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Thread: 200 to 300 amp service

  1. #1
    Join Date
    Mar 2006
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    249

    200 to 300 amp service

    Customer wants an upgrade from 200 to 300 amp service. This is for a single family residence. Is the easiest way to change there 200 amp panel to a 300 amp panel ( do they even make one for residentil)and sub feed the 100 amp panel they want, which will be about 100 feet away. They are not upgrading because of demand they believe the house will be worth more when they flip it . I have done many upgrades to 400 amp and grouped the two 200 amp panels together. thanks

  2. #2
    Join Date
    Jul 2003
    Location
    New Jersey
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    18,598
    Around here the POCO wants a load calculation before they will upgrade from a 200 to a 300. There may be an issue with the POCO if you can not show that you need more than 200 amps.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  3. #3
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    Feb 2006
    Location
    new york
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    4,258

    320 service

    The next step up from a 200 yet not quite a 400 which requires a trans s cabinet is what is called a 320 residential service I dont know why it is called a 320 when it is esentially a pair of 150s in parallel it should be called a 300. Traditionally these 300 amp res services are installed in the high number of 3000 to 4000 sq ft victorian houses built recently usually on 2 acres in our area the locals call these house tracts McMansions. Old potato fields sold to developers. It provides 2 150 amp 40 ckt pnls usually underground 350 alluminum monmouth cable to the meter then 2 sets of parallel 150 rope to the 2 150 panels. The water pipe ground must be a #2 solid bonded to either panel and the second panel must have the ground bugged outside of the panel usually right above where the #2 enters the adjacent panel that is how we do it on long island. Do expect to produce a load letter though to get LIPA approval.
    The tail does NOT wag the dog.

  4. #4
    Join Date
    Mar 2006
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    249
    If they allready have a 200 amp panel do I have to switch the panel to 150 amp or can I leave it and add another 150 amp panel next to it then sub feed the 100 amp panel ?

  5. #5
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    Mar 2006
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    What is a trans s cabinet ?

  6. #6
    Join Date
    Dec 2006
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    Chapel Hill, NC
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    25,172
    Some areas require a CT cabinet for 400 amp services. CT= current transformers. These devices read the current being used on larger loads.

    Aorund here we use the 320 amp meter base for a 400 amp service. A 200 amp is rated 160 amp continuous and 200 non continuous. A 400 amp base is the same 400 amp noncontinuous and 320 continuous.

    In your situation you can just add a 100 amp panel and use the 320 amp or what I call a 400 amp meter base.

  7. #7
    Join Date
    Mar 2006
    Location
    Westchester County, New York
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    8,169
    If you are unfamilar with this type of installation, the first thing I would do is contact the POCO, you will need to conform to their standards. They will give you the info you are probably looking for, try to get it in writing, especially if this is your first time performing this type of installation.
    Instructor, Industry Advocate

  8. #8
    Join Date
    Mar 2006
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    249
    What I should have said is the house already has a 200 amp main breaker panel and the home owner added a 100 sub panel about 100 away. If they wanted to change to a 400 know I would just have to add another 200 amp panel next to the existing and ground accordingly. In nj you need a ct cabinet for over 400 amps. So my question is should I just leave the 200 amp panel add a 150 amp next to it ,change to meter to 300 ( if they make one) and feed the 150 amp panel ,Then sub feed to the 100 amp? Would the feed for the 150 amp panel have to be the same size as the 200 or can I size it for the 150 . Sorry for the moronic question but i do mostly commercial. Does a 300 meter have double lugs?

  9. #9
    Join Date
    Feb 2004
    Location
    Chico, CA
    Posts
    231
    What about switching your meter/main out to a 320A "all in one". These usually have one 200A main with lugs for a feeder (in this case, you'd feed your existing 200A panel I believe), and a 2nd 200A main feeding a small built in loadcenter (about 24 spaces ). Add a 100A breaker for your remote panel, and now you have room to grow. You also don't have to worry about changing out your existing panel breaker, etc..
    Mike

  10. #10
    Join Date
    Dec 2006
    Location
    Chapel Hill, NC
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    25,172
    Quote Originally Posted by 101010
    So my question is should I just leave the 200 amp panel add a 150 amp next to it ,change to meter to 300 ( if they make one) and feed the 150 amp panel ,Then sub feed to the 100 amp? Would the feed for the 150 amp panel have to be the same size as the 200 or can I size it for the 150 . Sorry for the moronic question but i do mostly commercial. Does a 300 meter have double lugs?
    I have never seen a 300 amp meter base.

    They do make a 320 amp continuous meter base that is, in our area, good for a 400 amp non continuous load. Almost all our house with this meter base use 2- 200 amp panels. And YES, they have double lugs.

    You said that in your area if it is over 400 amps you must CT but what about 400 amp--- if you can do that fine otherwise I don't see how they will let you use a 150 amp main with a 200 amp already there--- that's usually equivalent to a 350 amp service. A 150 amp main breaker panel cost more than a 200 amp panel in our area because no one uses a 150 panel.

    So--- use 1- 200 with this non continuous 400 amp meter base or use this same meter base with a 100 amp main panel and then feed the other 100 amp sub panel from there. (this is in addition to the existing 200 amp panel)

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