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What Size Wire Should I Use To Supply 200 Amps Of Power To My Pole Barn?

July 26, 2006

Q: What size wire and how many conductor do I use to run 200 amp from my meter socket to my 200 amp main breaker my pole barn ?

A: The first thing you need to do is determine if you can do this work. Installing your main power is one of the few electrical wiring projects that most areas do not allow homeowners to do. Please check with your local building codes department before beginning any work. If you are able to do this work, please pull a permit and get the work inspected after completion. 

If your run is 100 feet or less you need to install 3/0 copper or 250 kCMil aluminum. If you also install phone, TV or gas to this building, you need to install 2 – hots, 1 – neutral and 1 – ground. In this instance, your ground wire needs to be a minimum #4 copper or #2 aluminum.

If your run is over 100 feet you need to plan for voltage drop and increase your wire by 1 size for each 100 feet over 100 feet. For example, if your run is 150 feet you need to install 4/0 copper or 300 kCMil aluminum. This will also increase your ground wire size to #2 copper or 1/0 aluminum.

If you don’t install any other utilities to your barn you may only run 2 – hots and 1 neutral. However, this will require you to install a ground at your panel in the barn. The best way to do this is to install 2 – 8′ x 5/8″ galvanized ground rods 6 feet apart. Then install a continuous #6 bare copper wire from your panel, to each ground rod and back to the panel. Do not cut this wire, make it one continuous loop from your panel through each ground rod and back to your panel.


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4 Responses to “What Size Wire Should I Use To Supply 200 Amps Of Power To My Pole Barn?”

  1. Bill on October 12th, 2006 8:42 pm

    I am hooking up a 50 amp 240 v outlet for a travel trailer. my run is 130 feet. what size aluminum or copper wire do you recommend?

  2. Administrator on October 13th, 2006 4:49 am

    Hello Bill,

    Thank you for your question.

    At 130 feet you would see a voltage drop of approximately 6 volts. At 240 volts, this is approximately 2.5% voltage drop and less than the NEC limit of 3%. So, there is no reason to upsize your wire.

    The wire size depends on what you are going to use and where it will be installed.

    The maximum ampacity rating for #6 copper NM cable (romex) is 55 amps. This type of cable is typically installed in houses. Refer to NEC article 334 for NM cable requirements.

    The maximum ampacity rating for #6 aluminum SE cable (service-entrance cable) is 50 amps. This type of cable is typically installed in houses. Refer to NEC article 338 for SE cable requirements.

    If you are going to install your wire in conduit -

    The maximum ampacity rating for #8 copper THHN is 50 amps.

    The maximum ampacity rating for #6 aluminum XHHW is 50 amps.

    I prefer copper wire but, at today’s prices, aluminum is a better value.

  3. Karl Burgeson on July 13th, 2010 7:03 am

    I need 50 amp service (30 for pump and 20 sprinklers etc) to my well 300 feet from my 200 amp service I am getting confused as to what type of wire to use is aluminum 2awg 3 strand ok? And what would be the maximum amps that I could get, a company in Denver that sells wire to contractors like me says that 2AWG aluminum is overkill for that distance? Thank-you Karl

  4. Paula on April 26th, 2013 8:19 pm

    Ok mom has a 2200 sf house. The electric has been going crazy. Shutting off and on for 5 sec. to 3 min (whole house) sporadically. The electric company put a reader at the pole and in side the house. Report has determined that it is inside her house or most likely the underground wire from the pole to the house. ( approx. 20 years old possibly no conduit, with massive tree roots). We replace the 20 yr old 200 amp service at the pole with new 200 amp box and breakers before el. company read the amperage in the house, they are saying she is getting about 1/2 the service. Now we have no Idea of what wire is needed. On company asked 100 or 200 (100 @1.60 a foot and 200 @ 3.46 foot), another person is saying to get 4/0-2/0-4/0 wire (@2.35 to 2.50 a foot) I need to know what exactly to ask for, it will go in 2″ PVC conduit. Needed to run approx. pole to in ground 5′ (rough) 105 ‘ across to house then approx. 10′ from in ground to inside house to main breaker box. Total of 120′ to 125′ (give or take). Please break it down to where I can understand, some knowledge of wiring, none as far as as out side the house. Thanks for your help I advance. Paula

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