Long distance outdoor lighting

Discussion in 'Electrical Forum discussion & Blog' started by Savageriver, Oct 18, 2009.

  1. Savageriver

    Savageriver New Member

    Messages:
    1
    Location:
    Maryland
    Good Morning,

    I am trying to run an outdoor lighting system from my main panel to the front gate of my property. The total one-way run to a 3-way switch at the gate will be 275 feet so I guess that the total circuit length will be 550 feet plus a few feet to the lights. The load will be approximately 660 watts (5.5 amps?) of outdoor spot lights and be connected to a 15-amp breaker at the main panel. Can I run from the main panel to the LB fitting with 12-2 NM-B and then run from the LB fitting with 10 gauge to a junction box approximately half way to the 3-way switch at the gate? I’d like to come from the junction box to the 3-way switch at the gate with 12 gauge as I have the appropriate lengths of the different gauges of wire already.

    Thanks in Advance!
    SR
  2. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    When you run wire long distances, you get "voltage drop". There are many free "calculators" for this on the internet. Search google.com for the words...

    voltage drop calculator

    Some are easier to use than others. (You would select 1 phase or single phase.)
  3. jbfan74

    jbfan74 Electrical Contractor

    Messages:
    131
    Location:
    Newnan, GA
    You can splice inside the lb, but it must have enough room to handle the connductors.
    It will be better to install a weather proof box and make the splices there.

    Do you not have enough wire to make a complete run without splicing in the middle?
  4. Ford2001

    Ford2001 New Member

    Messages:
    44
    Location:
    Manchester, Vermont
    Trying using UF-B 103/ground cable.
  5. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    1. Use a jbox instaed of an LB

    2. I always suggest against using birect buried cable/wire. Conduit is cheap insurance from damage, Stuff happens.

    3. Your voltage drop on 275' of #12 is about 5% or 6 volts. I would use #10 for that distance.
  6. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    Incands will last longer at lower voltages.
  7. Ian Gills

    Ian Gills Senior Robin Hood Guy

    Messages:
    2,777
    Location:
    USA
    A lot longer.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,537
    Location:
    Cave Creek, Arizona
    wire

    IF you are going from the panel, to the first switch, to the second switch, and then to the lights, you will need THREE wires, and the distance will only be 275'. If you go from the panel to the "second" three way, and from there back to the first one, and also to the lights, then you need FOUR wires and the distance will be 550'. PLus, either one will also need a ground wire.
  9. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    I would hope that much light will only be on infrequently. It would be awfully wasteful/hard on the wallet to have it on dusk to dawn (several thousand kwh/year). If it's going to be on dusk to dawn then you might want to consider more efficient lighting solutions.
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