what is the best way to wire this sub panel
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  1. #1
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    what is the best way to wire this sub panel

    A friend of mine just purchased a farm. He wants to run a line from a 200 amp box on one building to power a new panel in a building 150 ft away. The new box will be for 100 amps. He has enough copper wire to run to the other building. It is 4/O . It has been a long time since I did much of this but I told him the best way was to put a 100 amp breaker in the existing 200 amp box then connect the wire to the 100 amp breaker. The problem is that the lugs on the breaker are not large enough for 4/O wire.

    I am sure 4/O is plenty large enough for the load . How would you wire this per code? Would you run 4 wires or 3 and install a ground rod at the new box. How would you wire into the existing 200 amp box with this large of wire?

  2. #2
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    Re: what is the best way to wire this sub panel

    4/0 is way overkill for 100 amps. He might be able to get lugs to install in the breaker for the bigger wire. To do it right it should be 4 wired
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  3. #3
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    Re: what is the best way to wire this sub panel

    4 wires and ground rods. Both required. Many ways to deal with the 4/0. If you want to use the 4/0 buy some Polaris connectors to fit 4/0 and connect some #2 pigtails to it at the breaker. You will still gain the full advantage of the 4/0 regarding voltage drop. You could also just make the sub panel 200 amps and feed it with a 200 amp breaker but you may not be able to fit one in the main panel, or there may not be one available depending on the make and age. They are also pricey. Alternately if the present main panel has a 200 amp main you could just hook those 4/0s up to a terminal block. Keep in mind no matter what you do there needs to be a main disconnect at the detached building. Me I would get a terminal block for the main panel and a 200 amp main breaker sub panel at the detached building.
    Last edited by bigb; 08-16-2019 at 10:06 PM.
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  4. #4
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    Re: what is the best way to wire this sub panel

    I know 4/O is way over kill but he already has it so it costs nothing to use it if he can. I will investigate polaris connectors, I never heard of them .

  5. #5
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by thegary View Post
    I know 4/O is way over kill but he already has it so it costs nothing to use it if he can. I will investigate polaris connectors, I never heard of them .
    They are just rubber covered lugs. You can get them in as many holes, sizes and styles you need to accommodate your situation. Yours is easy to find 2 holes that are enterable from both sides would be better so it continues kinda straight rather than having to loop the smaller one around.

    These actually are Polaris brand but there are many manufacturers of these type of splice blocks. They have gator bites too that have teeth that penetrate the insulation so you don't have to strip the wire. I do not like or use them but they sell them.

    https://www.polarisconnectors.com/pd.../IT_series.pdf
    Last edited by danielplace; 08-17-2019 at 11:50 AM.

  6. #6
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by danielplace View Post
    They have gator bites too that have teeth that penetrate the insulation so you don't have to strip the wire. I do not like or use them but they sell them.

    https://www.polarisconnectors.com/pd.../IT_series.pdf
    I use them all the time and when you consider time & labor they are cheaper than split bolts. Where did you get the idea they have gator bites?
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  7. #7
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    Re: what is the best way to wire this sub panel

    NEC prohibits supplying one agricultural building from another.
    Ag code shows a central distribution point where each building gets power from.
    I'll study it better.
    Last edited by Willie B; 08-17-2019 at 01:12 PM.
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  8. #8
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by bigb View Post
    I use them all the time and when you consider time & labor they are cheaper than split bolts. Where did you get the idea they have gator bites?
    Ilsco brand Gator Bites. Seen plenty. Bolts are electrically isolated too so they could be bolted on without doing a shutdown.

    https://i.imgur.com/7wZCnyN.png

    Way better than a split bolt for sure. Just buy them with as many extra holes as the future will require and never have to tear apart a massive mess of a split bolt connection to add future services to the gutter.
    Last edited by danielplace; 08-17-2019 at 02:24 PM.

  9. #9
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by Willie B View Post
    NEC prohibits supplying one agricultural building from another.
    Ag code shows a central distribution point where each building gets power from.
    I'll study it better.
    I think it can be done as long as there is a single disconnect that will shut all the buildings down.

    Page 13 shows example of a building fed from another. Didn't have time to read it all. ??? 2008 also.

    http://www.adamselectric.coop/wp-con...-Buildings.pdf

  10. #10
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by danielplace View Post
    I think it can be done as long as there is a single disconnect that will shut all the buildings down.

    Page 13 shows example of a building fed from another. Didn't have time to read it all. ??? 2008 also.

    http://www.adamselectric.coop/wp-con...-Buildings.pdf
    Thanks for the link. I am going to print it off and give it to him. I will also tell him about the polaris connectors and to use some pig tails to wire into a breaker. Go 4 wires and a ground rod.

    What size ground would you run and would you use bare wire or insulated?
    Last edited by thegary; 08-17-2019 at 01:47 PM.

  11. #11
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    Re: what is the best way to wire this sub panel

    I don't know if I would trust those either. I don't even trust those low voltage thingys that look like beans with the teeth in them
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  12. #12
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    Re: what is the best way to wire this sub panel

    Pin adapter for the win IMO. Just do a google search for " pin adapter reducer " . Use a large lug adapter for the nuetral and ground.

