What wire to use instead of Romex

@roccity  

Using appropriate wiring and breakers on a split duplex has been around for years and it is most definitely code and designed to be used that way as well. It is essentially no different than using a single outlet on a duplex box. Wiring must be done properly and you have absolutely no issues with safety. 
I did this because each one of my amps requires its own 20 amp breaker and I wanted to minimize dry wall and stud issues. The changes are well indicated in the panel and in the duplex box so any future people opening either will realize that multiple breakers have to be turned off. 
 Chreers

@1971gto455ho Said:

Best Practices:

It’s recommended to use separate, appropriately sized 20 amp circuits with their own breakers and wiring to feed each half of the duplex receptacle. This ensures proper protection and avoids potential hazards.

Proper Method:

1. Separate Circuits:

Each 20 amp circuit should be run from its own 20 amp breaker in the electrical panel to its respective half of the duplex receptacle.

2. Appropriate Wiring:

Use 12 gauge Romex for both circuits, as it is rated for 20 amps.

3. Proper Termination:

Ensure the hot (black), neutral (white), and ground (bare or green) wires are correctly connected to their respective terminals on each half of the duplex receptacle. 
This is code ! 

This is code ! 

No it is not. I posted word for word from the 2020 NEC code book.

I will look tomorrow for when NEC 210.7 Multiple Branch Circuits, the code edition year it was added to the NEC code book.  You may have wired your outlets the way you have them before 210.7 Multiple Branch Circuits was added to the NEC. 

Best practices is no guarantee that it follows or meets NEC or AHJ code. 

Your quoted material might be old. It should be updated to meet current NEC code. Or at least for the NEC code edition your state is still using. 

Please post the Website for the quoted material in your post. 

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@jea48  

Do let me know for curiosity sake, it’s CSA approved here. I also run into many houses where 12 three was used in duplex boxes, that can get complicated and I personally don’t recommend it anymore, but it is legal. And I should add and don’t know that this would make a difference but the four wires and two duplex are in a double box. 
 

@1971gto455ho 

2011 NEC 210.7 was added to NEC.

FWIW, in the US if you wired the duplex outlets as you have them wired before the 2011 NEC was adopted by the state, or AHJ governing body for the county or city you live in, they would be grandfathered in.

I have no Idea what Canada electrical code says.

FWIW, I usually look up the username of a member before responding to a post of theirs. Don’t know why I missed looking you up. My bad. I wasted your time as well as mine on the subject.

I found this doing a quick Google search.

CEC Versus NEC: What’s the Difference?

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@roccity said:

Yes. It’s a short, straight run from the outlet down to the garage - just as it appears in the illustration I created above.

Best and cheapest way is to have the electrician install 10-2 solid copper MC cable.

You will save on labor and material. Labor is your biggest cost.

He may even be able to run the MC cable up inside the wall and recess the electrical outlet box. Just a suggestion for the electrician use a deep i gang cut-in switch box. He will appreciated the added space for make up of the duplex outlet to the #10 solid wire.

FYI if you would like 4 receptacle outlets have him install a 2 gang deep cut-in switch box for two duplex outlets.