Wiring for detached garage through first

[bradpac]

I am building a detached garage on the right size of my house about 10ft from house to garage. The electrical service is located about mid-way in the back of my house ~25ft from the right side. I have a blank electrical box on that right side by the AC it has some 12/3 romex in it, there used to be a portable shed over there with power, I'm thinking it was used for that. The house is brick with a ground level deck built along the back side.

My idea to power my new garage is to take romex from the panel (60 amp) or a separate disconnect (100 amp), depending on amps, run it into the house with the rest of the wiring and run it to the box on the side of the house in place of the 12/3 romex, then run conduit 12" down the side of the house 18" underground and to the garage. For the conduit I would need to switch to THWN. Not sure I can fit large enough wires in a standard box to supply the ideal 90-100 amps. But I only have a 200 amp service right now, so adding more amps for the garage with another disconnect might be out of budget right now anyway.

My real question is does my plan of running the wire into the house and out to that box work for code? Or will I need to move the deck and bury it in its own conduit?

 

[nadogail]

There are some things that have not been addressed.

Is the conduit large enough to pull the conductors you will need to service the planned load in the garage?

 

[bradpac]

There are some things that have not been addressed.

Is the conduit large enough to pull the conductors you will need to service the planned load in the garage?

No conduit in the house, it is just romex in the attic. The garage is not built yet and I will be running conduit for that. Right now my only firm piece is a single gang box in my brick veneer wall, so should be removable if I need to change that for some reason and then limitations of whatever size holes are drilled in the house framing and whether I can get access to enlarge those.

 

[Noltz]

Is your main panel inside the house or outside? If inside, do you have room to drill a pass through? I'm thinking your smartest & most direct solution might be to run a new conduit straight from the LC to the new structure outside the home. Surface mounted low on the foundation, or perhaps buried. You could run THHN in surface mount to a service box adjacent to the new building, then switch to THWN and bury the conduit as needed. Or if you have equipment on site, bury the whole thing straight out the back of the house. Or use all THWN and have a continuous run (ideal, really).



If it were me, I'd be running 100A for sure. EV's are the future and they'll need charging. 60A will do 1 car. 100A will do 2. It'll also let you run electric heat if you want.

 

[bradpac]

Is your main panel inside the house or outside? If inside, do you have room to drill a pass through? I'm thinking your smartest & most direct solution might be to run a new conduit straight from the LC to the new structure outside the home. Surface mounted low on the foundation, or perhaps buried. You could run THHN in surface mount to a service box adjacent to the new building, then switch to THWN and bury the conduit as needed. Or if you have equipment on site, bury the whole thing straight out the back of the house. Or use all THWN and have a continuous run (ideal, really).



If it were me, I'd be running 100A for sure. EV's are the future and they'll need charging. 60A will do 1 car. 100A will do 2. It'll also let you run electric heat if you want.

Nice suggestion, i didn't think about running conduit on the house, my main issue is the back of the house where the main panel is, there is a deck that goes along the whole length of the house, which is why I'm thinking it would be easier to run wire in the house to get to that other side than move the deck. I already have a 2.5" conduit running into the attic of the house. I might be better off running a conduit down the side of the wall from the soffit and underground if I can't get that much wire down inside the wall.

I'm not worried about EVs, especially in this garage. This is a hobby garage and I only work on old stuff. More worried about my 5hp air compressor, welder, and plasma cutter. My current daily is a 92 Dodge Cummins, specifically because it doesn't have any electronic junk. Yes, I'm one of those that will be kicking and screaming when I have to start driving a computerized smart car. My phone is plenty.

 

[Noltz]

200A service is plenty for a single story house. I'm just thinking that a small upgrade now means you or someone else isn't limited in the future. Compressors and Plasma have to run together, but 60A should be enough for that.

60A in Romex would be 6/3. Have you ever held that? Three 6 gauge conductors plus a ground is going to be a real bear to handle in the tight confines of an attic. You might be smart to investigate "smurf tube" flexible conduits and run single conductors. Not only can you run more amperage through single conductors but it's a helluva lot easier to run the wires one at a time, again without worrying about joining them.

 

[Norcal]

200A service is plenty for a single story house. I'm just thinking that a small upgrade now means you or someone else isn't limited in the future. Compressors and Plasma have to run together, but 60A should be enough for that.

60A in Romex would be 6/3. Have you ever held that? Three 6 gauge conductors plus a ground is going to be a real bear to handle in the tight confines of an attic. You might be smart to investigate "smurf tube" flexible conduits and run single conductors. Not only can you run more amperage through single conductors but it's a helluva lot easier to run the wires one at a time, again without worrying about joining them.

ENT aka “Smurf tube” is not one of the easiest materials to fish wire through, the fish tape will get caught on the ENT internal corrugations regularly.