Add another breaker panel

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  #1  
Old 08-02-07, 08:13 AM
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Add another breaker panel

I am hoping one of you experts can help me out with this one. I am trying to add a second breaker panel to my home and I want to make sure I am wiring it properly. I am planning to run conduit between the two panels but I am specifically wondering if, by code, can I connect the second panel into the main bus lugs from the first panel or do I need a different "box" installed and then have my main service run into that with lines running to each of my panels?

Thanks in advance for your responses!!

Tod
 
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  #2  
Old 08-02-07, 08:19 AM
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You cannot simply connect to the main lugs. You must either feed the second panel from a circuit breaker in the first panel or from a proper connection at the meter. This would likely require the meter connection to be changed.
 
  #3  
Old 08-02-07, 08:48 AM
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Racraft, thanks for the rapid reply!! That is what I was thinking I would need but wasn't sure. Since my current meter is likely not something that would be setup for a second main panel connection, can you recommend what type of meter box would be sufficient for this type of installation?
 
  #4  
Old 08-02-07, 08:52 AM
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Any job involving the meter and the connection from it is a job for a qualified an electrician. This type iof job is NOT do-it-yourself.

Any of us here will be able to help you with a sub panel, that is a panel fed from your existing panel, but what you are asking about is not appropriate for this board.

Why do you not like the sub panel idea? It seems like you want the panels right next to each other anyway.
 
  #5  
Old 08-02-07, 09:01 AM
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The issue that I have is two fold, the first of which could be solved by a sub panel but the second cannot. I currently have a 150 amp service in my house with a 32 circuit panel that is full. From that I also have a 100 subpanel running out to my garage where I have several large appliances (welder, air compressors, etc. ). So, I really feel the best solution is to add additional capacity in the form of a second main panel.

I do agree that this something that will require a qualified person to build out for me but I would like to purchase the items in advance and have them mounted and ready to wire up if possible. I have contacted my local electric company and will be speaking with one of their engineers today but I am trying to educate myself on what the best way to handle this is.
 
  #6  
Old 08-02-07, 09:17 AM
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I am not familiar with meter bases or what is involved with changing them, so I cannot suggest anything. Further, some electricians may not allow you to purchase equipment. Some may, but other's won't.

I think you need the advice of several electricians. Have them make suggestions. One solution may be to make the garage panel a second main panel, and to install a sub panel off the main panel where the garage panel used to fed from. It's hard to make suggestions without having the entire picture.
 
  #7  
Old 08-02-07, 01:04 PM
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IF---IF-- the "Working Dimensions" allow, I suggest you install a Servive panel with a 200 amp MCB next to the existing panel with the 150 MCB.

Extend 200 amp Service Condutors from the 200 amp MCB to the utility-connection ,routed thru a 200 amp meter-socket. The fomer panel with the 150 amp MCB is now a sub-panel fed with 100 amp conductors that are protected with a 100 amp CB in the new 200 amp panel.MAYBE this can be effected leaving the existing Service intact.

The existing 100 amp Feeder to the garage will be transfered to the new 200 amp panel. Also, the Grounding Electrode Conductor must terminate in the new panel.

The 200 amp Service Conductors will eliminate the the possibilty that the existing 150 amp SC's are in-adequate.

Submit your "proposed Service change" to the POCO for approval, and their requirements as to any Licence issues. Con Edison requires a License # on a "request to un-lock meter" form
 
  #8  
Old 08-02-07, 01:07 PM
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IF---IF-- the "Working Dimensions" allow, I suggest you install a Service panel with a 200 amp MCB next to the existing panel with the 150 MCB.

Extend 200 amp Service Condutors from the 200 amp MCB to the utility-connection ,routed thru a 200 amp meter-socket. The fomer panel with the 150 amp MCB is now a sub-panel fed with 100 amp conductors that are protected with a 100 amp CB in the new 200 amp panel.MAYBE this can be effected leaving the existing Service intact.

The existing 100 amp Feeder to the garage will be transfered to the new 200 amp panel. Also, the Grounding Electrode Conductor must terminate in the new panel.

The 200 amp Service Conductors will eliminate the the possibilty that the existing 150 amp SC's are in-adequate.

Submit your "proposed Service change" to the POCO for approval, and their requirements as to any Licence issues. Con Edison requires a License # on a "request to un-lock meter" form
 
  #9  
Old 08-02-07, 02:27 PM
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Also remember, since your current main panel is 150A, your service entry (meter, meter base, service entry wires) are all probably sized for a 150A services. This means the maximum main breaker you can have is 150A. So even if you change out the meter base to allow multiple (sub) panels from that point, the total can only be 150A. You wouldn't want to have two 100A "main" panels off a 150A service entry as the too-small wire would become a fire hazard.

As stated, the easiest way is to add a new breaker to your main panel to feed your subpanel. Since the whole system is protected by the 150A main breaker, you could have as many subpanels as you want (until the load maxes out the main breaker).
 
  #10  
Old 08-03-07, 07:24 PM
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Thank you for the responses but I did find the answer I needed from the engineer at my local electric company (Alliant Energy). What I found is that the maximum available service for a residence, without getting into some serious money, is 320 amp. There are several manufacturers of meter sockets at this rating but the most popular appears to be milbank manufacturing. I also found out that for an overhead service the unit I need is a u1779-rrl-k3-k2. This box has two feeder lugs to connect to two different breaker panels, each at 150 amps in my case or any combination not exceeding 320 amps. The retail cost for such a box is about $320.

Now that I have this information, what I need to find out is what gauge wire do I need to carry 320 amps. I found several sites that have calculators to determine the size and I just don't believe it. They say that a #4 aluminum or #6 copper is all that is needed but that just doesn't seem right. I have 2/0 running to my garage subpanel because that is what was the recommended gauge based on a local wire vendor.

I am thinking that 4/0 would be sufficient but I would like some feedback.
 
  #11  
Old 08-03-07, 07:31 PM
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More like #2cu. #6 is usually for the grounding conductor.
 
  #12  
Old 08-03-07, 07:35 PM
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I guess I am confused, so you are saying that a #2 copper would cover the service run into my meter at 320 amps? That seems small but I guess I am not an engineer.
 
  #13  
Old 08-03-07, 07:39 PM
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wrong chart, sorry.

350kcmil CU or 500kcmil Aluminum

NEC 310.15
 
  #14  
Old 08-03-07, 07:42 PM
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Again, thank you but can you translate that into standard AWG sizes? I am not familiar with what 350kcmil or 500kcmil is.
 
  #15  
Old 08-03-07, 07:45 PM
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Thousand circular mil;

wire size for multiple stranded conductors over 4/0 AWG in diameter. Formerly MCM.
 
  #16  
Old 08-03-07, 07:56 PM
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Mark,
Sorry for the stupid question and thank you for the answer. Obviously I have never dealt with anything of that size. I will contact my local electrical supplier and I am sure they will have some.
 
  #17  
Old 08-04-07, 06:54 AM
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twieder, I assuming you're planning to have an electrician perform the work? As Racraft said, this is not DIY unless you're an electrician. By the sounds of it you're not.
 
  #18  
Old 08-06-07, 10:08 AM
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If you install 350,000 CM Service Conductors, you will need a #2 Grounding Electrode Conductor between the Service and the "Primary" Grounding Electrode , which may be the metallic water service pipe/tubing.

The conductors between the 2 "Main-breakers" in the outdoor enclosure and the interior panels are "Feeder" conductors, and the Feeder "Neutral" conductors must be Ground-Isolated beyond the Main-Breaker enclosure .
 
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