Want to run new feed to garage

Discussion in 'Electrical Forum discussion & Blog' started by arfeller, Nov 12, 2009.

  1. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA
    I purchased my home about 2 year ago. The previous owner has used an exterior 12/2 with ground direct burrial cable to provide power to the garage.

    I would like to add a 220V circuit and up the power to the garage.

    I will abandon the 12/2 and run 6/3 with ground (romex, unless there is good reason to use single strand wires) in 2 1/2" conduit (underground). With a directly wired (No master) 100 amp 6 slot box mounted in the garage.

    Total wire run length is ~60 feet (box to box including bends). Actual distance is about 45 feet.

    I would use the 50 amp circuit in the house panel for the main.

    In the box, i would have a 20amp 220v circut, and then two 110v circuits, 15 and 20 amp

    So, if there are no problelms with this configuration, i do have a question about the grounding of the 100 amp box. The box comes with a grounding screw to connect the ground strip with the box. Do i use this?

    Thank you
    Last edited: Nov 12, 2009
  2. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    1. No romex. Not rated for underground.

    Use individual conductors. Black, black and white #8 and green #10 ground.

    2. 2.5" conduit is way overkilled. 1" is plenty.

    3. Neutral bus (white wires) is to be isolated from the enclosere. Do not install bond screw. Terminate grounds on a ground bar kit.

    Also, install two 1/2" x 8' ground rods at least 6' apart and run a #6 wire to the ground bus.
  3. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA
    1. Ok, good to know. This will save me on conduit also, I had chose 2 1/2" to get romex through.

    3. If i ground the box with ground bar kit, then why do i need to run #10 ground from the house? What will that connect to if I ground the box to the
    ground rods?


    Ok, I looked into this some more and think I understand. I will bring the grounding wire from the house to the subpanel in the garage. I will connect this to the grounding bar and then connect the grounding bar to the grounding rods. However, this bar will not be connected to the neutral bar with the supplied bolt

    Additionally, it sounds like my local code requires me to bring the feed into a 50 amp breaker (with a special bracket to secure in panel) to back feed the subpanel and create a shutoff

    This will be used in alternative to the main lugs. Then the other breakers will be installed beside it.
    And thank you for the reply!
    Last edited: Nov 12, 2009
  4. jar546

    jar546 In the Trades

    Messages:
    432
    Location:
    USA
    Finally a poster with a brain that is not trying to get out of good advice or waiting for someone to tell them what they want to hear. Congrats
  5. tjbaudio

    tjbaudio Sound and Light Suppervisor for a School District

    Messages:
    162
    Location:
    Wisconsin
    #8 is too light for a 50A feed. I would go #6.
  6. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    NEC Table 310.16 lists #8 as good for 50a in 75 degree column
    #6 is good for 65a
    If he's only going with a 50 a load/breaker he should be good
  7. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA
    Thanks again for the input and help.

    I have the ditch dug, conduit in, wire pulled, grounding rods pounded...

    Only thing I forgot was the darn grounding kit. Need to pick one up for the subpanel to hook up the grounding rods and ground.

    :)
  8. traffic626

    traffic626 New Member

    Messages:
    7
    Location:
    Boston

    If he's using conduit, why individual connectors instead of the underground rated wire? I'm asking because I have a 15A powering my garage and I was thinking of re-using the conduit to run a 30A panel.

    Regarding the ground rods, are they required if you have them at the meter for the service coming in from the street?

    Thanks!
    Eddie
  9. ActionDave

    ActionDave Electrician

    Messages:
    366
    Location:
    Colorado
    A better way to look at this is ask why would you use wire suitable for direct bury in conduit. Direct Burial rated wire can be in contact with the dirt, but if damaged you must redig to repair.

    Ground rods are required at each structure.
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