Convert 50 amp cooktop circuit to 20 amp HAVC circuit

Reply

  #1  
Old 09-05-14, 06:32 PM
Member
Thread Starter
Join Date: Sep 2009
Location: United States
Posts: 10
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
 
Sponsored Links
  #2  
Old 09-05-14, 07:05 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
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.
 
  #3  
Old 09-06-14, 11:34 AM
Member
Thread Starter
Join Date: Sep 2009
Location: United States
Posts: 10
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?
 
  #4  
Old 09-06-14, 11:43 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,991
YOu could also just leave the 50 amp breaker and install a fused disconnect at the A/C with 20 amp fused.
 
  #5  
Old 09-06-14, 12:12 PM
Member
Thread Starter
Join Date: Sep 2009
Location: United States
Posts: 10
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
 
  #6  
Old 09-06-14, 12:39 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,365
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.
 
  #7  
Old 09-07-14, 06:55 AM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
Can I extend the #6 circuit & use #12 and change to breaker to 20 amp
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.
 
  #8  
Old 09-07-14, 04:50 PM
Member
Thread Starter
Join Date: Sep 2009
Location: United States
Posts: 10
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
 
  #9  
Old 09-07-14, 07:27 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
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

I think Cutler-Hammer BR series are the recommended replacement .
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
 
  #10  
Old 09-07-14, 10:50 PM
Member
Thread Starter
Join Date: Sep 2009
Location: United States
Posts: 10
sounds expensive. Any idea how much?
 
  #11  
Old 09-08-14, 04:48 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,365
Even if you find the breaker you still have a design with known issues. Put the money into a new panel.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'