connecting air compressor to generator

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  #1  
Old 07-18-19, 03:04 AM
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connecting air compressor to generator

I have a 5hp air compressor I need to run on a generator. The compressor draws about 15 amps. It was connected to a generator with a 50 amp male plug. That generator was moved to another location that needed the extra power for HVAC intermittently. the generator I planned to use instead is a continuous 5500 watt but only has a L14-30 receptacle for 220/240 volt service. now to the problem/question.

I was changing the 50 amp male plug to a 30 amp L14-30 and discovered that there are only three wires to the compressor 2 lines and a ground/green wire . The green wire was connected to the ground terminal on the 50 amp male plug and the 4th neutral prong was left off the plug. I checked the continuity between ground and neutral on the L14 and they did not show continuity. Will not having a neutral hurt either the compressor or generator? Could I just jump the neutral to ground on the plug or in other words connect ground to both neutral and ground? I know gens etc can be picky about this type of thing. What can I do to run this compressor on that generator (assuming then generator would start the motor)?

Thanks in advance for any help to new member
 

Last edited by TKBB4; 07-18-19 at 03:25 AM. Reason: order of statements
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  #2  
Old 07-18-19, 03:39 AM
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Welcome to the forums!

I question whether or not that generator is enough to power your air compressor. I have a generator the same size and while it would power my airless with no issues it struggled to power my 120 volt 1hp air compressor - mainly on start up.

Those that know more about the electrical should be along shortly.
 
  #3  
Old 07-18-19, 06:37 AM
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Yes I wonder about startup power . Max about 8500 watts but remember yours was only using one 120 leg . I would expect it would start at least a 3hp compressor at 240 volt but it likely won't start 5 hp unless can get a hard start type kit for it but still want to put same plug on it which is accommodated by both generators. I mainly want to know about wiring the plug.

Thanks for reply!
 
  #4  
Old 07-18-19, 06:45 AM
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Compressors are the hardest thing to start on a generator, but it's unclear what you actually have.

I have a 5hp air compressor I need to run on a generator. The compressor draws about 15 amps.
These don't line up. A 5 hp compressor would draw around 30A @ 240V, and startup current would be well over 100A.
 
  #5  
Old 07-18-19, 07:43 AM
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The label on the motor states 3450 watts and states 15 amps at 230 volts . ! hp is about 746 watts so 5 hp is 3730 watts . So no not exactly lining up plus many efficiency questions, service factor etc, but thats what the label states. I would actually expect it to take 3 x 3450 to start or up to 5 x 3450. Maybe they are saying it draws equivalent of 5hp , I don't know. If I get a pic will post later.

I would still like to know how to wire the plug though.
 
  #6  
Old 07-18-19, 07:47 AM
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When wiring it up you connect two hots and a ground. The neutral is left unconnected on a straight 240V motor.
 
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