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  1. #1
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    Default setting up shop, running secondary to outbuilding

    Hey all

    I have been reading a lot on this forum, so thanks to you all for your insight. I have been attempting to learn what it will take for me to run secondary to a (sub)panel in my garage, 35ft from the main house (87ft from panel to proposed new panel location). I am a hobbyist woodworker with relatively basic machinery, with some exceptions.

    I have recently sat down and written my plan and thoughts down for the sake of getting them out of my head and onto paper. I was hoping someone might have a peek and tell me if I am on the right track or way off base in my understanding.

    The very brief version is:
    New homeowner and novice looking to run 60a secondary off 125a panel (200a service) from main building/main panel to garage panel, while oversizing things for future upgradeability. Looking for insights and error checking on specific/technicals and theory.

    The very long version is:

    Our house is brand new to us, but your basic late '40s 2bd/1ba with half-finished basement, a 2+car outbuilding and a mix of gas/elec appliances with an AC. According to city records, the house pulled and completed inspection on a work permit for 200amp service upgrade. There is a newish Eaton panel with 200 amp main breaker, though the panel is rated @ 125amps. So, being the weakest link, the service I am working with is 125amps - as i understand it.

    Here is the main:
    https://i.imgur.com/qPG0eLs.jpg
    https://i.imgur.com/k0g6iHs.jpg


    I will safely open the panel this weekend to observe the conductor sizes/ratings, but my assumption is that the previous owner upgraded to 200amp to add AC, but it cost less in material and labor to upgrade the panel to only 125a, which is probably a reasonable load limit for the previous occupants -- is that a reasonable assumption? I ask because I want to make sure I understand the panel setup and the limitations I will have for a secondary service to my garage shop. (hobbyist woodworker, basic shop setup with mostly 1ph, 120v single horse machines, a 240v jointer, and a 3ph 5hp old planer I will run on a 7.5hp 240v RPC. One machine+dust collection+lights at a time. )


    My plan, at current, is to occupy the final, top two slots with a 60amp (30/30) breaker protecting adequately rated and sized conductors from panel to basement/foundation wall, out and underground in a PVC raceway to a subpanel in the garage.


    I want to install a 100amp subpanel in the garage to give myself space for the future when I have the funds and/or time and knowledge sufficient to upgrade the main panel from 125 to 200a. So for the time being, I will make due with 60a service, which I believe would be plenty for my hobbyist needs right now (again: single machine via RPC+2hp dust collection+led lights at a single time is what I expect to max out at at any given time)


    The run from panel to panel is ~86feet, 35' of which will be 18" underground.
    I am thinking aluminum for the sake of cost, but I am a little unclear on the pros and cons versus cost with AL and CU. Im considering 4 wire (hot, hot, neutral, ground) romex/NM from main panel to foundation wall junction box to (4 wire, single strand (per code?)) URD in pvc raceway to the subpanel, which will have a main disconnect and non-bonded grounds and neutrals. I will add 2 8ft grounding electrodes, 8ft apart on braided CU.


    To make things a little more "futureproof", I am thinking of oversizing the feeder to guarantee a future move to 100a. This is where I get a little hazy. I assume I will be sizing based on the 75℃ column (but will verify all breakers and conductors are appropriately rated), but the actual gauge of things is a bit confusing. If using AL, I've read that I may need to be a size larger than I would if were in CU due to physical limitations. would 2-2-2-4 AL URD be capable of carrying 100amps over 90ft within safe voltage drop parameters? Is that overkill? I probably need to read more.


    That pretty much sums up where I am at in my understanding at this particular moment.
    Does it sound like I am on the right track?


    And to end it all on a question that I should probably ask right at the top?
    Is it necessary to run a comprehensive wattage/load audit on our house before I go any further? I also have access to our smart meter basic daily usage data - if that's at all useful.

    What else am I missing?

    Thanks for reading, if anyone made it this far!

    Similar Threads:
    Last edited by flargen; 09-09-2021 at 11:25 PM.
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  2. #2
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    Mar 2009
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    Colorado Front Range
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    Default Re: setting up shop, running secondary to outbuilding

    Exactly what is rated 200 AMPs? The panel you show is a 125 AMP so where is the 200 AMP breaker? Do you have a 200 AMP panel outside, or a main disconnect?

    The panel you show is marked as a main disconnect but if there is a 200 AMP over currennt device ahead of it THAT is the main disconnect.

    Pictures of everything starting at the meter would be most helpful here.

    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

  3. #3
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    Default Re: setting up shop, running secondary to outbuilding

    Quote Originally Posted by Bill Kriegh View Post
    Exactly what is rated 200 AMPs? The panel you show is a 125 AMP so where is the 200 AMP breaker? Do you have a 200 AMP panel outside, or a main disconnect?

    The panel you show is marked as a main disconnect but if there is a 200 AMP over currennt device ahead of it THAT is the main disconnect.

