100 Amp Service to my Barn

[TurbineTester]

I know this has been addressed many times but I'm posting this any way to make sure there are no major issues or updated code requirements which would affect my install versus the older advice I have used to come up with my plan. The two attached pictures show the run I need to make. Based on this post...

http://www.garagejournal.com/forum/showthread.php?t=169211

...I'm using the wiring diagram posted by pattenp and plan on using 2-2-2-4 AL mobile home feeder wire, and burying it 24" deep. I live in middle Georgia.

There is already 120v 30A service at the barn, but it only runs lights and a window a.c. unit. Among all the 120v tools I will be running the following 240v items:

3hp Jet cabinet saw
3.7 hp 60g Kobalt compressor
5hp Clear-Vue cyclone dust collector
Possibly a full size a.c. system
Possibly a small welder in the future

I just want to see if there are any concerns with such a long run of wire (~200') from the main panel. Only reason I'm running around the perimeter is because there might be a pool in the middle of the yard one day and I don't want to have to do this twice.

As this is my first post here, any comments or advice would be well appreciated.

Thank you,
Chris.

 

[Pantsfall_McFixit]

100 amp service will be cramped with some/all those things running, and doesn't give you a lot of room to expand. Have you looked at getting 200-amp service? Currently I'm dealing with how to manage a 100-amp service now for a small shop, it's getting tight with all the power equipment.

 

[theoldwizard1]

There is already 120v 30A service at the barn, but it only runs lights and a window a.c. unit.

You will have to disconnect that. Only 1 feed to an out building is allowed.

Among all the 120v tools I will be running the following 240v items:

3hp Jet cabinet saw
3.7 hp 60g Kobalt compressor
5hp Clear-Vue cyclone dust collector
Possibly a full size a.c. system
Possibly a small welder in the future

I just want to see if there are any concerns with such a long run of wire (~200') from the main panel.

MHF is good for a max of 90A from your main panel. At that current and wire length you will need 2/0-2/0-2/0-1. You are probably okay with the first 3 tools, but I don't know about the A/C. That may be the "straw that breaks the camels back". You don't want to run the welder while using the saw and dust collector either. You need to get specific amperage ratings of these items.

Simply shutting off the compressor when you are running the saw, dust collector and A/C would likely keep you under the breaker limit.

 

[sberry]

I wired 2 dozen garages over 30 years with number 2 and fed with a 60A breaker. Never,, ever had one call with a tripped overloaded main.

 

[Aceman]

I wired 2 dozen garages over 30 years with number 2 and fed with a 60A breaker. Never,, ever had one call with a tripped overloaded main.

I'm not sure why you always post this one size fits all answer. It seems crazy to me that you think everyone has the same electrical requirements and they are ALL under 60 amps just because no one has called you back to tell you a breaker has tripped.

Didn't you post a while back you burned up a 60 amp breaker?

Real electricians take present and future loads into account and wire accordingly. I don't tell customers their two dozen neighbors down the road all had 60 amp panels installed, it's good enough for them, it's good enough for you. I verify it, with a load calc.

 

[Pantsfall_McFixit]

A rough estimate of the current required, using 240 volts:

3hp Jet cabinet saw - 20amp breaker
3.7 hp 60g Kobalt compressor - 20amp breaker, says it uses 15a at Lowes.com*
5hp Clear-Vue cyclone dust collector - 30amp breaker*
Possibly a full size a.c. system - 15/20amp breaker - (mini split/heat pump, or full size?)*
Possibly a small welder in the future - 15/20amp breaker

Adding all that up is over 100* amps. Running it may be closer to 60, using in-head rough layman's estimation* This is not considering other circuits like lighting and outlets. Granted that's the breaker size and equipment won't be drawing exactly that, it still leaves no room. Since you may be sawing, the compressor may be refilling the tank, the dust collector is working to clear the air, and the a/c is running because it's hot, that's close to 100 right there.

If someone has a more accurate picture of current use with all this equipment, please add to the discussion.

