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Currently I have a detached garage about six feet from the closest wall of the house. The current garage electrical system is served by a sub panel (located in the garage) via a conduit from the 200 amp house panel and has two 20 amp circuits and includes a ground rod. This 40 amp service far exceeds the current calculated load for the garage. This panel serves all the outlets currently in the detached garage. The entire wire run to the garage sub panel from the house panel is no more than 30 feet.

I would like to install a 60 amp electric vehicle recharging outlet in my garage.

Is the following a legal possibility?:

I have a vacant 60 amp breaker in my house panel which formerly served a electric furnace (I have since gotten a natural gas furnace). There is also a considerable length of left over # 6 wire that served the uninstalled electric furnace which might come in handy for the project I have in mind.

Here is my question:

Could I run a separate circuit from there to the garage through its own properly entrenched and properly scheduled conduit to its own outlet in the garage and (if necessary) through its own disconnect and or separate sub panel?

Or must the electrical service to any outbuilding have ONLY one disconnect

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    What size and type (PVC, rigid steel, etc) is the present conduit to the garage?
    – Ecnerwal
    Apr 26 at 13:49
  • What size of feeder wires are in the conduit right now? The answer I'm hoping for is "8 AWG copper THHN" but I'll take others. I mean copper is a waste of money for a feeder, but if it's already copper we can take full advantage. What is the size, metal and type of the old furnace cable? Apr 26 at 17:44

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NEC 225.30 allows only one feeder to a detached structure. There are special conditions for some emergency type applications, but none apply.

You might want to check your service panel labelling for stab limits and consider a 90A breaker for a new #2 awg aluminum (mobile home) feeder to a new panel, and refeeding the existing garage panel as a sub.

In many jurisdictions a permit application for an EVSE outlet triggers a Load Calc, but if your service was properly sized for your former electric heat you should have that covered.

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  • 2-2-2-4 Al MHF should currently run about $3/ft lowes.com/pd/… Apr 26 at 13:13
  • It's normally closer to a buck a foot. Prices are mad because a) COVID is making everyone rethink life, so lots of home improvement + lots of job loss in manufacturing and trucking due to the Great Resignation; and b) COVID is still putting workers out sick and disrupting supply chain worldwide, coz, it's not over. Apr 26 at 18:59

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