Path: g2news2.google.com!news4.google.com!npeer02.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!spln!extra.newsguy.com!newsp.newsguy.com!news2 From: Gordon Shumway Newsgroups: rec.woodworking Subject: Re: 220VAC vs. 240VAC Saw Motor S.O.T. Date: Thu, 01 Jul 2010 17:02:51 -0500 Organization: NewsGuy - Unlimited Usenet $19.95 Lines: 63 Message-ID: References: NNTP-Posting-Host: p14caef09efe018152689b7ebed5ead2c803492d1b31f0b18.newsdawg.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Newsreader: Forte Agent 1.93/32.576 English (American) Xref: g2news2.google.com rec.woodworking:94402 On Thu, 1 Jul 2010 12:21:21 -0700 (PDT), Hoosierpopi wrote: >I was asked today about a motor stamped 240VAC. I kept saying 220 >volts and my neighbor would interupt and remind me it said 240 VAC. > >I told hm that I didn't think it mattered and that I'd never heard an >explanation of why we see stuff rated at 240 VAC when most of our >homes seem to come standard with 220 VAC and 115VAC. > >I've heard 120VAC bandied about and figure those two legs make up the >240VAC. > >I told hime that I knew where to post this question having seen days >of posts on similar Electrical (S.O.T. - somewhat off topic) posts >with some folks who appeared to know their stuff providing links to >references and resources. > > >So, if one og those folks is reading this, please respond and tell me >what gives with the 220 vs. 240 VAC. Can we ignore the minor >difference and usethese motors on "220" or "240?" > >FYI - The motor in question did not indicate it was a dual 120/240 >voltage motor - it just said 240! > >Thanks for reading. Please reply to author. I'll do my best to simplify the answer. I think its time for me to explain about 240 current and why it is so different from 120 volt service. First of all, it's twice as big. Secondly, it'll shock you more. Outside of that, 240 is really two 120 volt lines coming to your house from different parts of the globe. The up and down 120 comes from the northern hemisphere, and the down and up version comes from below the equator. Without trying to get technical, it all boils down to the direction water flows when it goes down the drain. In the top of the earth, it goes clockwise, while on the bottom of the earth it goes counter clockwise. Since most electricity is made from hydro dams, the clockwise flow gives you an up and down sine wave, while the counterclockwise version gives you a down and up sine wave. Between the two, you have 240 volts, while either individual side only gives you 120 volts. This is particularly important to know when buying power tools -- which side of the globe did they come from? If you get an Australian saw, for instance, it will turn backwards if connected to a US generated 120 volt source. Sure, you can buy backwards blades for it, but that is an unnecessary burden. Other appliances, like toasters cannot be converted from Australian electricity to American electricity. I knew one person who bought an Australian toaster by mistake and it froze the slices of bread she put in it. If you wire your shop with 240 and accidentally get two US-generated 120 volt lines run in by accident, you can get 240 by using a trick I learned from an old electrician. Just put each source into its own fuse box and then turn one of the boxes upside down. That'll invert one of the two up and down sine waves to down and up, giving you 240. DO NOT just turn the box sideways, since that'll give you 165 volts and you'll be limited to just using Canadian tools with it.