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Wiring a Shed for a woodshop

Posted by BradleySmall (My Page) on
Tue, May 24, 11 at 17:00

I am having a shed installed that is 12x17, my plans are to have it as a woodshop. I would like to do the wiring of it myself, for more reasons than saving money. However, I would like to do it correctly. I assume asking here would give me some direction. I have been looking through everything I can get my hands on such as the FP and Building codes. But so far still have a few unanswered questions. Some may be pretty dumb, but I will ask them anyway, in hopes that I do not get berated too much :)

In putting a subpanel in, fed off of my main panel, in a structure that is not attached to the house, do I need to have a grounding rod specific for that building?

My plan was to put in a 100 amp subpanel, which is likely overkill as I look at things, but I would prefer to have it and not need it than need it and not have it :) This raises a question though, my home electrical panel is 200 amp service. If I put in a 100 amp breaker and feed the subpanel from that, is that the right way of thinking? Or is this too much if the whole panel only has 200 amp service?

Once I figure out how to get the electricity to the panel in the shed, (I am looking at the distance, and other issues as to whether conduit is required or how to do the burrial and so forth) and I want to do the rough in, is it better to run two circuits rather than have a single circuit circumnavigate the whole room? Here's where this question is going.. as a 1 man woodshop I will not have opportunity to run more than one power tool at the same time. So I figure that I would have a set of outlets on a circuit dedicated to running the power tools, but some would be to one side and others to the other side. I would like to have the outlest on both sides of the room, but will not be using them simultaneously. I would think that running two circuits would be much more convenient for the wiring run. Am I thinking right, or do I need to be interested in adding up the amp ratings of the breakers that get put in the box?

Unlike my garage, I want to have the lights on their own circuit. The lights I have to work with are the flourescent shop light variety that hang from chains and have actual plugs on them. I assume that I can provide a place to hang them and simply have outlets in the vicinity of their hanging place on the ceiling... Or do I need to actually have them wired in and directly attached (rather than chained)?

Are there special considerations for putting an outlet in the floor (a la tablesaw in the center of the room avoiding extension cords)?

I am still reading fire and building codes, so I might find out these answers, soon enough, but I figured I'd ask anyway.

-- B


Follow-Up Postings:

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RE: Wiring a Shed for a woodshop

"In putting a subpanel in, fed off of my main panel, in a structure that is not attached to the house, do I need to have a grounding rod specific for that building? "

Grounding rods and depending on what year NEC you are under a 4-wire (hot-hot-neutral-ground) may be required.

The old 3-wire exception (hot-hot-neutral) is gone from the newer codes.

Do no skimp on the lines feeding the panel.

Induction motors have significant current surges at start-up, and if the voltage droops the starting surge is prolonged.
This can lead to heating of the motor and even early failure of the start capacitor and starting switch contacts.


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RE: Wiring a Shed for a woodshop

If the light fixtures come with plugs, install outlets and plug them in. Modifying the fixtures for direct wire would nullify the UL certification.
I would use a 40 amp breaker, but run a service cable large enough for 60 amps (or larger; air conditioning, heating, an arc welder at some time)
I'd have at least two outlet circuits, probably more so that adjacent receptacles are not on the same circuit. You may want an air compressor or dust collector at some time. (refrigerator, toaster oven, TV, micro-wave)
For the table saw, a 'floor wart' could be installed or a heavy duty drop cord from the ceiling.
For ground rods, I believe you'll need two, but check with your local AHJ for their requirements.
JMHO
R3


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RE: Wiring a Shed for a woodshop

I am not sure I understand the 4 wire thing if, I need a greounding rod also. The panel to my house has the neutral and ground connected to the same bar, If I run 4 wires out of that box I would be getting one each from either side of the breaker, then the white from the neutral bar, and as a 4th another one from the neutral bar? At the shed, I would then attach the ground and neutral to the bar and then the bar to the ground rod? Am I following that correctly? It seems counter-intuitive as they are all connected together a couple times right? Or am I missing something.

Brickeyee -- I am in VA so I think it is NEC 2005.
Are you suggesting that 100 amp wires are skimping? Should I be going higher? I do recognize that the motors can take some juice. Especially the jointer and thickness planer. I am planning on having some dust collection, even if I build it myself (most likely).

Randy427 -- Are you sugesting 40 amp instead of 100? Or merely suggesting that I have larger wires than necessary for whatever amperage I sub? As for other items in there, I may, in fact want a heater, I might also want a radio and perhaps to plug in a hand held drill but for the most part, I will not be running any 'major' tools at the same time. With 2 outlet circuits, are you suggesting that they both circumnavigate the room, and simply box every other one? I actually have a HD self retracting ceiling cord. It is what I use now in my garage for everything. So I guess one of the larger circuits should go to the ceiling then. Check!

Let's see if I have a real idea here..
2 Circuits for stationary tools.
2 circuits for (work bench convenience plugins, chargers, radios etc)
1 Circuit for lights
1 Circuit for AC or Heat
1 Circuit for Dust Collection
1 Circuit for smoke detector

I have not finished the over all design, but I was considering countertopping all the way around (3 walls) and potentially cabinetting at the floor level not unlike a kitchen layout. Would there be any issues of having all the wall outlets at 40" or so like in a kitchen? The other option is that they are extended out and mounted as part of a cabinet facing, but I can't imagine a good way to do that and meet code at the same time. Are there any things that cover such a thing, in a permanent installation?

