"The cooking range I have now is all electric, on an 80 amp circuit (2 40 amp breakers in breaker box). The stove I am getting is gas, but requires 20 amp electric for ignition, etc. Since it would be very difficult to pull a new circuit for the required 120 volt, 20amp plug, can I simply use one leg of the 240 volt circuit to install a 120 volt outlet next to the 240v? Or must I completely remove the 240 v outlet, replace it, and the breaker in the panel with 20 amp components?"

You may not pull 1 leg off and you don't have any neutral circuit if it is a straight 240V. You may have to run a 20Amp line to the range. Are you sure it needs a 20AMP?

Oh you, I forgot, no neutral in 240v... just ground and 2 hots. Let me modify my question... I do have a 120 20 amp circuit near the stove. The circuit has a 20 amp gfi in the first outlet, meaning, I think, that all the outlets downline are gfi controlled. Can I extend from that circuit (there are currently 3 outlets on that circuit) to provide another outlet for the stove?

Thanks for the reply!

What you have is not an 80 circuit. It is a 40 amp 240V circuit. A 240V circuit does not have a neutral. You may convert that circuit to a 20 amp, 120V circuit by replacing the 40 double breaker with a single 20 amp breaker. Connect the black to the breaker and the white to the neutral buss bar.

At the other end replace the present receptacle with a regular 15/20 amp receptacle. Because of the wire size, you will not be able to connect directly to the receptacle. Using wire nuts, connect a short piece of #12 wire to each wire. Then connect to the receptacle wire. The #6 or #8 wire will be stiff and hard to bend. Get a double switch box and a single outlet cover plate so you have lots of room in the box to work with.

I'm showing my ignorance by asking the questions. But I sure do thank you for your replies! Helps a lot.

Beat me to it, that was my next step if I got a reply. What if it's a red/black? Retask the red and put white tape on it?

You are much better asking the question than regretting a bad move. You would be surprised how many-" I plugged in my... into a 240V outlet and now it doesn't work, what's wrong? Careful with whever you do. Brian