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    Running two 100 amp main panels from a 200 amp service

    Asked Feb 9, 2007, 12:44 PM — 27 Answers
    Greetings!

    I live in a rural country area. The electric company will be installing a pole, meter, and 200amp service with disconnect at pole. (It will require 50 foot run of service cable from pole to main load center in mobile).

    Currently the double wide has a General Electric 100amp Main Load Center. This is not going to be enough as I plan on changing the gas hotwater heater, the gas cook stove and the gas central heating unit all to electric. There is no more room in the existing load center.

    I have another G.E. 100amp main load center. What I want to do if possible is to install a trough and use split bolt connectors and run service wires to each of the main load center thus giving me 200 amps total. I realize I will have use torque according to mfg specs and use an oxidant.

    My twofold question is:

    1. the SER cable will be rated for 200amp, but when I run feeders from the split bolt connectors can i go down to wire rated for 100amp?

    1. Since this will not be a "main" panel / "sub" panel set up, there is no reason to have one box with neutral isolated, it can be bonded - correct?


    If I am incorrect, please advise the best possible solution to get 200amp service out of 2 100amp load centers.

    Thank you
    Martin
    In Memory of Our Daughter
    Bailey DeLonais Maynard
    January 13, 2005 - March 28, 2005
    Healing Oklahoma Hearts - Home
    S.I.D.S. It's REAL!!

    Last edited by mdmaynard; Feb 9, 2007 at 12:52 PM.
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    27 Answers
    ScottLwood's Avatar
    ScottLwood Posts: 19, Reputation: 2
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    #2

    Feb 9, 2007, 03:09 PM
    Since your going to all this trouble why not change your panel out to 1 200amp 40 circuit box.
    Another alternative is your meter box disconnect should have spare circuits, run two separate lines to each panel box using 100 amp double pole breakers.

    Depending on where you live I'm pretty sure you will have to separate grounds and neutrals.

    I personally don't agree with using split bolts but I'm no expert
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    labman's Avatar
    labman Posts: 10,580, Reputation: 551
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    #3

    Feb 9, 2007, 07:40 PM
    I will leave most of your questions to our electrical expert. Life is much easier for me now that we have good people to cover areas I was struggling in.

    I see no reason to spend about a $100 on another panel, when you already have one if it will meet code.

    I am mainly posting to suggest you look at at a double throw disconnect. If you have one installed as part of the job, then in a power outage, you could legally connect in a generator.
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    tkrussell's Avatar
    tkrussell Posts: 9,638, Reputation: 722
    Senior Electrical & Lighting Expert
     
    #4

    Feb 10, 2007, 02:35 AM


    Changing the 100 amp panel out with a 200 amp would be simpler, but what you propose with the trough is fine. Just below the trough you need two 100 amp disconnects thou, before runnning to each of the 100 amp panels. #2-4 wire SER cable can be used to each 100 amp panel.

    If the trough and 2 100 amp disconnects are outdoors,they must be NEMA 3R rated, Rain-Tight.

    Grounding the neutral must be done at the 200 amp main disconnect that will be at the meter location. So one or more ground rod (check with local code how many are needed)will connect to the neutral in the main with #4 copper wire.

    From that point on 4 wire SER cable is needed, as you are aware. Only at the 200 amp main will the neutral and equipment ground connect. At any panel(s) the neutral must be isolated from the equipment ground.

    Instead of using split bolts,which must be taped well with one layer of rubber tape and one layer of vinyl tape, look for the mechanical lugs that use an allen wrench bolt, and are all insulated. Made by Burndy, Ilsco,Blackburn,NSI. Still must use antioxidant, but can get much better torquing done, and are pre-insulated.

    I do think changing the panel out, even thou it seems to be a much more difficult job because of dealing with all the existing branch circuit cables, will give you a better, simpler, and less expensive installation.
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    mdmaynard's Avatar
    mdmaynard Posts: 40, Reputation: 1
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    #5

    Feb 19, 2007, 09:24 AM
    Quote Originally Posted by tkrussell
    Changing the 100 amp panel out with a 200 amp would be simpler, but . . .

    I appreciate your input and have taken your advice.

    I purchased G.E.'s 200 amp main load center kit. (came with 10-20amp breakers, 1-30amp. And 1-50amp).

    I went to a local supplier to purchast the service cable and what I got was 3 wire direct bury cable along with a separate copper cable). The main disconnect/meter is about 45ft from service panel in house.

    Where I am some what confused on is grounding. When they install the meter there will be a 200amp main disconnect right there under the meter. The 200 amp main load center I purchased also had 200am disconnects (looks like 4 50 amp breakers all connected together when 1 trips they all 4 trip). If I understand correctly the 8' grounding rod should then be at the meter pole, the separate copper wire will run from pole to inside main load center in house. It is as this panel that the ground and the neutral should NOT be bonded together correct?

    So I will not run a copper wire from the ground to a ground rod at the house since it is grounded at the meter.