I assume I could simply have different colored outlets to indicate whether it was on one circuit or another, but now I am just thinking out loud.

I don't know of any of the tools I have that would require or even utilize anything larger than a 20 amp breaker. However, is there any reason to not make all the circuits on 20 amp breakers? I ask this because there is a panel box I can get that is rated at 100 amp, but comes with 7 breakers, 6 - 20 amp single pole and 1 - 30 amp double pole. Since it is the same brand as my home panel, and I had to replace 2 15's with a tandem I have an extra 15 amp breakers.

Do I need to be concerned that the breakers all add up to less than the main?

If I have a 100 amp breaker on the panel I am subbing from, do I need a main breaker in the sub panel also or could I use a main lug type panel, I have not measured yet, but it is likely close to 100 ft away?


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RE: Wiring a Shed for a woodshop

There's lot of things to consider when wiring a home woodworking workshop including how you work and room for future expansion (I haven't met a woodworker who didn't want more tools). I had a shop in a three bay garage and installed a 100 amp subpanel. That was probably overkill but I want to say by the time I was done I had filled 10 spaces in the panel. I also like lot of light and hate extension cords running over the floor.

In terms of lighting, I'd suggest staying away from the cheap "workshop" type of hanging fixtures and invest in good quality surface mount fixtures. The cheap fixtures have cheap ballasts which always seem to buzz and fail quickly. You'll want general illumination and task lighting for the various tools (or work stations). You can accomplish that by concentrating fluorescent fixtures or using something like track lighting. Lighting should not be on the same circuit as tools. If you happen to pop a breaker you don't want to be standing in the dark as a tool spins down.

I had a 220v table saw and jointer and I put each of them on a separate circuit. While, as a single worker, you may think you'll be using only one tool at a time, I found a few occasions when I used the table saw and jointer in conjunction. And you never know when a friend may stop by. I used drop cords from ceiling mounted boxes to power both tools (keeps cords off the floor).

I put two gang boxes along the walls in locations where I would have various tools. In each box was were two duplex receptacles on separate circuits. That way I could plug in, say, a router and dust collector without worrying about overloading a circuit or running extension cords. While it isn't necessary, I did use different colored receptacles to "remind" me of the different circuits. I also mounted one of those retractable extension cords on the ceiling for those times when I needed a extension cord. That was on it's own 20 amp circuit.

Not electrical but I suggest resisting the urge to fill the walls with countertop. While it may depend on what you make, I would suggest instead building a large, movable assembly table. There are plenty of projects were it's far more convenient and efficient to be able to get to all four sides of a project without moving the actual piece. I built a torsion box for the top because a wanted a really flat surface to work on. If you're dimension it correctly, it can also serve as an outfeed table for your saw.

Don't use 15 amp circuits for anything but lighting. All your power tool circuits should be 20 amp.

I would use a main breaker panel because it will save you the trouble of walking 200 feet to turn off power when you work on your sub-panel. The sum of the individual breakers will likely exceed the "capacity" of the panel, that's perfectly normal and acceptable. What's important is that your total power draw doesn't exceed the panel's rating.

Because this is a garage not a kitchen or living space, you're exempt from receptacle placement rules.


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RE: Wiring a Shed for a woodshop

Virginia is actually on the 2008 NFPA 70 (the NEC).

The neutral and ground are isolated in the sub-panel in the separate building, NOT bonded again.

The NEC is designed to prevent the grounding conductor from carrying normal working currents and causing the ground voltage to rise from voltage drops caused by carrying normal operating currents.

The rods at a separate structure are used to ensure the grounding conductor never rises above the local earth voltage from ANY cause.

Leakage from the pole transformer could still appear on the grounding lines of the separate structure (it depends on the circuit impedance for the house and the shed back to the pole transformer in this case) there is also the possibility of induced voltage from lightning in the wiring of the separate structure.

Instead of shunting this through the house panel it is better to try and dump it to earth as quickly as possible.

There is sub-panel FAQ ion this site that is actually very good.


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RE: Wiring a Shed for a woodshop

Ok, lots of excellent advice so far, and a few thing I got as clarification from the inspectors office.

1. Though they are officially on 2008 as of March 1, they are still allowing things that meet 2005.
2. I do not need to drop 2 ground rods, but only one.
3. I need to use Al #2 from the panel to the sub panel (or Cu #4) I have to burry it at 24" (or 18 if it is in conduit)
4. *** This caught me off guard ***
All non-dedicated outlets have to be GFCI. TO clarify this, if I have an outlet, not duplexed that I would only plug a table saw into or something like that, then it doesn't have to be. But, and I quote, "if they are duplexed, and you could plug a drill into it and take it outside to work with, then it has to be GFCI"
I am not sure how this relates to how many outlets I can have on one circuit. Doesn't that limit me to 2 or can I piggyback more than one outlet on a GFCI? (I seem to think I have 3 in my kitchen, but I didn't wire that. :)

I was also told that I had to have a mains breaker panel for this. It didn't have to have a breaker, but it had to have a shut off.

