110v 20amp circuit using existing #8 Alu wiring to 40amp breaker.

[MikiSJ]

I am abandoning an oven/microwave location that has an existing 220v 40amp (4-wire) circuit. I am leaving the wiring in place. I want to use the new counter space for a built-in microwave oven and coffee station.
Can I use one of the 110v circuits in the junction box for a 110v 20amp receptacle and also another 110v 20amp circuit? The wire from the existing 220v wiring to the new 110v circuits will be inches?
Or, should I install a small load center?

 

[Megawatt]

I am abandoning an oven/microwave location that has an existing 220v 40amp (4-wire) circuit. I am leaving the wiring in place. I want to use the new counter space for a built-in microwave oven and coffee station.
Can I use one of the 110v circuits in the junction box for a 110v 20amp receptacle and also another 110v 20amp circuit? The wire from the existing 220v wiring to the new 110v circuits will be inches?
Or, should I install a small load center?

The biggest problem I see is you will have to share the neutral with 2 different phases which is not allowed

 

[MikiSJ]

The biggest problem I see is you will have to share the neutral with 2 different phases which is not allowed

Thank you for your reply. Why would this be different than using a 3-wire circuit where the black goes to the top of a receptacle and the red to the bottom of the receptacle where the top/bottom is switched?

 

[Megawatt]

Thank you for your reply. Why would this be different than using a 3-wire circuit where the black goes to the top of a receptacle and the red to the bottom of the receptacle where the top/bottom is switched?

If you share a neutral on let’s say say A phase and no problem but you have a problem with the B phase for what ever reason and you take the neutral loose it can shock you since A phase ie also using the same neutral which will have some power on it. Sorry

 

[jasonvr]

WARNING - Homeowner and electrical engineer and not an electrician (though my grandfather and uncle are)

Isn't the OP just proposing turning the existing 40A circuit into a multiwire branch circuit (MWBC) - two hots on opposite phases sharing a neutral? Breaker would need to be changed out to 20A two pole (assuming the existing wiring can fit into the 20A breaker) with a common trip/handle tie, but that should be legal, right?

 

[Megawatt]

WARNING - Homeowner and electrical engineer and not an electrician (though my grandfather and uncle are)

Isn't the OP just proposing turning the existing 40A circuit into a multiwire branch circuit (MWBC) - two hots on opposite phases sharing a neutral? Breaker would need to be changed out to 20A two pole (assuming the existing wiring can fit into the 20A breaker) with a common trip/handle tie, but that should be legal, right?

Bingo you are right but the OP wanted to continue to use the 40 amp double pole breaker and share the neutra.

 

[davesparks]

Bingo you are right but the OP wanted to continue to use the 40 amp double pole breaker and share the neutra.

They haven't actually said that anywhere, they have just said they want to install 2 receptacles using the existing wiring.