Old fuse style wiring to run 230v compressor in garage.

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  #1  
Old 05-20-13, 07:00 AM
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Old fuse style wiring to run 230v compressor in garage.

I have an old fuse style main panel. Garage appears to be wired by the 2 time delay fuses on bottom right. In the garage sub panel the white lead reads 123v and the black lead reads 123v. However the white is ran as neutral and bonded with ground and grounding rod on ground bar. The garage is currently only running 120v appliances. I need to run a 230v compressor and am wondering how safe it would be to rewire sub panel putting black lead on one lug, relabel white lead and put on other lug, and use sub panel ONLY to power compressor with a double pole breaker.
 
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Old 05-20-13, 07:09 AM
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The garage is currently only running 120v appliances.... rewire sub panel putting black lead on one lug, relabel white lead and put on other lug, and use sub panel ONLY to power compressor with a double pole breaker
If this is a detached garage how would you power lights and any other 120 volt loads in the garage if you did that? The subpanel couldn't supply 120 volts and you can't by code run a separate circuit for 120 volts in a detached structure. You would probably also have a bit of a no-longer-grandfathered problem meeting code if you changed the subpanel.
 
  #3  
Old 05-20-13, 07:14 AM
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Here are some pictures to show what I'm talking about. Circled line running to garage. In other pic top circle is neutral/ground bottom circle is the casing coming into sub panel. Connected circles are black leads. Thank you in advance to anyone that can offer useful advice.
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Old 05-20-13, 07:18 AM
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What a mess! It looks like you need to rip that "subpanel" out and start over.
 
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Old 05-20-13, 07:23 AM
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I am talking about running compressor only. No 120 on the panel. To replace the sub panel I still only have an old school main panel. This sub panel is being ran by 2 30 amp time delay fuses. I just want to run my compressor.
 
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Old 05-20-13, 07:28 AM
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Just so we are clear is this a detached garage? If so I agree with Jason, start from scratch keeping only the new breaker box which does not seem to be wired correctly.
 
  #7  
Old 05-20-13, 07:28 AM
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What I'm thinking is pull everything from this sub panel and wire the 120 leads to opposite lugs and use one 30 amp double pole breaker.
 
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Old 05-20-13, 07:33 AM
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detached garage. from my understanding I don't need the neutral to just run a 240v compressor. I will have to sacrifice 120v everything. How will a new sub panel make that any different if I only have 2 hot leads and a bare ground? plus grounding rod of course.
 
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Old 05-20-13, 07:33 AM
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What I'm thinking is pull everything from this sub panel and wire the 120 leads to opposite lugs and use one 30 amp double pole breaker.
Not sure what you mean? What 120 vol leads. If you convert to 240 volts you will have only 240 volt leads. Would the 30 amp breaker be for the welder?

Some people posting here think 240 volts comes from two 120 volt leads. It doesn't. That isn't what you meant is it?
 
  #10  
Old 05-20-13, 07:45 AM
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when wired into a main panel there is a 110 (120) connection on each side. correct? this sub panel is wired from a 110 on each phase through a time delay fuse on each side. as of now one hot wire (neutral but it has 123 volts going through it) is bonded with the ground in the subpanel. the black lead is feading the breakers. I want to strip the wires from the box. connect white wire to other lug, then connect them with double pole breaker. connect black hot 120 to a lug. connect white (marked) 120 to opposite lug. connect with double pole breaker for 246 volts.
 
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Old 05-20-13, 09:54 AM
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when wired into a main panel there is a 110 (120) connection on each side. correct?
No. your house is supplied with 240 volts. The sides of the fuse box are the sides of the 240 volts. The 120 volts is derived from one of the 240 volt legs and the neutral.



Again I agree with Jason, run new cable from the main panel and get rid of the fuse box. Just use the breaker panel. Is the main panel a fuse box or a breaker box? What size fuse or breaker supplies the garage now?
 
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Old 05-20-13, 01:20 PM
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There is a picture of main panel below. It IS a fuse box.
 
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Old 05-20-13, 01:42 PM
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What size fuses to the garage? What is the disconnect below the fuse panel for?
 
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Old 05-20-13, 01:44 PM
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30 amp. but I want to run a 30 amp double pole breaker in garage.
 
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Old 05-20-13, 01:47 PM
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Those are Edison base screw in fuses correct? Do you have an unused cartridge fuse holder in the panel? What is the input amperage of the welder?
 
  #16  
Old 05-20-13, 01:47 PM
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disconnect is for dryer. and there is another for ac. garage is ran by screw in fuses.
 
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Old 05-20-13, 01:51 PM
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I think it is time for a new main panel. What size are the main fuses for the panel?
 
  #18  
Old 05-20-13, 01:51 PM
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24 amps at peak pull which would only be at initial start of motor. not continuous. compressor.
 
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Old 05-20-13, 01:54 PM
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24 amps at peak pull which would only be at initial start of motor. not continuous. compressor.
So is the full load less than 20 amps or is full load what you meant? Sounds like you can run both the compressor and lights from that subpanel.
 
