First timer here...
I have a 110 circuit (30 amp) breaker at main box. It has a #10 2 wire w/ground that runs through the attic and out an exterior wall in a junction box. I would like to use this circuit to power a garage with get this a "220 circuit". This would include installing a distribution panel in the garage.
Can this be accomplished with #10 2 wire w/ground and adding a separate ground and ground rod next to the garage?.
I am assuming this wire was run when the house was built as there are two bulkhead walls that extend floor to roof (House was built to withstand category 4 hurricane) there is no attic access between the bulkheads. Installing new 3 wire w/ground conductor would be very expensive...

• There is a 30 amp 110 breaker for this circuit
• A couple of blank spaces in the main box to add 220 breaker
• Total length of run Main to Distribution Panel about 130 feet
• Want to run welder in garage that requires 220v 20 amp breaker

Thanks in advance for your expert advice...
JAMdozer...

 

If you use 240V only (it is 120V and 240V in the US and Canada), you can. Most welders are 240V only.
You just have to mark white wire with black , red, or blue electric tape to repurposed it as hot wire and connect white wire to one of the poles on the breaker.

Adding additional ground will make no difference because you cannot use ground wire as current carrying wire.

 

But you will need to weld by the light of a coal oil lamp. Code says only one feed to a detached structure so if an existing 120v feed it would have to be abandoned.

 

The op said it is on 30A, so I assumed it is not the part of existing lighting or receptacles.
Also, I assumed it is attached garage.

If this in fact is detached, then you will have to run 8 AWG or 6 AWG then install a sub panel.

 

I may have guessed wrong when I read:

 

You cannot add a ground and a ground rod to allow that cable to also supply any 120 volt circuits.

 

First off, thanks to all for your valued input...

Seems that I can use the existing conductor to run 240v circuit

But will not have 120v circuit because both black and white conductors would be hot...120v circuit would require a neutral???

I would definitely want to have lights and 120 outlets for power tools...

Thanks
JAMdozer