I am doing some research for a project. I have an unfinished detached two story garage. The second story space 400 square feet. Inside the house is a 200 AMP main panel with a feeder to the garage. The detached garage has a 125 AMP sub-panel. The breakers in the main panel and sub-panel are 50 AMPS.
I believe the wiring from the main panel to the sub-panel transitions based on where it is located. For example, part of the feeder line is buried and pops into the sub-panel. The marking on this wiring are:
AWG (33.62 mm2) AA-8000 AL Type use-2/RHH/RHW-2 600V SUN RES XLPE
Here are my questions
Even though the breakers are sized at 50 AMPS, how much power can this feeder line supply safely?
Will the current configuration provide the power I need? The following is a list of devices/appliances I think I need for the space.
- Hot Water Heater (30 AMPS 2-pole)
- HVAC (outside compressor) (?)
- HVAC (inside air-handler) (?)
- HVAC (electric heat) (?)
- Refrigerator (20 AMPS)
- Microwave (20 AMPS)
- Washer (20 AMPS)
- Dryer (30 AMPS 2-pole)
- Two Electric Cars (?)
I believe electric cars will become more popular in the near future. So I want to plan for enough power to recharge two electric cars. For example, Tesla has two types of wall chargers:
- Standard: 60-amps (48A draw)
- High Amperage: 90 amps (72A draw)
- The sub-panel is 125 AMP. Can I just swap out the 125 AMP sup-panel with a larger panel like 200 AMP for the moment until I can upgrade the service? The reason is I want to wire the sub-panel one time. If I find out that I need more power in the future, I do not want to have to reinstall and rewire a sub-panel.
Based on the table below this 33.62 mm2 converts to 2 AWG Aluminum wire. Based on the second table below, this shows an allowable Ampacity of 75 amps @ 60 degrees C. I presume that the cable is rated for 125% of the estimated need (50 * 1.25% = 62.5 amps), rounded up to 75 amps.
I believe the full length of the feeder line is less than 80 feet.