    Alternatively you can use a " splicer reducer " (the square ones with two set screws are pretty cheap and are basically polaris connectors without the insulation). I believe you may need to install this in a junction box separate from the load center. Use large diameter UL listed heat shrink for a cleaner look over electrical tape on the splicers. Polaris connectors are large, EXPENSIVE, and I believe are required to be installed in a junction box outside the loud center - but they are easy to install and to re-work.

    Pin adapters are about the cleanest, easiest solution you'll find - and very reasonable price wise. Make sure whatever you use is legal code wise as codes are different everywhere, inspectors are usually pretty helpful in my experience as long as you treat them with respect and show you're not so smart you're an idiot (they don't like you getting "inventive" and playing lawyer ball with the code lol).
    Last edited by SlowBlues; 08-17-2019 at 04:40 PM.

  13. #13
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    Re: what is the best way to wire this sub panel

    Would sharkbites be any better than using backstabs on a switch or receptacle?
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  14. #14
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by SlowBlues View Post
    Polaris connectors are large, EXPENSIVE, and I believe are required to be installed in a junction box outside the loud center -.
    Code does not prohibit the use of any type of splicing device in a panel so long as the allowable cubic inches of box fill are not exceeded ....
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  15. #15
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    Re: what is the best way to wire this sub panel

    If you don't have a crimper you can usually get hydraulic crimping done somewhere local on the cheap. Check with local welding suppy, car audio installers, battery retailers, electrical supply places, and local mechanics/shops for prices/availability. A cheap hydraulic crimper can be found around $60 and is a handy tool to have.

  16. #16
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by danielplace View Post
    I think it can be done as long as there is a single disconnect that will shut all the buildings down.

    Page 13 shows example of a building fed from another. Didn't have time to read it all. ??? 2008 also.

    http://www.adamselectric.coop/wp-con...-Buildings.pdf
    As I say, I'd have to refresh on the subject. 10 years back one of those billionaire hobby farms turned into a foundation in their memory was doing a rewire. I studied the code, and conferred with the inspector. He assured me he would not approve without a "central distribution point"
    I was underbid by the inspector's neighbor. The job was done with 400 amps single phase to the first building, then all other buildings were fed from there. NO bonding was done at all. The inspector passed the job.

    The moral of this story is: It's not what you know, it's who you know, and Different rules for different fools.
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  17. #17
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    Re: what is the best way to wire this sub panel

    I did not see anything in NEC article 547 requiring a central distribution point for agricultural buildings, it is allowed/permitted though.

  18. #18
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    Re: what is the best way to wire this sub panel

    Our inspector allows feeding one building from another as long as wire sizing breaker sizing and bonding requirements are followed. Polaris connectors are a good option. 2 hole ones that fit 4/0 are probably 20$ each but are reusable and a clean option
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  19. #19
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    Re: what is the best way to wire this sub panel

    Is there room for a junction box next to existing panel ? Buy wire for beaker, add junction box or a disconnect and run 4/0 from there.

  20. #20
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    Re: what is the best way to wire this sub panel

    If it were my project I would go with the splicer/connector (square one with two set screws) to a smaller pigtail, some large UL listed heat shrink (heat shrink a layer or before installing, then cut out holes for the set screw and you have a "ghetto" polaris). I'd use a J-box if it was too jury rigged looking (those monkey knuckles/polaris and even the splicer/reducer can get REALLY large in 4/0 size). Really hard to justify the cost of the polaris connectors (unless it's a smaller gauge cap.) where I live. My .02 cents

  21. #21
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by SlowBlues View Post
    If it were my project I would go with the splicer/connector (square one with two set screws) to a smaller pigtail, some large UL listed heat shrink (heat shrink a layer or before installing, then cut out holes for the set screw and you have a "ghetto" polaris). I'd use a J-box if it was too jury rigged looking (those monkey knuckles/polaris and even the splicer/reducer can get REALLY large in 4/0 size). Really hard to justify the cost of the polaris connectors (unless it's a smaller gauge cap.) where I live. My .02 cents
    If you have more time than money just use split bolts. Yes 4/0 Polaris can be pricey, about $35-$40 each I think
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  22. #22
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    Re: what is the best way to wire this sub panel

    Quote Originally Posted by SlowBlues View Post
    If it were my project I would go with the splicer/connector (square one with two set screws) to a smaller pigtail, some large UL listed heat shrink (heat shrink a layer or before installing, then cut out holes for the set screw and you have a "ghetto" polaris). I'd use a J-box if it was too jury rigged looking (those monkey knuckles/polaris and even the splicer/reducer can get REALLY large in 4/0 size). Really hard to justify the cost of the polaris connectors (unless it's a smaller gauge cap.) where I live. My .02 cents
    You can use them in the panel legally.
    Hard to justify the cost of Polaris taps but your going to install a J box for the jerry rig. On the mains, oh sure. I bet that will be beautiful and cheaper.
    Last edited by danielplace; 08-19-2019 at 03:10 PM.

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