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Forum topic by Ian S posted 07-27-2016 07:54 PM 463 views 0 times favorited 12 replies Add to Favorites Watch
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Ian S

19 posts in 163 days


07-27-2016 07:54 PM

Hi all,
Next installment in my continuing series of posts about setting up a back yard workshop …

In this thread I figured out how to get started with closing in my shed and turning it into a proper workshop. Now I’ve got an insulated attic / ceiling, and eventually I’ll be doing the same to the walls.

Before that though, I want to re-do the wiring! I wanted to solicit some suggestions and learn from some “If I had only done XYZ first …” comments.

To start with
The shed is 10×20 with a (basically) 8 foot ceiling. Right now it has its own subpanel box, which has (IIRC) 6 slots, 4 of which are filled with 20 amp breakers. Right now, since the original wiring was done pretty sloppily, the entire shed runs off just ONE of those breakers—the rest of the subpanel is not being used. So obviously that’s dumb, I’m going to run separate circuits to utilize multiple breakers.

I still need to check on the service coming out from the house to the shed. Based on my initial research, it looks like I really need to take an inventory of what the maximum amperage that I plan to draw at one time within the workshop, and make sure the main service is AT LEAST that large, if not 1.2x or 1.5x that number. Is that about right?

Here’s the start of that “amperage inventory” at the moment:
• Table saw will get its own dedicated circuit—probably will be R4512 which draws 13 amps
• Several smaller stationary tools (shop vac, router, miter saw) draw between 11 and 15 amps apiece, so I’ll need at least 1 or 2 separate general plug-in circuits (aside from table saw) to make sure I can run my shop vac / dust collection at the same time as these
• Ceiling lights are LED and there’s a small powered duct vent in the attic—I imagine those can all be on one circuit
• I have a couple of exterior outlets that may be used for an electric tiller or electric chipper—those are both 11 or 12 amps so I presume they would want to be on their own circuit as well
• I have a window unit A/C which of course needs it’s own circuit

The largest concurrent usage I can imagine is:
- Several LED lights and attic fan (let’s be conservative and say 5A)
- Shop vac (12A)
- Miter saw (15A)
- Window unit A/C (6A)
- 1 or 2 cordless battery chargers (~2A ?)

... I can’t imagine running more than that, concurrently—but maybe I am naive about how my hobby will grow. So a total of about 40A at a time. That seems like not much to ask. Thoughts?

Meanwhile as for planning out circuits …

I need some confirmation that my thinking is on the right track here. The list above suggests I might have something like the following circuits
1) Ceiling / attic circuit for lights and attic fan
2) Dedicated circuit for window A/C
3) Dedicated circuit for using one large tool at a time—miter saw or table saw, for instance
4) Second general plug-in circuit so I can run the shop vac at the same time as using #3; will also be used for smaller handheld power tools
5) Dedicated circuit for exterior outlets

I’m thinking #4 might actually need to be two separate circuits, since (even though it’s a small shop) I’m likely to add something like a drill press, bench grinder, etc. in the future.

Overall am I headed in the right direction here?

What have I missed?
Aside from the general amperage approach I’m using to plan out circuits, what else should I think about? What else did you WISH you built in capacity for, or WHERE to put receptacles earlier, that I ought to know about?

Eager for your thoughts. Thanks!


12 replies so far

View Fred Hargis's profile

Fred Hargis

3945 posts in 1959 days


#1 posted 07-27-2016 08:03 PM

No plan for any 240V outlets? (That’s OK, if you’re sure you’ll never need them.) The only thing I would question is the need for the dedicated exterior outlets; seems fairly unlikely they would be in use at the same time the big tools in the shop are being used….but overall, I don’t see anything wrong with your thinking.

-- Our village hasn't lost it's idiot, he was elected to congress.

View WhyMe's profile

WhyMe

615 posts in 1026 days


#2 posted 07-27-2016 08:13 PM

You definitely need to look at the feeding breaker size and wire size currently being used. Also verify that the feeder is the correct type iwre and correct number of conductors including the ground. Should be four.

View rockindavan's profile

rockindavan

299 posts in 2101 days


#3 posted 07-27-2016 08:19 PM

If your ceiling lights/outlets are switched, add a couple outlets in the ceiling that are constant power for air filter or since your ceilings are low enough you can plug in tools in the middle. I would run a 240 circuit around and cap them off with blank plates. If you ever decide to need them, you can add outlets easily.

View MikesProjects's profile

MikesProjects

163 posts in 1367 days


#4 posted 07-27-2016 08:24 PM

It sounds like a fun project with an exciting goal. Be sure to post pictures as the project continues.

-- -Mike, Southern California, YouTube User ( Give & Take )

View Ian S's profile

Ian S

19 posts in 163 days


#5 posted 07-27-2016 09:22 PM

Great feedback so far. Thanks for the interest and help everybody!

On my to-do list:
- Research about how to run a 240V circuit
- Check on feeder size and total capacity at subpanel
- Get ready to post pictures :-D

Other questions:
1) I’m thinking of locating most of my outlets at the normal “knee” level, but would you all recommend putting some higher, e.g. at bench top or shelf heights? I mean, I will probably do that for some outlets anyway, but at this point I’m just making a wild guess. My main workbench will be in the center of the room on casters, so it may occasionally be against the wall, but probably not most of the time. What else have you all ended up plugging in (such a generic question) that would benefit from a higher outlet?

2) Whatever table saw I get, it will probably be dual-wiring. My understanding is that switching that kind of tool to 240V does NOT actually increase its power, it simply allows it to attain the same power with less amperage. Is that right? In that case, given that I’m going to have a dedicated 20A circuit for the table saw anyway ... is there any real benefit to having on 240?