OK, so I am pretty comfortable getting the juice out of the main panel, pretty sure I know how to drive a ground rod (though tips are most welcome)... But now, I am completely at a loss of what this spider's web of outlets is going to look like. Especially, knowing of the GFCI requirement.

I have a double door on one wall (12' wide wall) and a regular door on another 17' wall. Am I right in understanding that I can't put a recepticle within 6' or a door? Or did I read that wrong and it is 6"?

I assume if I run a circuit out to a receptical then laterally to another and so on, can I also go out vertically from that same box to one on the ceiling? Perhaps all the way across and down to another receptical on the other wall and then laterally to the next one?

Oh, yeah, and I am reconsidering the fully countertopped idea, but I may still do one wall that way to accomodate the chopsaw. I will be attempting to have as many surfaces at the same height as the TS as possible.

I like the idea of ceiling outlets as power sources, but is there any consideration that needs to be made for, perhaps locking outlets or such?


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RE: Wiring a Shed for a woodshop

GFCIs are required for accessory buildings with floor at or below grade.
GFCI's (either breakers or integrated with receptacles can protect other downstream receptacles). I've had a guy try to make me put them in my shop even though I'm not an accessory building as far as the county is concerned (it's actually part of the main structure).

You can put a receptacle as close as you want to the door. The rule for most dwelling unit rooms that no point on a wall can be more than 6' away. This means most people will place the first recetacle at 6' and then every 12' after that. Garages and Workshops would not seem to be subject to this requirement though.

You can go laterally or back up to the ceiling every time or combinations of both.

If they're letting you in under the 2005 code, then you don't need TR receptacles.


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RE: Wiring a Shed for a woodshop

Not having to do TR receptacles is a good thing, since I don't want them in there anyway (I can never get things plugged in them)

Again, the way he said it on the GFCI's I didn't need them on dedicated outlets, which he described as single outlets as opposed to duplexes. I guesss as long as it is not a duplex and I say that it is dedicated, then it is. However, if I want to do this right, and GFCI things properly, can I piggy back more than one additional outlet from a GFCI? I know in my kitchen, the wires come into the GFCI then from the other side of it they go to what appears to be a regular outlet, and from that to the next. I am not sure if this is normal or the best way to do it. But if I bring a wire into a GFCI receptacle, then from that box out any receptacle on that run of romex is GFCI protected as well? Could I simply put in regular old outlets, and just put in a GFCI breaker in the panel and satisfy the requirements?

As for the 6 foot rule, what is the other end of that? I mean how many outlets can I have on one run of a circuit? Is there a distance or other restriction to be concerned with? Not that I would, but could I put them on every single stud down the whole wall? In reality every 4-6' would probably be quite sufficient but this has peaked my curiosity. I have this scary vision of a wiring diagram that looks like the skeletal ribcage of a dinosaur in a museum, with a receptacle on each stud at two different heights, and three across the ceiling corresponding all the way dow the whole length of the building. Sounds like 60+ boxes :)

In reality I think I want receptacles by each window, probably on their own circuits in case I want to run 2 AC units. Then one circuit serving 3 light boxes across the ceiling area. Then what the heck, 3 circuits serving 5 receptacles each that cross from a traditional near the floor to a countertop level to a ceiling acorss back down the wall opposite for another counter top and floor level receptacle. So as I stand the receptacles to my right and left and directly above my head are all on once circuit, and if a step forward a couple paces, those would be on another and so forth.

I did however like the suggestion of gang boxes that carried 2 different circuits. On that note, it would be intersting to have gangs across the wall 3 or 4 per with two circuits in them, and one circuit to serve the ceiling 3 or 4. This way, if I get power from the red outlet it is one circuit or the blue is another and the ceiling is a third.

The other suggestion I was given (not here) was to simply make a fresh run to each receptacle and have every one on its own circuit. I am not sure I was buying that idea, but I felt I should share :)

Probably not the right place to ask, but dust collection was mentioned earlier. I was told that there is an outlet that can be setup that will turn on an appliance (such as dust collector) when any appliance plugged into it is activate (turned on) Is this a real thing, or just a fantasy?


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RE: Wiring a Shed for a woodshop

"I do not need to drop 2 ground rods, but only one. "

You can only use a single ground rod if you show its impedance is low enough (25 ohms comes to mind).

To measure the impedance you have to drive another rod to measure from.

No one wants to pull up a rod, so just count installing two and be done with it.

"I am not sure how this relates to how many outlets I can have on one circuit. Doesn't that limit me to 2 or can I piggyback more than one outlet on a GFCI?"

There is actually no limit on the number of receptacles on a branch circuit in residential use.
The limit is 180 V-A per in commercial space.

"I was also told that I had to have a mains breaker panel for this. It didn't have to have a breaker, but it had to have a shut off."

You are likely to find a panel with a main cheaper than a �lug only� panel, and the main is the required disconnect.

"I assume if I run a circuit out to a receptical then laterally to another and so on, can I also go out vertically from that same box to one on the ceiling? Perhaps all the way across and down to another receptical on the other wall and then laterally to the next one?"

