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Help with shop electrical layout

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Forum topic by Hoakie posted 1041 days ago 3781 views 0 times favorited 30 replies Add to Favorites Watch
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Hoakie

306 posts in 2641 days


1041 days ago

Topic tags/keywords: question

Earlier this year we had some work done on our deck and added some lighting that required us to run electric outside. Since our main distribution box was buried in the finished portion of the basement, I decided to have them run a 40 amp sub-panel into my workshop. I didn’t go over the top because I am not planning on staying in this house for ever and the price was right. The electrician left 4×20Amp breakers for me to use to wire up the shop so the question I pose to you is how best to distribute the power around the shop.

Just a couple of notes thing to consider
  • I already have all the shop lighting and some 15A outlets drops on the shop ceiling above the workbench that I can plug in routers, circular saws, etc. so I don’t have to worry about that.
  • Aside from low draw lighting and fan outside, this sub panel will only need to service the shop area.
  • There walls/ceiling are currently only framed in so I don’t have to worry about running wire
  • I have a one man shop that rarely has more than one piece of heavy equipment running simultaneously except for the DC.
  • All of my tools are currently wired for 120. I don’t plan on installing any 240 outlets since I don’t think I’ll need it in this shop
  • I think I would like to dedicate a circuit to the dust collector since it is on every time I fire up a major piece of equipment
  • There are several places where I would like to run a double junction box so I have different circuits in close proximity (designated by two red circles close together)

So my questions for you guys are:

  1. Would you use all 4 circuits or would you do fewer (still leaves plenty of room in the box they installed)
  2. Do you see any benefit to alternating/staggering the circuits/outlets as much as possible? For example: put the band saw on Circuit 1, sanding stations on Circuit 2, router table/RAS on Circuit 2/3 double gang, and isolate DC on #4, etc to or is that overkill.
  3. What other things should I consider?

LEGEND:

SUB PANEL is between band saw and table saw
RED DOTS = proposed outlet locations

-- John H. [To invent, you need a good imagination and a pile of junk. ~Edison]


30 replies so far

View Manitario's profile

Manitario

2268 posts in 1489 days


#1 posted 1041 days ago

In reality, you’re only going to be using one tool at a time, so running a bunch of different circuits for different tools will just waste wire. As well, if you are planning to use a few different tools at once, depending on the amp draw of your DC, you’ll be close to maxing out the capacity of your sub-panel; eg. my TS is a 1.75HP which draws 17 amps; my DC was a standard 1.5 HP canister which drew 15 amps; leaves only 8 amps “free”.

-- Sometimes the creative process requires foul language. -- Charles Neil

View TopamaxSurvivor's profile

TopamaxSurvivor

14624 posts in 2281 days


#2 posted 1041 days ago

Just dedicate the DC, then alternate the outlets. 2 circuits should be plenty for you under those circumstances.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Hoakie's profile

Hoakie

306 posts in 2641 days


#3 posted 1041 days ago

Thanks guys. I was having similar thoughts that you all brought up but now they are at validated

  • I will dedicate the DC
  • Run alternating circuits. Alternatively, I think I may double gang each spot, with one circuit/outlet pair because the cost to do it now is cheap compared later (time/effort) *There will be at least one outlet within easy reaching distance of every major tool
  • Even though this is the basement I could eventually add more outlets in the garage which starts behind the drill press

-- John H. [To invent, you need a good imagination and a pile of junk. ~Edison]

View HerbC's profile

HerbC

1155 posts in 1465 days


#4 posted 1041 days ago

Please note that the National Electrical Code requires GFI protection for outlets located in garages.

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

View HorizontalMike's profile

HorizontalMike

6915 posts in 1520 days


#5 posted 1041 days ago

Herb,
As best that I can find, NOT all garages have to have GFCI protection (though it is a good idea).

As I understand, GFCI is not required “IF” the garage is stand alone with a single electrical power source, has no water line, or other electrical conducting connection to the house’s main power supply (that could include telephone lines, security wires for cameras, metal roofing, and cable TV).

If I am incorrect on this then please point me to the appropriate code(s). And what about older buildings and homes?

-- HorizontalMike -- "Woodpeckers understand..."

