Powering the shop

McCracken

McCracken

Logan Can't See This
Joined
Jul 9, 2005
Location
With your mom at a nice seafood dinner
So I need some opinions / advice. I'll preface this by saying I can do mild wiring work. I've ran cable for welders and installed numerous outlet boxes. However, I have never ran large cable underground to a shop and hooked up a breaker panel but I plan to.

Now, having said that we just bought a house that has a small shop where I plan to spend some of my free time. It is devoid of power. I gathered some underground cable and think I can run it down to the shop but there's a couple of issues (see excellent MSPaint drawing).

shop power.png

The breaker panel for the house is in the basement corner furthest away from the shop. The garage is on the end closest. I wondered if I could pull power from the panel to a box in the garage, then run the cable from there to the shop. The thin, wavy lines are bands of rock. There appears to be a gap that I think would be the easiest route to get from the garage to the shop. So electrical gurus, how is the easiest way to do this. Cheapest always gets my attention too. I checked around and I don't think pulling a line off of the closest power pole will work. I'd have to install a couple of poles to get it there. Plus, underground will be a cleaner look on the property. Also, we have a lot of trees so that keeps branches off the lines. Lastly, I will say that if your comment is "hire an electrician" then keep it to yourself.
 
problem is going to be getting "much" power to said building. If your not interested in getting a big load safest is dedicated breaker like a 50 or 75 amp. right gauge and bury. Use that to supply small box and add smaller breakers as needed. I did this in a small shed building. I was limited from the start. Like running a welder and one light. The radio, small compressor, and welder was a no go.

Best way is a dual lug meter and pull service wire. Will depend on the supply from main poll. At best without seeing your current load, I doubt you'd safely pull more then 100 amps to basically what would be a high amp disconnect like a AC unit in your building.

This is why I had 400 amp and duel lug meter at the shop.....that was the next logical thing short of 3 phase. In my case booth are in the building. I think it may have some issue with load balancing on the separation length in your case I'm not sure. I have heard plenty of folk pulling out of a meter to feed another panel. Its just hot and should be pulled. To much load is going to burn up the incoming feed though!

I hired an electrician for the shop. The pieced up building previous got me by but doing it right was a high priority this time around.
 
Option 1 - Have you contacted utility and inquired about cost to add a second meter? That may be cheapest option.
Option 2 - Make sure it is direct burial cable and the size cable you have (since you already acquired it) will dictate what size breaker and panel you will need. How far away is the shop?
Distance will play a role there as well (de-rate and voltage dip potentially)


Do you have access to a trencher or is this going to be hand dug?
 
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How much juice do you need?
Go solar, then you don't have to run the cable :D
 
If you're going to have any substantial load (>30Amps?) in the shop, put in a sub-panel & make the sub-panel main breaker smaller than the breaker in the main breaker panel (less walking if it trips). If its more than 10 feet, and especially since you mentioned rocks, rent a trencher. Sunbelt rents them by the day, but are closed on Sundays...rent on Saturday & take back on Monday for the rental cost of 1 day. Just make sure you 100% know where everything is...it sucks when you're making good progress & trench right through your sewer line that you were told ran a different direction!

If you just want some lights & lightly loaded receptacles. Put some solar panels on the roof, get a good PV controller, connect battery & inverter and throw up some LED lights.
 
I plan to run a welder and an air compressor for the big stuff. Everything else is simple 110 fun. I would say that those would not be run at the same time. I have a blast cabinet that I'll need the compressor for and possibly some grinding.

The shop is probably ~75' feet away. Maybe more.
 
Lurch830 said:
make the sub-panel main breaker smaller than the breaker in the main breaker panel (less walking if it trips).
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No.
A sub-panel (I assumed) was a given.
You shouldnt be tripping you sub panel main, you should be tripping the branch circuit breaker.
 
I saw no mention if the panel in the house has adequate overhead & space for a 50+ amp breaker?

If it's "full" physically, you'd need to pull a couple of 15/20A for piggybacks...
If it's already maxed (80% of panel rating)... IMHO, you're asking for problems
 
Caver Dave said:
I saw no mention if the panel in the house has adequate overhead & space for a 50+ amp breaker?

If it's "full" physically, you'd need to pull a couple of 15/20A for piggybacks...
If it's already maxed (80% of panel rating)... IMHO, you're asking for problems
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I'll try and remember to snap a pic tonight of the box. I've got two panels in the basement right next to one another if that matters.
 
