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Old 09-28-2008, 06:35 PM   #1
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Subpanel help?


Good afternoon everyone I am a woodworker as a hobby of mine and im tripping the breaker in my garage all the time. I want to add a subpanel to the garage for all my woodworking equipment. I went to Home Depot and they have an Indoor 60 or 70amp panel box. Which one is the best option I would like to add 4 outlets off this. What gauge wire do I need from my main to the subpanel and what gauge from the subpanel to the outlets. Thanks for your help everyone. Also what size breaker do I need to add the main, as well as what size breakers do I need in the subpanel 15 or 20's.

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Old 09-28-2008, 06:42 PM   #2
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Is the garage attached to the house?

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Old 09-28-2008, 06:59 PM   #3
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I am to scared to answer this question haha
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Old 09-28-2008, 07:10 PM   #4
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I am to scared to answer this question haha
Why? What's odd about it?
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Old 09-28-2008, 07:11 PM   #5
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I am to scared to answer this question haha

This question comes up every week, whats the problem?
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Old 09-28-2008, 07:13 PM   #6
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This question comes up every week, whats the problem?
Funny thing is it is so true.
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Old 09-28-2008, 07:48 PM   #7
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Subpanel help?


Look into a 100 amp panel. You can often buy them with a hand full of breakers included. Many times this would be much cheaper than a 60 or 70 amp panel. In a wood shop I would used #12 wire with 20 amp branch circuits. Now you need to answer Chris's question for him to assist you further. Is the garage attached or detached?
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Old 09-28-2008, 09:26 PM   #8
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Subpanel help?


Its attached to the house. Really this question is asked alot? Huh cool I must have come to the right place then. So 12 gauge is enough from the main to the sub I was told 6/3 gauge at home depot whats the difference? I dont think I need a 100amp panel thats way more then I need really, you dont think thats overkill. I saw that 60-70amp load box for 20 bucks I just need 4 outlets really. I dont want to have to spend more than I have too.
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Old 09-28-2008, 09:31 PM   #9
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Its attached to the house. Really this question is asked alot? Huh cool I must have come to the right place then. So 12 gauge is enough from the main to the sub I was told 6/3 gauge at home depot whats the difference? I dont think I need a 100amp panel thats way more then I need really, you dont think thats overkill. I saw that 60-70amp load box for 20 bucks I just need 4 outlets really. I dont want to have to spend more than I have too.

6/3 NM is only good for 55 amps, but its more than enough for your application, and the #12 gauge wire was for the receptacles, not the sub-panel feeder.
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Old 09-28-2008, 10:00 PM   #10
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Thank you Chris75 so do you think I should go with something else besides 6/3
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Old 09-28-2008, 11:07 PM   #11
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The suggestion of a 100 amp subpanel is great. You can usually get them with several breakers included for pretty cheap.

However, you don't need to feed the garage with a 100 amp breaker. The 100 amp disconnect at the subpanel still serves as a disconnect if you buy a panel with a disconnect, but the overcurrent device isn't needed since the breaker feeding the subpanel at the main acts as the overcurrent device. If you install a feed breaker in the main panel rated for less than 55 amps the 6/3 will be fine. You certainly don't need 100 amps for a garage wood shop...Trust me, I have half my house and my wood shop on a 60 amp subpanel.

Running a couple 20 amp circuits for your wood shop will make it easier to use your tools without tripping the circuit. I ran a 20 amp dedicated for my 110v air compressor, and that helped out quite a bit. Before that, I could never use any other tool when the compressor was running!
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Old 09-28-2008, 11:09 PM   #12
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Hello fellow woodworker!
I'm just starting out in woodworking and am setting up a small 12' x 15' shop in my basement. Like you, I am in the process of installing a sub panel in my shop. I've found the advice given by the electricians on this forum to be extremely helpful and I've learned a lot just by reading the posts. That and reading a few books on home wiring have made me feel quite comfortable in tackling this project. You can also get free online access to the 2005 NEC code at the National Fire Protection Association website. I've found that actually reading the code helps clear up many questions.

If the only things you'll be powering from your sub panel are your woodworking tools, and assuming you're a one man shop, then 55 to 60 amps should be sufficient (unless you're one of those woodworkers with a huge 5 hp tablesaw and big cyclone dust collector). The nice thing about 60 amps, is that you can use 6/3 with ground cable to feed your sub panel its power from your main panel. This handles much like the standard Romex-type NM cable most people are familiar with. If you don't yet understand terms like NM or 6/3, then be sure to read one or two books on home wiring first to give you the background you'll need. I like the Black & Decker "The Complete Guide to Home Wiring" found at most big box home improvement stores. A small book called "Wiring Simplified" by H.P. Richter et. al. was also very informative.

If you want to go more than 60 amps then you'll need to use larger feeder wires that will have to run through conduit. I decided to go with 4 AWG feeder wires to give me 80 amps because 1) I'm going to run several circuits not related to my shop from my sub panel and 2) my sub panel is only about 3 - 4 feet from my main service panel, so runing a 1 inch conduit is simple. The feeder wires are connected to a doube pole breaker of the appropriate amperage rating within your main service panel. You'll be running 2 hot wires from the breaker plus a "neutral" wire plus a grounding wire. The books and the experts here can tell you in detail how this is done. Just remember the golden rule that "the sub panel is never bonded!" These feeder wires go into your sub panel. You can use any type of panel as a sub panel as long as it's rated at or above the amps of the feeding breaker. Your sub panel can have a 100 amp main breaker, like mine does, or it can be a "lug" type sub panel with no main breaker. I definitely prefer having a main breaker in the sub panel to make it easy to turn off the power to the panel if needed (of course you can also just turn off the feeding breaker).

