Wiring for the workshop

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Forum topic by skeemer posted 01-05-2012 03:41 PM 2698 views 1 time favorited 26 replies Add to Favorites Watch
View skeemer's profile


95 posts in 2603 days

01-05-2012 03:41 PM

Hi all

My wife and I bought our first house this past summer and although there is no garage, there is a detached shed in the backyard that is quite large (large enough to fit a sedan in tightly, I would guess 20×15 or so). This will be my workshop (and for now, the garage for the lawn tractor and snowblower as well). Unfortunately, it is not wired for electricity and thus I am currently running an extension cord back to the house for power.

A neighbor of mine is a superintendent for an electrician outfit and will be bringing home a ditch witch soon to run power out to his own shed and offered to help me do mine as well.

I plan to install 5 +/- 1 outlets (2 on either wall and 1 on a side wall), as well as overhead lighting and a front door light (shed has a door and a sliding garage door). My only corded tools currently are a RO palm sander, my shop vac, and my new JET JWTS-10JF table saw, which is a 1.5 hp and reads as a 115/230-Volt 1 Phase motor. My near term tool acquisitions are a router and maybe to build a drum sander, and in the long term probably a joiner, planer, and dust collection. But for the next few years I cannot afford to add the joiner/planer/DC.

My questions are:

1) Should I run 240v out in case I need it in the future? I don’t really know how this works or what power level dictates what voltage.

2) Should I add a subpanel and breakers in the shed? My neighbor had recommended this so I wouldn’t have to go back in the house if I trip a breaker, but how often am I likely to trip a breaker? Will my TS trip breakers if I’m getting into dense wood?

3) Any other suggestions about wiring/power needs?

I expect I will be a part time woodworker so I don’t see myself upgrading to a cabinet saw anytime soon, at least not in the next 10 years.


26 replies so far

View kizerpea's profile


775 posts in 2606 days

#1 posted 01-05-2012 03:57 PM

I,d do at least 220 volts 50amp max load with a breaker box in the shop..this protects the shop an the house. 15×20 at least 5 wall plugs on each wall. sounds like a lot of plugs but it cuts down the need for dropcords( safety first).my shop they are 3ft apart so i have lots of them goodluck


View mikema's profile


180 posts in 2825 days

#2 posted 01-05-2012 04:19 PM

+1 on the 220 with a sub-panel in the shop. This will make sure you have all the 110 you need, plus this will open up the opportunity to purchase machines that require 220. Since each 220 outlet needs its own circuit, you will have the breaker box right there to set it up.

-- Mike ---- Visit my woodworking blog:

View pmayer's profile


1032 posts in 3304 days

#3 posted 01-05-2012 04:23 PM

1) Should I run 240v out in case I need it in the future? I don’t really know how this works or what power level dictates what voltage.

Yes. 240 for sure. Easy enough to do.

2) Should I add a subpanel and breakers in the shed? My neighbor had recommended this so I wouldn’t have to go back in the house if I trip a breaker, but how often am I likely to trip a breaker? Will my TS trip breakers if I’m getting into dense wood?

Yes, for sure add this. It is possible that your table saw could trip breakers if it is underpowered or the circuit is not adequately sized. It it is underpowered, use a thin kerf blade, make sure it’s sharp, and use a slow feed rate.

3) Any other suggestions about wiring/power needs?

- I would put an 20amp 120V outlet on every other stud.
-Run a separate 15 amp circuit for lighting, and put a lot of outlets in the ceiling for this (or direct wired lights, whatever your preference)
- Add dedicated circuits for compressor, dust collector, table saw, planer. Typically these should be 20amp for 120V tools.
- put an outlet or two on the outside of the shop. you might like the option of plugging in a belt sander or planer out there if you are doing a prolonged messy operation on a nice day. Yeah, you could always run an extension cord, but it is not as cool as having an outlet out there.

