Garage Wiring Question

Discussion in 'The Bench' started by IlliniGSX, Jun 30, 2019.

  1. IlliniGSX

    IlliniGSX GSX #401

    Hi All,

    I assume we have to have a member or two who are electricians that can answer my question. A friend has a home with a detached garage The electric service drop enters the house through the mast and meter base as normal and connects to the main breaker. The main breaker feed is double tapped and feeds the detached garage breaker box. The double tap uses copper lugs that sit on top of the entrance cable secured by the set screws. The copper lugs have a socket for a wire end to terminate and a set screw to hold it in place. I know enough to know double taps are frowned on by the NEC so is there another way that is accepted by the code to feed the garage?

    Thanks Jim

    JESUPERCAT No Slow Boat

    My guess would be to put in a breaker in the main panel to feed the garage, based on the size of cable to garage.
    Smartin likes this.
  3. 64 skylark mike

    64 skylark mike Well-Known Member

    One way is to feed the garage from a 220 breaker in the main panel to a sub panel in the garage. You would have to have two spare spaces in the main panel and not be overloading the amperage already there. You can also have a disconnect on the house feeding a sub panel in the garage.
  4. Smartin

    Smartin Staff Member

    I have a 200 amp service going to the house, and ran a 100 amp breaker inside that box to a sub panel in the detached garage.
  5. 64 skylark mike

    64 skylark mike Well-Known Member

    I also have a 200 amp service in the house but a 60 amp breaker feeding the sub panel in the detached garage. It's only 16' x 20' so I don't need big power requirements in there like for a lift or welder. The sub panel is a 8 space Square D used panel I got for free on a remodel project.
  6. taf44667

    taf44667 69 Vert 4-Speed

    Same here with new garage. 200 amp service into house and 100amp ran to garage.
  7. IlliniGSX

    IlliniGSX GSX #401

    Thanks for all the replies. The double tap is what caught my attention as I know they are not approved unless the lug is specifically identified as suitable for double tapping. I will suggest adding a breaker to feed the garage. I am hoping there is space for another breaker.
  8. John Codman

    John Codman Platinum Level Contributor

    That sounds like you are cutting things a bit thin. If you are cooking with gas and don't have an electric water heater you are probably OK, but here in sunny Florida our AC is fused (breakered) for 50 amps by itself, and this is a new, more efficient unit then our old one that was fused for 60 amps. If we add a garage/shop (and I intend to), we will have to go to 300 amp service.
  9. Smartin

    Smartin Staff Member

    I’m on propane for several of my appliances. Unless I was running a bunch of stuff at once, it won’t be an issue here.
  10. ragtops

    ragtops Gold Level Contributor

    In my area things may or may not be the same as the rest of the country. I'm in southern Ohio.
    I live in town and the electric lines run through the alleys. So I did some work on my house and garage. I knew a guy who worked for the electric company, just saying I didn't know it existed until he told me that he would have the power company install a double lug (Or whatever term he used) meter base. One meter but in the base it has two 200 amp hook ups. We put the drop/meter base into the garage, I ran the house service underground and just put another 200 amp breaker box in the garage, the house also has 200 amp service. You may be able to do the same at your place. The new drop and that meter base with the double lug stuff cost me nothing.
    Another funny story about the power company doing the new drop. Several years later I had a problem, I lost power on a Sunday. Power co sent a man out, we checked everything and decided it was in the meter base. So he went up in the bucket and cut the power lines so no juice for sure. We pulled the meter and found the ground wire the power company co had installed had never been tightened up, It had been loose but working for years. He tightened it, then he had to reconnect the power wires. No problem since. Guy said he couldn't believe it ever worked and never saw anything like that before.
  11. Steve Craig

    Steve Craig Gold Level Contributor

    Couple options available. I'm familiar with the CEC, NEC not too much but believe they are similar.
    Ideally, as others have already posted, put in a 2P xx breaker based on the conductor size going to the garage. NEC will dictate the maximum size allowed.
    Second option:
    Remove an existing 2Pxx breaker & cabling. Put a new 2Pxx breaker in the existing panel, refeed a new pony-panel next to it. Refeed the circuit(s) you removed from the original to make space for the pony panel. Put a new 2Pxx breaker sized to suit the garage conductors.
    Any qualified electrician in your area could handle this.
    Wired a friend's garage a few years ago-2 story with a 4 post lift, a large compressor, in-floor heat & every gadget you can think of. He builds street rods & repairs/restores many cars locally.
    I put in a sub-feed from his house & installed a new panel in the garage. 60A 120/240 is plenty.
  12. Redmanf1

    Redmanf1 Gold Level Contributor

    The old garage that I added on to had a 30 amp braker panel feed from the house. I just had a new 200 Amp panel and service added to the garage. They did a new line drop just for the garage.
  13. gstewart

    gstewart Well-Known Member

    do u not need hardware to isolate the garage from the house?
  14. tt455

    tt455 T Bone

    Yes if the main breaker isn't designed for two conductors it could well overheat. What I did was added a 50 amp breaker with a 4 awg wire from the home main panel to a 50 amp main breaker to the detached garage sub panel. I had to get some thin 20 amp breakers to make room for the 50 amp breaker, which is what your friend may have to do. And 50 amps is plenty for me, I have 220 air compressor, lift, and heater plus the high hats, work bench lights and outlets plus I ran power to the shed. I never tripped a breaker yet, but every things never on at once.

    home garage
    breaker2.jpg breaker1.jpg
  15. wkillgs

    wkillgs Gold Level Contributor

    Anybody know what grounding is required at the garage?
    Just a ground wire to the main panel in the house, or add a ground rod at the garage? I believe both are needed but not sure...
  16. Dano

    Dano Platinum Level Contributor

    Per Code, IIRC the rule is greater than 25' and you need to have a way to disconnect the sub panel, but only if there are more than 6 "throws" in the sub-panel (incl. the main in the sub-panel if there is one). Otherwise the double tap is ok per code if designed for it so assuming it's more than 25' and more than 6 throws, you could either add an OC device (i.e. breaker) for the sub-panel if there's space or a disconnect if the existing main is designed for a double tap (I don't think the sub-panel has to be on an OC device, but I learn all this stuff when I need it and then wind up forgetting it). Size the OC device based on the wire size assuming he doesn't want to run new wire (backwards of how we'd normally do this, but the existing wire is now the limiting factor). Of course if less than 25' and less than 6 throws, you could set the main up correctly for the double tap if it's not (sounds actually like it may be) and be legal - It's possible that this whole setup passed inspection at some point. Go on Mike Holt's Electrical forum and search this up. I read a thread or two on there not long ago that addressed all this when I replaced the sub-panel in the shop and added a sub-panel for the pool. Ton of info on there are some real code gurus, but they have a strict rule on not asking "how to" questions.

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