adding a sub-panel about 2ft away from main panel

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Old 03-31-19, 11:46 AM
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adding a sub-panel about 2ft away from main panel

I am going to start working on my basement and I need to add a 100Amp sub-panel. as the main panel is completely full. The sub panel will be about 2 ft away from the main service panel. I beleive 3-3-3-5 is the correct wire.

As with most service panels, the top side of my main panel is quite crowded so I was considering coming out the bottom. The panels are mounted between 2x6 studs. There is one open space between the two panels. Would it be best to come out the bottom of the main panel, over one stud then up above the sub panel then down through the top of the sub panel or just over and up though the bottom of the sub panel?


Right now there is no dry wall on either side of the wall but there will be in the future. Do I need to install plates to protect the wiring?

Should I use a 60Amp breaker to receive the power from the main panel or do I need to use a 100Amp breaker. At this time I don't need 100 amp from the service panel but someone recommended using 100 Amp wiring just in case I needed it in the future.

Appreciate any comments and tips.
 
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Old 03-31-19, 12:37 PM
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Just come out of the bottom of the main panel using SER Cu 3-3-3-5 then over and up through the bottom of the new 100A panel. Where the SER passes through the studs it's best to use nailing protection plates. I would just go ahead and use a 100A feeding breaker in the main panel. The new 100A panel can be just a main lug panel without a main breaker. The neutral in the new panel must be isolated from the grounds, which usually means you have to buy a ground bar kit for the new panel and remove the bonding screw/strap from the new panel's existing neutral/ground bar. Also the new panel can be mounted either end up or down.
 
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Old 03-31-19, 01:19 PM
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I agree. If you are going to use wire that is rated for 100 amps you might as well install a 100 amp breaker.
 
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Old 03-31-19, 03:33 PM
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Is the main panel larger than 100 amp?

Does code allow a sub panel that is the same size as the main panel?

If the main panel is full you will need to free up a couple of spaces for the sub-panel main. I think the code may allow that main breaker to be in the sub-panel, if the wiring is less than a certain length.
 
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Old 03-31-19, 03:59 PM
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Does code allow a sub panel that is the same size as the main panel?
Yes it does. There isn't a restriction listed.
 
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Old 03-31-19, 04:46 PM
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I think the code may allow that main breaker to be in the sub-panel, if the wiring is less than a certain length
A sub panel can have a main breaker if desired, it is just not required. The only time it is required is when the sub panel is installed in a detached building.
 
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Old 03-31-19, 07:45 PM
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Thanks everyone. I think that answered all of the questions. Need to order the 100amp breaker the the length of SER 3-3-3-5 that i need.
 
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Old 03-31-19, 08:51 PM
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For finishing a basement a panel fed by 60 amps is going to still give you plenty of reserve capacity.
 
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Old 04-01-19, 04:54 AM
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I agree 60amp should be more than enough for the basement. A friend had recommended using 100 Amp wire to sort of future proof it. I will have to check the cost differential as it is unlikely that I would go over 60Amp. I want to move the heat pump for the basement to the sub panel that is going to be the biggest draw. one possiblity is that one of the rooms would become a small kitchen area. That would be the other big draw.
 
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Old 04-01-19, 07:04 AM
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Yeah with a possible kitchen and HVAC on this panel, just do 100A and be done with it. The price difference will not be much.
 
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Old 04-01-19, 06:41 PM
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Thanks. That confirms it.
I would like to stress to everyone on this board how helpful thediscussions on this website has been to me. I am probably an advanced DIY'er but certainly not an expert. What would be a good way for me to help the success of doityourself.com?
Take Care all.
 
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Old 04-02-19, 06:05 AM
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If there is an area where you have expertise, find the forum in that area and contribute good content. There are a couple dozen boards like this one on various topics related to home ownership, auto repair, personal finance, gardening, hobbies, etc: https://www.doityourself.com/forum/
 
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Old 05-11-19, 10:41 AM
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Got my new 100Amp service installed. That is behind me. One question: Do I need to install AFCI type breakers for the new circuits? Home was built in 2002. All of the existing breakers are conventional. The new circuits would be for my basement;rooms and lights and a work shop
 
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Old 05-11-19, 10:46 AM
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When your house was built the code only required bedroom receptacles to be protected by AFCI's if they had adopted the 1999 Code. The requirements had expanded since then in later codes and most areas now call for AFCI protection.
 
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