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PLanning 20 x 20 Garage Workshop

pharper

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Joined
Aug 17, 2015
Messages
138
Location
Atlanta, GA
Overview
My family recently purchased a new house located in the southeast. It does not belong to an HOA, so I will be able to finally build a decent wood working shop. There's a lot to do, since it is not insulated, cooled, well lit, or powered. I would like to share my plan in hopes that I can gain some wisdom from those of you who have done something similar.

Electrical
The currently has 150a main service and the breaker box is located in the garage. I would like to add 100a sub-panel next to the main panel, but don't know if this would meet code. I would never expect to exceed more than about 50a at any given time. Running my 5hp Jointer/Planer, a dust-collector, and a mini-split AC would be the most I'd ever run concurrently. I'm planning on getting a few quotes for the job once we get moved in later this month.

I'll also have to rough in a disconnect for the AC, but don't' know if I could do this myself. I plan to do most of the rough work myself. I plan to do at least 4 110v outlets on each side wall split between 2 x 20a circuits. I'll put the lights on their own dedicated circuit. I'll probably run about 3 additional 220v circuits for my big tools. I will be doing all of this with the drywall torn out to make things easier.

Heating and Cooling
The garage is currently not insulated, so I plan to tear out the drywall and install R13 bats on the two exterior walls. This will also give me a chance to rough in the electrical, install a window, and exterior door. I plan to replace the double garage door with an insulated Clopay door (R13) and spray cellulose in the attic space.

Once the garage is insulated and the drywall is back up, I'll install a Mr. Slim 9000btu mini-split heat-pump. I'd like to do some of the work myself to keep costs down, but I'm not sure how much I could do without voiding warranties. I've heard that many AC guys prefer electrical to be run by a qualified professional. Is 9000btu enough for 365 sq/ft? I've heard you want to slightly under size in the south to keep humidity down.

Lighting
My current garage workshop is short on light. I currently only have 2 x 4ft dual T8 fluorescent fixtures. I'm planning on at least 6 x ft T8 bypass LED's for the new space. I'll also add an exterior door with a window and an single-hung window. Will this be enough light? Should I place the lights on a single circuit or two?

Any thoughts or suggestions would be greatly appreciated. Is there anything I missed?

I've attached a few pictures to show the wall that attaches to the house, the exterior, and my tool locations.
 

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pattenp

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Joined
Jun 4, 2008
Messages
10,175
Location
Virginia - USA
Looks like you have a good plan. I have a wood shop the same size and all my tools are on mobile bases. I have a couple outlets in the ceiling to drop cords from if needed, but I put a longer cord on my table saw to plug into a wall outlet because a cord to the ceiling gets in the way when cutting larger pieces. Having two circuits for the lights is okay. I have one circuit and it has never been a problem. I do suggest that you break up the lighting on multiple switches. For the AC I use a 10000 BTU window unit and it cools my 380 sqft fine and the shop is insulated, so I believe 9000 BTU for your space should do. As you said you don't want an over sized unit because it will short cycle and not remove the humidity.

Edit: Forgot to say I have right at 90 lumens per sqft for lighting. I believe 100LU per sqft is a good target for a wood working space.


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pharper

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Aug 17, 2015
Messages
138
Location
Atlanta, GA
pattenp, thanks for the reply.

Can you separate the lights on two switches if they're on the same circuit? My electrical experience is to simple 110v outlet circuits and dedicated 220v. I've replaced a few switches, but never installed any new ones?
 

pattenp

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Joined
Jun 4, 2008
Messages
10,175
Location
Virginia - USA
pattenp, thanks for the reply.

Can you separate the lights on two switches if they're on the same circuit? My electrical experience is to simple 110v outlet circuits and dedicated 220v. I've replaced a few switches, but never installed any new ones?

Absolutely. You have one hot coming into box at two switches and each switch is serving a different set of lights.

Example:
144-0.jpg
 
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pharper

Well-known member
Joined
Aug 17, 2015
Messages
138
Location
Atlanta, GA
Any input regarding lighting? Will 6 x dual LED T8 fixtures be enough for 19x19 with 8.5ft ceilings?
 

pattenp

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Joined
Jun 4, 2008
Messages
10,175
Location
Virginia - USA
Any input regarding lighting? Will 6 x dual LED T8 fixtures be enough for 19x19 with 8.5ft ceilings?

What I'm seeing is 1900 to 2000 LU per lamp. So you are saying 12 4' LED lamps in 6 fixtures? That is 24,000 LU / 361 sqft is 66.48LU per sqft which is on the low side for me. I'd probably go with at least 8 two lamp fixtures. That will be around 88 LU per sqft if I got my numbers correct for the LED lamp output. Light level is such a personal opinion thing as to what's enough.

Edit: I see there are other LED lamps that output 2400LU per lamp. I'd still shoot for at least 75LU per sqft or better overall.
 
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