shop wiring question

redneckjeep87

redneckjeep87

Landscaper Extroidanaire
Joined
Oct 10, 2007
Location
Woodleaf, NC
Okay im in the process of finishing up the exterior of my 18x40 shop, which means its time to really start on the inside. Which means running power.

I have a small subpanel im going to put in my shop which will be ran off of the main panel on the outside of my house about 100' away. The main panel on the outside comes off the meter(200 amp? ) then runs into the house via to the sub panel there. The well pump also comes off this panel via a double throw 20amp breaker. There is also a hottub that has a double throw 50amp breaker but it is not running currently do to needing some work.

The question i have is this....what size wire and breaker do i need to run from the main panel to the sub panel in the shop? I have space for 2 double throw breakers on the main panel.

I was planning a leg for dedicated 220 for welder and compressor and the other for outlets and lighting.

Or is this not the correct way to go about it? If not how should i power the sub panel in the shop.

Thanks in advance and hope I dont sound too ignorant of electrical. I have a decent knowledge but have never messed with wiring in panels.
 
First thing you need to decide is what amperage service you wan to supply to the subpanel and whether or not you have the space to add another breaker in the main panel.
 
You wouldn't run two circuits to your sub panel, just one properly sized 240v, and the neutral then ground the panel at the shop. What kind of equipment do you plan on putting in the shop?
 
braxton357 said:
then ground the panel at the shop.
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One and only one path to ground per system. Don't bond sub panel. But we are getting ahead of ourselves....
 
Lincoln 180c 220 welder, 5hp ingersol compressor, fullsize fridge, lights, outlets, more lights. Will probably wind up with a decent drill press etc. Standard shop fare nothing crazy that i can think of
 
I went and looked at a friends setup this evening and he had a 90amp 220 breaker with 2gauge(i think) aluminum wire feeding the sub panel. It was farther than what i am running i believe. I forgot to look at his ground rod
 
@lockedup5 did you run that the whole way from panel to panel? If so why? I thought you werent supposed to run a neutral(common) between the two panels. Just two runs of power and then run a ground rod to the new panel. Am i wrong?
 
You run the two hots and a neutral, but the ground is supposed to be separate for the shop. There is a screw you'd remove inside the sub panel to unbind or separate the neutral and common bus bars
 
I went and looked. I think what I ran was 2-2-2-6. And yes all wires run from one panel to the other. Running 100 amp off a 200 amp main panel. No ground rod at the garage. Whatever I did came from the guidance of my electrician I've used for years.
 
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redneckjeep87 said:
Lincoln 180c 220 welder, 5hp ingersol compressor, fullsize fridge, lights, outlets, more lights. Will probably wind up with a decent drill press etc. Standard shop fare nothing crazy that i can think of
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I'd bet you'll want 100A or more.
Gotta guess how much stuff you could ever have running at one time. Potentially welder, air compressor (assuming you let it just stay open), fridge, lights. And thats if its just you - have a wrench-fest w/ some buddies and it could be more.
What about heat? A/C?
 
Ron said:
One and only one path to ground per system. Don't bond sub panel. But we are getting ahead of ourselves....
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That is not compliant with NEC. NEC says accessory buildings get their own local ground, and it gets tied back to service ground with an appropriate size conductor. Subpanels are not neutral bonded. You should have four wires from the main panel to the accessory panel for 240V split phase service.
 
Heat is taken care of by a twin 55gal woodstove. Ac is doors open and fans on. So its SUPPOSED to have 2 2g wires for hot, a neutral, a local ground and a tie back to ground for the main panel?


I just got off the phone with a contractor buddy of mine and he said all i would need to pass code (like im gonna call an inspector, right) is 2 2g hots 4 gauge common and a local ground.

That said i have another contractor friend that did his fil's huge garage, ran 90 amp to it with the twin 2g, local ground....and i swear i didnt see a common ran. Would it work without it?
 
@Ron you live in Raleigh as well, im sure its much like mecklenberg county with their codes....which are f'n strict as hell. I guess i need to look up rowan county. To be honest i really dont care if it passes code or not at the moment, i just want it to be safe and work. Hell theres an addition on my house that was here when i bought it and i KNOW that its probably not perfectly to code. The part that i redid is but the other half who knows
 
redneckjeep87 said:
I just got off the phone with a contractor buddy of mine and he said all i would need to pass code (like im gonna call an inspector, right) is 2 2g hots 4 gauge common and a local ground.

That said i have another contractor friend that did his fil's huge garage, ran 90 amp to it with the twin 2g, local ground....and i swear i didnt see a common ran. Would it work without it?
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Why wouldn't the neutral/"common" need to be the same ga? Maybe some EE type can explain? In A/C power isn't the amplitude of current equal on both conductors?

EDIT - ok after some thinking about the physics of how it works, I think I get it.

I'm sure your FILs garage has a neutral, unless the twin 2G is just 1 hot and 1 common, e.g. only 120V. Unless maybe it is *only* 240v, I guess you could get away w/o a common then.
 
I just know mine works the way I explained. Never kicked a breaker I don't think. I run a 80 gallon compressor, millermatic 200, 30 amp camper plug in, 6 flouescent light fixtures, space heater/large fan, and everything in a garage. Most the time I'm not running multiple high draw things at once but could if I wanted to unless I'm drawing to much in the house. In that case it would trip the main in the house if I'm drawing 200 amps between the garage and the house.
 
I guess it did have a common...just didnt see it. He def has 220 out there bc he runs a stove for fish frys, along with multiple 120 deep fryers.
 
lockedup5 said:
I just know mine works the way I explained.
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Getting power usually isn't the issue. Protecting against personal injury and/or death when things go sideways takes a bit more attention to detail.
 
I'm still alive. Lol

I don't know what else I can do but listen to my licensed electrician that has been in the business over twenty five years. If the way I did mine is wrong please let me know and I will research a little deeper and change it if necessary.
 
lockedup5 said:
Not being a smart ass. I'm actually concerned now.
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I'm no electrician, I only know what I've been told by EEs or had to research on my own. I know there are instances when the neutral conductor can be smaller than the hots. I do not know how to determine when that's acceptable. As far as the grounds go, my understanding is that the only place in the system where the neutral and ground are bonded is at the service entrance. And when we wired our detached garage, we had to pull a four-conductor feeder to the garage and sink two ground rods at the accessory structure. The main building has its own grounds, and they're all bonded to one another. I believe this is so that if there is a fault with the neutral feed, current can not be sent back up the ground to the main building. Likewise, you provide a four-conductor connection so that any water pipes/conduits/other cables/etc, don't become inadvertent ground connections between two structures.
 
Your talking over my head now. So your saying my system is wrong and I need two ground rods at my garage?

Explain me something. What is the difference between a neutral and a ground? They attach to the same bar in the box.
 
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