Subpanel for detached shop/garage

Reply

  #1  
Old 07-15-11, 08:19 PM
Member
Thread Starter
Join Date: Feb 2004
Location: Missouri
Posts: 63
Subpanel for detached shop/garage

Home has 200 amp main panel with several available slots, I am wanting to run a 100 amp subpanel to detached garage area. Garage is located about 28 feet from exterior of home and would then run either outside or inside another 20 feet to main panel in home.

Wiring would be all within conduit of some sorts not sure or what kind and underground to the garage. What size wiring should I use to feed the panel. How deep should it be buried? Will it need its own seperate ground rod?

Thanks in advance.
 
Sponsored Links
  #2  
Old 07-15-11, 10:43 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,374
Use PVC conduit. It needs to be buried 24 inches deep, that's 24 inches from the top of the conduit to the surface of the ground. If any conduit is above ground or "subject to physical damage" (kind of a judgement call on the possibility of physical damage) it needs to be rated for UV exposure and should be of schedule 80 thickness. Personally, I like to use Intermediate Metallic Conduit (IMC) to transition from the underground PVC to above ground. Minimum size is 1-1/4 inch and a maximum of four 90 degree bends between access points.

If you truly need 100 amperes at the garage it will require #3 copper conductors for the two hots and the neutral with the equipment grounding conductor a #8 copper. If you use aluminum wire the sizes are #1 and #6 respectively. However, 100 amperes is a LOT of power for a garage and/or home workshop. What exactly are you planning on running at any one time?

Yes, you will need a ground rod at the garage, maybe two. The panel will need to have an auxiliary equipment grounding bus installed and both the equipment ground from the house and the ground rod will connect to this bus. The neutral bus must be isolated from the panel case. The conductor between the equipment grounding bus and the ground rod (the Grounding Electrode Conductor or GEC) needs to be a #6 copper.
 
  #3  
Old 07-16-11, 07:22 AM
Member
Thread Starter
Join Date: Feb 2004
Location: Missouri
Posts: 63
I was also planning for future use as the attic area will eventually be converted to extra living space. Currently I will just be using lights, garage door openers, pool pump and filtering system, an air compressor, radio, television, misc hand power tools, table saw, lathe, planer, drill press etc. Doubt I run multiple power tools and such at the same time as I only have two hands lol. There will also be a smaller mig welder used occassionally
 
  #4  
Old 07-16-11, 03:38 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,374
If your attic living space will have electrical water heating, cooking or space heating equipment then the 100 ampere panel is not overkill. Since 100 amperes is 24,000 watts you can add up the watt rating of everything that may be in use at any particular time and see how close it comes to 24,000.

Generally a home shop would be about 10,000 to 12,000 watts maximum but with your pool equipment and additional living quarters you will likely exceed that home shop average.
 
  #5  
Old 07-18-11, 11:51 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
Originally Posted by jvriffel View Post
pool pump and filtering system
This modifies the panel requirement a little bit. The ground wire to the panel must be green insulated copper, bare copper or any type of aluminum cannot be used for the ground.

With a possible living space and a welder the 100A panel sounds appropriate.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'