I'm planning on running a single circuit from my sub-panel in the garage to my backyard storage shed. This is an uninsulated, unheated wooden structure (pressure treated lumber, painted T1-11 siding, roof felt/asphalt shingle roof) for storage only - there will be no room for a workbench or tools or potting table or anything else. This is purely an extension of the attic/garage/junk-room storage areas.
I'd like confirmation that my plan is correct, and confirmation on a few details I'm not sure about.
4 - 8 plug in LED strip lights
- each lamp: 1.1 amp, 60 watts
- each lamp will be plugged into a NEMA 5-15 or 5-20 outlet at the ceiling (i.e. it will be very inconvenient to plug anything but another light into the other receptacle).
- All lights controlled by a single switch just inside the door.
1 duplex outlet, NEMA 5-15 or 5-20
- We're running the wiring so may as well put in an "accessible" outlet "just in case".
- No planned usage beyond possibly running a small heater for short periods in the late-fall/early-spring.
- If the potential draw over the proposed distances would be too great for any additional loads, I'll nix it.
- According to the Indiana Association of Building Officials, it looks like we're on NEC 2009 with some state amendments.
- Welcome to Indiana, we're a decade behind. :/
Either a 15 amp or 20 amp GFCI breaker (yet to be determined)
- I'm leaning toward 20 amp, so I won't be sorry later. WAF is high on this at the moment.
12 or 14 AWG THHN/THWN-2 wire (white, black, green) or 14/2 UF-B (which I already have, but may not have enough of)
- 14 AWG and a 15 amp breaker or 12 AWG for either a 15 or 20 amp breaker
- Assume from here that all wire is appropriate gauge for the breaker, I won't be specifying 12/14 at every mention
Run NM-B from the breaker, through the garage to a junction box inside the building where the exit point will be.
- Up to the rafters, across the structure and down to the exit point will be 50 feet maximum
Terminate the NM-B in the JB (with a blank cover plate accessible inside) to feed through the outside wall of the house.
- Wire nut to the THHN/THWN-2/UF-B in the box with standard "indoor" rated wire nuts
Exit the building through a short stub of conduit directly into a pull hub on the outside to turn 90° down into the ground
- The pull hub will be 12-18" above ground level.
- Seal the hole in the vinyl siding with silicone caulk from the outside.
- Seal the hole in the OSB sheathing with more silicone from the inside.
Schedule 40 or 80 conduit vertically down, through a 90° elbow, horizontally about 20-25 feet and 12" or so below the surface, through a 90° elbow, then vertically up through the floor of the shed.
- Backfill with the dirt that came out of the trench. I'm not worrying about gravel or drainage.
Once the conduit is through the bottom plate of the wall, it will end and the wiring will run into a standard single-gang box where it will be pig-tailed to NM-B for the remainder of the inside wiring and to the "accessible" outlet using standard "indoor" wire nuts.
I'll probably use metal "handy-box" type boxes with metal covers since they'll be mounted in the stud bays but exposed (i.e. not behind drywall).
- I've got some push-in bushings for metal boxes, but will probably need more.
The Conduit Questions
I'm sure it will be significant overkill for a single circuit, but for the minimal price differential, I'm looking at running 1" conduit. What's the minimum size conduit I can use?
- This will ease pulling, especially if I've got enough UF on hand to make the run (I understand that pulling cable is much more difficult than pulling wire).
- Buying and pulling the THHN would be more fun and make me feel professional, but justifying the cost may be a bit tough. (Hmmm... 50' rolls aren't that bad!)
- This gives the capacity to easily pull another circuit to the shed should the need ever arise.
Is standard Schedule 40 plumbing pipe acceptable as buried conduit or must I use the stuff in the electrical aisle of my favorite big-box store?
What kind of fittings are necessary at the garage between the inside junction box and the conduit, and the conduit and pull hub outside?
With only about 12-18" of conduit between the pull hub and where the conduit will disappear in the dirt, is 1 conduit clamp sufficient?
- Do I even need a conduit clamp for that short a run?
I presume, especially for burial, that the conduit should be glued together to keep water and dirt out. Do I use standard schedule 40 type plumbing primer and glue or is there something special for electrical use?
Once inside the shed, do the wires need to be run in conduit between fixture boxes since they won't be covered by an inside finished wall?
- i.e. the wiring will all be exposed. It will be neatly wire-stapled to the side of the studs.
Is there anything glaringly obvious that I've missed?