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Old 05-20-13, 02:59 PM
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it's a compressor with an fsa of 24. only time it could possibly pull that is for a second when the motor kicks on. it has an 80 gallon tank so there's no way I will be running it continuous.
 
  #21  
Old 05-20-13, 03:04 PM
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and I can't run lights off of it cuz I wont have a neutral.
 
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Old 05-20-13, 03:09 PM
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and I can't run lights off of it cuz I wont have a neutral.
I know but all you need to do is run 10-3 UF-b from the main panel to the garage.
 
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Old 05-20-13, 08:00 PM
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In the garage sub panel the white lead reads 123v and the black lead reads 123v. However the white is ran as neutral and bonded with ground and grounding rod on ground bar.
I son't know what is happening in the connection between your main panel and your subpanel now, but I do know one thing that isn't happening. The white feeder wire is not carrying 123V relative to either neutral or ground. It can't be, if it's bonded with ground.

How did you test to determine that?

In a subpanel, the neutrals must be bonded together but isolated from ground. I can't tell if that bar above the breakers is isolated from the box , but it obviously has both neutral and ground wires connected to it. The grounds need to be moved to a second bar that is bonded to the enclosure, and the neutrals need to be isolated.

Since you know what cable is feeding the subpanel, take the cover off the main panel and see how the wires are connected at that end. Also, what type of cable is run from the main panel and what size are the wires in it?

Bottom line, as Ray said, all you need is 10-3/G Type UF between the panels, and you can have both 240V and 120V in the garage.

Or you may be able to re-work the wires you have now to only have 240V. If the wires are big enough.
 
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Old 05-20-13, 08:01 PM
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and I can't run lights off of it cuz I wont have a neutral.
If you run 10-3/G you can.
 
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Old 05-21-13, 04:51 AM
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Thanks for the replies. Was hoping to not have to run a new line but seems like that will be the best route.
 
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Old 05-21-13, 10:25 AM
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Also the water pipe being used as a ground for the romex to the garage with a radiator clamp needs to be addressed. and also the 30 amps fuses in that bottom row scare me because if one those fuses is feeding the garage the rest have to be the general lighting and outlet circuits, the wire probably is 14 or 12 so you need 15 or 20 amp fuses respectively

its time for a new electrical service
 
  #27  
Old 05-21-13, 04:49 PM
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Yea I was thinking at least a main panel upgrade is in order... these fuse boxes disgust me.
 
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Old 05-21-13, 04:53 PM
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and the ground definitely raised an eyebrow o.O I am afraid to see the rest of the wiring. It's not my house so I don't want to pay for all this. Don't want to burn anything down though either.
 
  #29  
Old 05-21-13, 06:22 PM
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If you don't own it don't touch it. Just too much liability there. Ask the owner to fix the problems or ask to go halves on hiring an electrician. Do not change any wiring in the garage.
disconnect is for dryer.
Or plug it into the dryer circuit and run a long hose to the garage.
 

Last edited by ray2047; 05-21-13 at 06:43 PM.
  #30  
Old 05-24-13, 06:36 PM
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so just wire it to a plug or wire directly to the circuit?
 
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Old 05-24-13, 07:11 PM
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Wire to a plug. The neutral blade would not be used.
 
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Old 05-25-13, 01:56 PM
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how long of wire would be safe with that setup?
 
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Old 05-25-13, 02:55 PM
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How far is the dryer from the garage? #10 service cable isn't cheap so you probably need to balance the cost of service cable against the cost of hose or PVC pipe instead of hose if it can be used for compressed air. Assuming 25 amps 100 feet of 10-2 service cable would have a voltage drop of 2.6%. That should be acceptable so anything less than 100 feet would be okay.

Service cable in case you are not familiar is similar to those heavy duty round extension cords. Unlike house wire the ground counts in the naming so 10-2 means two #10 wires no wire for the ground. I am suggesting 10-2 because I suspect the dryer receptacle is three wire not four wire so you would need a NEMA 10-30 plug which is not a grounded plug*. No ground could be considered a safety issue so your decision if you want to do it that way. If the dryer is four wire you are golden you can use 10-3 service cord and have a ground.

*Third prong on a 10-30p is technically a neutral not a ground.
 
  #34  
Old 05-26-13, 07:26 AM
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What would happen if neutral was wired as ground?
 
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Old 05-26-13, 10:22 AM
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Maybe nothing. I can't say for sure but that wiring is so bad I can't say you wouldn't end up with voltage potential between the metal of the compressor and an earth ground such as a water pipe. It would definitely be a code violation. Lets wait and see if a pro answers.

Edit: Talked with a pro about it and best answer is don't because the wiring is just to old and risky. Is that dryer plug even fused. I see the safety switch but does it have fuses.
 

Last edited by ray2047; 05-26-13 at 08:56 PM.
  #36  
Old 06-03-13, 04:48 AM
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yes 2 30 amp fuses. there is also the oven that is wired to same type of plug. not sure what the range fuses are.
 
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Old 06-03-13, 05:59 AM
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Gasoline powered compressor or move are the only safe answers I can offer.
 
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