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Thread: 200 Amp residential service

  1. #1
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    200 Amp residential service

    What I thought should have been a simple answer to a simple question turned out to have multiple answers from some of my EC colleagues of whom I asked several questions.

    I'm repairing/replacing an existing 200A service on a residence. The service comes down the side of the house on the driveway side. The existing service had to be temporarily re-suspended using SEU cable due to a hardy-plank siding installation. The existing service had been run in 2" PVC with (3) 2/0 copper conductors. I want to install new 2" PVC and I'll be using a 90 and a PVC LB on the load side of the meter enclosure and into the existing MBP. The MBP is not being changed. FYI, NJ is still on the 2014 NEC

    Here were my questions :
    1. Can I use 2/0 copper THHN for the service ? (Most of my colleagues say no they always use 3/0 for all conductors)
    2. Can I down-size the neutral 2 sizes to # 1? (most of my colleagues say no)
    3. Can I use an LB on the load side of the meter where it enters the house ?
    4. Do I have to use sch. 80 on the load side of the meter where it enters the house ? (Remember it's on the driveway side and can be hit by a car if the HO comes home drunk )
    5. Is an LB rated for use with sch. 80 PVC ?

    Some of my colleagues suggested that I use aluminum. That would mean I'd have to go to 4/0. My reason for wanting to use #2/0 copper is so it will fit easier inside the LB.

    One of my colleagues also suggested I look at section 310.15 (B)(7)(1) thru (4)
    310.15 Ampacities for Conductors Rated 0–2000 Volts.
    (B) Tables.
    (7) 120/240-Volt, Single-Phase Dwelling Services and Feeders.

    For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, service and feeder conductors supplied by a single-phase, 120/240-volt system shall be permitted be sized in accordance with 310.15(B)(7)(1) through (4).
    (1) For a service rated 100 through 400 A, the service conductors supplying the entire load associated with a one-family dwelling, or the service conductors supplying the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the service rating.
    (2) For a feeder rated 100 through 400 A, the feeder conductors supplying the entire load associated with a onefamily dwelling, or the feeder conductors supplying the entire load associated with an individual dwelling, unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the feeder rating.
    (3) In no case shall a feeder for an individual dwelling unit be required to have an ampacity greater than that specified in 310.15(B)(7)(1) or (2).
    (4) Grounded conductors shall be permitted to be sized smaller than the ungrounded conductors, provided that the requirements of 220.61 and 230.42 for service conductors or the requirements of 215.2 and 220.61 for feeder conductors are met.
    So, in reading this I see that if I have a service rated at 200A, 83% of that would be 166A wire rating. Can I then use 2/0 wire rated at 175A ? Can I also drop the neutral down to # 1 ?

    Thanks

  2. #2
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    Yes, 2/0 CU or 4/0 AL is ok. No need for schedule 80, which would do you no good if a car hit it anyway. You will want to install a bollard of some type in the driveway in case my wife ever tries to park there. Personally I would run 4/0 AL (full size) in 2".

  3. #3
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    If using PVC then Sch80 is required where the raceway is subject to physical damage which IMO includes in a driveway. If you're using an LB check the maximum conductor size that is stamped inside of the LB, it is often smaller than what is permitted in the raceway.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  4. #4
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    2/0 - 2/0 - 2 copper is common here

  5. #5
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    Quote Originally Posted by DBoone View Post
    2/0 - 2/0 - 2 copper is common here
    Thanks. I thought you could only drop the neutral down 2 trade sizes.

  6. #6
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    Quote Originally Posted by infinity View Post
    If using PVC then Sch80 is required where the raceway is subject to physical damage which IMO includes in a driveway. If you're using an LB check the maximum conductor size that is stamped inside of the LB, it is often smaller than what is permitted in the raceway.
    I have stripped the sheath off SEU cable and installed the (2) 4/0's and the bare 2/0 in PVC to the MBP before but that's a bear. I was trying to avoid that. Do you happen to know what the cu in of a 2" LB is off hand ?

  7. #7
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    Quote Originally Posted by Leespark57 View Post
    Yes, 2/0 CU or 4/0 AL is ok. No need for schedule 80, which would do you no good if a car hit it anyway. You will want to install a bollard of some type in the driveway in case my wife ever tries to park there. Personally I would run 4/0 AL (full size) in 2".
    I contacted several EI's. Some require the sch. 80 and some don't. For the few extra $$ I'll put in the sch 80 on the load side of the meter. Thanks for your reply.

  8. #8
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    Quote Originally Posted by goldstar View Post
    I have stripped the sheath off SEU cable and installed the (2) 4/0's and the bare 2/0 in PVC to the MBP before but that's a bear. I was trying to avoid that. Do you happen to know what the cu in of a 2" LB is off hand ?
    Conduit bodies are mostly all sized based on a prescriptive listing which gives a maximum of 3 XHHW conductors. The conductor size depends on the conduit trade size. (Table 40 on page 121 of UL 514B)
    So a 2" LB would be three 3/0 XHHW or 0.2642 IN your max fill then would be 0.7926 IN
    Cheers

  9. #9
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    Quote Originally Posted by goldstar View Post
    I have stripped the sheath off SEU cable and installed the (2) 4/0's and the bare 2/0 in PVC..
    Does that void the SEU listing for outdoor wet locations in raceway?
    Roger Ramjet NoFixNoPay

  10. #10
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    Quote Originally Posted by tortuga View Post
    Conduit bodies are mostly all sized based on a prescriptive listing which gives a maximum of 3 XHHW conductors. The conductor size depends on the conduit trade size. (Table 40 on page 121 of UL 514B)
    So a 2" LB would be three 3/0 XHHW or 0.2642 IN your max fill then would be 0.7926 IN
    Cheers
    Thanks.

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