# Sub Panel for Garage Woodshop



## briankb (Oct 19, 2012)

I've converted one side of my two car garage into my woodshop. I also have a small detached "shop" that was converted to an office space that has it's own 60amp sub-panel from the main panel which has a 200amp main breaker.

The main breaker panel (photo below) has 200amp main and 5 (1+4) open breaker slots. The panel and breakers look old and perhaps should ALL be replaced. Obviously replacing the entire main panel is a major upgrade. Something I would hire a professional electrician to perform.

For now though I need to add a few circuits so I can use my woodshop tools. Last week I purchased a 2hp Rikon Dust system. And from what I've read and tried in my shop it needs it's own 20amp circuit. The garage outlets (2) are shared with the garage lights and laundry room outlets (2). So that circuit is being used by quite a few things. In the laundry room there is a small freezer. So I'm worried that trying to run my new 2hp dust system with any of my stationary tools (table saw, miter saw, planner, jointer, ect…) will just cause the breaker to trip.

My question is should I just add a few new breakers into the main panel or buy a small sub-panel to use just for the woodworking tools. If I go with sub-panel, What capacity should I make the sub-panel? I would appreciate any other suggestions or tips on this aspect of my garage woodshop.


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## JesseTutt (Aug 15, 2012)

I am in favor of sub-panels. They put the breaker that is most likely to trip closer to the device causing the trip. Therefore, I would suggest that you run a 220V 30-50 amp sub-panel. The wire has to be properly sized. I would size the wire for 50A even if you go with a smaller panel. Over sized wiring does not hurt anything, would support future upgrade, and would be better to handle a overload. Same with the panel. You could put a 100A sub-panel if you want.

Note: code usually imposes two requirements on sub-panels:
1. Use a sub-panel *without* a main breaker
2. Do not connect the common (white) bus bar with the ground (green or bare) bus bar. This should *only* be connected at the main panel. You may need to remove a screw on the sub-panel.

Almost of all of my outlets are "home runs" back to the panel. This means that there is only a single outlet connected to the wire and the wire runs directly back to the panel, or a junction box next to the panel. I usually run 10 gauge 3 wire + ground (red, black, white + green) which allows me to connect the outlet as 120V (ignore the red wire at each end - do not cut it off) or 220V (by using the red wire). This creates maximum flexibility. 10 gauge will allow the circuit to be 30A if needed and the breaker allows.


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## MJCD (Nov 28, 2011)

Jesse:

Great advice - I think your recommendation is on-the-mark. The sub-panel approach allows local expansion & flexibility. 
MJCD


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## NormG (Mar 5, 2010)

I might try that as well


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## TopamaxSurvivor (May 2, 2008)

Don't let any one tell you to change that panel. It is Cutler Hammer, one of the best ever installed in houses. The only thing comparable is a Square D QO style. They will cost you $400 today where a residential grade panel will be in the neighborhood of 100 to 125. I would just put in a few more circuits unless you do not have enough spaces. But, that is just me. Been doing this for about 45 years. I have ripped out a lot of the cheaper garbage. The only brands I will install is Sq D or CH. Anyone who wants to burn themselves out can get someone else to install the other brands.


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## toolie (Mar 16, 2011)

+1 on jesse's suggestions. 6 gauge wire needs a 60A breaker. while i run my whole shop on a 30A sub panel, tapping a 60A sub panel from your main panel can also provide for additional home wiring slots should the need arise.


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## briankb (Oct 19, 2012)

*Wow, thanks for all the detailed advice.* And I'm really glad someone identified my panel. One of our local hardware store is closing (owner is retiring) and they have a lot of breakers at 50-60% off. Of course I need to know the type of panel.

Today after struggling with my old Craftsman contractor table saw I found a Rigid R4512. I read a lot of good reviews, most of them on this site. I was happy to read in the manual that it can be converted to 220v. I understand that its better on many levels to run your equipment at 220v. I wish my Rikon 2hp dust collector was convertible but according to their techs, the motor doesn't support it.

My next purchase will be a 6" jointer. I haven't decided on the brand but I would like to find one that can be converted between 110/220v. If I have more than one 220v tool, and only use 1 at a time. Can they share a breaker like normal 110v outlets do?


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## TopamaxSurvivor (May 2, 2008)

The brown handled CH are the only ones that will fit. The black ones are different for the residential grade panels. You can run a 20 amp 220 volt circuit and use it just like you describe. CH won't let you overload like some of the other brands will.


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## IsaacH (Aug 29, 2012)

Im with Topamax, don't change that panel!

If your concerned about the breakers being old, its a helluva lot cheaper to replace the breakers than the entire panel. And its not a bad idea since unlike fuses breakers, especially frequently used or tripped breakers, DO GO BAD! Back in my wire twisting days, when responding to a frequently tripping breaker, I would insist that the customer pay the extra $10 or $20 in material for me to install a new breaker. I usually didnt have to charge any extra for the time to do the install since it takes just a few minutes. One time I responded to a call of an A/C unit tripping a breaker. Determining it was the A/C compressor I told them to call me when the A/C guy came and i would replace the breaker at the same time…wasn't even going to charge extra for the extra trip….they never called…well that was until the breaker burned up half their panel! They had the A/C replaced but the guy screwed up and created a large over current (somehow locked up the new compressor)....the breaker never tripped. The ended up paying me a few grand to replace the panel.


