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Woodturning (rec.crafts.woodturning) To discuss tools, techniques, styles, materials, shows and competitions, education and educational materials related to woodturning. All skill levels are welcome, from art turners to production turners, beginners to masters. |
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#1
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wireing problem
I just purchased a 3/4 HP vacuum pump and would like to hard wire it up to
220V power. The shock came when the big box stores don't sell double pole single throw (DPST) switches and Grainger's motor starters start over $100. I can always leave it at 120V, but there must be a better way! Anyone know where I can get a 220V switch for $15? Now I am a chemist, not an electrician. I assume that I need a double pole switch. Is that correct? Second question: All of the rigs I have seen for vacuum chucks are, shall we say, not quick change insulations. To change to a spur drive and the knock out associated with that drive requires dismantling the vacuum apparatus. My lathe is a PM 3520. Does anyone have a quick change plan that could be adapted to this lathe? |
#2
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wireing problem
"Paul Gilbert" wrote: (clip) I assume that I need a double pole switch. Is that correct? ^^^^^^^^^^^^^^^^^^^^^ Correct. I have a printing press with two motors--each is controlled by a single throw, double pole switch. That suggests to me that these switches must be available as parts for various kinds of shop and industrial equipment. You could even use a knife switch of the type used in your meter box. |
#3
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wireing problem
In article ,
"Paul Gilbert" wrote: I just purchased a 3/4 HP vacuum pump and would like to hard wire it up to 220V power. The shock came when the big box stores don't sell double pole single throw (DPST) switches and Grainger's motor starters start over $100. I can always leave it at 120V, but there must be a better way! Anyone know where I can get a 220V switch for $15? Now I am a chemist, not an electrician. I assume that I need a double pole switch. Is that correct? Second question: All of the rigs I have seen for vacuum chucks are, shall we say, not quick change insulations. To change to a spur drive and the knock out associated with that drive requires dismantling the vacuum apparatus. My lathe is a PM 3520. Does anyone have a quick change plan that could be adapted to this lathe? Check an electrical supply store. Or online, or maybe Radio Shack |
#4
Posted to rec.crafts.woodturning
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wireing problem
In article ,
Dan wrote: In article , "Paul Gilbert" wrote: I just purchased a 3/4 HP vacuum pump and would like to hard wire it up to 220V power. The shock came when the big box stores don't sell double pole single throw (DPST) switches and Grainger's motor starters start over $100. I can always leave it at 120V, but there must be a better way! Anyone know where I can get a 220V switch for $15? Now I am a chemist, not an electrician. I assume that I need a double pole switch. Is that correct? DPST 250V returns plenty of options (google search) Not the cheapest, but with good motor ratings well above what you want to run (safety factor) http://www.pressureparts.com/Pressure-Part-337205.aspx Cheaper by far, and adequate for your horsepower rating (beware of link wrap): http://www.newark.com/arcolectric-sw...pst/dp/92B3802 DPDT 250V adds a few more - you can ignore the second throw. 250 tends to be the rated voltage, rather than 220, so that may help your search. -- Cats, coffee, chocolate...vices to live by |
#5
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wireing problem
In article , "Paul Gilbert" wrote:
I just purchased a 3/4 HP vacuum pump and would like to hard wire it up to 220V power. The shock came when the big box stores don't sell double pole single throw (DPST) switches Yes, they do. You're just not looking in the right place. Really. I can always leave it at 120V, but there must be a better way! Anyone know where I can get a 220V switch for $15? Lowe's, Home Depot, Menards, Ace Hardware, Tru-Value Hardware, Do-It-Best Hardware... you get the idea, I'm sure. Example: http://www.lowes. com/lowes/lkn?action=productDetail&productId=70625-334-1245-1V-SP-L Now I am a chemist, not an electrician. I assume that I need a double pole switch. Is that correct? That is correct. |
#6
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wireing problem
"Doug Miller" wrote in message news In article , "Paul Gilbert" wrote: I just purchased a 3/4 HP vacuum pump and would like to hard wire it up to 220V power. The shock came when the big box stores don't sell double pole single throw (DPST) switches Yes, they do. You're just not looking in the right place. Really. I can always leave it at 120V, but there must be a better way! Anyone know where I can get a 220V switch for $15? Lowe's, Home Depot, Menards, Ace Hardware, Tru-Value Hardware, Do-It-Best Hardware... you get the idea, I'm sure. Example: http://www.lowes. com/lowes/lkn?action=productDetail&productId=70625-334-1245-1V-SP-L Now I am a chemist, not an electrician. I assume that I need a double pole switch. Is that correct? That is correct. actually, a single pole switch will work, but one side will stay live all the time so a double pole single throw switch is preferred - widely available - get a motor rated switch and do NOT go to radio shack for it. for vac info, DL the article from my web page - it will give you some hints |
#7
