Jwest

Shop Electrical Set Up

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Hello All,

 

Haven't posted or checked the site in awhile due to moving and lack of internet. We recently purchased a great place on 6 acres with a 30 x 40 metal shop/barn. I was originally going to build a new shop since we have plenty of space, and use the old one for tractor and yard work type equipment. I recently have decided to just spend money to remodel and fix up the current shop and just build a small out building for the tractor. Sorry for the long intro, I tend to do that without realizing sometimes. Anyhow, I noticed that this shop has a subpanel with two breakers; a breaker for 1 outlet and a breaker for the lights. Yes...that's only one outlet...110.

 

So, that is what brings me to you all for counsel. I'm going to upgrade this shop in stages and first is electrical, since I can't really do much at all in there at this point. My question is, based on everyone's experience here how should I set this up? I'm guessing I'll need to have something like a 60amp breaker on the main panel to feed my shop. I'm going to have to bury a new power line for this, but no biggie. I don't have any 220 tools yet, but I would like to get them in the future.

 

What size sub panel would you all recommend?

How many 220 lines and 110 lines do you all typically run in your shop?

I'm guessing I should prep for all the major tools to be 220 right? (ie tablesaw, jointer, planer, DC, drum sander, etc??) All I have is 110 stuff right now.

 

I'm kinda unsure of what questions to even ask for electrical needs. I just want to do it right the first time, even if it's costly. Hope someone can give me some direction here. Thanks everyone. Sorry for the long post.

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I am sure there are a lot of knowledgeable folks on here, but if you go to ridgidforum.com, they have a dedicated electricians forum board where you can ask questions like this. Lots of pro electricians on there to help.

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What is your service entrance at the home? 100amp, 200amp? Large or small home? I have seen electricians pull sub panels of 70amp capacity out of a 200amp main panel. I have rarely seen more than 30amp sub out of a 100amp service.

That said, a one 100amp sub panel can be used and then limited with a 60 or 70amp main breaker in place of the normal 100amp main. This is typically the economical way to purchase equipment rather than purchasing specialty lesser amperage feed boxes. This also offers a range of circuit space letting you dedicate circuits so a high amp DC can be run at the same time as a high amp milling machine. This is one short answer. Other guys will chime in as you post more info about your setup.

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Thanks for the link franklin. I'll definately check them out.

 

As for the answers on service:

200 amp service and fairly large home ~ 3200 sqft.

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My 3400 sq ft with 200amp service currently has a 70amp takeaway back feeding a prior 100amp panel installation. 70amp breaker replaced the 100amp in the main breaker slot. I doubt I'll ever stretch the 70amp limit in small shop format as long as tools spool up separately.

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Approximately how far is it from the main panel in the house to the subpanel in the barn?  I assume you want to plan to be a one-man shop (e.g. one major tool on at a time)?  Do you want to plan for HVAC or hot water in the shop?

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For a sub panel just get a typical 100A panel with main breaker in it and at least 12 full slots. The 100A main breaker in your sub panel acts like a disconnect so you can kill power to the whole shop without running back to the house. At the house you can install a 60A double pole breaker in your existing 200A panel to feed the new sub panel. This is a good size because it allows you to run #8 wire to the shop, but if the shop is some distance away and/or you want to future proof then bump up the size of the wire a bit. Grounding is an issue I'm not that familiar with when it comes to detached buildings, but I think you'll find you need to drive ground rods out at the shop.

 

If you don't have a lot of circuits just get some NM-12/2 cable and put in 20A circuits everywhere, 120V and 240V. If you have a fair amount of wiring to do then it may be more economical to also get some NM-14/2 for the lights and 120V outlets. Put the lights on their own breaker(s) and do not share them with any outlets, you don't want to find yourself in the dark holding a tool that just malfunctioned. I would run NM-12/2 to each outlet that you plan to dedicated to a major tool and only put that one outlet on that wire and circuit breaker. This allows that tool a dedicated 20A supply and you can switch between 120V and 240V simply by changing the breaker and the outlet. For general purpose 120V outlets just chain a bunch of them around the walls on one or two 15A or 20A circuits. Some of us like our outlets at least 48" off the floor so they are easy to reach and will clear a piece of plywood stood on edge. In my shop there is 4" square box with outlets every 4' along the walls so I'm never searching for an open outlet to use. Where, how many, and what kind are all up to you to decide based on your tools and needs. If you think you might need a 30A circuit some day install NM-10/2 wire in a few places. If you fancy a welder in the shop then plan to put that outlet near your sub panel. If you want to mount an air filter in the rafters plan that out now so you're not tempted to put it on the lighting circuit later on.