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## toolie (Mar 16, 2011)

*Can they share a breaker like normal 110v outlets do?*

i have that same issue. while my electrician friend noted that the code doesn't support the activity, provided the current draw isn't so great that it trips the breaker, it can be done. one 20A 220v circuit in my shop supports my 3 hp unisaw and my 1.5hp 50-850 dust collector. should i cause the amperage draw of the unisaw to increase by over feeding hardwoods, for example, the breaker will trip. but that would only be because the motor would then be drawing closer to it's 16A 220v FLA in conjunction with the DC's 6A 220v FLA (16+6=22, >20a breaker, breaker trips).

if that happens, just add another 220v circuit to the panel, assuming spaces and capacity are available.


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## mojapitt (Dec 31, 2011)

The more circuits the better. Sharing circuits with other parts of the house causes outages. Most homes are wired that way simply because it's cheaper. If you can afford it, also try to use heavier gauge wire than minimum require ments. Less line loss and headache. I wired my house. Nothing less than 12 gauge. Check your codes. It's starting to be more common that garage wiring be in conduit (new requirement in a local jurisdiction).


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## IsaacH (Aug 29, 2012)

Im partially with Monte. Always 20A circuits with #12AWG wire AND *20A outlets *You can however hit a point where you have more circuits than practical or needed. Heres how I had it divided out in my old shop from my bachelor days.

3 general pourpose circuits with 4 outlets each. one of those circuits also had the lights.
Dedicated circuit for dust collector.
1 shared circuit for all large machine tools. (2 tablesaws, planer, bandsaw, lathe, miter saw, drill press.)

*a circuit just for the dust collector and only 1 circuit for all of those machines??? *....yep….cant really use any two of those at the same time, therefor they were never running at the same time. However the dust collector ran with all of them.


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## TopamaxSurvivor (May 2, 2008)

*Can they share a breaker like normal 110v outlets do?*

*the code doesn't support the activity*

As long as the equipment is plug and cord connected, where does the code preclude it?


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## toolie (Mar 16, 2011)

topamaxsurvivor ….... you neglected to include "while my electrician friend noted that" before *the code doesn't support the activity* . just passing along what my licensed electrician friend noted. i am not an electrician and cannot quote chapter and verse of the NEC. as i also noted, multiple outlets on a 220v circuit will work. but there are also a lot of things that can be done with electricity that will work which may still not be sanctioned by either the NEC or a local requirement.


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## briankb (Oct 19, 2012)

I just did a quick layout on the existing main panel and I barely have enough room for my tools. I plan to upgrade my guest bathroom with a whirlpool and that requires a 20a by itself. Leaving one for dust coll., one for stationary tools, and one 240v. I also plan to do some welding at sometime in the future. And unless I share the 240v with the table saw, jointer, and welder (one at a time). That seems like I'm just asking for trouble.

I think a sub-panel is the way to go so I can have dedicated breakers for each stationary machine and one for each large tool like the TS, Jointer, and a welder.

If you add the welder requirements, should I setup a 50amp or 100amp sub-panel? Will any of this overload my main panel if the oven, dryer, and the other 240v circuits on the main are in use?


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## TopamaxSurvivor (May 2, 2008)

Do you have electric heat? How big is the house?


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## briankb (Oct 19, 2012)

Yes. If you look at the main panel the circuits are as follows:

*Left (Odd 1-29)*
- Range / Oven (240v 30a)
- Dryer (240v 30a)
- Well / Pump (240v 20a)
- Washing Machine (15a)
- Kitchen (20a)
- Living Room (15a)
- Garage & Laundry Room (15a)
- Bed Room - Back (15a)
- Bed Room - Middle/Office (15a)
- Detached Office (240v 60a)

*Right (even 2-30)*
- Furnace / AC Heat Coils (240v 30a)
- Air Conditioner (240v 30a)
- Hot Water Heater (240v 30a)
- Refrigerator (15a)
- Dishwasher (15a)
- Dining Room (15a)
- Bathrooms (15a)
- Master Bedroom (15a)

3 bedroom, 2 bath not sure about size in sq ft but it's pretty standard size.


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## briankb (Oct 19, 2012)

Here is the list of circuits I would like for the garage shop:
- Table Saw (240v 20a)
- Jointer (240v 20a)
- Welder (240v 50a)
- Wall Outlets (20a)
- Stationary Tools (20a)
- Air Compressor (20a)
- Workbench Powerstrip (15a)
- 2hp Dust Collector (20a)
- CNC Router (20a)

I'm not sure if it's possible but if the sub-panel is two phase I would like to keep the dust collection on one phase (A) and the stationary and other tools that may be in use at the same time on the other (B).


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## TopamaxSurvivor (May 2, 2008)

You might run this past the authority having jurisdiction and see if they will accept it. If you were my customer, I would recommend putting in another 200 amp panel for the sub and feeding it with 80 to 100 amps. If you ever need to up grade to 320 or 400 amp service, you will have the the panels in place. The 200 will not cost much more than a 100 sub panel.


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## toolie (Mar 16, 2011)

*I'm not sure if it's possible but if the sub-panel is two phase *

what is "two phase"?


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## AnsonW (Dec 1, 2011)

Sounds like a fun wiring day. If you decide to do it yourself and need some help/support I live here in Fort White. Just check the codes and get the permits (if necessary) and I'll help however I can. I've done more wiring than anyone else who isn't a electrician not that it's all that difficult anyway, just keep track of which wire is which and its relatively simple.


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## briankb (Oct 19, 2012)

Cool thanks Anson! After all of this discussion and figuring out the expense of it all. I'm going to convert my detached garage which was finished about 4 years ago for a multi-room office, BACK into a open space wood shop. It has a 60amp panel and should be enough until I get more than two 240v stationary tools. Right now all I have is a table saw that can be converted to 240.


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