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Kevin
Kevin, Licensed Electrician
Category: Electrical
Satisfied Customers: 2953
Experience:  29 years as a Licensed Electrical Contractor in Illinois, 5 year college Electrical Instructor, Former Electrical Inspector, Diploma in Digital Electronics, Former Illinois Licensed Home Inspector
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I am adding a 100 amp service in a barn located

Customer Question

I am adding a 100 amp service in a barn located approximately 330 feet from the 200 amp service box in my home. I am planning on trenching the line and placing in 1-1/4 inch electrical pvc conduit. Please advise as to the size of the line. I would prefer to use aluminum. Thank you.
Submitted: 1 year ago.
Category: Electrical
Expert:  Kevin replied 1 year ago.

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) The National Electrical Code recommends that the voltage drop be 3% or less. Using 240 volts @ 100 amps on a 330 foot run results in using 3/0 AWG Aluminum conductors with an insulation rating of type "THW" for wet conditions. The voltage drop on the 3/0 Aluminum feeder conductors will be @ 3% or a loss of 7.1 volts. Therefore, the 3/0 Aluminum feeders are code compliant.

2) The feeder circuit needs to be a 4 wire circuit comprised of 2 hots, 1 neutral and 1 equipment grounding conductor. The equipment grounding conductor needs to be a size 2 AWG Aluminum.

3) The 4 feeder conductors need a minimum of a (2") two inch trade size diameter Sch. 40 Gray electrical PVC conduit buried a minimum of 18" below final grade. In order to make the wire pull easier, I recommend to increase the conduit diameter to 2 1/2". The PVC conduit also requires expansion fittings at the elbows to allow for any frost heaving and/or soil movement.

Since you have a long conduit run, make sure you use plenty of Yellow wire pulling lubricant when fishing the conduit as well as when pulling the conductors.

I recommend to install a warning ribbon tape above the entire conduit run and place the tape around 6" below final grade. The warning ribbon tape will provide a warning to anybody digging in the future that an electrical line exists below.

I also recommend to pound a few metal stakes in the ground and spray paint them red and use these as nearby markers for the conduit run. Then create a final "as-built" drawing with dimensions referenced from the red stakes or the barn corners or property boundary lines. The "as-built" drawing will also provide documentation for any future trenching or digging near the conduit path in the future. Place a copy of the drawing in each electrical panel for future reference.

4) Since the barn is a detached building, you will require (2) two 8 foot ground rods spaced a minimum of 6 feet apart. You will need a 6 AWG copper wire as the grounding electrode conductor from the ground rods to the sub-panel equipment ground bar. The ground wire needs to be (1) one contiguous run from each rod to the panel.......ie........ no splices allowed. I suggest installing the 6 AWG ground rod conductor in 1/2" EMT metal conduit on the exterior and interior in order to protect the ground rod conductor from any damage.

5) At the sub-panel, you will need to install a separate equipment ground bar to land all branch circuit ground wires as well as the ground rod wire and equipment ground wire from the feeder circuit.

6) At the sub-panel, DO NOT install the green main bonding screw or a main bonding jumper strap. On all sub-panels, the neutral must remain isolated from the panel metal enclosure. By not installing the main bonding is how the panel neutral remains isolated. At the sub-panel, only neutral conductors will terminate to the neutral bus bar and never any ground wires. DO NOT inter-mix white neutrals and/or any bare copper or green insulated ground wires on the neutral bus bar as this will result in a code violation as well as create a safety hazard.

7) At the barn, all receptacles need to be GFCI protected.

8) At the 200 amp main panel, you will need a 100 amp double pole circuit breaker for the feeder circuit. I also recommend that the 100 amp sub-panel be a main breaker type and not a main lug type of panel. The 100 amp main breaker will be used as the "means-of-disconnect" at the barn.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.

Thanks............Kevin:)

Expert:  Kevin replied 1 year ago.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.

Thanks..............Kevin:)

Expert:  Kevin replied 1 year ago.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.

Thanks..............Kevin:)

Expert:  Kevin replied 1 year ago.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.

Thanks..............Kevin:)

Expert:  Kevin replied 1 year ago.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.

Thanks..............Kevin:)

Expert:  Kevin replied 1 year ago.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.

Thanks..............Kevin:)

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