I will echo the load ratings. But I will say it depends on the home situation. If you have wife, 3 kids, and renters it will be a lot different than just you. (I.E. predictable load). Do the code load rating for each room and major appliance and see what you have left over. You might be able to get by if you exclude things like the dryer and stove if it's just you and you're close to the max
 
Ron said:
Option 1 - Have you contacted utility and inquired about cost to add a second meter? That may be cheapest option.
Option 2 - Make sure it is direct burial cable and the size cable you have (since you already acquired it) will dictate what size breaker and panel you will need. How far away is the shop?
Distance will play a role there as well (de-rate and voltage dip potentially)


Do you have access to a trencher or is this going to be hand dug?
Click to expand...
X2 call your utility company. South river emc came out and trenched and ran a new line from the transformer to my shop for a second meter at no charge. I now have a dedicated 200 amp breaker box and meter for my shop. It's overkill yes but no worries of overloading the 200 amp all electric house service if the dryer, heat and oven are all in use in the house.

The second meter has a fixed minimum fee if no electricity is even used of 20 or 30 dollars but that fee is waived if usage goes over on the second meter. With heat pump AC and electric strips that don't get turned on unless I'm out there my average bill is 60 to 70 dollars anyway between welders, lights, AC and air compressor and a fridge.

Sent from my HTC6545LVW using Tapatalk
 
Tim C said:
X2 call your utility company. South river emc came out and trenched and ran a new line from the transformer to my shop for a second meter at no charge. I now have a dedicated 200 amp breaker box and meter for my shop. It's overkill yes but no worries of overloading the 200 amp all electric house service if the dryer, heat and oven are all in use in the house.

The second meter has a fixed minimum fee if no electricity is even used of 20 or 30 dollars but that fee is waived if usage goes over on the second meter. With heat pump AC and electric strips that don't get turned on unless I'm out there my average bill is 60 to 70 dollars anyway between welders, lights, AC and air compressor and a fridge.

Sent from my HTC6545LVW using Tapatalk
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I'll give my guys a call and see what they say. I may get lucky!
 
If you are going to pull from the box inside, i would rent a trencher or mini-ex/hoe and dig a trench to the new shop. It will cost a little more, but put a pipe in for the power, and I would put a second or 3rd pipe in for water, cat5, etc in the future. It will also protect or be easier to pull a bigger power cable in the future.
 
Ron said:
No.
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I may have not been clear, or maybe what I've been told isn't the "by-the-book" method? Since I don't do residential electrical work professionally, but never mind learning something new; would it not be correct to have your main panel circuit breaker that feeds the shop at say 60 amps and the sub-panel main breaker at 50 amps? That way the sub-panel main breaker would trip before the main panel branch breaker would? Then you would have your branch breakers in that sub-panel that should trip before the sub-panel main.

Ron said:
A sub-panel (I assumed) was a given.
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Same here, just wanted to point it out. I hope for anyone doing electrical work that it would be, but I've seen people try to cheap out on stuff that could burn their house down.
 
Lurch830 said:
I may have not been clear, or maybe what I've been told isn't the "by-the-book" method? Since I don't do residential electrical work professionally, but never mind learning something new; would it not be correct to have your main panel circuit breaker that feeds the shop at say 60 amps and the sub-panel main breaker at 50 amps? That way the sub-panel main breaker would trip before the main panel branch breaker would? Then you would have your branch breakers in that sub-panel that should trip before the sub-panel main.
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I dont do resi either, and non adjustable trips sure makes coordinating more difficult, Ill give you that.
But If I am understanding what you are suggesting it is to take a load center or other similar resi style sub panel, rated for 50A and then feed it with 60A of OCP and wire? If so you just turned the entire sub panel into an expensive fuse. With a 50A panel the bus (in theory) could melt before the feed breaker tripped.
 
Ron said:
But If I am understanding what you are suggesting it is to take a load center or other similar resi style sub panel, rated for 50A and then feed it with 60A of OCP and wire? If so you just turned the entire sub panel into an expensive fuse. With a 50A panel the bus (in theory) could melt before the feed breaker tripped.
Click to expand...

