Need 220vAC electrical help - change 4 prong outlet to 3-prong

   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #1  

Sodo

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Cascade Mtns of WA state
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Kubota B-series & Mini Excavator
My welder has a 3-prong plug, the generator has a 4-holer. I guess someday I'll make an adapter but today I want to weld so the only way is to put a 3-hole outlet in the 4-hole generator.

I have two questions:

1) Can I do this?

2) What do I do with the gray wire? Can I simply isolate it?

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   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #2  
Does the green / yellow go to frame ground while the grey attaches to a terminal ground? I believe they are both grounds but not sure how they are connected to the generator and if not using one will mess up the electronics in some fashion.
 
   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #3  
Hi. I would not recommend wiring from 4 to 3. But if you are so inclined you can just swap out the plug. the (gray)white wire should be neutral, just tape it off and leave it in the box. the reason for the 4 wire plug is so that appliances can use the neutral from the circuit box to tap off half the 220v and get 110v for internal motors or controls. That is not needed for a welder.
 
   / Need 220vAC electrical help - change 4 prong outlet to 3-prong
  • Thread Starter
#4  
Ok I will isolate the gray wire.
 
   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #5  
Just remember if you use the gen for equipment that need the neutral you will need to change it back.
 
   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #6  
In your pics you show the 4 prong receptacle wiring as red/black/gray/green w/yellow. The red & black are the hot leads, gray is neutral and green / y is ground.
Temporarily connect the red /black /and green w yellow to your 3 hole receptacle and wire nut and tape off the gray.
Later after you reconnect the 4 prong outlet, make an adapter with a 4 prong male to 3 prong female to plug in the welder. Just don't use the gray wire in the adapter.
 
   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #7  
Most generators have a label affixed to them that say "Neutral bonded to frame" or "Neutral not bonded to frame." For portable generators it is usually the former while for permanent backups like Generac sells the neutral is not bonded. You need to be certain you have not compromised this by taping off the grey.
Do you see any wire connected to the bare frame of the generator usually with a proper lug and screw into the frame.
If you are not familiar with the bonded vs unbonded or floating this link may help.
GenTran Accessory for Neutral Bonded Generators

What does yours say?
Dave M7040
 
   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #8  
The generator will actually like this arrangement as it will run perfectly balanced leg to leg. I run all my generators into an auto transformer when feeding the buildings 110/220 so all the gensets see is a nice balanced 220 load.
 
   / Need 220vAC electrical help - change 4 prong outlet to 3-prong
  • Thread Starter
#9  
Dangit Dave I didn't chase down the gray wire, just taped it off and put it all together, so I could get back to my welding project. I agree the generator should be restored to 4-wire. I'll probably add a 3 wire (50R) outlet (in its own box, but tapped off the terminals of the 4-wire) if I can find a space for it.

All done, generator's running the welder now. Thanks for all the help.
 
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   / Need 220vAC electrical help - change 4 prong outlet to 3-prong #10  
Why not make a nice conversion/adapter cable for future use?
 
 
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