 

One last issue is load balancing across the two hot legs supplying your shop. If you have all 240V loads then it isn't an issue, but if you'll be running some 120V loads at the same time it's a good idea to balance them out. Your dust collector is used with pretty much every tool so you can try to put the other 120V loads on the other leg so they balance each other out. If you have two breakers feeding general purpose 120V outlets then put those on separate legs as well. When you look at a panel each row of two breakers is on the same leg and as you move down the column of breakers every other row is on the same leg. It's not a big deal, but a little planning now will help keep everything flowing smoothly in the shop and back at the main panel.

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Steve M,

I would not feed with 60amp and leave the 100amp master. If you ever blew at 60amps you would have to go to the house to reset it.

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Correct. What's the problem with that?

 

If you put a 100A feeder at the house and 60A at the sub panel you have to run 100A wiring to the shop. If you put a 60A breaker at both locations you never know which one will trip. Do you have a solution to offer?

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I would not mismatch the service and sub. Here local code doesnt allow it anyways. I'd go 100/100. Dont worry about running amperage. A 3 hp dust collector needs 30a dedicated. Lights 25a dedicated. Now look at what else may be running. 3hp tablesaw on a 20a and your almost at your 80%

If you just look at breaker size and dont cheap out and try skimping by just adding up running amps you will never have a problem and will always have enough power.

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steve, the way electrons flow, the breaker at the subpanel would trip first. the machines are what pull for electrons. You always want to have matching breakers for your subpanels. 100A in the house 100A in the subpanel. or 60 for each...

 

Since you don't have any power tools yet, i suggest running your wires through EMT. It allows you the best freedom to change wiring in the future. i priced out the difference between 12/2 romex and EMT and saved about $300. I bought one spool of black wire and put white tape on my neutral leeds. I used 4sq. boxes with industrial raised covers and bought all my plugs and parts in bulk from the local electrical supply house. They beat Home Depot's prices by about 10%. i did find it easier to use 14/2 romex for the lights because my ceilings are 20 ft. and i don't own scaffolding. i put a 40 space panel in my studio just for kicks. i figured maybe one day i will need a lot of 2 pole breakers... there's no problem with putting a panel with a lot of spaces. just make sure you calculate your service wire size properly for the future.

 

it may benefit you significantly to purchase the NEC electrical hand book. http://www.amazon.com/gp/product/0877659168/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=1532201582&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0877659141&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0C8YTVFV0ZQG5TS4C22K

 

the handbook has pictures and explanations written in plain english instead of "legal code speak" as the paperback version does. 

 

I have used the code book as a guide to help me interpret a proper installation for my work studio. Maybe someone in your community has a copy and could lend it to you. even if you decide to hire an electrician to consult, it's fabulous to look through and understand specific points of the way things are supposed to be done. Another note about the code book. Most city's and states are behind with adopting the most current electrical code. Every three years, the NEC comes out with the latest codes. so make sure you look into the codes for your county or city before you make a concrete plan for attack. 

 

electrifying your own shop really pays off every time you use it! 

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It's an outbuilding -- I'd hire an electrician to run the line and bond the grounds properly.  Seriously, It will be worth it in the long run -- a flaky ground will cost you tools over time (assuming something more serious doesn't happen).  You can wire your tools from the box later.  The other reason to use an electrician is loss w/ distance -- the electrician can tell you how much to up-gauge to match the loss.  Don't forget inspections -- if you ever build-up a decent tool inventory and go to insure it, the insurance guy may require an electrical inspection (mine did) and you don't want to be fixing things down the road.  If an electrician does the job, then he can get it inspected for you...

 

I'd get a standard SquareD box with local disconnect (I think mine is 125a).  The point is you may never need that much power, but having the extra breaker positions is welcome over time.  

 

Always run more power then you think you need.  As someone mentioned, you may want HVAC, hot water, etc at some point down the road.  As an example, it does not cost that much more to run #4 over #6.

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+1 on everything hhh said!

