Convert 50 amp cooktop circuit to 20 amp HAVC circuit

I have an existing 50 amp circuit 2 blue, 1 white and braided bare 6 wag wires. I have to assume that this is romex although i can't see the jacket at either end. This serves a cooktop that has been replaced with gas.
I would love to use this line to serve a 2.5 ton AC condenser. The cooktop location is very close to where it will go.
The min. brch. cir. ampacity is 12 & br. cir. prot. rtg. is 20 max & 20 min..
How best to do this?
I'll most likely pull a permit.
I'm pretty handy electrical wise & am a plumbing contractor as well.
The breaker in the panel is 50 amp.
I'll put a fused disconnect at the AC unit.
Running conduit & junction boxes are no problem.
Any help would be appreciated

 

Yes, you can use the circuit, but you should change the breaker to a 20 amp 2 pole. Use the two blue wires for the hots and use the ground, all terminated in a 30 amp disconnect, non-fusible would be my choice. You can buy the disconnect for $6 to $7 at a big box. I would use 3 - #12 THHN/THWN conductors (Blk, Red, Grn) to wire the new condensing unit in 1/2" Liquidtite flexible conduit. You can use either metallic or non-metallic flex. You could use #14 conductors to wire the unit, but I never recommend anything smaller than #12 for these applications.

 

Thanks for the reply.
Do I need to tag the #6 wire at the main panel?
If someone just looked there, they would have no idea that there was #12 as part of the circuit.
Part of this run goes from a second story attic down to the first level.
Can I run plastic or emt conduit on the exterior to the disconnect?
Why no fuse at the disconnect?

 

YOu could also just leave the 50 amp breaker and install a fused disconnect at the A/C with 20 amp fused.

 

I should have been clearer. The AC condenser is about 15' from where the cooktop was. I need to extend the circuit as well. Can I extend the #6 circuit & use #12 and change to breaker to 20 amp

 

NM cable would not have two blue conductors. Perhaps you have conduit?

A splice could be made in a properly sized and permanently accessible junction box.

 

Yes, the breaker must be changed to 20 amps if you extend the circuit with 12-2 NM cable. What brand panel do you have? Some 20 amp breakers will accept a #6 and some won't.

 

It's a GTE Sylvania panel. I believe it accepts Zinsco breaker. I looked at a 20 amp breaker. A #6 may possibly fit but it would be tight. I could always go to a 30 amp breaker & run #10

 

I'd start by replacing that panel and not look back! It's a known fire hazard.

How to Report Failures of Zinsco Electrical Panels & GTE-Sylvania-Zinsco Circuit Breakers

No, a BR Cutler-Hammer will not work. The best source I know of a breaker would be a UBI breaker from Menards, but they have to order them, but I don't believe they are U.L. Listed.


http://www.menards.com/main/electric...839-c-6416.htm

 

sounds expensive. Any idea how much?

 

Even if you find the breaker you still have a design with known issues. Put the money into a new panel.