Wiring choice in fabric building

Discussion in 'General Electronics Chat' started by way0utwest, Nov 26, 2011.

  1. way0utwest

    Thread Starter New Member

    Nov 26, 2011
    My wife has a fabric building (steel frame, PVC cover) that we want to wire lights in. My plan is to run the wires along the frame and hang a series of T-8 fluorescent lights from the steel arches, about 20 feet in the air.

    The building is secure from the weather, but since the fabric can tear or have condensation or other issues, I'm not sure that the wiring choice for indoor wiring is the best. Can anyone shed some light on what type of wiring I should choose inside the building? Would I use the NM-C or NM-B wire choice? Or UL?

    I have attached an image of the inside framing to the post. My plan was to tie wrap or perhaps clamp the wires along the frames and bring them back to a panel (outdoor rated) near the main entrance.

    One other question. Since the lights will be 20 feet in the air, we have been considering putting the lights on pulleys, but I'm not sure what that means for wiring. I assume I'd need some sort of coiled cord near the end that would flex down 10-12 feet for us to lower the fixtures to chance bulbs. Any suggestions here?

    Thanks in advance
    Last edited: Nov 26, 2011
  2. SgtWookie


    Jul 17, 2007
    I'd probably go with UF type cable (rated for underground use and UV exposure) run inside gray PVC conduit, and install an outdoor outlet & cover in a box at the high end.

    The outlet would need to have the type of cover that would still be water-resistant even though something was plugged into it.

    I'd then use a long 3-wire appliance power cord to plug in the lamp. Be careful; some of those fluorescent fixtures will fail early if you have them too close to a ceiling. They do dissipate power as heat; and that heat will tend to age the fabric immediately above the fixture(s). You may wish to have a small fan up there to move the air around and prevent hot spots.

    You don't say if power is available at ground level inside the building. If not, you'll need to dig down two feet to run conduit to whatever building has power accessible.

    The circuit must be GFCI (Ground Fault Circuit Interrupt) protected.

    Cable TV and telephone wires are one foot down.
    Water lines and sprinkler lines are 1-1/2 feet down.
    Electric is 2 feet down.
  3. way0utwest

    Thread Starter New Member

    Nov 26, 2011

    Right now we don't have power, and it's cost prohibitive to run it all the way since we expect only about 100 hours a year of usage. So we are using a portable generator (outside, separate shed building) to power things. The total wattage of the 10 lights is only 2200 watts, using a 3.5watt generator, so lots of overhead.

    Do I really need conduit all over? If I have UF, clamped to the frame, does conduit substantially change the safety? I'm asking because it's a lot of plastic to run through the rafters.
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
  5. way0utwest

    Thread Starter New Member

    Nov 26, 2011
    Thanks. This is to be lightly used, though I planned on outdoor rated panel, and outdoor junction boxes, and cables to keep things going. We want a panel to be future proofed.

    The generator will be in an oversized (for the generator) building, with ventilation for cooling and exhaust. We'll use a weatherproof cord to slide under the fabric to the panel. We have a whole house propane gen for emergencies already, and will use similar guidelines for what we did there. Definitely don't want too much heat.

    Feels like too much distance for extension cords, so would like it to be semi-permanent.

    Very much appreciate the advice.