*Edited to update requirements with what I could find on those pieces of equipment

 

[chew]

I wired 2 dozen garages over 30 years with number 2 and fed with a 60A breaker. Never,, ever had one call with a tripped overloaded main.

Had to post this. I'm an electrician my self and after reading that I couldn't help but think they must have been federal pioneer breakers lol

 

[sberry]

I'm not sure why you always post this one size fits all answer. It seems crazy to me that you think everyone has the same electrical requirements and they are ALL under 60 amps just because no one has called you back to tell you a breaker has tripped.

Didn't you post a while back you burned up a 60 amp breaker?

Real electricians take present and future loads into account and wire accordingly. I don't tell customers their two dozen neighbors down the road all had 60 amp panels installed, it's good enough for them, it's good enough for you. I verify it, with a load calc.

I know you are a master but this was in response to the one size fits all assumption that we will be close to overloading a 100A service. 2nd,,, listing every piece of equipment a guy owns isn't a load calc and in the real grand scheme of things a garage barely effects demand. Many of them seen to get by on a single circuit.

Real electricians take present and future loads into account and wire accordingly. I don't tell customers their two dozen neighbors down the road all had 60 amp panels installed, it's good enough for them, it's good enough for you. I verify it, with a load calc.

No one is saying not to consider circumstances, that I am saying is there is no need to be in a panic till there is a legitimate reason to think 100 wont be enough and from sheer experience have never seen Joe 30x40 or 2 car garage not only not trip a 100 but not trip a 60. It would be true however that its highly unlikely any of them put a big tig on it either.

 

[wyliesdiesels]

Had to post this. I'm an electrician my self and after reading that I couldn't help but think they must have been federal pioneer breakers lol

Thats the Canadian version of Federal Pacific Electric or FPE for short right?

 

[jvitez]

A rough estimate of the current required, using 240 volts:

3hp Jet cabinet saw - 20amp breaker
3.7 hp 60g Kobalt compressor - 30amp breaker
5hp Clear-Vue cyclone dust collector - 40amp breaker
Possibly a full size a.c. system - 15/20amp breaker, perhaps 30 if large barn?
Possibly a small welder in the future - 15/20amp breaker

Adding all that up is about 130 amps..............

If someone has a more accurate picture of current use with all this equipment, please add to the discussion.

OK, I will!

As you've stated, adding the breaker amperage doesn't help. What anyone needs to do when calculating service to a detached shop/garage is do a proper load calc. Only simple math required!

1. Figure out everything you could possibly want inside your garage that might use electricity, now and in the future.

2. Determine the power draw of each item, in WATTS not amps.

3. Add up the wattage. Divide by 240. This is the actual amperage your building will be using, at the very most.

 

[TurbineTester]

Ok I think I'll tone down my "maybe" requirements so that I can work with the 2-2-2-4 wire, unless it's not too much more expensive? I don't think they carry 2/0 at home depot, and I'm guessing it's probably much more expensive? Any one have any idea what 2/0, for conductor MHF would cost per foot? Also I'm not crazy about the idea of running conduit down through existing walls, so I'm thinking of using SER to go from the panel to the outside conduit. My question is what would be the cheapest to-code method to splice the MHF and SER wire together? I'm trying to avoid having an $80+ breaker or $200 disconnect box...thank again guys for your help.

 

[theoldwizard1]

Ok I think I'll tone down my "maybe" requirements so that I can work with the 2-2-2-4 wire, unless it's not too much more expensive?

2-2-2-4 to 2/0-2/0-2/0-1 is about twice as expensive.

With 2-2-2-4 you can use a 60A breaker in the house. Make sure the compressor and the A/C are off when you run the saw and the dust collector and you will have no problems. (Hmmm ... Isn't that what sberry said back in #4 ? )

Also I'm not crazy about the idea of running conduit down through existing walls, so I'm thinking of using SER to go from the panel to the outside conduit. My question is what would be the cheapest to-code method to splice the MHF and SER wire together?

Use aluminum SER and any mechanical splice block approved for aluminum.