-- PaulMayer,

View Sawkerf's profile


1730 posts in 3307 days

#4 posted 01-05-2012 04:40 PM

+2 on the subpanel. Since he has offered, take your neighbor up on helping you size your setup. You’ll never get a better chance to do it right for less money. – lol

If this were my project, I would place at least two conduits. One for your feed to the shop with a spare conduit for future changes. Conduit is inexpensive and you’ll never have a better opportunity.

Finally, I would re-think the priority of a dust collector. IMO, dust collection is part of the “backbone” of a shop and should be part of the planning from the get go.

-- Adversity doesn't build reveals it.

View TheBirdMan's profile


21 posts in 2643 days

#5 posted 01-05-2012 05:10 PM

No one ever complained that they had too much power capacity in their workshop so I would ask your neighbor to help you put in the largest sub panel you can run. Also make sure you install at least two 120V outlets on the outside of the shop.

I agree with Sawkerf about dust collection. Wood dust is in the top 10 carcinogen list. Not only do you want to think about a dust collector, but you also want to look at an Ambient Air Cleaner to clean the air you breath while in the woodshop. Most dust collectors do a marginal job of collecting dust from the saw and the rest goes into the air. Using your lungs as your Ambient Air Cleaner is not your best option.

-- -- Pat, Colorado;

View skeemer's profile


95 posts in 2603 days

#6 posted 01-05-2012 07:18 PM

Thank you for all the suggestions everyone. 240v it is!

As far as dust collection goes, I would like to add it but I am on a pretty limited budget. It’s just not in the budget right now, or I wouldn’t be able to buy any wood either! But I plan to use a respirator until i eventually get a DC.

View richgreer's profile


4541 posts in 3313 days

#7 posted 01-05-2012 07:35 PM

I’ll raise the cautionary note. You hinted that this may be a temporary setup. While 20×15 is adequate for a very basic shop, it is still on the small side. I’ve found that 17×22 is not adequate for my needs.

220 volts and a sub panel costs money. I suggest you think about that extra cost in light of your intentions for the future. If you are committed to this space for the long term, go for it. If not, think about it.

You can do okay with just two 110 volt lines. I advise 2 lines as a minimum because when using 2 tools at the same time (table saw and dust collector) it’s best to have each tool on a separate circuit. I advise that each line be a 20 amp line.

As an FYI, I am a very active woodworker who has been doing this for quite a while. I have not installed 220 into my shop. I have one 15 amp circuit and one 20 amp circuit and that works great for me.

To answer your question – Yes, a table saw can trip a breaker. It will happen when your saw binds up due to internal stress in the wood. It can happen in virtually any wood, but, at least for me, this is a rare event. I don’t think I trip a breaker more than once every 6 months. I would not pay much to avoid an occasional trip into the house to reset a breaker.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View NBeener's profile


4816 posts in 3413 days

#8 posted 01-05-2012 07:37 PM

Rich (and others):

I plug my table saw into a breaker-protected “power strip.” If it trips, I reset it AT the power strip. It also serves to provide six outlets, which … works for me, since … I almost NEVER run more than one tool, at a time.

[DC is on its own circuit, in my case]

-- -- Neil

View Dallas's profile


3599 posts in 2726 days

#9 posted 01-05-2012 08:39 PM

I would be very cautious about anything to do with electrical work if I were you.
There are a few reasons for this.
No. 1.. If the shed catches fire and it’s caused by an electrical problem (or could have possibly, maybe, kinda been), your home owners insurance ain’t gonna want to pay.
No. 2.. You aren’t an electrician and although many municipalities allow you to do your own work as a home owner, you really need to know what you are doing before you decide to set your system up. As a detached structure, most places require a sub panel.
Be certain that your main panel in the house can handle the load of the extra circuits. I would make sure that you can get at least 50a per leg of circuit from your 200a main coming into the house.

If all else fails, bite the bullet and bring in a new service and meter. The transformer from your power pole is rated at least 800a and it’s not that expensive to run a new service.

Buy yourself a PAL Publications “Electrical Pal” soft cover book. (order at 800.355.8816) and read it, learn about it and don’t play with your life or thoe lives of the ones you love.

Good Luck, I’m off the soap box now.