Any way you want.

For a shop there is no requirement to have lighting on a separate circuit, but standing in the dark while tools run down is not very reassuring.

"I like the idea of ceiling outlets as power sources, but is there any consideration that needs to be made for, perhaps locking outlets or such?"

Twist lock receptacles are preferred so the plugs do not fall out under their own weight.


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RE: Wiring a Shed for a woodshop

It was actually the inspector that said I only need to drop one rod. I asked about 2 rods 6' feet apart, and his actual words were "We don't do that around here"

My garage where I use my tools now, was wired on a single 15 amp breaker including the lights, and door opener, and all the outlets one circuit. I tried to run a tool and shopvac at the same time and ended up standing in the dark with a spinning blade... I vowed not to have that happen again. :)

I will look for some twist lock recepticals, but I have at least one self retractable drop cord that mounts to the ceiling on a hook so I can use one of those to start with. It is very convenient to be able to raise the cord out of the way as well.

Shed should be in place by Friday, I will add the storage lofts before I do anything else, and then apply for the electrical permit. I will then drop the rod or two if someone here can convince me that is is necessary even though it is not required by our current local code. Then start trenching. Hopefully\, by the time the permit comes through I will have a good drawn out diagram of how I want the circuits run and I will be ready to go!


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RE: Wiring a Shed for a woodshop

It's technically all the 15 and or 20 A 120V receptacles. Perhaps those in a dedicated appliance space might be exempt, but just because you dedicate it to a particular piece of equipment isn't technically an exemption. However, do what the inspector will let you get away with.

I would have to believe you need two rods for detached structure.


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RE: Wiring a Shed for a woodshop

I am not sure how he made that as an exception, but I am just repeating what he said. Of course as soon as it is a duplex receptical it immediately disqualifies. But certainly if every run starts with a GFCI outlet I should be covered right?

I personally would consider things like directly wired lights and smoke alarms and things like that which did not have a receptical to be 'dedicated'. I could even understand a single outlet receptical below a window to serve an ac unit or a single outlet over a door to serve exit lighting or a wall mount clock 'dedicated'. However, I have no understanding of why a single outlet receptical in the middle of a wall would be considered as such merely by virtue of its being single, and my word that I only intend to plug a table saw in it. Obviously, to me at least, a stove or dryer outlet or even possibly 15 amp 250 v (funny looking one) but by his description the goal seemed to be to prevent plugging in an extension cord and going outside of the structure and using for example a drill. I could do that with any standard outlet whether or not it is duplex or single.

I will follow the code as much as necessary to pass, but just because I can do something doesn't mean it is a good idea to do so. I am not so naieve to believe that just because the code allows me to do technically do something one way or another, that it is the best and safest way to do it. That is kind of the reason I started asking here.

I do wonder, however, if it would simply make more sense to install all GFCI breakers.


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RE: Wiring a Shed for a woodshop

"We don't do that around here"

Plain old incompetent.

Without measuring the ground impedance a single rod provides (if it is the only electrode) the NEC REQUIRES a second rod (but you get to stop there).

Sounds like your AHJ is confused.

If a metal water line is available (at least 10 feet in contact with the earth) it must be used as the primary electrode, and only a single rod is required as a supplementary (AKA 'made') electrode.

If no water line is present (or the line is not metal with at least 10 feet of earth contact) then a rod can serve as the primary electrode.
If it has an impedance of less than 25 ohms to earth it is all you need.
If it is not low enough another rod ('made electrode' actually) is required.

Since checking the rod impedance to earth requires a second rod to be driven to measure from, just driving and bonding the second rod avoids having to drive, measure, and then remove if the first rod was low enough.

There is no actual limit on the number of receptacles on the load side of a GFCI receptacle.

They are a lot cheaper than the breakers, and it is a lot easier to simply push the reset button if one trips instead of going to the panel.

You can also put two GFCI receptacles in the first box, then split the downstream receptacles between top and bottom by running 2-2 cable down the line.

I generally aim for a split receptacle about every 4-6 feet in workshops.

If you do split them, make sure to wire all the tops on one circuit and all the bottoms on another consistently.
That way you can be sure if you put a heavy load on the top of one, you can put another load on any bottom and not overload the circuit.

It works well if you do things like use a shop vac to collect shavings from a router.

My router table has two plugs on separate cords.
One feeds the router and the foot switch, the other feeds a receptacle with a switch for the shop vac.

All the controls are then right on the front of the table.


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RE: Wiring a Shed for a woodshop

I will likely spend the extra $9 and drive a second rod, in the scheme of things that seems like a sort of cheap insurance policy. I assume I will not get gigged for going above and beyond the requirements.

I wasn't really thinking about split recepticals. So lets say I run 4 circuits for the wall outlets, as in 2 separate runs on each wall. I assume I can get a duplex CGFI outlet that can be split top and bottom. Then down the row of outlets the top feeds the top and bottom feeds the bottom. Then I can take a pair of runs up to the ceiling outlets as well. This will mean that each box will have 6 romex cables in it. I assume all wire nutting and pigtailing etc, has to be inside the box so I guess the question is do I need a special box to house all that stuff? It would seem crowded for most duplex boxes I have seen, are there specifically deeper or wider ones to accomodate such things, or am I just being a baby and need to learn how to fold wire more efficiently? :)


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RE: Wiring a Shed for a woodshop

"I assume I can get a duplex CGFI outlet that can be split top and bottom."

