Advice on wiring external lighting

Discussion in 'Electrical Forum discussion & Blog' started by Taylor, Jun 30, 2008.

  1. Taylor

    Taylor New Member

    Messages:
    143
    Location:
    Northern Joisey
    I would like to remove POS conduit on the side of my house feeding external lights. I can run wire through fire-blocking in stud wall and out through the siding. The question is, assuming I use lampholders rated for wet-damp locations, what options do I have for a junction box?

    One option appears to be a "T" box, but it looks like these are designed to bring wires in from conduit.

    Another option is a device box such as a pancake box. Can I put this over the sheathing or should I recess it? If I just recess into beveled siding, parts of the box will be exposed. There is an overhanging roof but still.... Is caulking the only option for flashing?

    Thanks for any advice.
  2. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    The main idea is to keep all rain water out of the electrical boxes...

    If running just outdoor romex outside to a junction box, don't run the wire down the wall and then into the box. Instead run the wire down, then back up into the box. This is called a "drip loop". Use a weatherproof connector (has rubber grommet inside to seal out water) screwed into a weatherproof box.

    You might be able to see outside wiring work done elsewhere where the wires run down, then back up to go into the building. These are drip loops. Water drips down to bottom of loop instead of into building.

    I don't quite understand what you are doing exactly. But basically for outside, use outdoor rated wiring only (if exposed), use outdoor sealed boxes, and use outdoor connectors for the boxes. If it looks like water might get into something, use caulk. (Around here it rains "sideways" sometimes, so I do this even if under overhanging roof...)

    I also caulk between the outside electrical box and the building so water will not get into screw holes or whatever. Then I caulk where the wire goes into the building. This is to keep wind from blowing in through the hole (heating is not cheap these days!)
  3. Taylor

    Taylor New Member

    Messages:
    143
    Location:
    Northern Joisey
    Thanks for the advice, I did not know about the drip loop. I want to get rid of conduit running along the siding, and have no wiring on the outside of the house at all. My plan is to drill a hole in the sheathing and bring the wire in through the back of the box. The question is, can I put a pancake box on the sheathing or do I need to recess it?
  4. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    You should use a weatherproof round electrical box and this can be mounted on the wall surface.

    Like this...
    http://www.fdsons.com/images/elect/5361-5.jpg

    But just use your judgement. If there is enough of a roof overhang and it looks like water will not get in there (like on a covered porch), then the weatherproof box / fixture may not be necessary. So long as water stays out, you are OK.
  5. Taylor

    Taylor New Member

    Messages:
    143
    Location:
    Northern Joisey
    Thanks, I believe that is designed to mount on top of the siding. My objections are (a) it's a bit unsightly and (b) all knockouts are for conduit. There's a knockout on the back so conduit could come from inside the house, but there'd need to be a junction box on the other side.

    I'm thinking an ordinary pancake box mounted on the sheathing, with the roof overhang, and a gasket between it and the light fixture, will be okay.

    As far as I can tell, all existing outside boxes on my house are ordinary boxes, painted over. Not something I plan to emulate, but ignorant as I am, I can't screw up worse than those that went before me.

    Thanks again for the advice.
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