I would go 1 size over the code required size of the cable to the house. A pro electrician will be familiar with the proper way to trench and bury the cable as well. Take numerous pictures of the trench and reference points should you need to locate it in the future. Print the pictures and have a copy near the electrical panel and mount one on the wall near your gardening tools as a reminder where not to dig!

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I would at least get someone qualified to tell you what is needed to get power to the shop. Chances are pretty good you will nee #2 or #3 from the main panel and if its a long distance you may have to pull from the pole with a separate meter. IIRC mine is #2 and only 75ft.

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hhh, I do plan on hiring an electrician for the work. I'd rather have someone with the proper skill set to tackle this job. This was more of an excercise in what you all think I'll need, what you all have learned through experience, and what layout you all have found that works. I want to be able to have an educated conversation with the elctrician and have a baseline for what I think I'll need. Also, I want to be able to overlay what you all have suggested with the electrician's suggestion to make sure we are working in the same direction. I don't want to cut any corners, so I'll pay for a pro.

 

I'm not sure on the distance to the shop from the house, but I'm going to guess its roughly 150 - 200 feet. That's a rough estimate btw. I do have power tools, just nothing requiring 220 yet.

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hhh, I do plan on hiring an electrician for the work. I'd rather have someone with the proper skill set to tackle this job. This was more of an excercise in what you all think I'll need, what you all have learned through experience, and what layout you all have found that works. I want to be able to have an educated conversation with the elctrician and have a baseline for what I think I'll need. Also, I want to be able to overlay what you all have suggested with the electrician's suggestion to make sure we are working in the same direction. I don't want to cut any corners, so I'll pay for a pro.

 

I'm not sure on the distance to the shop from the house, but I'm going to guess its roughly 150 - 200 feet. That's a rough estimate btw. I do have power tools, just nothing requiring 220 yet.

 

As far as layout goes I think I have more 220v outlets than 110v. Since you dont have machines yet Id put  a couple 220v outlets on each wall. Just keep in mind some stuff will need 30a breakers so maybe 1/2 of them use bigger wire and breakers. Probably the same amount of 110 and maybe a couple in the ceiling. Extension cords are a pain in the but and proper 220V cords are more expensive than just running more hardwired outlets.

 

You can take a look at my shop pics and see the outlets. The shop wiring is dedicated to what machines you see so I had it pretty easy. 

http://www.thewoodwhisperer.com/shop-tours/dons-workshop-2/?woodworker_type=professional

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I always suggest people run 1+wire size bigger, and 1+ size bigger conduit if its underground.  If you do those two things future upgrades are a snap, you just have to replace any breakers.  Upsizing the wire will also negate any voltage drop as thats how voltage drop is fixed basically.  IF you want to wire for the future and cost isnt much of an object then id suggest upsizing now.  If costs are a factor and you arnt worried about the future then spend some time figuring out what you need and how you want it, id also suggest getting a couple of estimates and picking each contractors brain when they come out and go over what they want to sell you and why.  Other then that we have a similiar conversation going over on that thread of Milos, detailing installation of alot of this stuff.  So if your planning on doing it yourself you may want to check that thread out as well. 

 

 

 

Nyles

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Hi Jwest,

 

At a 150-200ft distance you are going to want to upsize the wire a little bit to compensate for voltage drop, probably up one size.  For example a 60A panel would normally require #6 copper wire, you should run #4 copper.  My recommendation is that a 60A panel and feeder would be adequate for a one-map shop, but if you have extra room in the budget go ahead and install a 100A panel and feeder if you think your shop might expand.  A reasonable compromise is to install larger conduit and a 100A subpanel with only 60A feeder from the house; if at some point in the future you need more power in the shop you can simply repull larger wires in the conduit and replace the feeder breaker.  Conduit is quite cheap so it doesn't cost much to upsize now whereas the larger wire could add several hundred bucks that you may never need to spend.  Talk to your electrician about this and get a quote for both 100A and 60A panels; explore conduit vs. direct burial cable -- for example a 60A panel in pipe with copper wire may be more expensive than a 100A direct burial aluminum cable.  Some local codes may come into play as well which favor one option over the other.  If you're a DIY kind of person, most electricians will be happy to let you do grunt work like digging trenches and installing pipe to save on your overall bill if you're so inclined.

