110V or 220V

[Rick Christopherson]

And having NEC require a 10 ga wire for a 1.75 hp shop motor, I guess I better do some reading, never ran across that.

You never ran across it before because it is a misinterpretation of code that was presented as though it was fact.

+1. Speak in theory all you want, and hypothesize that ......

I always get a kick out of it when people say "it's theory...and hypothetical". That's forum-speak for "I don't understand it, therefore it is only a theory."

Relativity is a theory.

Most electrical equations are driven by scientific Laws. It's not "Ohm's Theory", it's Ohm's Law. It's not "Kirchoff's Current Theory" it's Kirchoff's Current Law.

Just because something is not understood by the average layman doesn't mean it is only theoretical. The engineers that design the motors used in our tools aren't just taking shots in the dark as to how they work (well except for those unnamed-countries that just copy designs). Motor performance can be exactly modeled to several decimal places long before a single piece of copper is ever wound.

For every case where a woodworker claims to achieve significant improvements in motor performance between 120 and 240 volt operation, a knowledgeable engineer will find the other overlooked variables that were also changed in the process. It's comparable to saying that since 90% of all cancer patients drink milk, then obviously milk causes cancer. Don't overlook the other variables.

[Ole Anderson]

You never ran across it before because it is a misinterpretation of code that was presented as though it was fact.

Hmm. This is getting interesting, stay tuned...

[George Bregar]

Hmm. This is getting interesting, stay tuned...

They always do! http://www.sawmillcreek.org/showthre...00#post1616500

[scott spencer]

...I always get a kick out of it when people say "it's theory...and hypothetical". That's forum-speak for "I don't understand it, therefore it is only a theory." ... For every case where a woodworker claims to achieve significant improvements in motor performance between 120 and 240 volt operation, a knowledgeable engineer will find the other overlooked variables that were also changed in the process. It's comparable to saying that since 90% of all cancer patients drink milk, then obviously milk causes cancer. Don't overlook the other variables.

I don't agree with the last part of that statement at all, and I suspect that the "forum-speak" definition is putting words in other's mouths. My point, and the way that I interpreted Homer's point, is that I'm aware that there are many other potential variables in the equation that can influence the end results (many of which I definitely don't understand), but in many cases there are noticeable benefits to an average user by making the switch to 240v if it's readily available, regardless of the actual causes as identified by those with a more expansive knowledge of them. I'm not trying to draw any conclusions other than describing the real world changes I noted in laymen's terms.

[Darius Ferlas]

I always get a kick out of it when people say "it's theory...and hypothetical". That's forum-speak for "I don't understand it, therefore it is only a theory."

Relativity is a theory.

Most electrical equations are driven by scientific Laws. It's not "Ohm's Theory", it's Ohm's Law. It's not "Kirchoff's Current Theory" it's Kirchoff's Current Law.

Rick, I think you put too much stress in the popular meaning of the word theory and that leads you to creating a hypothesis about posters, which is what you probably think a "theory" means.

A lot of indisputable facts are called theories. A glaring example is Newton's "theory" of gravitation. You know... Newton... the guy who discovered the apple? That apple will still fall, even if it's just a theory.

But... sticking to the subject, the fact is that a lot of what people write in these threads are based on a unified "theory" of electricity and magnetism (published by Maxwell and aka as electromagnetic theory) and on circuit "theory". These are not hypothesis.

[Lee Schierer]

Mark,

If your new table saw is a Delta Contractor saw, somewhere, perhaps in a FWW tool review, I read that the saw has more power at 240V. Something about a set of windings in the motor that are energized at 240V but not at 120V.

Jim

If the motor is 1.75 HP then it is 1.75 Hp no matter what the voltage is. Motor manufacturers don't install extra windings just in case. P=IV =115 *14 = 1610 watts 230 * 7 = 1610 watts. All you do when rewiring a motor to change voltage is change the order in which the windings are connected. You don't leave any out or add any in. If your supply circuit is properly sized for the voltage and length of run the performance will be exactly the same. As others have stated a 20 amp breaker and 12 gauge wire may not be sized right for a 1.75 Hp saw.

[Barry Lyndon]

More complicated than you'd expect...
If you're using the "toaster or coffee maker plugged into a 20A kitchen circuit" analogy, then you only need the plug to match the max amperage of the device it feeds.

Folks bite off on this all the time and forget that for motors in a shop, you probably took advantage of some assumptions that disallow this attitude/analogy.

If you're running a 230V circuit in a garage or basement (below grade) shop, and you DIDN'T put a GFCI breaker on it, then you are likely using the exception for "dedicated circuit" in the NEC (even if you didn't know it)... and if you're using a dedicated circuit then you should make everything on that circuit match the possible amperage of the circuit. Again, there are arguments to be made for the view above, but IMO once you're assuming a dedicated 230V circuit, then dedicated means calculated for and engineered for the load on the circuit. Therefore, IMO, the correct answer becomes making the extension cord, plug, receptacle, and wiring all match the proper load calculations for your machine. I would then make the CB match that load, with the caveat that for motor loads I know that motors may be thermally overload protected which allows me to boost the CB amps higher IF NEEDED to allow startup without problems (IAW some complicated rules in the NEC).
Remember, the entire point of all these calculations and circuit breakers is to keep your house from burning down. When wires and their terminal connections (plugs, receptacles, lugs/screws) have electricity flowing through them, they get HOT. The CB is on there to limit the flow of elec. (amps) to an amount that EITHER the wire itself OR the terminal connections can take and stay cool enough to meet NEC requirements. So, if you have a 12 ga wire with a 20A circuit breaker, then you need 20A receptacles and plugs on it. And sure, if you're plugging a thermally overload protected toaster or such into it in a non-dedicated circuit way, obviously you use the plug that matches the toaster.

