Changing Electrical Sub Box

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Old 08-01-17, 07:20 PM
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Changing Electrical Sub Box

I live in a Modular Home and my main power comes in from the ground to a 12x12 box underneath the unit. (Image #1)The input is split and goes inside the house to a main (image #2) and to a sub box (image #3). The sub box is the item in question. It feeds some misc. outside receptacles, my main AC unit, a aux room and a 12x20 Shed. I don't have any real issues but have been advised to change the sub box to a main breaker type load box. There in lies my problem. I really don't know what to look for. I had one box from Home Depot which was 100amp
Renovation Load Center and has a 100 amp main breaker feeding 10 circuits but it doesn't have the necessary lugs for the #6 load wires that feed the sub box. Since that is 220v feeding the box I presume I will need a breaker that accepts #6 awg.

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Old 08-01-17, 07:50 PM
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Is the a breaker in the large panel to feed the small panel or do they both come out of the 12x12? How close are the panels to each other? Is there a means of disconnect ahead of the 12x12?
 
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Old 08-02-17, 01:09 PM
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Yes, there is always the main disconnect at the meter box on the street. The 12x12 box tap was made due to the fact that the original AC unit on the roof was removed an a new one installed on the ground. Instead of using the original wiring (through the roof) a new run was made in the 12x12 box and run to the sub box. I have the new box now and a electrician has told me to just reduce the 2/0 wire down to the 100 amp main breaker size 2 or 4 awg. Box 1 is about 3 feet from Box 2 and is connected by 3" flex conduit as shown. That is the main power coming in is split inside the #1 box.
 
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Old 08-03-17, 11:16 AM
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What you are calling a sub box is a bit misleading because both are actually subpanels from the disconnect at your meter. I am just assuming the original feeder from that disconnect is 4/0 aluminum because of the 200 amp main breaker in the indoor panel. You had mentioned #6 conductors so at first I thought this was a simple case of the 10 foot tap rule where a 4/0 feeder was tapped with #6 conductors to feed a 2nd panel, but in your last post you say you have 2/0 conductors that an electrician has told you to reduce down to fit a 100 amp breaker. I don't see how the original 200 amp feeder, which should be 4 wires, could be tapped with the 4 wires (some of which are 2/0 conductors) required to feed this 2nd panel all within a 12 x 12 x 12 junction box. I feel like I am missing something here. However, I do agree that there needs to be a MOCP (main breaker) in that 2nd panel.

So, what size is the protection at the disconnect at the meter? What size and how many wires are there in the original feeder from the disconnect at the meter? What size and how many wires were used to tap the original feeder in the 12 x 12 x 12 junction box?
 
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Old 08-06-17, 07:30 PM
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Protection from the street is a main breaker which will turn off everything. For now we can forget about the #2 (main house box) since it isn't part of the equation. The 12x12 box from the street tap to the sub box #3 are 4 wires, black, white, green and ground #2 awg. You can actually see them in the #3 photo.
 
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Old 08-07-17, 10:02 AM
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The 12x12 box from the street tap to the sub box #3 are 4 wires, black, white, green and ground #2 awg.
I'd change the small subpanel fed by this tap to a 100 amp main breaker panel.
 
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Old 08-07-17, 12:09 PM
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That puts us back at my original question. I have a new loadbox with 100amp MB. Problem is the feed wires from the 12x12 panel are too large. Is is okay to just remove the existing wires and lower the awg to fit the 100amp breaker . . . The run is about 3 feet.
 
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Old 08-08-17, 07:01 PM
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The 12x12 box from the street tap to the sub box #3 are 4 wires, black, white, green and ground #2 awg.
#2 conductors will fit the lugs on a 100 amp breaker. If I were to replace them I wouldn't use smaller than #3s.
 

Last edited by CasualJoe; 08-08-17 at 07:55 PM.
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Old 08-08-17, 08:40 PM
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Final Question - Removing the existing feed from the 12x12 box to the sub box, which is red, white, green and ground, can I use Mobile Home Feeder Wire; 2/2/2/4 or 2/2/4/6 from the existing split bolt taps to the sub box? Also, aluminum or copper?
 

Last edited by joe645; 08-08-17 at 09:24 PM.
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Old 08-09-17, 08:01 AM
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Removing the existing feed from the 12x12 box to the sub box, which is red, white, green and ground, can I use Mobile Home Feeder Wire; 2/2/2/4 or 2/2/4/6 from the existing split bolt taps to the sub box? Also, aluminum or copper?
The existing tap should have been Blk, Red, Wht and Grn. Whether copper or aluminum is dependent on the type of tap connector you are using. Generally, copper wire should never come in direct contact with aluminum wire. Of the sizes you listed, either is fine for 100 amps.
 
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