Not available.

Both receptacles of a GFCI receptacle are on the same circuit.

There is not enough room to put two GFCI circuits inside a single device.


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RE: Wiring a Shed for a woodshop

Hmm, I thought I saw one, it has two different test/reset buttons on it. I just assumed it was duplex. No matter, I can do it in a 4 gang instead, right?


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RE: Wiring a Shed for a woodshop

Yes, if you install a double gang box you can then install two separate GFCI receptacles to handle each branch circuit.


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RE: Wiring a Shed for a woodshop

Does that seem like a good idea? Immediately out of the panel wire 2 GFCI double gangs (one on each side) then from there go around the room with 2 runs into each box and have split top and bottom circuits. Will I have any issues with the GFCI and startup of my tool motors like table saw and jointer or thickness planer?


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RE: Wiring a Shed for a woodshop

"Will I have any issues with the GFCI and startup of my tool motors like table saw and jointer or thickness planer?"

You may, but the newer GFCIs seem to be less prone to nuisance tripping from motors.

It can be a real PITA when you have an otherwise 'unfinished' basement being used as a workshop.

For longer tool life and better operation you might want to move any larger stationary tools to 240 V.
The current is cut in half reducing the voltage drop in the wiring from start-up surges.
This allows the motor to come up to speed faster reducing heating in the motor and use of the start winding and start capacitor.
They starting circuit is normally turned off by a centrifugal switch when the motor reaches a major fraction of operating speed.

For larger motors in table saws the shorter start-up can be heard.
On 240 V the motor snaps to speed very quickly, while on 120 V there is a noticeable period of winding up.


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RE: Wiring a Shed for a woodshop

I assume you are not suggesting I can run my regular table saw on 240 but rather that I change out the motor?


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RE: Wiring a Shed for a woodshop

"I assume you are not suggesting I can run my regular table saw on 240 but rather that I change out the motor?"

Depending on what motor you have it may be a simple change to move it to 240 V.

Look on ht motor nameplate and see what voltages are listed.

Unless it is a very small saw using a universal motor, it should have a 120/240 V listing on the motor's nameplate.


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RE: Wiring a Shed for a woodshop

It is the Rigid TS2424, I will look at it when I get home.


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RE: Wiring a Shed for a woodshop

My shop has GFCI's on all my 120 20A circuits. It's NEVER been a problem. I've got a jointer, a small planer, a router table, drill press, and various small stuff. Can't say I ever had a false trip.

The 220V circuits for the air compressor, table saw, bandsaw etc... do not have the GFCI.


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RE: Wiring a Shed for a woodshop

ok, so I looked at the saw and I can see that the motor is rated for both 120 and 240 and I see in the manual there are directions for wiring it. I will look at the jointer and thickness planer and drill press to see if they are likewise convertible. If they are, can I have runs of multiple outlets on the same circuit like I would for the 120 outlets? It seems like a dumb question, but I have never seen a 240 outlet in the US that was not all alone on its own curcuit.

I am off to go look at the rest of my motors.


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RE: Wiring a Shed for a woodshop

So it appears that the Table saw and Jointer/Planer can do 240, but the thickness planer is only a 120 v motor. I don't mind changing a plug and some wiring, but I am not abotu to replace a whole motor that is currently working :D


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RE: Wiring a Shed for a woodshop

Who'd a thunk?

Here is a link that might be useful: 120/240 Volt Duplex Outlet (non-ul) (400025)


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RE: Wiring a Shed for a woodshop

Ick...first I wouldn't put a non listed device in.
Second, you can never have too many receptacles (nor circuits) in a shop. I have 4-240 V "general Purpose" receptacles plus lots of 120V 20A ones spread around the shop
(and that's not counting the ones reserved for the DC and the air compressor).


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RE: Wiring a Shed for a woodshop

"Second, you can never have too many receptacles (nor circuits) in a shop."

I'll second that.

I have at least six 20 amp circuits for 120 V tools, and seven more 240 V circuits (with a real moster for the welder) for stationary equipment (including a mill and lath on 3-phase VFDs pulling from 240 V).


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RE: Wiring a Shed for a woodshop

Talked to the inspector again today. He said that there would be no problem running multiple 240 outlets on the same circuit with the caveat that I was careful not to not overload the circuit during use.

I also asked about running the conduit along the wall until I got past the deck before going underground. He said there was no concern for 90 degree angles, as to how many I cared to use.

Next question is a matter of aesthetics:
The meter head is to the left of the main panel. The meter is fed from underground. The knockout that I will have to use on the panel is on the right hand side. The direction I need to go with the wiring is to the left. Is there a nice clean way to cross over one conduit with another?


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RE: Wiring a Shed for a woodshop

Regardless of his interpretation of the code, if you have excessive amounts of elbows between pulling points you'll find it extremely difficult to actually pull the wires in that conduit. Some times even the code minimums for conduit bends and diameter aren't enough for convenience.