    Pictures of everything starting at the meter would be most helpful here.
    Thanks Bill - in a way, you answered a basic question - I have a fundamental and important misunderstanding of double pole circuit breakers. I dont know if I created this lie myself, or was told this at some point long past - but I just assumed the 100a double pole meant 200a, not 100a, 240v.

    I have placed a call to the city to try to discern what a permit at this address with a case description of "200amp service and one ckt for office" actually means. I assumed it meant they increased the service, but that doesnt exactly track when the main is still set up for 100a.

    There is a meter outside, but no exposed panel (perhaps its behind the aluminum siding?). sorry - homeownership is also new to me.


  4. #4
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    Mar 2009
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    Default Re: setting up shop, running secondary to outbuilding

    I've never understood why someone would put in a 200 AMP service, that is, the meter housing and service wiring and then install a 125 AMP panel - that has a 100 AMP main breaker, which you appear to have.

    I think you really need to have someone evaluate this set-up for you so that there is no guessing what is involved, and exactly what you have.

    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

  5. #5
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    Default Re: setting up shop, running secondary to outbuilding

    Quote Originally Posted by Bill Kriegh View Post
    I've never understood why someone would put in a 200 AMP service, that is, the meter housing and service wiring and then install a 125 AMP panel - that has a 100 AMP main breaker, which you appear to have.

    I think you really need to have someone evaluate this set-up for you so that there is no guessing what is involved, and exactly what you have.

    If you're confused by that premise, imagine what the levels of confoundment I am dealing with.

    So, while I wait on the city to return my call, I also put in an email to the previous owner's agent and friend in the hopes she might have saved some work orders or has a recollection of what took place.

    In the meantime, I cut power and opened up the panel.

    Photos:
    https://i.imgur.com/nViuubn.jpg
    https://i.imgur.com/bkxrNg5.jpg
    https://i.imgur.com/a6eZAqJ.jpg
    https://i.imgur.com/PTgPbPc.jpg
    https://i.imgur.com/0zIaXlN.jpg

    A couple things stood out -

    1. my hopes of using the final slot to run 60amps to the outbuilding are immediately dashed as there is no more actual space on the bus. So a new main will be needed no matter what I plan on doing.

    2. I dont see a green bonding screw anywhere.

    3. The feeder lugs are floating freely. All examples I have seen in my research thus far have been anchored to the panel above the bus.

    3. Theres signs of past arcing behind the panel face - no signs of damage to any current hardware or cabling, but perhaps the person who ran the job didnt properly tape the lugs before he threw the cover on?

    4. This looks like 3/0 AL. All i can glean from the sheathing is Hatvinol 909__3 Type THW. Appears to be a few hairs more than 3/8 in dia. 3/0AL supports up to 155a @75C, if im not mistaken?

    What do you see in this setup? Is there potential that this is actually 200a service coming in from the meter?

    Anything else seem immediately wrong here?

    thanks much for chiming in.


  6. #6
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    Mar 2009
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    Default Re: setting up shop, running secondary to outbuilding

    Pictures need to start at the meter end of things. I'm seeing about what I expected in the panel.

    The red cable supplying the 100 AMP breaker in the panel is #3, not 3/0, wire size.

    I suspect that whatever was permitted, the only thing that probably happened is that an older 100 AMP panel was replaced with a newer panel. The service feed to the panel is too small for a 125 AMP breaker.

    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

  7. #7
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    Sep 2021
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    Default Re: setting up shop, running secondary to outbuilding

    Thanks Bill.
    I'll look into getting access to the meter.
    I assume that will involve calling the power company since there is no accessible panel under the meter outside.


  8. #8
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    Aug 2008
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    Maryland
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    Default Re: setting up shop, running secondary to outbuilding

    You do not add up each pole of the breaker. That breaker is 100 amps.

    All answers based on unamended National Electrical codes.

  9. #9
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    Sep 2021
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    Default Re: setting up shop, running secondary to outbuilding

    Yes Jim, Bill helped me see the error in my understanding there. Thanks.

    I spoke to the city's sr. inspector today and he informed me that the 200a service note does not mean necessarily that 200amps was installed. Apparently that is an umbrella for all amperage upgrades up to 200a.

    So I'm waiting to hear from the POCO to schedule a meter locate so I can discuss my options going forward.

    Luckily, according to the inspector, homeowners in my juris. are allowed to do electrical work on primary residence. So I will be able to continue to plan this out and learn along the way.

    Thanks for the help so far. I'm sure I'll be back to this thread to post updates and ask questions.


  10. #10
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    Mar 2009
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    Default Re: setting up shop, running secondary to outbuilding

    You don't know where your meter is?

    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

  11. #11
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    Sep 2021
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    CA
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    Default Re: setting up shop, running secondary to outbuilding

    Quote Originally Posted by Bill Kriegh View Post
    You don't know where your meter is?

    I know where the meter is.

    I need to know what's going on inside and what next steps are for upgrading service since there are some questions as to how the box is see into the side of the house, the masts location under the eave, etc.

    I asked the inspector on the phone what steps I would take to get things going and his advice was to call poco and request a meter spot.


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