All you need to do is place a weatherproof box at the top of the Schedule 80 conduit sweep (for the MHF as it transitions underground) where it goes into the ground. I don't think there is any code requirement for a disconnect there, although a non-fused disconnect might be cheaper and/or easier to find !

 

[pattenp]

To splice MHF to SER is best done by using a large junction box. You may be surprised as to how much a 12"X12"X4" PVC box cost. Also splice/reducers can be used to splice the wires. Use heat shrink tube or tape very well.

 

[Falcon67]

100 amp service will be cramped with some/all those things running, and doesn't give you a lot of room to expand. Have you looked at getting 200-amp service? Currently I'm dealing with how to manage a 100-amp service now for a small shop, it's getting tight with all the power equipment.

Bah. you should see what's crammed in my space and I can't trip 70A. 90% of that was in the old shop and it ran on 60A without a trip. And I loaded that feed up for testing by running everything.

 

[theoldwizard1]

To splice MHF to SER is best done by using a large junction box. You may be surprised as to how much a 12"X12"X4" PVC box cost.

Hence my comment to just buy a 60A rated A/C disconnect box. They start at about $10 at HD !

 

[Pantsfall_McFixit]

OK, I will!

As you've stated, adding the breaker amperage doesn't help. What anyone needs to do when calculating service to a detached shop/garage is do a proper load calc. Only simple math required!

Thank you for adding to the discussion. I just looked up the draw on those pieces of equipment (what could be found anyway), and updated the estimated breaker size. Of course, some manufacturers make amp draw hard to find online and fuzz the HP numbers on motors, making it difficult to estimate amp loads using standard charts. Also equipment often doesn't run a motor to its full load, which is a good thing, better to have more power than not enough. In my head around 60 amps popped up, with all equipment running. If we can get the nameplate amps on that equipment, a more accurate picture can be made.

Bah. you should see what's crammed in my space and I can't trip 70A. 90% of that was in the old shop and it ran on 60A without a trip. And I loaded that feed up for testing by running everything.

Indeed. I just don't want this guy to run a line and find out it's not enough, or leave no room for expansion. After several project underestimates on my part, and lots of rework, perhaps others don't have to make the same mistake.

 

[bdkw1]

Also, what kind of welder? Small MIG will run on a 20A breaker. My TIG welding aluminum will pop the 50A no problem. The new shop will get a separate 100A breaker for the TIG.

 

[pattenp]

Hence my comment to just buy a 60A rated A/C disconnect box. They start at about $10 at HD !

The knockouts on that 60A Square-D disconnect box are only 1" and can't handle the required size of conduit to get 2-2-2-4 MHF into the box. And the terminals are rated only up to #4 line and #6 load.

 

[Falcon67]

Indeed. I just don't want this guy to run a line and find out it's not enough, or leave no room for expansion. After several project underestimates on my part, and lots of rework, perhaps others don't have to make the same mistake.

For sure.
My test was:
1 HP mill, 3/4 hp lathe, 1/2 hp drill press, 20A/5 kW heater unit, 1/3 hp grinder, 14 each 4' two bulb T8 lights, 3.5HP air compressor. All running at once. Leg topped out at 49A, other leg at 46A as I recall.

Normal load in the new shop would be some machine (1/3 - 2HP max), two AC units or one heater, some lights and the occasional compressor cycle. Only one guy in there.

 

[theoldwizard1]

The knockouts on that 60A Square-D disconnect box are only 1" and can't handle the required size of conduit to get 2-2-2-4 MHF into the box. And the terminals are rated only up to #4 line and #6 load.

Bummer !

Well, HD has 12x12x4 PVC J boxes and the have splices. Good quality electrical tape or heavy duty double wall shrink tube.

This seem like over kill QO 100 Amp Two-Pole Outdoor Enclosed Circuit Breaker - $42 Plus a breaker !

 

[TurbineTester]

2-2-2-4 to 2/0-2/0-2/0-1 is about twice as expensive.

