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How to wire a 3 phase 220v device?

by Racerx72 / March 4, 2009 11:26 PM PST

I have two questions that I've been getting conflicting answers and I'm hoping this will help. I installed a 220v 2post lift in my garage recently. The garage has a 50amp outlet with a 50amp breaker. The lift motor only draws 18-20amps. Would it be wise to lower the breaker size in this situation?

And secondly (most importantly), the lift motor is a 3 wire configuration, Green, White and Black. The 50amp recepticle is a 4 wire (Green, Black, White and Red). According to the lift directions, the white and black are both 110v and the green is ground. The recepticle considers the white neutral. Should I wire the lift motor's white and black to the two side posts on the recepticle (black and red), the green to the green on the recepticle (top) and the bottom of the recepticle leave open? I have a unshielded (wrapped in paper) wire that isnt connected (4 wire 220v, 20ft of wire I purchased from HD, goes from the lift motor to the recepticle).

Thx

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wiring
by Cindi Haynes / March 5, 2009 2:21 AM PST

Hubby says it's not 3 phase, it's single phase.

The 3-wire cord is good if minimum AWG 10. Two wires being hot (120v each), 1 wire being a ground grounded to a bolt inside the cathead. You will have to change your receptacle to a 3-wire 30-amp configuration. Neutral not required. Do not terminate.

You should drop to a 30-amp 2-pole breaker.

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actually, I think it's a double phase
by James Denison / March 6, 2009 7:43 PM PST
In reply to: wiring

Both 110 lines on a 220 are out of phase with each other.

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Google for Stove wiring
by James Denison / March 5, 2009 8:57 AM PST

And do it the same.

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As Cindy says
by Steven Haninger / March 5, 2009 9:29 AM PST

Looks like no neutral. This isn't needed since you're tapping 110 from each side of the transformer which is what house wiring does. The two AC wave forms are 180 degrees out of phase. Red and black will be hot at the receptacle. You may want to recode the white wire to the motor anywhere it's exposed. Use red electrical tape. This indicates it's hot and not neutral.

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I try to use 3-wire for that reason.
by Dan McC / March 6, 2009 1:36 AM PST
In reply to: As Cindy says

That way, any time someone is in the box or finds the wire they see the two hots, neutral, and ground.

I've seen and heard too many stories like "I didn't know the white was wired hot in there! WOW! ! !" It can get scary.

It's easily worth the extra money for the cable.

Dan

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It's common for switched outlets
by Steven Haninger / March 6, 2009 6:23 AM PST

to use the white wire from the wall switch as a hot return. You can't really switch the neutral side because that leaves the receptacle hot. Of course circuit breakers do serve a good purpose. Even with the breaker off, I've still learned to check all wires with a DVM before grabbing bare copper. Some of the lessons were difficult ones.

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(NT) I'm not sure what you mean by hot return.
by Dan McC / March 6, 2009 10:42 PM PST
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The return leg from the switch
by Steven Haninger / March 6, 2009 11:13 PM PST

Black (hot) is intercepted in the receptacles workbox and routed to the switch via the black wire. The white wire (normally neutral) returns to the receptacle and is hot when the switch is in the "On" position. When you pull the cover off the workbox, that white wire looks like the rest unless it has been recoded. My house has several switched outlets. Most of these are for bedroom lighting because no lights were on the ceilings until I installed lighted ceiling fans. While trying to figure out the wiring scheme I discovered that, just because a wire was white, you cannot feel safe to grab and pull it out of the box. The term "return" or its variables such as "return leg" or "ground return" would refer to the wire that goes away from a device toward a point that completes a circuit. Mostly I work with DC components and we use the term frequently.

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Got it.
by Dan McC / March 6, 2009 11:25 PM PST

I would have called it a switch loop. The white should be taped black at both ends to indicated its changed status.

Dan

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3-4-5 wires, 2-3 phase, 110/220/380/400/440V
by jonah jones / March 6, 2009 2:13 PM PST
In reply to: As Cindy says

not to mention 50/60Hz..

no wonder i got 'zapped' a couple of times while putting a plug on a piece of cable Sad


one thing, from reading this thread, can i wire up a
European 220V AC 1PH 50Hz appliance on American wiring?


jonah "i always glow in the dark" jones

.,

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You'd have to check local/national electrical code
by Steven Haninger / March 6, 2009 7:20 PM PST

before proceeding. These specs are designed for both safety and uniformity of practice. AC frequency (50/60 hz) doesn't affect wiring practice but only devices with coils such as motors, transformers, etc. I'm thinking that, at 50 hz, the wiring needs to be a bit beefier or overheating becomes an issue.

In the US, wiring gauge depends on the maximum current the circuit can carry. 14 gauge is suitable for up to 15 amps but you 12 gauge to go to 20 amps. Strangely, as gauge # decreases, wire size and capacity increases. So, you'd need to know how much current an appliance draws to know what gauge wire to use. Hz isn't an issue but it can affect current draw by some devices.

So, I don't see any reason why using American wiring standards wouldn't work as long as you do the math properly. But, it might become a liability issue if something goes wrong. I'm not sure about where you live but, in the US, it would be good to be careful....even in your own home....about any custom wiring done if you have any intention of selling the place at some time.

Lawyers are standing by the phone to assist you by lightening the burden of carrying your wallet. Happy

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yes, but it might run faster if a motor.
by James Denison / March 6, 2009 7:40 PM PST

If it's a heater, it might burn out.

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