pwhaakej
Member
Hi all - I have a ~350 sq ft detached garage that is about 135 ft from my main panel and I'm trying to determine the best subpanel to install in the garage and how to feed it.
The garage currently has a couple lights, invisible fence, and the door all on a 20 Amp circuit that is fed through 1.25 inch PVC (I think schedule 80). I am planning on converting it into a small woodshop that will need 120 and 240v circuits.
I think a 60 Amp service is probably sufficient given that the most that would ever be running concurrently would be a table saw, dust collection, some LED lights, the invisible fence (which is almost nothing), a mini-split for heating/cooling and maybe a laptop or phone charger. However, I'd like to provide as much power as possible since plans change and getting as close to 100 Amp service would be nice.
From what I've read #1 Aluminum is ideal for this application, but it won't fit in the existing conduit, and I've no interest in digging it up or running a new line since I'd need to dig up a patio/walk and deal with driveway and possibly shrubs or trees.
I see a lot of people using 2-2-2-4 MHF to feed 100 Amp subpanels, but most pull it through 2" conduit, which is obviously a huge difference to 1.25. Is it worth even attempting or am I better off with 3-3-3-5 Cu and shelling out?
I'm also a bit confused about determining ampacity. For the Copper I'd need 3 AWG THWN-2 for this since conduit is considered wet, which at 75C is rated at 100 Amps. Factoring in the voltage drop over 135 feet and I figure I'd use a 90 Amp breaker, but from what I understand if the breaker doesn't have a temperature rating on it you assume 60C - I'd need a square D homeline breaker, and I can't seem to find a temp rating anywhere.
Any input is much appreciated
The garage currently has a couple lights, invisible fence, and the door all on a 20 Amp circuit that is fed through 1.25 inch PVC (I think schedule 80). I am planning on converting it into a small woodshop that will need 120 and 240v circuits.
I think a 60 Amp service is probably sufficient given that the most that would ever be running concurrently would be a table saw, dust collection, some LED lights, the invisible fence (which is almost nothing), a mini-split for heating/cooling and maybe a laptop or phone charger. However, I'd like to provide as much power as possible since plans change and getting as close to 100 Amp service would be nice.
From what I've read #1 Aluminum is ideal for this application, but it won't fit in the existing conduit, and I've no interest in digging it up or running a new line since I'd need to dig up a patio/walk and deal with driveway and possibly shrubs or trees.
I see a lot of people using 2-2-2-4 MHF to feed 100 Amp subpanels, but most pull it through 2" conduit, which is obviously a huge difference to 1.25. Is it worth even attempting or am I better off with 3-3-3-5 Cu and shelling out?
I'm also a bit confused about determining ampacity. For the Copper I'd need 3 AWG THWN-2 for this since conduit is considered wet, which at 75C is rated at 100 Amps. Factoring in the voltage drop over 135 feet and I figure I'd use a 90 Amp breaker, but from what I understand if the breaker doesn't have a temperature rating on it you assume 60C - I'd need a square D homeline breaker, and I can't seem to find a temp rating anywhere.
Any input is much appreciated