian sausage, exactly 12" long and connect a copper coil at each end.
2.) Connect one wire into the left outlet hole and the other into the right side outlet hole.
3.) Set your alarm clock for 9 minutes and 38 seconds.
4.) Switch on the power.
If you had 120V nothing happens, with 220V the sausage will be medium rare, at 230V, medium and at 240V it will be well done.
If you have harmonics in your supply, as multiples of 5, the sausage goes red and becomes real hard, this being a good way to test for potential damage of electronic components.
But I went to get my Italian sausage after 9 minutes and 38 seconds and someone had already gotten it - either that or the timing was too long because only a little smoke was left.
Do you have to adjust your time for the inclusion of parsley, cheese or fennel to get a proper reading? Pat
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