Electrical size conductors and conductor rating

Jimongee · Mar 17, 2022

Hello, I’m building a wood shop. I’m planning on installing 240 and 120 outlets. I plan to connect to my supply panel using a 90 amp breaker. They’re run to the shop is 140 feet. I will use 2” underground conduit. I’m just not sure what size and what rated copper conductors to use. I used to work as a forensic electrical fire inspector. But that was many years ago. I did just complete the 400 amp service with all the bells and whistles in my own new construction home and it passed final inspection on the first pass. Thanks for your accurate help. Jim in Franklin, TN

Megawatt · Mar 17, 2022

Jimongee said:
Hello, I’m building a wood shop. I’m planning on installing 240 and 120 outlets. I plan to connect to my supply panel using a 90 amp breaker. They’re run to the shop is 140 feet. I will use 2” underground conduit. I’m just not sure what size and what rated copper conductors to use. I used to work as a forensic electrical fire inspector. But that was many years ago. I did just complete the 400 amp service with all the bells and whistles in my own new construction home and it passed final inspection on the first pass. Thanks for your accurate help. Jim in Franklin, TN

Well you have a big enough conduit for your conductors. You need three # 3 and a # 6 ground. Two of the # 3 are your power and the last one will be your neutral. Keep in mind that all buildings have to be GFCI protected. Good job on your 400 amp service and good luck with your building. You being a forensic fire inspector then you know we have to have main disconnect panels so you guys can kill the power in case of fire to protect your people. Congratulations

Jimongee · Mar 17, 2022

Megawatt said:
Well you have a big enough conduit for your conductors. You need three # 3 and a # 6 ground. Two of the # 3 are your power and the last one will be your neutral. Keep in mind that all buildings have to be GFCI protected. Good job on your 400 amp service and good luck with your building. You being a forensic fire inspector then you know we have to have main disconnect panels so you guys can kill the power in case of fire to protect your people. Congratulations

Thank you megawatt. I appreciate the help..