 

If you want to do a rough calculation of what size panel you need and what size you might want, add up all the watts of everything you intend to run at the same time (lights, A/C, tools, etc).  Divide that by 240 to get the minimum required amperage of the panel and then leave room for about 20% on top.  Use 750W per horsepower if you're calculating motors.  An example of largest tool, dust collector, lighting and window A/C unit:

 

3 HP table saw (2250W) + 2 HP dust (1500W) + 10 32W fluorescents (320W) + big window A/C (2000W) = 6070 W

6070 W / 240 V = 25A

25 A * 120% = 30A

 

The absolute minimum size panel needed to run these items is 30A.  Of course a typical shop will have some additional misc stuff you forgot in the calculation and it never hurts to leave a little extra room for motor startup.  In this case I would tell the client that if they need the lowest cost option they should install a 40A panel, if they can afford some future flexibility go with 60A and if they want a premium installation go with 100A.

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Taking the cheapest route or doing the bare minimum possible to meet the requirements of the NEC isn't always the best way. The NEC is a set of minimum standards that will on average help ensure people don't get killed and buildings don't get burned down by faulty wiring. There is a whole lot more you can do to both make things safer and more convenient for you and those that may need to work on the circuits after you're no longer around. The suggestions people have to run larger than required conduit and cabling is an example of this, isn't not required but will keep your shop running smoothly and make future upgrades and changes possible and economical.

 

 

I would not mismatch the service and sub. Here local code doesnt allow it anyways. I'd go 100/100. Dont worry about running amperage. A 3 hp dust collector needs 30a dedicated. Lights 25a dedicated. Now look at what else may be running. 3hp tablesaw on a 20a and your almost at your 80%

 

The 2011 NEC has no requirement for the sub panel to even have a main breaker so I find it unlikely that the AHJ in Centrailia has added this requirement for both breakers being rated the same. Do you have a reference to the code making this requirement?

In my experience a 1.5-3HP tool is just fine on a 20A 240V circuit and only the >3HP to 5HP tools need 30A 240V circuits. There is a reason why 3HP and 5HP are very common motor sizes on our power tools, it's right around the max size that you can put on a 240V 20A and 30A (respectively) circuit. Magically enough, a 1.5HP motor is a popular size as well because it is about the max that you can put on a 120V 20A circuit.

Putting lights on a 25A circuit seems like an odd suggestion as single-pole 25A breaker isn't a standard size, you'd have to use #10 wire (which is 30A capable so you may as well have just used a 30A breaker), and use all hard wired light fixtures since you can't put 15A or 20A receptacles on a 25A circuit (2011 NEC 210.21).

 

steve,
the way electrons flow, the breaker at the subpanel would trip first. the machines are what pull for electrons. You always want to have matching breakers for your subpanels.

 

No sir! The way electrons flow if you have 60A arriving at the main breaker of your sub panel then 60A must also be flowing through the feeder breaker in the main panel in the house. This is something that electricians have known since 1845. The only way around this is to connect a generator to the cable running from the house to the shop to inject extra current (please don't anyone try this). If both breakers are rated the same (this is not a 2011 NEC requirement BTW) then the one that trips is based on random manufacturing tolerances. Let's say that the feeder breaker in the house trips every 20 years when you somehow manage to overload the shop circuit. What is the big deal with a 150' walk to reset it? What is your reference for this requirement and your rational (that doesn't violate the laws of physics) for making them equal? The wire feeding the shop must be protected by an appropriately sized feeder breaker in the main panel, the main breaker in the sub panel simply acts as a local disconnect for the shop so any breaker rated the same or higher than your feeder breaker will do fine.

 

 

Since you don't have any power tools yet, i suggest running your wires through EMT. It allows you the best freedom to change wiring in the future. i priced out the difference between 12/2 romex and EMT and saved about $300. I bought one spool of black wire and put white tape on my neutral leeds. I used 4sq. boxes with industrial raised covers and bought all my plugs and parts in bulk from the local electrical supply house. They beat Home  Depot's prices by about 10%. i did find it easier to use 14/2 romex for the lights because my ceilings are 20 ft. and i don't own scaffolding. i put a 40 space panel in my studio just for kicks. i figured maybe one day i will need a lot of 2 pole breakers... there's no problem with putting a panel with a lot of spaces. just make sure you calculate your service wire size properly for the future.

