How to wire in 100 AMP Sub-Panel?

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  #1  
Old 03-02-05, 11:43 AM
garo24
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Exclamation How to wire in 100 AMP Sub-Panel?

I currently have 150AMP service to my home with 2/0 aluminum service enterance wire from the meter to my 150AMP main panel. I would like to install a 100 AMP sub-panel. I was thinking of installing a 100AMP DP breaker in my main panel and feeding it to my subpanel. Questions:

1)Is it ok to run 100 AMP to my subpanel? If not, why not? If so, what size wire should I use between the two panels?

OR

2) Install a 70amp breaker? If so, what wire size?

3)How do I setup the sub-panel in regards to the ground and the neutral?

My house is mostly all gas except for my dryer which is 220 and A/C which is on a 25 amp breaker.

Any help is appreciated and needed!!

Thanks.
Gary
 
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  #2  
Old 03-02-05, 11:58 AM
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You can run a 100 amp sub panel from your main panel.

What is the wire distance from the main panel to the sub panel? The distance will determine the wire size needed.

Is this panel to be located in a detached building? This will help determine the type of wire needed.

You will need to run four wires to the sub panel. At the sub panel the ground and neutral will need to be isolated. The neutral must NOT connect to the panel itself or to the ground in any way. For a detached building you will want ground rods.
 
  #3  
Old 03-02-05, 12:04 PM
garo24
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It will be less than two feet away from my existing 150amp panel in my house.

Wire size and how to isolate ground and neutral bars?

Thanks.
Gary
 
  #4  
Old 03-02-05, 12:17 PM
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You can use #4 copper wire.

At the sub panel throw away the green screw that comes with the panel. It is used to connect the ground/neutral bar to the panel itself. Buy a separate ground bar which will attach to the panel. The bar that comes with the panel is the neutral bar, and the bar you buy becomes the gropund bar.
 
  #5  
Old 03-02-05, 12:32 PM
garo24
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Thanks for the info. Does the #4 copper wire come all together with the 2 hots, ground, and neutral all together?

Also, the square D 100 AMP panel I bought has two bars on the left with lug for ground and on bar on right. Do I still need to buy a grounding bar?

Just FYI, I just spoke with my inspector, he said that I could use #2 copper to connect them together. So, #4 or #2?

Gary
 
  #6  
Old 03-02-05, 12:41 PM
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I consulted two wire charts on the net, and both indicate #4 is acceptable. However, if your inspector says use #2 then you might want to, just to make him happy. The price difference is not worth discussing for a couple of feet.

You can by individual conductors and run the wire in conduit, or you can by a cable. I believe that the ground wire can be smaller, but I am not sure how small.

I do not understand this sentence, "Also, the square D 100 AMP panel I bought has two bars on the left with lug for ground and on bar on right."
 
  #7  
Old 03-02-05, 12:47 PM
garo24
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Ok.. Which wire is better, #2 or #4? Also, what I meant is that there are already what appears to be grounding bars installed in my 100 AMP subpanel. Two bars on the left which has a lug attached, and one bar on the right with no lug attached.

I subpanel I bought has a 100amp Main installed. Was cheaper then buying lug only from distrubutor.

Gary
 
  #8  
Old 03-02-05, 12:49 PM
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  #9  
Old 03-02-05, 12:52 PM
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#2 wire is larger wire. If #4 wire is okay, then number 2 wire is also okay. larger wire (smaller gauge number) is more expensive and harder to work with. However, you are not buying much and should not have to bend it much.

Here's the key. In the subpanel, the ground wires and the neutral wires cannot be electrically connected. This connection happens only in your main panel. If you have separate bars already installed, and if the neutral bar is isolated from the metal panel then you are all set.
 
  #10  
Old 03-02-05, 01:30 PM
garo24
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Thanks for all the help. I think that I need to buy a ground bar as the previous picture look similar to mine except I have a main installed. I will get back to you on this project. If anyone else has any other good information to suggest, I will take that too!

Thanks again.
 
  #11  
Old 03-02-05, 06:28 PM
garo24
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Ok.. Can I use 3 #2 Copper, (2 hot, 1 neutral) and #6 for ground to run 100AMP from main panel to subpanel?
 
  #12  
Old 03-03-05, 08:27 AM
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Yes.......
 
  #13  
Old 03-03-05, 10:54 AM
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What do you need a subpanel for if your house is "mostly all gas"?
 
  #14  
Old 03-03-05, 06:56 PM
garo24
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because I am out of spaces on my main panel. U got a better idea?
 
  #15  
Old 03-04-05, 04:27 AM
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Have you considered tandem breakers?
 
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