View Hoakie's profile

Hoakie

306 posts in 2641 days


#6 posted 1041 days ago

I do plan on GFCI protection on each series of outlets

-- John H. [To invent, you need a good imagination and a pile of junk. ~Edison]

View Belg1960's profile

Belg1960

786 posts in 1671 days


#7 posted 1041 days ago

PLz, use boxes that are large enough for the 12/3 rx to go in and out plus don’t forget that the devices need space as well. Are you planning on sheetrocking the walls after the electric is in? If you need help calculating the size of the box just ask. In your sitiuation you’ll need to allow for 11 #12 conductors in any box with two wires and 2 recp, I would oversize it at least by one. I would use a 4” sqaure by 2 1/8 deep. http://www.munroelectric.com/silvereclipse/index.jsp?path=product&part=549&ds=dept&process=search&ID=,Boxes...Covers,Metal.Boxes...Covers,Misc..Boxes...Accessories,Box.Accessories Also do yourself a favor and add a stand-off support on them so when you plug things in and out the box won’t flex.
http://www.munroelectric.com/silvereclipse/index.jsp?path=product&part=549&ds=dept&process=search&ID=,Boxes...Covers,Metal.Boxes...Covers,Misc..Boxes...Accessories,Box.Accessories

-- ***Pat*** Rookie woodworker looking for an education!!!

View Hoakie's profile

Hoakie

306 posts in 2641 days


#8 posted 1041 days ago

@Bleg

Are you saying to use 12/3 to carry two different circuits to the dual junction boxes? I guess I hadn’t considered that I figured I just run each on their own 12/2.

I guess I’m not sure I understand what you are trying to get at by saying allow for “11 #12 conductors in any box with two wires and 2 recp” are you saying there should be 11 places for the romex to come in the back?

I like the idea of the standoff but can you repost the link to the box? you duplicated the standoff link

Thanks

-- John H. [To invent, you need a good imagination and a pile of junk. ~Edison]

View TopamaxSurvivor's profile

TopamaxSurvivor

14624 posts in 2281 days


#9 posted 1041 days ago

You cannot use a common neutral; ie, 12/3 on 2 GFCI protected circuits. You will need 12/2 on each circuit or 12/2/2 (2 sets of 12/2 with a ground). Also, the code now requires all 120 volt circuits to have its own neutral or use a multi-pole breaker if they share a neutral; ie, 2 pole 20 in this case using 2 120 volt circuits on 12/3.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Hoakie's profile

Hoakie

306 posts in 2641 days


#10 posted 1041 days ago

Thanks Topamax…that is what I figured and was/am planning on doing. I have a bunch of 12/2 wiring already so that isn’t an issue.

Also forgot answer one of Belg’s question…. I am planning on putting up sheeting when electric is in. I was probably going to use OSB instead of sheet rock because I think it would be too easy to accidentally punch holes in the drywall.

-- John H. [To invent, you need a good imagination and a pile of junk. ~Edison]

View HerbC's profile

HerbC

1155 posts in 1465 days


#11 posted 1041 days ago

HorizontalMike,

Sorry, I was speaking in generalizations, I believe you’re correct in the specific exceptions you noted.

On the other hand, I believe that new circuits in an existing attached garage would require gfi…

All these changes, that’s why I got out of the electrical trade and into something really stable (computer networking and support)...

Herb

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

View TopamaxSurvivor's profile

TopamaxSurvivor

14624 posts in 2281 days


#12 posted 1040 days ago

Herb, the NEC only changes every 3 years, not every day like networking ;-))

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View HorizontalMike's profile

HorizontalMike

6915 posts in 1520 days


#13 posted 1040 days ago

Topa,
Yabut, to us old geezers it seems like every 3 months!

;-)

-- HorizontalMike -- "Woodpeckers understand..."

View Belg1960's profile

Belg1960

786 posts in 1671 days


#14 posted 1040 days ago

Yes, you can run 12/3 to the first box and have a GFI recp on each circuit within that box. This will be much cheaper than buying 2 GFI circuit breakers. You would then have to run 12/2 to each recp downstream of this first box. I would do it this way just in case you need to run 2 machine at the same time in the same small area. As per the code boxfill rules(how many wires you can have in each box) is calculated by adding together the number of wires, red white and black all grounds count as 1, every recp counts as 2, and I forget to add 1 counted for the clip holding the wires in place.
http://www.hardwareandtools.com/Hubbell-8240-Raco-4-Inch-Square-Steel-Box-2-1-8-Inch-Deep-6228613.html and then you need to use one of these but use the thickness of your wall covering http://www.ronshomeandhardware.com/8769-4-SQ-5-8-Box-Cover-p/881224.htm

-- ***Pat*** Rookie woodworker looking for an education!!!

View TopamaxSurvivor's profile

TopamaxSurvivor

14624 posts in 2281 days


#15 posted 1040 days ago

If you run 12/3 from the panel, you will have to use a double pole 20 amp breaker, You cannot have 2 individually protected circuits on the same neutral.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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