3) What other favorite tools do you have that need to run on 240V? I can’t think of anything right now, but I’m only just beginning this hobby. Maybe a welder? I can’t think of anything else.

4) Receptacle preferences. I’ve only done a bit of electrical work so far (and am preparing to do a lot more research to make sure that I’m safe). Right now I have those simple blue plastic (Carlon) boxes in my shed, but I’m wondering if it’s worth my time to upgrade to more durable all-metal boxes with metal covers. #1 because they look sweet and aesthetics are important, and #2 bc it’s a shop and so everything needs to be a little more durable. Are metal receptacles worth the investment, or a waste of money?

View Fred Hargis's profile

Fred Hargis

3945 posts in 1959 days


#6 posted 07-27-2016 09:28 PM

You may have 240V already, that’s part of looking into what’s feeding your shed currently. If it’s there, all you need is a 240V breaker, if not it’s a much bigger deal. My comment was more directed toward it being there, and you could install a 240V outlet and still have 4 120V slots left.

-- Our village hasn't lost it's idiot, he was elected to congress.

View rockindavan's profile

rockindavan

299 posts in 2101 days


#7 posted 07-27-2016 09:41 PM

240 is nice to have since most 120 tools are 1.75 hp or less. Might not need extra hp but it is nice to have. I got an old 2hp 240 only air compressor for super cheap since most people don’t have 240 in their garage and the guy couldn’t use it. It opens up possibilities. The other think to think about since you have a relatively small feeder is balancing your panel. If you put all your main 120v circuits on one branch, you are limited to 40 amps total. Splitting it between the legs opens up 80 a of 120. 240 simplifies this by splitting the load between both legs. Switching dual voltage tools to 240 is beneficial here, but generally it’s not worth your time until you over 1 hp. I had a small shop similiar in size that I redid the wiring with a 40a panel. At one time the 5000w heater was running, 2 hp jointer, dc, lights, 2 hp air compressor and small hot tub. That was pretty unlikely to happen, but it did so whatever could be the max, it might happen. Worse case scenario it trips the panel, but think about loads on each leg.

View muleskinner's profile

muleskinner

881 posts in 1902 days


#8 posted 07-27-2016 09:48 PM

Other questions:
1) I m thinking of locating most of my outlets at the normal “knee” level, but would you all recommend putting some higher, e.g. at bench top or shelf heights? I mean, I will probably do that for some outlets anyway, but at this point I m just making a wild guess. My main workbench will be in the center of the room on casters, so it may occasionally be against the wall, but probably not most of the time. What else have you all ended up plugging in (such a generic question) that would benefit from a higher outlet?

- Ian S

All the outlets in my shop are at 42”. I can’t remember once in the 25+ years that I’ve been using it wishing I had normal “knee” level (18”) outlets. I have, however, at times wished I’d put them at 52”.

-- Visualize whirled peas

View martyoc's profile

martyoc

27 posts in 382 days


#9 posted 07-27-2016 09:53 PM

I suggest you put outlets about a foot above your bench height. You will be using them for routers, sanders, etc. If you can, a floor outlet would be useful for the table saw and any other large stationary tools. Lower wall outlets will often be covered by items leaning against the walls and may be difficult to reach. Best of luck with your new shop.

-- Marty O'C

View oldnovice's profile

oldnovice

5730 posts in 2833 days


#10 posted 07-28-2016 03:28 AM

I agree with those that said higher placed outlets as there is no reason to bend over to use an outlet. You might also consider a couple of ceiling outlets or cord drops. I had those in my old basement shop in Illinois and I miss them in my garage shop (the door gets in the way).
I would really consider some 220/240 VAC connections, better now than working them in later.
Check on your local requirements for GFCI protection?

One last point, go with LED lighting if at all possible as they save money, don’t draw bugs (no UV), don’t hum, don’t flicker, no strobe effect on rotating tools, and instant on! Have I sold you on these?

-- "I never met a board I didn't like!"

View Ian S's profile

Ian S

19 posts in 163 days


#11 posted 07-30-2016 02:07 PM

Okay, so … this morning I finally took a closer look at the feeder. Looks like it’s only a 10/3 UF-B, just like this:
https://www.wireandcableyourway.com/10-3-UF-B-Wire-w-Ground.html

From what I understand, that’s a huge bummer—30 amps max. And from what little I understand, I’m probably facing a significant voltage drop as well—the panel is on the far west end of my house, and the shed is on the northeast end—I have a big yard, so the total distance could easily be 100 – 150’.

The 10/3 feeder is hooked up to a 20/30 breaker in my main panel. I have no idea if that’s correct but at least there’s the 30 amp limit again.

Based on my math from the first post, regardless of how I set up my circuits I’m going to go past 30 amps—between running my 15A table saw, 13A shop vac, 6A AC, and 2-3A for lights, that’s already over the limit!

I’m getting into the neighborhood where, yeah I could probably figure this out and hack it DIY, but I’m probably better off getting expert guidance at this point. Probably bailing to “plan B” now and calling an electrician.

Any thoughts are welcome though!

View oldnovice's profile

oldnovice

5730 posts in 2833 days


#12 posted 07-30-2016 06:10 PM

That is a bummer!
Remember though that not all of the current hogs will be on at the same time!
LED lights will save a bunch of amps you can use elsewhere.

Those are my only suggestions at this time.
It won’t be cheap bringing in more power over that distance!
I had to add a 220 VAC, 40A, GFCI line 40’ to my garage.
It cost me $400+ because I am not able, or willing for that matter, to crawl under the house or climb in the attic!

-- "I never met a board I didn't like!"

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