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Thread: Line-Side Tap on Residence

  1. #11
    Join Date
    Sep 2012
    Location
    Clinton, WA
    Posts
    73
    Having no main breaker in the garage sub-panel complicates things a little when doing a feeder tap. You have to follow 705.12(B)(2)(1)(a), which usually requires upsizing the feeder conductors, and nobody wants to do that. To get around this you can land the feeder conductors in the sub-panel on a breaker with a tie-down kit, instead of the main lugs. That will allow you to qualify under 705.12(B)(2)(1)(b), which doesn't require upsizing the feeder conductors.

    I was not aware that some municipalities do not allow feeder taps. It would be a drag to find that out after the install was done.

  2. #12
    Join Date
    Mar 2015
    Location
    Berkeley, CA
    Posts
    68
    This is a photo of the main panel: https://ibb.co/iNsCbS

    What kind of panel is this? I'm not sure if you would call this a main breaker type panel? It just looks a lot different than what I am used to seeing.

    I would ultimately just like to relocate this breaker to a new subpanel right next to the main panel, and then put the PV breaker in the new subpanel, too. The feeder tap was just sort of a last resort.

    Andy

  3. #13
    Join Date
    Jun 2004
    Location
    Cherry Valley NY, Seattle, WA
    Posts
    3,806
    Quote Originally Posted by andrew.tkelly View Post
    What kind of panel is this? I'm not sure if you would call this a main breaker type panel? It just looks a lot different than what I am used to seeing.

    Andy
    I have wondered that myself. I call them circuit breaker enclosures. Its just a circuit breaker and an enclosure. I am not sure what the NEC considers them. Maybe they are still panelboards but I'm not sure. Anyone know?
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  4. #14
    Join Date
    Mar 2015
    Location
    Berkeley, CA
    Posts
    68
    Quote Originally Posted by electrofelon View Post
    I have wondered that myself. I call them circuit breaker enclosures. Its just a circuit breaker and an enclosure. I am not sure what the NEC considers them. Maybe they are still panelboards but I'm not sure. Anyone know?
    I'm glad I'm not the only one that's stumped. Here's a pic of it from the outside, too: https://ibb.co/ey5yGS

  5. #15
    Join Date
    Jun 2004
    Location
    Cherry Valley NY, Seattle, WA
    Posts
    3,806
    Yeah I have used things like that, mostly as a service disconnect where the main panel cant be "nearest the point of entry". Sometimes I use a safety switch but sometimes a circuit breaker and enclosure - or whatever the technical name is.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  6. #16
    Join Date
    Oct 2009
    Location
    Austin, TX, USA
    Posts
    8,960
    Quote Originally Posted by andrew.tkelly View Post
    This is a photo of the main panel: https://ibb.co/iNsCbS

    What kind of panel is this? I'm not sure if you would call this a main breaker type panel? It just looks a lot different than what I am used to seeing.

    I would ultimately just like to relocate this breaker to a new subpanel right next to the main panel, and then put the PV breaker in the new subpanel, too. The feeder tap was just sort of a last resort.

    Andy
    It's not a panel at all; it's an enclosed breaker used as a main service disconnect. Panel bus rules do not apply.

  7. #17
    Join Date
    Mar 2015
    Location
    Berkeley, CA
    Posts
    68
    Quote Originally Posted by ggunn View Post
    It's not a panel at all; it's an enclosed breaker used as a main service disconnect. Panel bus rules do not apply.
    Awesome! Thank you for clarifying this.

    Andy

  8. #18
    Join Date
    May 2011
    Posts
    3,944
    Quote Originally Posted by andrew.tkelly View Post
    This is a photo of the main panel: https://ibb.co/iNsCbS

    What kind of panel is this? I'm not sure if you would call this a main breaker type panel? It just looks a lot different than what I am used to seeing.

    I would ultimately just like to relocate this breaker to a new subpanel right next to the main panel, and then put the PV breaker in the new subpanel, too. The feeder tap was just sort of a last resort.

    Andy
    You should see if it's possible to put a main breaker in the subpanel that that breaker is feeding. If so, a load side tap will probably be a lot easier. I've done the new subpanel thing a lot with 100A feeders. With 200A, the equipment is more expensive, there's fewer options, more space required, and much more difficult to handle 200A wiring. Looking at your photos and trying to imagine how you're going to get two 200A feeds in and out of that enclosure makes me wince.

  9. #19
    Join Date
    Mar 2015
    Location
    Berkeley, CA
    Posts
    68
    Quote Originally Posted by jaggedben View Post
    You should see if it's possible to put a main breaker in the subpanel that that breaker is feeding. If so, a load side tap will probably be a lot easier. I've done the new subpanel thing a lot with 100A feeders. With 200A, the equipment is more expensive, there's fewer options, more space required, and much more difficult to handle 200A wiring. Looking at your photos and trying to imagine how you're going to get two 200A feeds in and out of that enclosure makes me wince.
    After reviewing it with others, we decided to de-rate the "main breaker" in the circuit breaker enclosure down to 150A. This would allow us to keep the existing 4/0 aluminum conductors. From my understanding of the Code, the conductors on the load side of the inverter output connection have to be able to handle an ampacity equal to the value of the primary source overcurrent device plus 125% of the inverter output circuit. In this case, it would be 150A + (21A x 1.25) = 176.25A. 4/0 aluminum conductors have an ampacity of 180A.

    As far as the 10-ft tap rule, the tap conductors would have a minimum circuit ampacity of:
    0.1 x [150A + (21 x 1.25)] = 17.625 amps

    However, 125% of my inverter output current is greater than that (26.25A), so I would size the conductors to the higher ampacity.

    New questions:

    1.) Do the tap conductors HAVE to be protected by a fused AC disconnect, or is okay if I use a circuit breaker?

    2.) Can I do a feeder tap in any old NEMA-rated electrical enclosure?

    Andy

  10. #20
    Join Date
    May 2011
    Posts
    3,944
    That's a good way to do it.

    You can use a circuit breaker instead of a fused disco. But the only reason I can think of for doing so is if you have a combined panel for your solar, and you want to save a piece of equipment.

    And yes, you can use any electrical enclosure that has a NEMA rating appropriate to the location. There are also some size requirements based on the wire size and such.

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