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3 Wire 220v connections. Safe>

Zrxpilot

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Nov 19, 2011
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Just purchased a new (to me home) and getting the shop together.

100 amp service in the garage. Allready wired nicely but adding an additional 50 amp 220v receptacle for my welder and tapping into the existing 20amp 220v receptacle to wire my two post lift.

One observation has me concerned for perhaps no reason. Both my welder and my lift (both 220V) utilize a white/black/green wire set as supplied from the factory to make the electrical connection.

I understand that 220 v are essentially two hots coming from the box. Input from my box to the receptacle is two red wires and a white. No bare and no green. I chased them. One coming off each pole of the breaker (the reds), and obviously the matching white coming off the ground bar. Seems legit so far.

Making the actual connection, obviously I have no matching colors. From the unit being wired, I ran the black to red, the white to red and the green to the white. From the unit, I taped both the white wire and black with red tape to indicate both were hot. I connected the green (again from the unit..to the white from the box).

All is well and works fine.


I see no other way to do this but wonder why in the dickens were these color wires allowed to be sent from the factory that way? One is an older Miller welder power cable (6g B/W/G) going to a standard 50 amp 3 prong plug. Presumably my much newer Miller 175 would also yield similar colors if I were to take its power cable apart.

The big concern is no earth wire. I fully understand how I am getting it to work but think that a 4 prong plug would be much safer. However...this wiring configuration is commonplace and has been for many years.

The fix would be to run a bare ground thru my whole friggn system and change everything out to four prong plugs on both ends.

I am considering doing this over time but where does the other (new) bare wire go on the unit? Just find something in the chassis and screw it in? Seems so.
 
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Aceman

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If all these wires are installed in emt conduit, that is your ground. Not the "white" wire installed with the reds. I would tie the green wire in the cords to the box via a green 10-32 ground screw.
 

pattenp

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You don't need four prong plugs for the lift and welder. Those devices use only 240V and need only 3 wires, 2 hots and a ground. Four wires are 2 hots, neutral and ground and are used for appliances such as a stove or dryer that also need 120V. Just curious, what kind of lift do you have that only requires a 20A 240V supply?
 

wyliesdiesels

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The white wire being used as a ground wire is not to code. If the the circuit is ran through EMT as Aceman suggested, then the white wire should be moved over to the neutral bar and a pig tail should be connected from a ground screw on the receptacle box and go to the ground terminal on the outlet.

Sounds like someone got their colors mixed up but this wont hurt anything. Its just not to code!!
 
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Zrxpilot

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Everything is in conduit. That makes sense why there is no dedicated ground. My mistake regarding the big white going to ground bar. It is going to the neutral bar. In this box there is no separate ground bar.

Hoist pump motor (I think its a pump), requires 220 20amp according to the instructions that came with it. Tag on the motor is 1.25 hp. However, there is another tag on the front of the motor that says "equivalent torque 2.5hp".

I have this hooked up to a 20 amp 220v breaker using 12g wire. This seems ok
 
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wyliesdiesels

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Everything is in conduit. That makes sense why there is no dedicated ground. My mistake regarding the big white going to ground bar. It is going to the neutral bar. In this box there is no separate ground bar.

Hoist pump motor (I think its a pump), requires 220 20amp according to the instructions that came with it. Tag on the motor is 1.25 hp. However, there is another tag on the front of the motor that says "equivalent torque 2.5hp".

I have this hooked up to a 20 amp 220v breaker using 12g wire. This seems ok

Is the feed to the garage 3 or 4-wire? And is it fed by metal conduit?
 
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Zrxpilot

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^ Feed to this sub panel is a 3 wire that is not fed by metal conduit. Everything downstream of this box is in metal conduit.
 

pattenp

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I was curious as to the brand/model of 2 post lift you have. The 2 post lifts that I'm familiar with call for a least a 240V 25A circuit with at least 2HP motors . The 1.25 HP motor seems smaller than normal.

Everything is in conduit. That makes sense why there is no dedicated ground. My mistake regarding the big white going to ground bar. It is going to the neutral bar. In this box there is no separate ground bar.

Hoist pump motor (I think its a pump), requires 220 20amp according to the instructions that came with it. Tag on the motor is 1.25 hp. However, there is another tag on the front of the motor that says "equivalent torque 2.5hp".

I have this hooked up to a 20 amp 220v breaker using 12g wire. This seems ok
 
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Zrxpilot

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The lift is a 10,000 lb Complete Hydraulics made by Powerrex. I looked at the tag on the motor. Definetly 1.25 hp. FLA listed as 10.9 amps.
 

pattenp

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Oh.. I believe you. With a 1.25HP motor I wouldn't think your lift is a speed demon lifting. Some lifts you can get 120V pumps and they are slower lifting than the 240V pumps. If you're a service shop then the lift speed helps, but for us home DIY'ers it not an issue. My lift has a 2HP pump and the specs say lifting speed is 45sec to full lift, but I've never timed it.

The lift is a 10,000 lb Complete Hydraulics made by Powerrex. I looked at the tag on the motor. Definetly 1.25 hp. FLA listed as 10.9 amps.
 
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Zrxpilot

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Is there any parrallel metal pathways between the buildings such as a water line?

Actually there is. ( I think anyways). The feeder power box initially breaks ground (earth to floor), in shop "a" from the house. It breaks ground in the same general location as my water line is coming thru. I see there is also a very heavy bare ground cable that comes from the box in shop "a" into this "pit" that the power and water enters the shop.

Leaving this "pit" the piping is encased in grey colored underground PVC and goes directly to the box as such. Leaving the box in shop "a", everything is in metal conduit until makes the exit outside the building to run to shop "b". This final run again in underground pvc to the sub box in shop "b"

Note both shops are in close proximity to each other

All wires exiting the sub box in shop "B" are in fact encased in metal conduit,
 

wyliesdiesels

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Actually there is. ( I think anyways). The feeder power box initially breaks ground (earth to floor), in shop "a" from the house. It breaks ground in the same general location as my water line is coming thru. I see there is also a very heavy bare ground cable that comes from the box in shop "a" into this "pit" that the power and water enters the shop.

Leaving this "pit" the piping is encased in grey colored underground PVC and goes directly to the box as such. Leaving the box in shop "a", everything is in metal conduit until makes the exit outside the building to run to shop "b". This final run again in underground pvc to the sub box in shop "b"

Note both shops are in close proximity to each other

All wires exiting the sub box in shop "B" are in fact encased in metal conduit,

Do u have any pics?

If u DO have metal pathways between the house and the shop, then the feeder feeding the shop should be 4-wire and the neutral bar in the garage sub panel should be insulated/isolated from the enclosure and the ground bar. Do u have any pics? Is the water line metal?

U can have issues with electricity returning on metal pathways where it shouldnt be.
 
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