# now for electrical requiremnets on new shop



## farmall (Jan 8, 2012)

Good morning folks. I just about have the outside of the wood shop completed and now it is time to start roughing in the electrical. I have about 35 circuits left on a 200 amp service, single phase (in the original part of my garage that I added on to). I am going to be working by myself with maybe another person occasionally. I am wondering how many circuits I need to drop and especially wondering about the 240 volt drops. My shop is 30' x 31 feet with a pole in the middle. I am not sure how many 240 volt drops I will need but I am thinking about putting one on the pole in the middle and 1 circuit on each 30 foot wall, with 2 recepts per circuit (6 total) How many amps should I expect to pull? about 15? Do the 240 machines hard wire or do they have plugs on the cable? Any advice would be greatly appreciated.


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## Hammer1 (Aug 1, 2010)

It's always a good idea to have plugs on all machines so you can easily disconnect from the power when working on them. A decent sized dust collector will take 220, 20 amp and will usually run at the same time as other machines, put it on a separate circuit. The other more common 220 users are the table saw, stationary planer and shaper. These could share a circuit since they don't run at the same time. Others will depend on what you have for equipment, check the motor stats for amp use. A compressor can be a large draw and you would want a separate circuit for that. I would use a lot of quad outlets for 110 since you often need to plug in several tools or accessories at the same time and keep them high at bench height. Where cords will run is something to consider. You might want the outlet for a planer on the ceiling, for example. My DC is next to my pole and my table saw, jointer and shaper are placed around that with short runs from the DC. I only have two ceiling DC runs to the planer and or RAS/SCMS and the pole supports that first up duct. The rest are on the floor, short and not in a walking area. Placing the big dust makers around the DC keeps runs short and efficiency up. There may be other need for outlets on the ceiling, an ambient DC for example or roving task lights. Plenty of lights directly over most machines like the table saw, I have 4 4' double fluorescents over mine and the outfeed table, placed so your head doesn't block the light. Good luck with the new shop.


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## woodnthings (Jan 24, 2009)

*How many motors? What size?*

http://www.engineeringtoolbox.com/electrical-motor-hp-amps-d_1455.html 

in general ...
1 HP motors on 120 V need 20 amps, 2 and 3 HP motors on 240 V need 20 amps double pole, 5 HP motors on 240 V need 30 amps, double pole. Wires and breakers must be sized accordingly back to the panel. 

Keep your lighting circuits separate from your tool circuits.

Put in "extra" for expansion and more tools. :thumbsup: 
For what it's worth I used an entire 100 amp panel for my shop, no empty slots remaining.  bill​


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## Steve Neul (Sep 2, 2011)

farmall said:


> Good morning folks. I just about have the outside of the wood shop completed and now it is time to start roughing in the electrical. I have about 35 circuits left on a 200 amp service, single phase (in the original part of my garage that I added on to). I am going to be working by myself with maybe another person occasionally. I am wondering how many circuits I need to drop and especially wondering about the 240 volt drops. My shop is 30' x 31 feet with a pole in the middle. I am not sure how many 240 volt drops I will need but I am thinking about putting one on the pole in the middle and 1 circuit on each 30 foot wall, with 2 recepts per circuit (6 total) How many amps should I expect to pull? about 15? Do the 240 machines hard wire or do they have plugs on the cable? Any advice would be greatly appreciated.


First, how far is your wood shop from the breaker box? If you are a substantial distance it would probably be better to have a sub-panel installed. As far as how many outlets, I would make a layout of how you want your equipment arranged and include a wish list for future equipment. Then I would wire with the appropriate wire and breaker for each application. If you can afford it, it's always better to pull a heaver wire then NEC standards and use the smaller breaker. The smaller breaker will help protect the equipment. 
When you figure your wire and breaker size, add everything you conceive being turned on at the same time together. You should stay within 80% of the breaker size. For example a 20 amp breaker with a 12 ga. wire you shouldn't load more than 16 amps on it. This is based on NEC standards and your local building codes may vary so you can get specifications where they issue building permits in your area.


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## cabinetman (Jul 5, 2007)

I would suggest that before you add a subpanel, or pull any wiring to DIY, to consult with a master electrician familiar with shop electrical experience and discuss your plan. It may save you time, money, and problems.









 







.