Is there anything exiting the top side of the meter? I might make two left turns and go over the top. Otherwise, if you've got the room, a gentle bend to bring the conduit forward enough to cross the conduit and back again.


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RE: Wiring a Shed for a woodshop

"He said there was no concern for 90 degree angles, as to how many I cared to use. "

What a bozo.

The limit is 360 degrees of bends in a run between pull points.

Even before you get to 360 it gets to be a real PITA to pull wires into the conduit unless it is very oversize (and you still may need lube).


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RE: Wiring a Shed for a woodshop

Ok, let's see if I can reply to everything in turn:

>>
Ick...first I wouldn't put a non listed device in.
Second, you can never have too many receptacles (nor circuits) in a shop. I have 4-240 V "general Purpose" receptacles plus lots of 120V 20A ones spread around the shop
<<
I totally agree. I am not sure what you are calling 'unlisted' but nothing I was planning on doing should violate the UL listing of the devices that I am aware of.
I intend on putting in as many circuits as practical, but I wanted to be able to put more than one outlet on them. Seemed acceptable to the AHJ.

>>
excessive elbows..
<<
My choice was to rotate the first elbow out a few degrees and hope to curve the conduit back to the wall across the other one. Once I get to the deck it is a straight shot to burial, but already that is one elbow going down, and another coming back up, one coming out of the main box, and one at the ground. That makes 360 already right? I would not be able to route around the other one with elbows without using up 4 at that point alone. I could go over the top, but it would really look crazy and I think SWIMBO would be opposed, which I personally fear more than the electrical inspector. :)


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RE: Wiring a Shed for a woodshop

(1) That "ick" was directed towards the link that saltcedar pointed out.

(2) The 360 limit is between pull points.
So you can use these around the main box instead of the sweeping 90 degree bends:


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RE: Wiring a Shed for a woodshop

Yippy! The shed is finally installed, and I can actually do stuff with it.

I should apply for my electrical permit today or tomorrow. This weekend, however, I will be getting some 2x6's and make ceiling joists for the lofting, but I was thinking I might as well do them the whole way so that I have something from which to hang lights and ceiling outlets.

As I look at the inside, it is apparent that the wall facing the house has the two windows and the single door and the north adjoining wall has the double doors. This is the most convenient corner to bring in the power run from the house panel. That would require the least trenching and the shortest possible run. As I am understanding I must mount the panel in an area:

30"x36" without obstruction
Not over a work bench or cabinet
Not in a crawl space or area with a ceiling under 78"
Below 60" high

I think I have the requirements unless I misses some.
I think the corner between the window and the double door would be the best place to put it, relative to wasted space and proximal convenience to the wires coming in. However, it seems like all my runs from that point will be relatively inconvenient laterally, since I would have to negotiate the double or single door depending on the direction I go. However, I assume that there is no reason to not run most if not all runs straight up across my ceiling joists and down the other side. Does this seem like a reasonable thing to do?


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UL and CSA Listed!

Leviton 125/250 Volt Duplex Receptacle Commercial

Here is a link that might be useful: 5-15R_6-15R Duplex Receptacle Commercial


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RE: Wiring a Shed for a woodshop

That one seems mroe reasonable, though I don't know if it will satisfy the 'dedicated' criteria for non GFCI outlet.


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RE: Wiring a Shed for a woodshop

Who knows, because the "dedicated" criteria appears to be an invention of your local inspector who seems to be at odds with the code (what jurisdiction is this?) in a number of ways.

The code requires all 120V 15 and 20A receptacles to be ground fault protected in your shop if it is at or below grade. There's no exception for dedicated receptacles for appliances/tools/equipment. In fact, the code commentary specifically states that they DO NOT make such an exception intentionally.


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RE: Wiring a Shed for a woodshop

This is in Fluvanna County in Central VA.

How would you install that outlet with GFCI then? Apparently one leg is exposed as a 120 which I assume will require the neutral. Normally doesn't the 15 amp 240 just use the two hots and ground, so you would have to use 12/3 I guess?

Anyway, I am torn on the whole 240 thing. I can use my saw now as wired on 120 and will likely do so during the process of getting much of the work done. I can do that on a heavy gauge extension from the house if needs be. If I convert it over, then I can't use it until I get done. At present, I haven't really gotten an overwhelming argument to make the change over.

Obviously if I want to have the 240's I will need to have them in several positions as who knows what kind of moving around I will do with my saw over time?

I am pretty sure I will simply GFCI all my 120 outlets whether I have to or not. I assume there is no reason to put in an outlet that is any less than 20 amp. I will, however, wire the lights as 15 amps because I can't for the life of me see a reason for any permanent lighting needing more than that. Though, I am still debating on what will be the best lighting choice. Initially I was considering the old standard long bulb fluorescent shop lights, I may relegate then to the areas over the lofts and go with some type of recessed can and look into LED technology. We just added a pair of the 9w screw in flood style ones in our breakfast nook, and they are nice and bright with some pretty clean lighting. We'll see. Especially since I will be working with less than an 8' ceiling.

Since the windows are so tiny, I will need to come up with a different AC solution as well. Another reason I am still considering a few 240 outlets. Am I thinking right that I can get away with lower amperage on the 240's than the 120's? Seems all the suggestions I have seen involve using a 15 amp plug/outlet on the 240s.

