I recently bought a home built in 2007. I had the chance to meet with the original homeowner who shown me some of the things that were on his list to finish before he sold the house but never got the chance. One of the things was the completion of a 100 amp subpanel in an outbuilding I will use as a shop. Eventually I will add another 40 amp subpanel that will come off the 100 amp subpanel in the shop, to go to a nearby barn in the future.
What he has set up already is a 100 amp double pole circuit breaker in the main panel. I had no idea where it terminated at until he shown me a J box on the back of the house, which it was not tied into yet, but it was in the wall. It just needed to be brought out, so I did. I tested it to make sure the breaker operated that cable. All good so far.
The shop has a wire ran in ground that can handle the load also. It was coiled in the crawlspace, so I brought it out through the wall. The pic I have below is the pair I brought out.
What I am looking for in the picture is what type of weatherproof low profile box is out there that I can use to tie these into, preferably not using "bugs" that will take a ton of tape and what ever else is used to keep the cables from shorting out.
The cable from the breaker is going to enter the Jbox from the top, the one feeding the shop is going to exit out of the bottom.
Maybe it is expecting too much, but if there is a box that will recess into a 2X6 wall and leave room for insulation behind it and had enough cubic inches to handle the cable with out sticking out too far would be pretty cool. I imagine if there is such a thing, knowing the name of the Jbox would prove handy. I really want to stay away from a trough.
The next pic is of the subpanel itself. It has 3 lugs. I am figuring with the right name and a hopeful edit of my pic, that the ground wire can be sorted out too.
I figure, but I would like confirmation, that the new lug for the ground can be screwed or bolted to the back of the box and tie it in there.
The biggest cables are 1/0, I can't remember the size of the ground wire…
Then again, I may need to get a different panel for the shop, and use this for the future barn. I hope this one works, only because it will save a trip.
Thanks guys.
Best Answer
First thing I would do it get a larger sub-panel. Those dinky 6/12 panels are terrible for space and future expansion. You also need a means of disconnect at the outbuilding. I would get a 20 space main breaker panel which would correct both of these issues.
In the sub-panel you would also need to install a grounding bar to the back of the panel box and NOT install the bonding screw. The green wire would terminate there as well as the required grounding electrode (ground rod typically) conductor.
At the house you MUST protect that URD cable where it is exposed. Typically we'd use Sch80 PVC conduit. For the splice you can/should use Polaris connectors. They are available at any electrical supply house or even some home centers. They make larger aluminum wire splices a breeze!
There are a LOT of other code requirements for a job like this. Are you experienced enough to tackle this job?