With 2-2-2-4 you can use a 60A breaker in the house. Make sure the compressor and the A/C are off when you run the saw and the dust collector and you will have no problems. (Hmmm ... Isn't that what sberry said back in #4 ? [emoji106] )


Use aluminum SER and any mechanical splice block approved for aluminum.

All you need to do is place a weatherproof box at the top of the Schedule 80 conduit sweep (for the MHF as it transitions underground) where it goes into the ground. I don't think there is any code requirement for a disconnect there, although a non-fused disconnect might be cheaper and/or easier to find !

I'm confused, why am I using 60 amp breaker and not 70 or 90 as previously mentioned?

Also, I can't find splice blocks at home depot...at least they don't look like what you have pictured.

The three tools i have now will look like this when installed I think...
Compressor -rated 15 amp, breaker at 20
Saw-rated at 15 amp, breaker at 20
Cyclone-rated at 20, breaker at 30

I'll most likely add the a.c. system first

In auxiliary heat mode it will probably pull 38 amps, and straight cool will be closer to 20.

A medium MIG welder might pull 20 amps.

I think worst case scenario I would be using the saw and cyclone and the heat happens to come on...~73A? I would never be using the compressor and the saw the same time.

I checked a calculator at powerstream.com and at 70 amps over 225' of#2 AL , the voltage drop is only 9.854V or 4.11 percent. Still leaving 230+V at the branch panel.

I think I'll just run the MHF all the way to the main panel, running the conduit from the ground to the panel, to avoid all the mess of junction boxes etc.

 

[sberry]

The 2 cents I added was just for discussion. Number 1 would help but not sure you can find the deal like number 2 which is super competitive. My neighbor did a similar test, turned on everything he could and didn't go over 50A, tried to. Only thing is he didn't hit the buzz box which would have put it well over the top.

 

[pattenp]

Just a FYI... the NEC suggest no more than 3% VD. You definitely don't want a setup where you see a 5% or more VD when in use. The #2 MHF at 225' will start having a VD of more than 3% with loads over 50 amps. An 80 amp load will push it close to 5%. My personal opinion is with the A/C and Heating I'd run #2/0 AL and breaker it at 100A. In the long run I think you'll be better off and happy. The #2/0 MHF should cost about $1 to $1.25 more per foot than the #2 MHF.

 

[sberry]

As I mentioned,,, and not to pick a fight with the real electricians but,,,, I have done this a lot over a long period of time. I have seen a couple residential on old 60A service with all electric with busy family overloaded, a couple restaurants and taverns on Friday night fish fry in hot summers.
I don't work in it full time so what I see is limited. I know a couple buds including myself have ran welding shops from 100, did it once with lots of men on it. The thing was a temp after a fire and even the inspector commented on the potential for overload but I never had a problem.
My air comp is thrifty which helps a lot, I use a 3 for main supply but got a 3 hp well and a 4 hp walk in cooler, my pressure washer runs at 24, a half a dozen fridges and 2 possible window units, another horse cooler and ahah,,, almost forgot electric dryer.
I could add a bit more, none of those are 100% but if I weld likely could see spikes over 100 but would be pretty rare.
From metering things on occasion I think we over estimate our demand, not that its al a bad thing but is also something to be aware of. You cant make perfect and make it unaffordable in some cases.
A move to number 1 would help with motor starts a little and allow for larger air comp on this long run. Air is usually on demand, anything less than 5 hp the number 2 is likely going to serve this load fine. (the OP)

 

[justin1795]

how long is your run 2-2-2-4 might be stretching it. I calculated out 1/0 for about 130 foot for 100amp service for myself.

 

[theoldwizard1]

Also, I can't find splice blocks at home depot...at least they don't look like what you have pictured.

Look for something like this.

Make sure they say they can be used with aluminum wire. There is also a special compound/grease you can pu on th end of the wire before inserting it in the splice that prevents corrosion.

Use HD double wall shrink tube or at least 2 layers of GOOD electrical tape, like 3M 88 or Linerless.