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## GeorgeC (Jul 30, 2008)

cabinetman said:


> I would suggest that before you add a subpanel, or pull any wiring to DIY, to consult with a master electrician familiar with shop electrical experience and discuss your plan. It may save you time, money, and problems.
> 
> 
> 
> ...


Oh yes. This suggestion makes a lot of sense.

Otherwise you are goiiung to have a hodge podge of suggestions from people who can only offer generic opinions because they do not know your speific situation.

George


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## johnnie52 (Feb 16, 2009)

Other than what Cabinetman already told you I will add only one thing.

As you plan things forget about running more than one 220 outlet per circuit. 220 works differently from 120 and the amp drop of two outlets may cause problems if more than one machine is running at a time.


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## GeorgeC (Jul 30, 2008)

"As you plan things forget about running more than one 220 outlet per circuit.* 220 works differently from 120* and the amp drop of two outlets may cause problems if more than one machine is running at a time."

Will you please explain this statement?

George
__________________


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## farmall (Jan 8, 2012)

Thanks for the comments/ suggestions. I am building this shop on the back of my 28 x 32 (2) car garage. The panel is on the front wall of the existing shop. So...i am looking at a max pull of about 70' plus drops. I have talked to my electrician friend and he couldn't really recommend what wire to use for the 240V, without knowing the amperage. He said that a 10-3 with ground would be okay up to 30 amps. The only reason i am thinking about doing (2) 240 volt recpeticles is for flexibility. i would not plan on running 2 machines at the same time... but you know how that goes. I really like the idea of the DC being at the pole with the heavy dust machines close by. That is not what I had planned but will now. I do plan on putting a duplex 110 volt, 20 amp recepticle every 8 feet or so around the perimeter. Probably 2 or 3 per circuit. For example, a 30 foot wall will have 5 recepticles on 2 different circuits as well as a 240 volt recpticle somewhere along that wall, just in case. Lighting is another animal that I have not tackled.


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## Steve Neul (Sep 2, 2011)

farmall said:


> Thanks for the comments/ suggestions. I am building this shop on the back of my 28 x 32 (2) car garage. The panel is on the front wall of the existing shop. So...i am looking at a max pull of about 70' plus drops. I have talked to my electrician friend and he couldn't really recommend what wire to use for the 240V, without knowing the amperage. He said that a 10-3 with ground would be okay up to 30 amps. The only reason i am thinking about doing (2) 240 volt recpeticles is for flexibility. i would not plan on running 2 machines at the same time... but you know how that goes. I really like the idea of the DC being at the pole with the heavy dust machines close by. That is not what I had planned but will now. I do plan on putting a duplex 110 volt, 20 amp recepticle every 8 feet or so around the perimeter. Probably 2 or 3 per circuit. For example, a 30 foot wall will have 5 recepticles on 2 different circuits as well as a 240 volt recpticle somewhere along that wall, just in case. Lighting is another animal that I have not tackled.


70' is why I asked how far you were from the main. I believe you will have trouble with power for an air compressor unless you plan to use a small portable unit. If you plan to use a compressor in the 3 to 5 hp range it would be better if you could locate it closer to breaker box and pipe the air to the shop. The rest of the equipment would probably work alright. Without knowing the amperage I couldn't tell either but it would work with the equipment I have.


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## woodnthings (Jan 24, 2009)

*Air Compressor location*



Steve Neul said:


> 70' is why I asked how far you were from the main. I believe you will have trouble with power for an air compressor unless you plan to use a small portable unit. If you plan to use a compressor in the 3 to 5 hp range it would be better if you could locate it closer to breaker box and pipe the air to the shop. The rest of the equipment would probably work alright. Without knowing the amperage I couldn't tell either but it would work with the equipment I have.