Open to suggestions. :)


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RE: Wiring a Shed for a woodshop

Your inspector is at odds with the state law. As Brick points out the local jurisdiction is not supposed to be deviating from the state code which is essentially the NEC2008. Of course, sometimes you gotta do in Fluvanna as they do in Fluvanna and it's easier to comply with their additional requirements than go another way. HOWEVER, absent some compelling reason to do otherwise, I would not deviate from the actual code requirements.

How you use the GFCI? Easy, you either put the GFCI receptacle on the first one in your string and connect the others to the protected side or put a GFCI in the panel.

The 220V receptacles do not require a GFCI by code. If you want them, the only way you're going to do that is with a GFCI breaker.

If you want to be flexible, either install both 120V and 240V receptacles. Put them side by side (on different circuits). You can never have too many. Even if you have a 240V saw, you might some day put a router in the extension table, or a stock feeder, or a work light, or something else right there as well.

The other option is to home run every box to the panel and install individual receptacles there and you can upgrade them to 240V at will by just changing the breaker termination and putting a new recetpacle in.

I agree, use GFCI on all (it's required technically) 120V and put 20A receptacles everywhere. That makes good sense.
I'd even put 20A on the 220V receptacles. 12G won't cost you that much more and you can plug a L6-15 plug into an L6-20 receptacle just like you can put a L5-15 plug into an L5-20 receptacle. When you get to the larger table saws like my 3HP one, you'll want the 20A.

Frankly, you can't have too much light either. I'd use some of the 4' bulb high efficiency fluorescents. That's what I have (plus some task lighting on the drill press, etc.). I also put in two "Solatube" skylights which give a large amount of natural light (my shop has no windows, it's actually interior a larger building). A lot of times I don't even kick on the overheads it's reasonably bright.

As for climate control, you can get inexpensive split systems, essentially a fan coil unit that hangs high up on the wall and an outside heatpump compressor. They're easy to run and you can put both halves wherever convenient. Gives you both heat and cool (of course I've got radiant floor heat and a geothermal heat pump for AC).


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RE: Wiring a Shed for a woodshop

T8 fluorescents are a pretty sweet spot for initial cost vs. efficiency.

Heat pump mini-splits work well and can be very efficient. They are a lot quieter than window units. OTOH, putting a unit through the wall, rather than a window would be a lot less expensive, and they are getting better, wrt noise and efficiency, all the time too.


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RE: Wiring a Shed for a woodshop

T8 fluorescents are a pretty sweet spot for initial cost vs. efficiency.

Heat pump mini-splits work well and can be very efficient. They are a lot quieter than window units. OTOH, putting a unit through the wall, rather than a window would be a lot less expensive, and they are getting better, wrt noise and efficiency, all the time too.


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RE: Wiring a Shed for a woodshop

What should I look for to find info on 'heat pump mini split'? Any particular brands of other considerations?

My walls are 74" high. I will be hanging ceiling joists on top of the cap rails at 16" oc and covering top with plywood or osb for loft storage. That will probably only be about 4' deep on each side of the building leaving me with 8' of overhead to play with. I don't really want to wack my head on lights, so I can embed them between ceiling joists or recess them or whatever. I don't want to have any question about seeing anything, or safety. So I will not skimp on them. However, I don't want to go overboard cost-wise. So I would like good bang-for-the-buck...

Where possible, I will do my best to comply with NEC2011 above and beyond my inspector's requirements. I don't see anything they are requiring that is above what is in NEC so far.

Now that once again the idea of home runs to each outlet has been raised, what does that suggest about the size of panel I need?

In theory, I could put a box (4 gang?) every 16" with a single 250 outlet above it or perhaps 6 gang and have them all together. So I could have 4 120's plus 1 240 every 16". But wait there's more! Initially I wanted to have knee level outlets as well as counter top level outlets, and what the hell, how about a ceiling one as well.

That would come to 12 120 outlets and 3 240 outlets every 16 inches (with the exception of the wall with the double door and where the single door is (and the windows, would not really have a counter top level position. That would add up to a severely ridiculous number of outlets, and if they were all home runs, I thing would require a panel the whole size of one of the walls.

That said, 'you can never have too many' is probably incorrect, though idealistically I can agree. Realistically, I need to come up with a reasonable number somewhat less than that. :)

It seems reasonable that I can get a panel that has 22 slots. I assume that gives me up to 44 circuits on 120 tandems, or up to 11 240 circuits, or more likely some combination thereof. because I am a cheap b*d, and I had to yank 2 perfectly fine 15 amp cutler hammer breakers to put in a tandem so that I could even fit a 100 amp breaker in the house panel, I will be purchasing a cutler hammer panel, and using those 2 15 amp breakers. I assume they would be fine to run lights and perhaps a smoke/fire alarm. I think I would have to be running a bunch of 500 watt halogen work lights to toss the breakers on that, and I don't really intend on running halogens in there anyway. I will wire the runs with 12/2 or 12/3 anyway, so when those breakers do give up the ghost I will not feel bad replacing them with 20's... just because. That does away with 2 slots leaving me with 20. If I put in 6 240 circuits that would leave me 8 slots and I could tandem them to 16 120 circuits.