-- Improvise.... Adapt...... Overcome!

View Manitario's profile


2704 posts in 3122 days

#10 posted 01-05-2012 09:03 PM

As others have commented, I strongly encourage you to put in a sub-panel. This allows you the flexibility to expand your power needs as your tool collection grows (and if you’re like most of us here on LJ’s, grow it will). I’d make all the recepticles in your shed 20 amps; you won’t blow the breaker if you get a jointer or a planer. My sub-panel in my garage is 100amps, but I run a 22amp DC and a 20 amp heater most of the time I’m out there. Unless you’ve installed sub-panels before, get someone to do this for you. Knowing the proper elec. codes and properly and safely installing it is a must.

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

View Gregn's profile


1642 posts in 3222 days

#11 posted 01-06-2012 03:56 AM

Rich brings up a good cautionary point. With that said plan for unforeseen needs, while you may not need much now that may change in the future.
Having just wired my detached shop a 12’x30’ shed.
First I had to check the main to see if I could safely add another sub panel for the shop. I was able to add another 100 amp breaker to the main for the shop. I then ran my main power lines underground to a 100 amp sub panel in the shop. From there I added 6 240v 30 amp circuits and 12 120v 20 amp circuits for different needs the lights on there own circuit etc.
Once your sub panel is in you should be able to meet your current needs and any future needs that may come up. If your interested check out my blog about my electrical journey.

-- I don't make mistakes, I have great learning lessons, Greg

View MrRon's profile


5270 posts in 3482 days

#12 posted 01-07-2012 07:39 PM

I had a 200 amp service installed for my 1200sf shop, so I never have to worry about tripping breakers. Sometimes I have my 3hp saw and DC running and my son is welding with a big MIG welder. I may even have a fan running and lots of lights. Never had a breaker trip or lights dim. It doesn’t cost that much more to go 200 amps. With a small shop, you could get by with 100 amp service. Anything over 50 amps; I would recommend a separate service, as your house panel may not have enough spare capacity.

View Jeremiah's profile


82 posts in 2563 days

#13 posted 01-21-2012 09:26 PM

My 2 cents:
-Totally agree with everything pmayer said.
- make sure all the plugs are 50” off the floor, that way sheets of ply or what ever wont block one (its helpful)
-build for what you have NOW. put the 100amp 240v service in and don’t worry about the shop being too small. There is a greater chance you will love woodworking and buy bigger tools that need it; than the likely hood of you suddenly getting a bigger shop.
-don’t be afraid to “commit” you maybe just starting off, but plan like this is a life time hobby (for most it become one :)
-Lastly, don’t worry about spending the extra cash on it. if you move, take the panel/breakers/plugs with you.

ps i have a 400sq shop with 100amp sub box. it has 2 240 circuits, one for my big tools the other for my dust system and compressor. i have 2 15amp 110 circuits for my plugs, 1 15amp circuit for the 8 8’ florescent lights and 1 15amp 110 circuit for my built in window ac unit. Never tripped anything yet, and i have room to grow.

View skeemer's profile


95 posts in 2603 days

#14 posted 11-29-2012 12:32 PM

Thanks for all the tips everyone. I am finally getting around to doing this (only been a year, lol) this coming weekend.

The plan is to have 2 120/240 outlets on each side of the shed (to allow me some flexibility in setup), and then 3 more 120 outlets on either wall, with 3 more 120 on the back wall. I’ll run 60a service out to the shed, with two 20a, and 3 15a circuits to allow me to run up to 2 240v machines (which I have 0 of currently), dust collection, lighting, and a heater or AC unit. I plan to have four 4’ fluorescent lights on the ceiling w/ 3 way switches.

Trencher is reserved and I’ll be stopping by Home Depot today to pick up my supplies! I’ll soon be able to work past 4:30 PM now that I’ll have light. Very exciting!

Thanks again everyone!

View treaterryan's profile


109 posts in 2526 days

#15 posted 11-29-2012 12:42 PM

20×15? Thats a big sedan!

-- Ryan - Bethel Park, PA

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