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wireing problem
"Bill Noble" wrote: (clip) do NOT go to radio shack for it. ^^^^^^^^^^^^^^^^^ There is a good chance that the clerk at Radio Shack won't know what it is. One good reason, besides safety, not to use a single pole switch, even though it will turn the motor on and off, is that a double pole switch is much better at suppressing arcing. This is an issue on inductive loads like motors. |
#8
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wireing problem
In article , "Bill Noble" wrote:
actually, a single pole switch will work, "Work" in the sense that it will stop the device from operating. But not safely... but one side will stay live all the time ... for exactly that reason. so a double pole single throw switch is preferred If by "preferred" you mean "required for safe operation" then I will not disagree with you. |
#9
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wireing problem
note that the "one side live all the time" is pretty much unique to the USA,
whose standard 220 is really based on a grounded center tap neutral - most other countries have a 220 that has a neutral leg and the hot leg is 220 above it, and the neutral is nominally at ground. So, in some other country - say the UK, a single pole switch on the hot lead would eliminate any "live" voltage past the switch. "Doug Miller" wrote in message ... In article , "Bill Noble" wrote: actually, a single pole switch will work, "Work" in the sense that it will stop the device from operating. But not safely... but one side will stay live all the time .. for exactly that reason. so a double pole single throw switch is preferred If by "preferred" you mean "required for safe operation" then I will not disagree with you. |
#10
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wireing problem
"Bill Noble" wrote in message ... note that the "one side live all the time" is pretty much unique to the USA, whose standard 220 is really based on a grounded center tap neutral - most other countries have a 220 that has a neutral leg and the hot leg is 220 above it, and the neutral is nominally at ground. So, in some other country - say the UK, a single pole switch on the hot lead would eliminate any "live" voltage past the switch. ^^^^^^^^^^^^^^^^^^^^ And your point is? Since this is the only place in the world where a two pole switch is needed, it must be only a technicality. This is the only place in the world where you can be electrocuted by a technicality. |
#11
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wireing problem
"Bill Noble" wrote in message ... note that the "one side live all the time" is pretty much unique to the USA, whose standard 220 is really based on a grounded center tap neutral - most other countries have a 220 that has a neutral leg and the hot leg is 220 above it, and the neutral is nominally at ground. So, in some other country - say the UK, a single pole switch on the hot lead would eliminate any "live" voltage past the switch. "Doug Miller" wrote in message ... In article , "Bill Noble" wrote: actually, a single pole switch will work, "Work" in the sense that it will stop the device from operating. But not safely... but one side will stay live all the time .. for exactly that reason. so a double pole single throw switch is preferred If by "preferred" you mean "required for safe operation" then I will not disagree with you. aaah, no, my point was that in my experience that there are other countries in the world, and that sometimes residents of those other countries might read this news group, and that it is only common courtesy to suggest how a discussion that is unique to the peculiar way the USA does things might differ if it were applied to their situation. Because of our lawyer rich society, I have offered no opinion on the safety or legality of any switch configuration, I have merely offered specific information on the way that power is supplied world wide and how a motor might possibly be controlled by a device capable of interupting said power. Any application to actual electricity is at the risk of whomever elects to be in the presence of said electricity. Many countries have recommended configurations for such devices. Some countries even have laws and regulations governing the employment and application of such devices. It would be incumbent upon the user to establish saftey, legality, permitting, and to comply with all local, national, international, galactic, and intergalactic regulations that might possibly apply to their situation and to make said determination after proper consultaion with those fully authorized and empowered to supply said determination. I hope that the above elucidates my position with respect to possible confgurations of power supplies and the means that one could in theory use to supply or interrupt them. |
#12
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wireing problem
In article , "Bill Noble" wrote:
note that the "one side live all the time" is pretty much unique to the USA, I'm sure that's news to thousands of electricians in Canada and Mexico. whose standard 220 is really based on a grounded center tap neutral - most other countries have a 220 that has a neutral leg and the hot leg is 220 above it, and the neutral is nominally at ground. So, in some other country - say the UK, a single pole switch on the hot lead would eliminate any "live" voltage past the switch. True, but irrelevant. If the OP had been located in the UK, he would not have been looking for a DP switch to disconnect a 240V load. The fact that he *was* shows that he's located somewhere in North America. |
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