I agree with Steve, get the A/C unit as close to the panel as possible and... as far away from ear shot as possible if it's a oil less type. Mine is a 5 HP 3450 RPM and it's as loud as a jack hammer. I would like to put it in an isolation closet someday. The piston type units are far more quiet. :thumbsup:

One plan might be to locate a 100 AMP subpanel on the pole with a master ON/OFF breaker. Then your power tools can be located centrally with short runs to the panel using SJ rubber wire. http://www.awcwire.com/ProductSpec.aspx?id=Portable-Cord-SJ
I would plan on about 4 receptacles attached right on the panel with 240 V, 3 -20 Amps for 3 HP motors and 1 -30 AMP for a 5 HP table saw. That's what did next to my main panel. I also ran an overhead across the ceiling and dropped down the far wall with  3 more 20's and a 50 Amp for a welder. 
You really need to layout your machines on paper or with card board box mockups in the space and get a feel for where there should go. I used thinwall conduit so I can easily change or add to the circuits. John Deere guy here...  bill


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## WillemJM (Aug 18, 2011)

Due to career moves, I have done this three times now, hopefully I'm done. Best is to lay out your shop, exactly where everything goes then consider where the outlets and lights have to be. This last time my outlets are in the walls close to my machines and where machines are not close to a wall, I have outlets in the ceiling. Previous shop, these were in the floor, which worked much better.


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## jigs-n-fixtures (Apr 28, 2012)

This is entirely dependent on the equipment you want to run. 

Layout your dream shop, and make enough outlets for that plus a few. 

I'm a big fan of installing 220-volt, 30-amp twist-lok receptacles in the ceiling on about a ten foot grid. At least install the boxes now with a foot or so of slack in each box for make up in the future. 

I also recommend parallel runs of 110 receptacles down the walls with boxes on opposite sides of the studs. This gives you the capacity to run a shop vac and a sawdust producer such as a portable planer at the same time without voltage drop. 

I also recommend wiring the outlets through a contactor with a key lock. This keeps the grand kids &other visitors from running your tools. It also prevents accidental restarts after power failures.

Sent from my iPhone using Wood Forum


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## johnnie52 (Feb 16, 2009)

GeorgeC said:


> "As you plan things forget about running more than one 220 outlet per circuit.* 220 works differently from 120* and the amp drop of two outlets may cause problems if more than one machine is running at a time."
> 
> Will you please explain this statement?
> 
> ...


All I meant was that 240 circuits have two "_HOT_" lines of 120 each, a neutral line and an earth ground. They can carry much larger amp loads, but if two or more machines are running at the same time on one circuit, say a dust collector and table saw, that have the same amp ratings it can cause problems. Whereas, those same two machines running of separate circuits will function perfectly all day long.

Having wired several manufacturing shops for up to 440 volts, one thing I learned early on was to never put more than one outlet on any circuit over 120 volts. Around here its not only a good idea, but part of the electrical codes.


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## farmall (Jan 8, 2012)

I am wondering if I might need 10/2 with ground or 10/3 with ground. Do you all know if any of the 240 volt machines require 4 wires or just 3?


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## Steve Neul (Sep 2, 2011)

farmall said:


> I am wondering if I might need 10/2 with ground or 10/3 with ground. Do you all know if any of the 240 volt machines require 4 wires or just 3?


Most of the box stores sell books on electrical wiring for under 20 bucks. I think it would be helpful to you to get one of these books to understand basic wiring. It will give you wire to breaker sizes which is within NEC codes. 

To answer your question 10/2 with ground is for 110V. You would have one black wire for the power, one white wire for the neutral and the bare wire for a fault ground. 10/3 with ground is for 220V. It would have one black wire for 110V power, one red wire for 110V power, one white wire for neutral and the bare wire for the fault ground. The two 110V wires make the 220V. The fault ground wire is a dedicated ground wire so in the event the machine would malfunction and the body of the machine would become hot the wire would carry the power safely to the ground. Electricity will follow the easiest route to the ground and it would rather go through the copper wire than a person. 

Now on woodworking equipment, many machines are not wired for the fault ground. Some are double insulated and the fault ground isn't really needed. They just have a typical 220V household plug like what is found on air conditioner units. On these you can leave them like they are and not use the fault ground or you can install a new cord for the machine which uses 4 wires. On the fault ground you can just attach the bare wire to the body of the machine. Personally nearly getting electrocuted on one of these machines I like it. One time I was working bent over with a old skill saw with a metal body and my back was hurting so I reached over and grabbed the fence rail on a unisaw to stand up. I soon found myself having to tell myself over and over to let go. Apparently I was getting 110V in each hand.