    Please instruct me correctly on this issue. Also with the service cable I purchased, will it need an anti-oxidant and torqued a specific way?
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    tkrussell's Avatar
    tkrussell Posts: 9,638, Reputation: 722
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    #6

    Feb 19, 2007, 09:48 AM


    Quote Originally Posted by mdmaynard
    I went to a local supplier to purchast the service cable and what I got was 3 wire direct bury cable along with a seperate copper cable).
    The forth wire will now be called an equipment grounding conductor from this point on. Any green or bare branch circuit wires will connect to this wire at the panel on a separate equipment grounding bar, not the Main Neutral bar, which is only for white neutral bracnch circuit conductors.


    Quote Originally Posted by mdmaynard
    Where I am some what confused on is grounding. When they install the meter there will be a 200amp main disconnect right there under the meter. The 200 amp main load center I purchased also had 200am disconnects (looks like 4 50 amp breakers all connected together when 1 trips they all 4 trip).
    The 4 pole breaker is actually two 2 pole 100 amp breakers, each side in parallel, for a total of 200 amps per leg. Manufactures are doing this to use up a great deal of 2 pole 100 amp breakers still in inventory, or are less expensive to make that a true full size 200 amp breaker. They work fine.


    Quote Originally Posted by mdmaynard
    If I understand correctly the 8' grounding rod should then be at the meter pole, the seperate copper wire will run from pole to inside main load center in house. it is as this panel that the ground and the neutral should NOT be bonded together correct?
    Exactly correct, the equipment grounding conductor will connect to a separate equipment grounding bar, which must be purchased, and bolted directly to the panel's metal box using machine thread screws. Every panel already has screw holes drill and threaded for this bar.

    Quote Originally Posted by mdmaynard
    So I will not run a copper wire from the ground to a ground rod at the house since it is grounded at the meter.
    Correct, only at the meter/service disconnect will the two main neutrals one from utility and one going to house), the grounding electrode conductor,(GEC to rod), and the equipment grounding conductor(to house) will all connect together, the GEC to the rod or rods, check with local code if more than one is needed.

    Quote Originally Posted by mdmaynard
    Please instruct me correctly on this issue. also with the service cable I purchased, will it need an anti-oxidant and torqued a specific way?
    I have included an aluminum cable's manufacturer's instructions for proper connections. Let me know what you are not sure about.
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    mdmaynard's Avatar
    mdmaynard Posts: 40, Reputation: 1
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    #7

    Feb 19, 2007, 11:14 AM
    Quote Originally Posted by tkrussell
    The forth wire will now be called an equipment grounding conductor from this point on. Any green or bare branch circuit wires will connect to this wire at the panel on a separate equipment grounding bar, not the Main Neutral bar, which is only for white neutral bracnch circuit conductors. . .

    Exactly correct, the equipment grounding conductor will connect to a separate equipment grounding bar, which must be purchased, and bolted directly to the panel's metal box using machine thread screws. Every panel already has screw holes drill and threaded for this bar. . .
    I purchased PowerMark Gold™ Load Center Indoor Main Breaker Load Center 200 amp Main breaker 32 circuit from Lowe's, you can see same panel at this link:

    200 Amp Main Single Phase 32 Circuit Panel - TM3220CCU | Wholesale Electrical Supply Company

    The old panel was set up so that the left bus/bar was for the main neutral the right bus/bar was for the ground (bare/green copper wire's). The left was bonded to the right.

    The new panel appears to be set up the same in that the left and right are bonded at the bottom by a bar (could be wrong but it appears to be this way). If this is correct why would I need to purchase a separate equipment grounding bar, when I could must remove the bar that bonds the neutral to the ground? Am I missing something (I am sure I am). Am I confusing ground from neutral?

    On a side note the cable I purchased was 4/0 direct bury and #4 thhn for the equipment ground conductor.

    I hope I am on right track.
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    tkrussell's Avatar
    tkrussell Posts: 9,638, Reputation: 722
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    #8

    Feb 19, 2007, 12:23 PM


    Sorry I was working on a question with Square D HomeLine also and got confused. No your right, all you need to do with GE is to remove the jumper bar at the bottom, bond one side with the green screw, that side becomes the equipment ground bar.

    The side that does not connect to the panel box will be just for the white neutrals.
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    mdmaynard's Avatar
    mdmaynard Posts: 40, Reputation: 1
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    #9

    Feb 19, 2007, 12:30 PM
    Whew! Thanks for the clearifcation :-) I was worried I was all messed up.

    I appreciate what you guys do here, helping others. In all sincerity I appreicate it very much!
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    mdmaynard's Avatar
    mdmaynard Posts: 40, Reputation: 1
    Junior Member
     
    #10

    Feb 23, 2007, 06:47 AM
    Argh!! I was running the service wire (#4/0 alu 3-wire; #4 THHN) from the pole to the newly installed 200 amp panel inside the house and I am 15 foot short.

    The wire makes it just inside the conduit going from the bottom of the panel inside my house.

    Can I use split bolt connectors or wire splice and just add the 15 feet I am short? Or do I need to scrap the 45' I already (as you cannot return cut wire) and buy 60' of the wire.
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