Obviously, I could have multiple outlets still on such a layout, but I obviously could not use them all simultaneously without going over the 100 amps. But, let's see where I can go with this.

If I go to 4 gang plus 1 per placement that would give me 4 circuits per box duplicated above and below and on the ceiling and same for the opposite side of the room. This could be repeated 4 times down the length of the building giving me a plug point every 32" that will give me a choice of 4 different circuits or a 240, with the understanding that so long as nothing else is plugged along that 'longitude' it will not share the same circuit. This also leaves me with 2 additional placements of 240's that perhaps could be reserved for special purpose things, such as a welder, or climate control unit or something of that ilk.

That is not counting the GFCI, but that is a detail. So we are talking about 48 split duplex 20 amp outlets, and at least 12 20 amp 240 outlets and perhaps a 30 or 50 for good measure. That is the closest I can get to overkill and still feel like I am describing a somewhat sane layout. Still, it seems almost double what I will more likely do. I assume there is a limit to the number of wires that I can fit through a hole in a 2x4, and again, if I am using 4 gang boxes to put 4 separate circuits in each one, I am not sure I have the confidence that I can fit all the pigtails and wire nuts inside the boxes and still have room for the outlets themselves.

Is there a tool for planing the layouts/runs online or on the computer other than just pencil and paper?

Am I just getting silly, or would someone actually wire a shop like this?


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RE: Wiring a Shed for a woodshop

The smallest mini-split I've seen was 9000 BTU. Wouldn't that be a bit much for a 12x17 room, unless the insulation were pretty flimsy? It might not run enough to keep the humidity down.

(PS - I'd like to find a good quality ~5KBTU heat/cool mini-split for my tiny home office.)


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RE: Wiring a Shed for a woodshop

They do make (and Home Despot used to sell them, haven't checked lately) recessed fluorescent fixtures. These are cleverly designed to be 15" wide so they fit between floor joints.

The problem is they are letting you do things that are required by the NEC 2008 which was what was surprising, that's not supposed to happen, but you're free to be more prudent (as long as they don't tell you to you HAVE to do something that's counter to the code).

You'll have a hard time finding a panel with more than 42 OCD spaces in it. The criteria has been relaxed but not many people make them. You'll find that on the larger panels, you're limited to which slots you can put tandems or skinnies.

I wouldn't do every receptacle but I'd definitely put a few dedicated circiuts in to various places and then wire lots of general purpose 120V's on a few circuits (I have four just for that purpose).


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RE: Wiring a Shed for a woodshop

"The smallest mini-split I've seen was 9000 BTU. ... I'd like to find a good quality ~5KBTU heat/cool mini-split for my tiny home office.)"
Probably better to take this to the HVAC forum, but good minisplits throttle well. You can get units down to 6000 BTU in multi configurations. It has been so long since I looked at singles that I don't remember. The ones that I know about have a dehumidify mode where the indoor blower runs at a very slow speed.


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RE: Wiring a Shed for a woodshop

For that size room, especially if I convert any of the tools to 240, I would assume that 4 circuits for general putpose should be enough, but I also thought that no one would ever need more than 512 k of memory on a personal computer either.Or as least no more than 640 k :)

The panel that I am looking at seems to be the biggest Cutler Hammer makes for 100 amp sevice. It has 22 slots, and will allow tandems on all of them. I believe they even sell a kit that comes with 6 20 amp breakers and a 30 amp dp breaker.If I add my two existing 15 amp breakers to that, I have 2 circuits for lights, 6 circuits for general puspose and 1 whopping circuit for doing 240. Considering that I don't have anything that runs on 240 I am in no hurry to wire it. With 6 circuits I think I have a circuit for every major tool and some left for a few smaller ones.
1. Table Saw
2. Thickness Planer
3. Jointer/Planer
4. Vacuum
5. Drill Press
6. Band saw
Let's see what's left:
3 Bench grinders, 1 angle grinder, circular saw, sanding station, 4 sanders (belt, 1/4 sheet. ros, half sheet etc.),3 routers one in table, jig saw (hand held), drills, plate joiner, battery chargers, air compressor... I just don't see ever running more than 2 of these at a time under any circumstances.

Another interesting development is that there is no rough in inspection. Not sure how that works, but he will probably not be seeing wall board, but he may be looking at insulation and vapor barrier along with wired and completed circuits and outlets when he comes. It makes me wonder if it is merely a 'handwave.'


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RE: Wiring a Shed for a woodshop

Rough-ins inspections are dying in a lot of places. They kind of feel you can staple the wire and not hide any junction boxes (especially if you're a pro). The details are compliance with the overall design and terminations.


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RE: Wiring a Shed for a woodshop

I will probably leave one open so he can see the piggies and let him know that the rest are just the same and none have two wires on the same screw. My guess is that he will stick the circuit tester in one of them and open one up and unless there is anything glaring he will probably just be in and out. It didn't sound like there was intent of thouroughnes, but I will be doing it for my perosnal safety rather than making him happy.

He does want the beginning and end of the trench open so he can see that it is all burried deep enough though.


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