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Thread: 400 amp residential service

  1. #21
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    Folks, thank you for the interesting responses.
    Si hoc legere scis nimium eruditionis habes.

  2. #22
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    Dec 2007
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    Quote Originally Posted by readydave8 View Post
    not very unusual to have 3 heat pump w/ 10-15kw heat strips each, 2 water heaters, clothes dryer, electric range, etc.

    So not very likely for all this to be going at the same time?

    Well it is upon family's return from vacation
    Correct that it seldom is all going at one time. But there is occasions when it is.

    Good example I have seen is rural churches. If you looked at monthly billing you would think there is no way that building needs a 400 amp service, but it sits there most of the time with very little load. Every Sunday there is high demand for maybe an hour up to 4 hours, and maybe a few other times here and there with similar demand cycles. You need to be able to handle that demand when it is there.

  3. #23
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    Aug 2003
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    Quote Originally Posted by Besoeker View Post
    Ignorant Brit.............
    What kind of residence needs a 400A service?
    Typically here we have 40A or 60A.
    I have single breakers that big

    My house is all-electric. No gas. No propane.
    The house is approx 3000 sq ft, plus a 1000 sq ft heated garage, 2700 sq ft of basement. Plus a 1200 sq ft outbuilding with 800 sq ft of potential living space above.
    3 water heaters (including the garage, which is limited-use and seasonal)
    House is heated/cooled with 7 mini-split heads and 2 outdoor units (a handful of 500W baseboards for extreme cold days that I don't expect to use)
    Attached garage is in-floor radiant via a 13kW tankless water heater (that'll never see that load)
    Basement and outbuilding are prepped for hydronic in-floor as well

    I'm on a dedicated transformer... can't recall the size.
    400A service to the meter.
    Two 200A panels immediately inside the garage at the meter.
    One panel serves the garage side of the house, and the basement wood shop
    The other panel feeds a remote 200A panel that handles the other side of the house and feeds the outbuilding.

    Am I going to draw anywhere close to 400A at a time? Heck no.
    It is possible to draw more than 200A at one time? Perhaps

    But I need to get the wires run from the meter to the panels first

  4. #24
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    Quote Originally Posted by ddecart View Post
    And this is why I despise reading the NEC. It says little and references itself ad nauseum.
    Service conductors entering a building shall be installed in accordance with 230.6 or protected by a raceway method identified in 230.43.

    230.43 says Service Entrance Cable is good to go....kind of. It says "Service entrance cable is ok if you use the applicable parts of this code".
    230.6 seems to be irrelevant (determining if conductors entering a building are outside of a building?)

    By that, exposed service entrance cable should be a-ok.

    Of course, there's the "if subject to physical damage" caveat, which appears to be left to the whims of the individual inspector.

    I would not consider SER cable a raceway & inspectors should not inspect using whims as code but should read the code for what it says
    Last edited by mwm1752; 08-02-17 at 02:59 PM.
    CircuitRyder --- Unfortunately not all good ideas are code enforceable.

  5. #25
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    Apr 2016
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    Quote Originally Posted by lucky1974 View Post
    Hi, I am hoping some one has some pics of a 400 amp service they have done( and are willing to post). This will be my first one. I was wanting to come out of the meter can with two sets of 4/0 alum SE cable with side by side 200 panels directly behind meter can. All the pics i can find all have pvc or have a gutter put in. I was hoping to see how it looks before going ahead. Thanks
    Why make it so difficult. 2-2" nipples out the back of the meter, through the exterior wall, installed wide enough to simply nipple into your panels directly though the wall!!

  6. #26
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    Quote Originally Posted by ddecart View Post
    I have single breakers that big
    Well, yes.
    I've engineered systems with breakers rated at 2000A.
    But not for residential applications.
    Si hoc legere scis nimium eruditionis habes.

  7. #27
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    Aug 2003
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    Quote Originally Posted by mwm1752 View Post
    I would not consider SER cable a raceway & inspectors should not inspect using whims as code but should read the code for what it says
    Then we need to look at 230.43 which spells out service entrance cable as a method. No whims involved.

  8. #28
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    Quote Originally Posted by ddecart View Post
    Then we need to look at 230.43 which spells out service entrance cable as a method. No whims involved.
    still didn't read - yes - SER Cable is in 230.43 but you shall use a raceway to protect it so your statement of "By that, exposed service entrance cable should be a-ok" is not correct & if you keep the ser outside of the building it in underground raceway it is not compliant.
    or protected by a raceway method identified in 230.43.
    CircuitRyder --- Unfortunately not all good ideas are code enforceable.

  9. #29
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    Aug 2004
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    Northern illinois
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    Quote Originally Posted by Besoeker View Post
    Well, yes.
    I've engineered systems with breakers rated at 2000A.
    But not for residential applications.
    the largest I have used as well. you get above that and you are out of the realm of MCCB for the most part. I think someone makes a 2400 A MCCB but that is the largest I have heard of.
    Bob

  10. #30
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    Aug 2003
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    Quote Originally Posted by mwm1752 View Post
    still didn't read - yes - SER Cable is in 230.43 but you shall use a raceway to protect it so your statement of "By that, exposed service entrance cable should be a-ok" is not correct & if you keep the ser outside of the building it in underground raceway it is not compliant.
    or protected by a raceway method identified in 230.43.
    The issue is that 230.43 has nothing to do with raceways. The word "raceway" doesn't even appear. So after multiple references to other paragraphs, we end up on one that's irrelevant for the purpose for which it was referenced.

    Unless, of course, we look at 230.43 and realise that service entrance cables are mentioned in the same list as pretty much every sort of "conduit" available. Regardless of the topic, that would suggest that, for example, ENT and SE cables are equivalent in the eyes of the code in some circumstances.

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