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-   -   Wood shop 100 amp sub panel (http://www.diychatroom.com/f18/wood-shop-100-amp-sub-panel-171390/)

tinybear 02-08-2013 02:36 PM

Wood shop 100 amp sub panel
 
DIY members, just wanting to run this by you guys on my plans to upgrade the panel in my wood shop. The situation is my main panel is attached to a pedestal along side my meter. ( I live in a mobile home ) Right now the wood shop (a detached building) is fed with a double pole 40 amp breaker [ #8 AWG NM-B copper inside 1 1/4" conduit, [ I know its not code, but we're gonna change that ] about 50' in length] I installed coming from the 200 amp service that also powers my mobile home. The panel in my mobile home is a 100 amps. My plan is to install another 100 amp sub panel [ powered with #2 AWG THHN copper with neutral and equipment ground, from lugs at the base of the buss bars in the 200 amp main panel ] to replace the existing small panel in the wood shop I am using now. What I want to do is use the same small panel and move it to the other end of the shop using the same 40 amp breaker with the #8 feeder that exist now and be ready for the future shop expansion I'm planning for the spring. It will be used for a lighting circuits and dedicated GFI protected wall and exterior recepticles. One of the questions I have, will I have to install two more grounding rods where the second sub panel is going ? Also, I want to use some EMT conduit ( 1/2" w/ 4 #12 THHN wires ) to surface mount a couple of 220v receptacles. The interior walls of my shop are sheathed with 1/2" CDX. What is the proper way to exit the wall bay ? [LB inside wall bay, short length of EMT to another LB on the outside ? ] I know this is a long winded request, but I wanted to try and get all the info you guys might need to help me out ! Thanks

rrolleston 02-08-2013 02:42 PM

Quote:

Originally Posted by tinybear (Post 1112493)
DIY members, just wanting to run this by you guys on my plans to upgrade the panel in my wood shop. The situation is my main panel is attached to a pedestal along side my meter. ( I live in a mobile home ) Right now the wood shop (a detached building) is fed with a double pole 40 amp breaker [ #8 AWG NM-B copper inside 1 1/4" conduit, [ I know its not code, but we're gonna change that ] about 50' in length] I installed coming from the 200 amp service that also powers my mobile home. The panel in my mobile home is a 100 amps. My plan is to install another 100 amp sub panel [ powered with #2 AWG THHN copper with neutral and equipment ground, from lugs at the base of the buss bars in the 200 amp main panel ] to replace the existing small panel in the wood shop I am using now. What I want to do is use the same small panel and move it to the other end of the shop using the same 40 amp breaker with the #8 feeder that exist now and be ready for the future shop expansion I'm planning for the spring. It will be used for a lighting circuits and dedicated GFI protected wall and exterior recepticles. One of the questions I have, will I have to install two more grounding rods where the second sub panel is going ? Also, I want to use some EMT conduit ( 1/2" w/ 4 #12 THHN wires ) to surface mount a couple of 220v receptacles. The interior walls of my shop are sheathed with 1/2" CDX. What is the proper way to exit the wall bay ? [LB inside wall bay, short length of EMT to another LB on the outside ? ] I know this is a long winded request, but I wanted to try and get all the info you guys might need to help me out ! Thanks

You can't go off the lugs with #2 wire. You will have to use the proper sized breaker in the panel to go to your shop.

oleguy74 02-08-2013 06:14 PM

useing feed through lugs,you have to size your wire to the required size for the 200 amp main breaker.3/0 copper or 250 aluminum.

rrolleston 02-08-2013 06:45 PM

Quote:

Originally Posted by oleguy74 (Post 1112665)
useing feed through lugs,you have to size your wire to the required size for the 200 amp main breaker.3/0 copper or 250 aluminum.

Why 250 al

tinybear 02-08-2013 06:47 PM

In my original post I failed to state the proper size feeder to my sub panel. Actually it's 2/0 AWG THHN, and now I realize its still too small. I'll use a 100 amp breaker at the main to feed the sub, also with a 100 amp main breaker. Thanks oleguy74. Would sure like to meet rrolleston with his special discount and that "cocky attitude" of his ! Sounds like he needs a little tune-up. People from Grandville, what do you expect ?

rrolleston 02-08-2013 07:03 PM

Quote:

Originally Posted by tinybear (Post 1112708)
In my original post I failed to state the proper size feeder to my sub panel. Actually it's 2/0 AWG THHN, and now I realize its still too small. I'll use a 100 amp breaker at the main to feed the sub, also with a 100 amp main breaker. Thanks oleguy74. Would sure like to meet rrolleston with his special discount and that "cocky attitude" of his ! Sounds like he needs a little tune-up. People from Grandville, what do you expect ?

3 2/0 and one #6 ground in a 1-1/4 is way too much.

Stubbie 02-08-2013 10:31 PM

Quote:

Originally Posted by oleguy74 (Post 1112665)
useing feed through lugs,you have to size your wire to the required size for the 200 amp main breaker.3/0 copper or 250 aluminum.

Not exactly this only applies if your feeding a main lug panel from those lugs and both panels are indoors..

Since his service equipment is located outdoors on a pedestal he is allowed to use his feed thru lugs to feed a 'main breaker' panel so long as that main breaker is sized properly to protect the conductors of his feeder. Lookup unlimited tap rule in the NEC. It's not a lot different than what is going on from his service equipment to the main breaker panel in his house. I belive you can also use the summation rule for the sub if a main breaker does not exist.


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