Service needs and UF size

[transferguy]

posted by: DD61

I am building a new detached garage/shop, 54' X 36'. I do have a medium sized compressor and will use a 220V electric furnace. Plus extra lighting for work and will use several hand power tools. No welder or such. I have 200 amp service coming into my house. How many amps will I need to have going to the new building and what gauge UF cable will I need? Please advise, thanks.

[transferguy]

posted by: suemarkp

You need to list the amp and volt ratings of the compressor, and furnace, to have a hope of giving an accurate answer. Assuming the compressor is 15A at 240V and the furnace is 20A at 240V, I'd run a 50A feeder to the garage. How far is the garage panel from the house panel (e.g. how long will that UF cable be)? UF cable is harder to find larger than #6 copper, and that is what you'll need for a 50A feeder. If you anticipate a higher load (more stuff, especially things that run at the same time), or the distance is over 100', I'd run a 1.25" to 1.5" conduit and upsize the wire.

Code requirements for a detached garage are nearly zero. You'd need a circuit for lights, and enough capacity to run the installed equipment (especially fastened-in-place or heavy equipment). But installed equipment can change over time...

Mark
Kent, WA

[transferguy]

posted by: navyguy

Just to add to Mark's reply...

I always recommend the installation of conduit(s) from the house to the garage that will accommodate a larger size of cable. The cost is negligible and you will likely be digging up the ground anyway. You can simply use the conduit as mechanical protection or finish it off and use it as a complete raceway with individual conductors.

Adding a second conduit will allow for telephone, CATV, Cat5e, doorbell, etc. In my house I have a third conduit for individual circuits that allow the switching of lights from the house and interconnection of smoke detectors.

Cheers

John