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## farmall (Jan 8, 2012)

Thanks for the info Steve. I am not sure that I can agree with the 10/2 not being used for 240 volts. I am a floor sander by trade and my 240 volt sander runs on 10/2 with ground. the black and white each have 120 volts and then there is the ground. It sounds like the woodworking machines might be the same. I think a 10/2 will allow 30 amps on 240 volts


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## Steve Neul (Sep 2, 2011)

farmall said:


> Thanks for the info Steve. I am not sure that I can agree with the 10/2 not being used for 240 volts. I am a floor sander by trade and my 240 volt sander runs on 10/2 with ground. the black and white each have 120 volts and then there is the ground. It sounds like the woodworking machines might be the same. I think a 10/2 will allow 30 amps on 240 volts


Technically 10/2 wire could be made to run 240 volts but the advise I'm trying to give you should pass your local building codes. I don't think using the fault ground as a neutral would pass a building code anywhere. As far as running 30 amps you should not run more than 24 amps on a constant basis on a 30 amp circuit.

To start over I think if it were me I would hard wire the shop with 120V outlets and skip the 220V outlets. Then after the walls were sheetrocked and you had the machinery arranged like you want it, then I would run the 220V circuits externally through conduit. That way if you rearranged the shop you could just demo the wire and move it somewhere else.


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## GeorgeC (Jul 30, 2008)

johnnie52 said:


> All I meant was that 240 circuits have two "_HOT_" lines of 120 each, a neutral line and an earth ground. They can carry much larger amp loads, but if two or more machines are running at the same time on one circuit, say a dust collector and table saw, that have the same amp ratings it can cause problems. Whereas, those same two machines running of separate circuits will function perfectly all day long.
> 
> Having wired several manufacturing shops for up to 440 volts, one thing I learned early on was to never put more than one outlet on any circuit over 120 volts. Around here its not only a good idea, but part of the electrical codes.


I agree that only one machine on one circuit is best. However, still do not understand your statement on the problems of two machines. That should not happen unless you are running those machines in series instead of parallel. 

George


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## Shop Dad (May 3, 2011)

Having recently wired my shop for 240v I can relay my experience and research but urge you to consult with an electrician to make sure what you do meets your needs and maintains safety. A woodworker friend of mine had wired his shop with 12/3 (20 Amps) as that's what he was told to use. However, when I looked into it I found that some appliances require both 220v and 110v, and subsequently have a four prong plug for the two hots, a neutral and a ground. My tools have three prong for two hots and a ground as they do not also require 110v. The receptacles for these machines have a hookup for two hots and one ground. The phase opposition of the two hots cancel each other out and any residual difference is carried by the ground. I asked my friend what he did with the neutral wire - he connected it to the ground making it completely redundant. Before installing any wire I confirmed with my electrician that 12/2 was appropriate for my application and in the last couple of months it's been working as expected.

I would have liked to install drop lines but couldn't figure out how to make it work within code so just put them on the walls. I like the idea of using the locking plugs for an extension cord. Might add one in the future.


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## Brink (Nov 22, 2010)

Steve Neul said:


> Technically 10/2 wire could be made to run 240 volts but the advise I'm trying to give you should pass your local building codes. I don't think using the fault ground as a neutral would pass a building code anywhere. As far as running 30 amps you should not run more than 24 amps on a constant basis on a 30 amp circuit.
> .


A 220v circuit doesn't use a neutral. Just two hot leads and a ground. The only time a neutral is used is like what ShopDad stated. For example, on an electric cloths dryer or range. The neutral, and thus a four prong plug, would be for a120v light bulb.


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## farmall (Jan 8, 2012)

Thanks for all of the info guys. I do have an electrician friend who is going to coach me through it. I would just get him to do it but he is really busy and has assured me I can do it. I did wire my house back years ago and have only had a few fires (jk).


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## Steve Neul (Sep 2, 2011)

Brink said:


> A 220v circuit doesn't use a neutral. Just two hot leads and a ground. The only time a neutral is used is like what ShopDad stated. For example, on an electric cloths dryer or range. The neutral, and thus a four prong plug, would be for a120v light bulb.


 We seem to have a confusion on terms. What I call a neutral is the white wire and the ground is the bare wire or fault ground.


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## Brink (Nov 22, 2010)

Steve Neul said:


> We seem to have a confusion on terms. What I call a neutral is the white wire and the ground is the bare wire or fault ground.


That is correct.


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