 

I agree with the suggestion of using EMT and using panels with lots of open spots. EMT can be an economical alternative to NM and it ensures proper protection of the wiring at all times. Prior to re-wiring my shop the NM cables were legally routed through the rafters of the 8' ceiling where it normally would be protected, but I kept snagging the cable with sheets of plywood and 8' long boards and would have eventually damaged the wiring. EMT and better routing solved that problem. What I must disagree with is your violation of the 2011 NEC 200.6(A) by using black wiring and white tape. The neutral cannot be black wire with white tape. The correct and safe way to run wire in EMT is to use black, white, and green (or bare) conductors where appropriate. I know that you don't always need a ground wire when you use EMT to meet NEC requirements, but I have multiple sources saying it is wise to run a ground wire in EMT anyways as it is a more reliable path to ground.

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Thanks Ben, that was very helpful and something I was was going to calcualte at some point. Actually, thanks everyone and I appreciate the help. I've found this to be very informative, and I think I have a much better idea on how to plan this project. I am positively hiring an electrician, and hopefully he will let me do some of the grunt work like digging trenches to save a few bucks. However, I've learned that there are some things I'd just rather hire out. This would be one of those things. At least now, I feel like I can articulate what I'm looking for.

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Taking 

 

 

The 2011 NEC has no requirement for the sub panel to even have a main breaker so I find it unlikely that the AHJ in Centrailia has added this requirement for both breakers being rated the same. Do you have a reference to the code making this requirement?

In my experience a 1.5-3HP tool is just fine on a 20A 240V circuit and only the >3HP to 5HP tools need 30A 240V circuits. There is a reason why 3HP and 5HP are very common motor sizes on our power tools, it's right around the max size that you can put on a 240V 20A and 30A (respectively) circuit. Magically enough, a 1.5HP motor is a popular size as well because it is about the max that you can put on a 120V 20A circuit.

Putting lights on a 25A circuit seems like an odd suggestion as single-pole 25A breaker isn't a standard size, you'd have to use #10 wire (which is 30A capable so you may as well have just used a 30A breaker), and use all hard wired light fixtures since you can't put 15A or 20A receptacles on a 25A circuit (2011 NEC 210.21).

 

Local codes are different everywhere, some have them some don't. Our inspections are done by the utility company. Tacoma public utilities required a in ground stake along with the 20 ft in rebar under the slab. PSE has no such requirement nor does NEC. TPU wants the verification bar on the same wall as the panel if wall is over 20ft. PSE wants it on opposite walls I dont think NEC cares.

 

No you not correct about the blanket amperage draw of electrical motors. In my shop the 3hp cyclone will not run on a 20a wont even start the motor. The 3hp 12" jointer also will not run for more than a minute on a 20a. 5 Hp shaper will run all day long on a 20A. Its all about load not HP.

 

25 was a typo should be 20.

 

I dont know if its nec or local but we are required to have a main disconnect at the sub panel in detached building with 6 throws but not attached. This both TPU and PSE inspectors.

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So I am the only one who thinks it is foolish to require travel of 150' in rain or snow for a simple breaker reset? I would plan to not need to ever reset a breaker of that size so please do not think I would be planning to reset it. I just go back to all my experiences as a child being screamed at through 60' of house while my dad replaced fuses:-)

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So I am the only one who thinks it is foolish to require travel of 150' in rain or snow for a simple breaker reset? I would plan to not need to ever reset a breaker of that size so please do not think I would be planning to reset it. I just go back to all my experiences as a child being screamed at through 60' of house while my dad replaced fuses:-)

 

I wouldnt mismatch the main panel and sub. On the other hand dont see how you could trip a main breaker either. The individual tool breakers in the sub panel trip before the main. 

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Even though you don't have everything for your "full" shop (who does?), you should go through an exercise to layout your ideal shop:

  • Figure out where you would put every tool.
  • Figure where workstations/benches will be where you use handheld power tools.
  • Figure out where you want what kind of lighting
  • Put a 220 outlet next to every single major tool, even if you only plan on buying a 110V tool for that location
  • Figure out where you want additional outlets along each wall, then put another one halfway between everywhere you thought you'd need it.

Once you have all of these outlets laid out, you can come of with wiring schemes to address all those outlets/lights.

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