220v conversion question

I just had an upgrade for my electric service to a 200 Amp panel as part of an HVAC upgrade. At the same time, I had the electrician put in 2 220 circuits and 2 120 circuits for my shop (lights were already separate). Last night I switched over my table saw to 220. Wow, start up is almost instant.

The question: I plan to switch over my bandsaw to 220 as well. What happens to the gooseneck lamp? The switch over instructions don't mention it. Rewiring for the motor is pretty straightfoward. Am I missing something?

Reply to
Dave - Parkville, MD
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I wired the lamp with one hot line (110v) to the center, and connected a neutral to the outside. ( Sorry - I don't know the precise terminology.)

As an alternative, you can find 220v lamps on line.

Reply to
joeljcarver

In most 240 circuits there is no neutral (certainly not those used for tools). Wiring it to ground isn't a good idea either.

A much better idea.

Reply to
keithw86

Heh heh, I had that kind of experience when I converted my arc welder from 230V to 400. No more sticky electrodes! (NB: I'm not in the US,

230V is our 'normal' voltage).

I believe 400V on a thicknesser is a nice thing to have, too. My fairly light German over and under planer/thicknesser has just about done its dash; and it doesn't owe me much either after 26 years. I might give that a second thought.

-P.

Reply to
Peter Huebner

I am no electrical expert but iIwould guess it will work OK. If you have normal residental home wiring you will actually have 2- 110 volt lines going to your BS. Add them up and you get 220 volts. The lamp will probably continue to have 1 single 110 volt line going to it.

Electric ovens and ranges have the same set up.

Reply to
Leon

If it makes that much difference, there was probably something wrong with the 120V circuit or wire size. If everything was sized properly there shouldn't really be any difference.

My bandsaw has a separate plug for the lamp. If it's not mentioned they're probably using the safety ground as a neutral which you're not really supposed to do.

Chris

Reply to
Chris Friesen

What he said. I'm in Baltimore and on the same lines as you, Dave.

Ed

Reply to
Ed Edelenbos

snipped-for-privacy@s6g2000vbp.googlegroups.com...

Good point Leon. I know in a 4 wire 220 supply you can have two hots, a neutral and a ground. The outlet and plug will only have a 3 wires (2 hots and ground). I haven't pulled the plate off of the motor yet, maybe there is more info there. I am a bit shocked (no pun) that Powermatic's site doesn't have much support.

Reply to
DLB

snipped-for-privacy@s6g2000vbp.googlegroups.com...

It'll work but it's against code and (somewhat) unsafe. To split off

120V you need a neutral.

Electric ovens have a neutral, or at least they do now.

Reply to
keithw86

Sorry, but that's not correct. At 240V, it will draw half the current that it did at 120V. This will provide a much faster start, even if the 120V circuit was properly sized.

More than "not supposed to do". It's unsafe, because it energizes the ground conductor, thus energizing the chassis of *everything* that's plugged into that circuit. Remember that electricity does not "follow the path of least resistance" as many people believe; rather, it follows all possible paths. That includes the path that goes through the grounding conductor to the chassis of the saw to the saw table to the hands of the operator.

Reply to
Doug Miller

snipped-for-privacy@gmail.com wrote: ...

Well, split-voltage appliances (ranges, dryers, ...) have run that way for approaching 100 years w/o any significant issues.

Only w/ a relatively late NEC revision did the requirement for 4-wire service come into play.

While it strictly speaking, isn't up to current Code, for a load no larger than the work lamp there's no issue imo.

This came up not too long ago and someone noted that between an early manual and later the particular manufacturer of his dp had dropped the illustration/wiring diagram for the split voltage, undoubtedly to maintain strict Code compliance from a liability standpoint. However, they hadn't changed the wiring iiuc... :)

Take your choice; I'd just rewire it meself...

--

Reply to
dpb

It'll work but it's against code and (somewhat) unsafe. To split off

120V you need a neutral.

Electric ovens have a neutral, or at least they do now.

Correct, I was just trying to point out a logical picutre. Absolutely they have neutral lines.

Reply to
Leon

I agree it will draw half the current. Assuming properly sized conductors such that voltage loss is negligible, why would 6A at 240V behave any differently than 12A at 120V? In both cases we're drawing 1440W.

Now it's possible that the motor itself could be designed such that it runs more efficiently at 240V than at 120V. This isn't necessarily the case here, but if it is it would be due to the motor design, not the higher voltage as such.

It's true that electricity will follow all possible paths, but the higher the resistance of a particular path relative to the other paths the less electricity will flow through it. The safety ground is a low-resistance path, so most of the electricity will flow through it rather than through the operator.

Older electric dryers and kitchen ranges using 3-pin plugs generally run their control circuitry and lights at 120V using the safety ground as a neutral. Not ideal, but it's not unusual either.

Chris

Reply to
Chris Friesen

Woah up a second here!

That's true if the device is built to run off of 240 Volts.

But if the internal resistance is the same as it was in the 120 device, it will draw TWICE the amperage - until it "opens".

Reply to
cavelamb

Higher voltage.

Quite true; OTOH, at 120VAC 60Hz, it takes only a few tens of milliamperes to interfere with heart rhythms, thus *any* current flowing through the operator is a potential hazard.

Reply to
Doug Miller

I was under the impression we were talking about reconfiguring a dual-voltage

120/240 motor from 120 to 240. I don't think anybody was suggesting operating a 120V motor at 240V.
Reply to
Doug Miller

Exactly so. Pure 240V circuits (in North America) don't have, or need, a neutral.

No. It will work, but it's unsafe, and violates both the U.S. and Canadian electrical codes.

It's 240, not 220. And no, it doesn't need a neutral. 120 needs a neutral; so, if an appliance has both 240V and 120V loads (e.g. electric stove: 240V heating elements, 120V control circuits; electric dryer: 240V heating elements, 120V motor) then it needs a four wires: two hots, neutral (for the

120V) and equipment (safety) ground. Pure 240V loads (e.g. a table saw or welder) need only three: two hots and equipment ground. No neutral.
Reply to
Doug Miller

220V wired to a three pole socket has HOT1, HOT2, and ground. Wired to a four-pole socket, it has HOT1, neutral, HOT2, and ground.

While generally considered poor practice, it was normal for many years in the US for stoves and clothes dryers to have a heavy three-prong plug for 220V 30A, and a small (fused 10A) auxiliary 110V circuit that ran from one hot wire to ground. Safety code had an "appliance exception" for this, and it was done because a 4-wire 30A circuit and socket would have been excessive and expensive.

Think about it: there's gotta be a 30A ground wire for these items, and it carries NO current; to add a 120V 10A convenience socket, do you want to add a 30A neutral wire as well?

Reply to
whit3rd

Dual voltage motor - correct.

Reply to
DLB

Slightly OT but relevant.

I am a no nothing in terms of electrical. I can properly wire a plug or wall sockets but don't understand the flow, grounding, etc. Just never studied it. But on a related topic, I have always wondered why my planer and my big sander have a 220 line to run the big moter and a

110 line to run the feed table. I asked on of the Mfg's if there was a way to wire the 110 from the 220 and they clearly ran and hide, saying don't ask us.

So I ask here. Is there some way to "pr> >

Reply to
SonomaProducts.com

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