Not only that, but for a one-man home shop operation, I don't understand the sequence of events that leads up to you popping the main breaker. An unheated outbuilding might have a 70A branch, but that's split across maybe some "always running" equip like a 20-30A air compressor circuit, then maybe a 30A welder circuit and some branch receptacle circuits and a lighting circuit. To pop the main, your air compressor, welder/plasma, and a couple of other big plug loads (chop saws, etc), would all have to be spinning at the same time, and even then I'm not sure it would be enough.

Maybe you'd have a problem if you have a bunch of guys over on a Saturday, but then you can always send Logan back to the house to reset the breaker.

It still comes back to "what size is this 'free' wire you have?" Given the choice, I'd try to get as close to 100A as possible.

Edit: The other big unanswered question is what your equipment demands are. I'm assuming some welding/cutting and related Jeep stuff, but for all I know, you're shopping for phase converters and knee mills.
 
Ron said:
I dont do resi either, and non adjustable trips sure makes coordinating more difficult, Ill give you that.
But If I am understanding what you are suggesting it is to take a load center or other similar resi style sub panel, rated for 50A and then feed it with 60A of OCP and wire? If so you just turned the entire sub panel into an expensive fuse. With a 50A panel the bus (in theory) could melt before the feed breaker tripped.
Click to expand...

That's not what I'm saying or at least not what I meant. The branch breaker in the main panel should be sized for the sub-panel & wire size. The main breaker in the sub-panel should be sized for the load. If you have ~45A worth of load you know you'll have in the shop, I'd get a 50A sub-panel main breaker & size the sub-panel & wire for 60A. That way the 50A breaker will trip before the 60A breaker...saving you time & sanity walking back to the house if they were both 60A. But everything should start with how much load you think you'll have.
 
shawn said:
Not only that, but for a one-man home shop operation, I don't understand the sequence of events that leads up to you popping the main breaker. An unheated outbuilding might have a 70A branch, but that's split across maybe some "always running" equip like a 20-30A air compressor circuit, then maybe a 30A welder circuit and some branch receptacle circuits and a lighting circuit. To pop the main, your air compressor, welder/plasma, and a couple of other big plug loads (chop saws, etc), would all have to be spinning at the same time, and even then I'm not sure it would be enough.

Maybe you'd have a problem if you have a bunch of guys over on a Saturday, but then you can always send Logan back to the house to reset the breaker.

It still comes back to "what size is this 'free' wire you have?" Given the choice, I'd try to get as close to 100A as possible.

Edit: The other big unanswered question is what your equipment demands are. I'm assuming some welding/cutting and related Jeep stuff, but for all I know, you're shopping for phase converters and knee mills.
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I agree 100amps of free current....not intermittent from the house load.

70 is not enough. I had a 110 Compressor Crapman. Four 110 60 watt bulbs, One box fan, a basic radio, and a 220 volt 210 wire welder. Every time the compressor fired i was in the dark. Now add a 280 volt Syncrowave old school transformer based unit. It struggled to weld 3/16 aluminum. I could choose the fan or lights. Not both cause I had to have tunes. Moral of the story: Electricity is like HP in a buggy. Build what you can afford but don't build just to get in the game.....your game will suffer.
 
with all this 'advice' seems it will be time well spent to drop a case of beer off and introduce yourself to the local volunteer fire dept.:bounce:
 
WARRIORWELDING said:
70 is not enough. I had a 110 Compressor Crapman. Four 110 60 watt bulbs, One box fan, a basic radio, and a 220 volt 210 wire welder. Every time the compressor fired i was in the dark. Now add a 280 volt Syncrowave old school transformer based unit. It struggled to weld 3/16 aluminum. I could choose the fan or lights. Not both cause I had to have tunes. Moral of the story: Electricity is like HP in a buggy. Build what you can afford but don't build just to get in the game.....your game will suffer.
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That math doesn't work. Were all of the 110V appliance circuits on the same leg?

I can say for absolute fact that I can run a 40A 220V plasma cutter, a 15A 220V compressor, some fluorescents, and whatever misc crap I wanted on a 70A branch circuit simultaneously.

The 210 mig only pulls 30A wide open.
 
a_kelley said:
@shawn
That is neglecting inrush current, beyond sticker rating but transient.. fast acting or old breaker catches it and trips..
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Maybe. I'm not convinced yet that there wasn't a wiring problem. That's a shitty breaker that pops at half its rating.
 
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