Boy, that WAS more complicated than I'd expect. I ended up using a 20A receptacle and plug and the circuit is a dedicated 20A circuit using 12-2 wire so if I understand you correctly, I think I'm in the clear. I am, however, using the original cord for the machine which is 14 ga. Hope that doesn't cause any issues.

[Rick Christopherson]

Rick, I think you put too much stress in the popular meaning of the word theory and that leads you to creating a hypothesis about posters, which is what you probably think a "theory" means.

No, I was actually pointing out the "Popular meaning" of the term. It's a valid observation I have made over the years spent on many forums. There is no insult intended. It is just an observation I have seen, and one which I stand behind.

Another observation is that the overall direction of the information is dependent on the most active participants. That is to say, the same question asked on different forums will get different ratios of answers based on the level of knowledge of the primary participants.

When this question gets asked here, you will get about 50:50 pro/con. When you ask this question on another (unnamed but well known WW forum) the ratio drops to 20:80 pro/con. If you asked this question at the MikeHolt electrical forum, you're gonna get 1:99 pro/con responses.

The caliber of the users drives the direction of the information. But that is not the same as saying the correctness of the information drives the information. The reader of the information needs to know this to understand why they are reading contradictory information from the various forums that they read.

Over the years, I have even seen the word "theory" applied to simple mathematics in woodworking discussions, where it was quite clear the poster was using it as a blanket term to cover concepts not fully understood by the poster. There is nothing wrong with not understanding the core information. What is wrong, is assuming that because a person does not understand the core information, that therefore, no one else is capable of understanding the core information; and it is therefore, just hypothetical or theory.

[Dan Friedrichs]

I've personally experienced noticeable differences in startup speed and power on stock length cords when converted from 110 to 230 on both contractor saws and jointers.

Fine, but as Rick is trying to articulate, this is not caused by MAGIC. If you have a 12ga cord, and you hook it to either 220 or 110V, I agree that you will see a faster startup on 220. The reason for this is well-understood: at 220V, you pull half the current for the same power, resulting in less I^2*R loss in the wire, meaning there is a higher voltage available at the tool.

However, if you have the option of installing a new run of wire for a tool, you can choose to use a larger gauge of wire if the run will be 110V, or a smaller (less expensive) run of wire if using 220V (as the current will be half as much). If you size the wire correctly, the start-up speed will be exactly the same for either voltage.

People incorrectly infer that 220V is "better", but fail to realize that this is entirely a product of the gauge of wire used in the circuit. A 110V circuit using sufficiently large wire will perform EXACTLY THE SAME as a 220V circuit.

[scott spencer]

Rick (and others) - If 220v is available, what are the "cons" of wiring with 220v instead of 110v?

[Rod Sheridan]

Scott, there aren't any unless you need an expensive upgrade because you're out of panel space.

Wire and wiring devices are less expensive at 240 volts because the wire gauge and current carrying capacity are half.

A 30 ampere 120 volt receptacle and #10 wire cost more than a 15 ampere 240 volt receptacle and #14 wire, yet run the same size motor.

Of course the single pole breaker for 120 volts is less expensive than the 2 pole for 240 volts, however that is often offset by the savings in wire and receptacles.

Regards, Rod.

[Mike Henderson]

Rick (and others) - If 220v is available, what are the "cons" of wiring with 220v instead of 110v?

About the only "con" I can think of is when you re-arrange your shop you may have problems with the location of your 240V outlets. Usually, you have a lot of 120V outlets so you can plug in almost anywhere (assuming you don't need a "special" high capacity 120V circuit).

Mike

[Jim Falsetti]

If the motor is 1.75 HP then it is 1.75 Hp no matter what the voltage is. Motor manufacturers don't install extra windings just in case. P=IV =115 *14 = 1610 watts 230 * 7 = 1610 watts. All you do when rewiring a motor to change voltage is change the order in which the windings are connected. You don't leave any out or add any in. If your supply circuit is properly sized for the voltage and length of run the performance will be exactly the same. As others have stated a 20 amp breaker and 12 gauge wire may not be sized right for a 1.75 Hp saw.

Lee - On my 2001 Delta contractors saw motor, the nameplate says "Delta No. 62-044, Horsepower 1 1/2-2, Volts 115/230, Amps 12.8/8.6". So for some reason it has a higher power output at 230V than 115V. I read the bit about extra windings in a contractor's saw tool review, perhaps in Wood or FWW. Perhaps from a sourcing perspective, it was cheaper for Delta to buy that motor than another with a constant power output at 115/230V.

If the OP is purchasing a saw, he should check the motor nameplate to see what the ratings are at the different voltages.

Jim

[George Bregar]

Lee - On my 2001 Delta contractors saw motor, the nameplate says "Delta No. 62-044, Horsepower 1 1/2-2, Volts 115/230, Amps 12.8/8.6". So for some reason it has a higher power output at 230V than 115V. I read the bit about extra windings in a contractor's saw tool review, perhaps in Wood or FWW. Perhaps from a sourcing perspective, it was cheaper for Delta to buy that motor than another with a constant power output at 115/230V.

If the OP is purchasing a saw, he should check the motor nameplate to see what the ratings are at the different voltages.

Jim

Really? http://www.interschola.com/template/...0/p2220116.jpg

[Jim Sebring]

Those twist locks work very well for ceiling drops - like I have for my tablesaw and 8 inch jointer.