For woodworking tools, at your sub panel you'll want to run 12 AWG wire from 20 amp breakers for all your 120 volt outlets, which should be rated at 20 amps. You may want to wire up at least one 240 volt circuit (or more if more than one of your tools uses 240). This can be 12 AWG if you'll only be using a 20 amp 240 volt outlet. If you think you might be needing a 30 amp 240 v outlet in the future, use 10 AWG wire to wire it. You can always put a 20 amp breaker and 20 amp outlet on it now and it will be easy to change to a 30 amp breaker and outlet should the need arise in the future. Run a separate circuit for you dust collector. Also run a separate circuit for your overhead air cleaner if you have one. That way they won't be competing for amps on the same circuit with your power tools. Keep your lights on a separate circuit so they'll stay on if you pop a breaker with your tools.

Anyway, I've rambled on enough and I'm still a newbie, trying to learn from all the experts here. Good luck.
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Old 09-29-2008, 12:47 AM   #13
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Subpanel help?


Hey WoodWorkerDave Thanks very much buddy! I kinda like it when people ramble. That way I get the whole picture of what is needed. Yeah your right my compressor is sucking to much juice and when something else is on even my overhead light it pops the breaker. I sware a total idiot wired this garage but I guess when your using a lot of power tools its way to much.

Ok so let me see if I got this correct. A 60amp breaker would be ok and I can use any load panel box I want? I bought the black and decker book you recommended and it says I need a 60amp in the main then run the correct gauge wire to the sub. Where I have 3 20amp breakers is that right or can I use 4 15amp breakers because I want 4 outlets if possible.
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Old 09-29-2008, 02:07 AM   #14
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Subpanel help?


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Originally Posted by Killertea08 View Post
Hey WoodWorkerDave Thanks very much buddy! I kinda like it when people ramble. That way I get the whole picture of what is needed. Yeah your right my compressor is sucking to much juice and when something else is on even my overhead light it pops the breaker. I sware a total idiot wired this garage but I guess when your using a lot of power tools its way to much.

Ok so let me see if I got this correct. A 60amp breaker would be ok and I can use any load panel box I want? I bought the black and decker book you recommended and it says I need a 60amp in the main then run the correct gauge wire to the sub. Where I have 3 20amp breakers is that right or can I use 4 15amp breakers because I want 4 outlets if possible.
HI
Most of the time you wire more than one outlet to a circuit, however this is not required, and it may be helpful to run a dedicated outlet for some reasons, like a dedicated outlet for the compressor.

I would use 20A breakers, 20A outlets, which will require 12 gage wire. You can put as many breakers in the sub panel as you want, and they can add up to any number. You will be limited by the breaker (and corresponding wire gage) that is installed in your main panel. i.e. 50A breaker with 6gage wire. The breakers in your sub panel can add up to 200A, but you will never be able to draw too much because the breaker in your main panel will trip if you actually did draw too high of a load.

One thing that can be very useful in determining what you actually need is to get a Kill-A-Watt meter. They have them at Harbor Freight for about $30. With this meter, you can plug in any 120v appliance / tool and see how many amps it is actually using. This can help you with capacity planning.

Keep in mind that all wiring projects like this require a permit in almost all parts of the US. The inspection that the city performs is a good safety precaution especially for someone that is new to wiring a project like this.

Good Luck
Jamie
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Old 09-29-2008, 08:03 AM   #15
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Jamie has some great advice. When reading on the woodworking forums, I've found that many woodworkers do some variation of the following setup if they have one or more tools running on 240 volts -

1) 20 Amp breaker with 12 AWG wire feeding several outlets on one wall(s).
2) 20 Amp breaker with 12 AWG wire feeding several outlets on a different wall(s). Sometimes they will bring two different circuits to one wall and alternate outlets, so no two adjacent outlets are on the same circuit. This is handy if all your tools reside along one wall, the idea being that you plug any two tools you might be running at the same time into different circuits.
3) 20 Amp breaker with 12 AWG wire feeding a single outlet dedicated to your dust collector
4) 20 Amp breaker with 12 AWG wire feeding single outlet dedicated to your air compressor.
5) 20 Amp breaker with 12 AWG wire feeding single outlet for your air cleaner
6) 20 Amp dual pole breaker with 10 AWG wire feeding single 240 volt L6-20R receptacle.
7) (optional) 20 Amp dual-pole breaker with 10 AWG wire feeding single 240 volt L6-20R receptacle on a different wall.
8) 15 Amp breaker(s) with 12 or 14 AWG wire feeding overhead lights.

A lot has to do with your individual shop layout and equipment so be creative in your planning. You may not need a first or second 240 volt outlet if you don't have any 240 volt tools (although it's probably easier to wire one now just in case you acquire such a tool). You might need a 30 Amp breaker and L6-30R receptacle in the future if you acquire a tool that draws more than 20 amps. By using 10 AWG wire now for your 240 volt circuit(s), it's easy to upgrade. If you never anticipate needing 30 Amp outlets, you can wire your 240 volt circuit(s) with 12 AWG.

As you can see, a well-equipped shop might require 10 or more slots in your sub panel. Make sure you buy a panel with enough. I bought a panel with 20 slots. Plan not only for your current power needs, but where you might want to place your equipment in the future. Also, you can never have too many overhead lights.

Dave


Last edited by WoodworkerDave; 09-29-2008 at 08:08 AM.
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