Need 240V in the shop, is it already in this OLD panel box?

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TylerW

TylerW

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Hey guys...
I hope everyone is staying healthy in these trying times. here's the scene:

I have a detached metal shop building that is supplied with electrical power from the house about 50ft away through an underground conduit. The house was rewired with a new 200 amp service about 10 years ago(before I got here). I initially assumed the shop had only 110V going to it because there is only a small breaker panel in there supplying one outlet and one 4ft fluorescent overhead. However, I took a closer look at the main panel and sure enough there is a double breaker for the garage, just like the oven and dryer.

I cut the power to the garage and pulled the cover off this old box to see what was in there. This is an old GE "load center". There is indeed two hots coming in to the box, which unless I'm mistaken means 220/240v available. However, I'm a little lost on how to do that with this box. The 2 black wires run directly into the main breaker as you can see, then underneath there are four 120v breakers. The wiring into the garage is 10 gauge wire.

1. Do I want to even fool with this box?
2. Is getting 240V out of this box simply a matter of pulling 2 of the single breakers and installing a double, then wiring as appropriate?
3. The breaker for the garage in the main panel in the house is a 30 amp and so is the breaker on the subpanel in the garage. What dictates how "large" of a breaker you use on a branch like this?

This is what I want to do:
1. Install a 240V circuit for a compressor. I HAVE to have shop air going forward. I have 3 vehicles that need paint and body this year.
2. Add at least 2 more 110V outlets and relocate the existing outlet somewhere other than right next to the man door.

Here are some pictures. Thanks!

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That’s a 240 double pole breaker. With #10 wire it should be a 30 amp.
If your planning on an air compressor and lights and receptacles you need to
up the wire size. Looks like a 3/4” conduit coming up in the box do you know if it’s conduit all the way from the main panel? Wire size dictates what size breaker you
can safely use.
 
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That panel is small, as is the wire feeding it. As stated above, it needs larger wire to be safe.
 
I don't know what size wire you have feeding this box but by the looks of it it's not much.
 
#8 would get you a 50 amp breaker and a #6 would do 60 amp. You would need a 30 amp double pole breaker just to run your compressor that doesn’t leave anything for lights and receptacles.
 
That appears to be wired for 110V. Black hot, white common and green ground. Only one leg. Black. I have 100amp service in my shop run with 2/0 2/0 4/0 100amp wire.
 
RustyRatRod said:
That appears to be wired for 110V. Black hot, white common and green ground. Only one leg. Black. I have 100amp service in my shop run with 2/0 2/0 4/0 100amp wire.
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the panel is fed with 220/240 on the main breaker the four circuits are 110/120.
 
If were doing the job Id recommend #6 wire
On a 60 amp double pole Off the 200 amp main panel
to a 60 amp double pole sub panel in the shop.
Three #6 wires and a #8 ground and depending on how many 90 degree bends there are it may be a tough pull. the conduit needs to be up sized to 1” or go with 3 #8 wires and a #10 ground for a 50 amp sub panel and the 3/4 conduit would be fine.
 
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cudascott said:
#8 would get you a 50 amp breaker and a #6 would do 60 amp. You would need a 30 amp double pole breaker just to run your compressor that doesn’t leave anything for lights and receptacles.
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At minimum run #6 wire to match your 60 amp box then you should be able to have a 240 30 amp and two 20 amp circuits. I would go with #2 wire then you could have a 100 amp box for future needs. 100 amp box isn't very expensive. #2 wire though is very expensive. Good luck. Steve
 
That's crazy. For the amount of work it takes to get the wire routed and the minimal cost why the owner did step up the gauge to atleast #8 is beyond me. I personally would pull a #6 depending on the conduit.

The good news is you can easily make the changeover. However if you are not comfortable with AC voltage work find someone who is to help out.

Good luck,
JW
 
Just a thought,cheaper to run air hose than electrical cable,no?
 
put a 100 amp in if you can...of course you will have to upgrade the wiring feeding the new service. it looks like that GE box is compatible with square d homeline breakers. if you buy a homeline box you can probably reuse those 4 single pole breakers...Good luck
 
Lord Sparky said:
Hire an electrician if you don’t want to get electrocuted/burn shop down.
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Hello All,
If you do it yourself (Not saying you cant) and you don't do it correctly (Local code) and there is a problem (Fire) your Insurance company can and probably will deny any claim.
Just a thought.
Happy Mopar :)
Arron
 
dibbons said:
I thought with higher voltage (220 vs 120) that smaller gauge wire was OK, isn't that why large power lines are super high voltage, so the lines can carry more power safely?
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your correct the wire size is what determines the amps that it can safely carry without overheating. Now in free air the amp rating on the same size wire goes up. Romex and THHN etc. are rated for 600 volts. The higher the voltage the lower the amperage for a given load.
 
Arron tate said:
Hello All,
If you do it yourself (Not saying you cant) and you don't do it correctly (Local code) and there is a problem (Fire) your Insurance company can and probably will deny any claim.
Just a thought.
Happy Mopar :)
Arron
Click to expand...
My friend's brother was a lineman. Died on the pole.
 
run 1" rigid air supply from the original 220V compressor location out to the barn. would give you that much more capacity and would allow you to wrench in solitude, no compressor noise over the radio. Could tap it to a few locations to allow multiple hose angles and get you a moisture sump (just run a vertical run to the ground with a drain on the end)
 
I come across power touching phone or cable lines probably 2-3 times a year. No joking around up there. Anything can be hot from contact hundreds of feet away. I still like the piped in air supply idea.
 
The big question is what's the amp draw on the compressor. There should be a nameplate on the motor.

As far as that panelbox, looks can be deceiving, as long as the box is not corroded when you pull one of the breakers off the bus. You can use forced air to clean that box up,

Once you deem the panel is not corroded, you can remove two of those single pole breakers and replace with a two pole breaker as long as the motor nameplate amp rating at 240 volts is less than 30 amps.

Voltage adds and current divides.
 
My brother-in-law tapped into our breaker box where the power lines connect from the street to do some welding in the backyard. A couple of years later, some of the lights/sockets started acting up (on again/off again). We found this main burned up wire. Don't know whether to blame him or if the problem arose from some other defect/problem/installation/act of God.

DSC06434 copy.JPG
 
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