Replacing Wall Oven & Cooktop -- Keep On Same Breaker?

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  #1  
Old 04-05-13, 04:49 PM
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Replacing Wall Oven & Cooktop -- Keep On Same Breaker?

I'm remodeling a kitchen and replacing the old cooktop and Avacado-Green oven with new ones. They are both on the same 60-Amp breaker. I think this breaker should be a 50-Amp, but other than that can I legally/safely keep both on one circuit?

-The new wall oven is rated at 3.4 kW at 240V.
-The new cooktop is rated at 6.7 kW at 240V.
-Both new appliances have whips.
-The wire running from the breaker box to the junction box where both appliances connect is Aluminum 6 gauge 3 conductors (about 50 feet long).
-The wire running from the junction box to the wall oven is 10/2 NM copper, about 7 feet long.


Here is a picture of the junction box:
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From what I've read, I think I need to use some CU/AL fittings and probably replace the current 60A breaker with a 50A breaker. Is this correct, or do I need to run a whole new line? For what it's worth, my breaker box is already full.

Any advice would be appreciated.
 
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Old 04-05-13, 05:52 PM
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Welcome to the forums! You say both appliances have whips. What size wire is in the whips? I question the use of 10-2, since newer appliances will need a conductor cable, and of sufficient size to handle the load. I should think a 50 amp breaker will handle the loads you have on the oven and cooktop. That's a long way for a cable run.
 
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Old 04-05-13, 06:07 PM
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If you have two whips of 10-2 NM cable, you'd be protecting them at 50 amps. I also would question using a breaker any larger than 40 amps on the #6 aluminum circuit. I wouldn't do it. In addition, those big blue wire nuts in your picture are not approved for direct connecting aluminum to copper conductors
 
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Old 04-05-13, 06:55 PM
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On your new units.....it should clearly state what size breaker to use or circuit size.

Running two units on a common cable is not the safest thing to do. I see it all the time.
Your combined load is 42 amps at 240 volts.

Your oven uses 14 amps at 240 volts. It should be on a 20 amp circuit.
Your cooktop is 28 amps at 240 volts. It should be on a 40 amp circuit.

If you're asking what is proper......leave the cooktop on the old circuit and run a new one for the oven.
 
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Old 04-06-13, 08:48 AM
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The cooktop says it requires 30A circuit and the oven requires 20A. So is both on a 50A safe?

I am mainly referring to posts such as this one I've read on this forum:
"NEC 210.19 (A)(3) exception 1
You are indeed allowed to have both a cooktop and oven on the same branch circuit. The catch is it must be a 50 amp branch circuit.The tap conductors must be at least rated to carry 20 amps and not longer than necessary and big enough to serve the cooking appliance to which they are connected. These tap conductors are generally the appliance pigtail."

Read more: http://www.doityourself.com/forum/el...#ixzz2PhM5yJx7

I think I meet the requirements for this exception but the one I'm not sure about is they are both 3-wire hookups and while I am not modifying the circuit I am replacing the appliances.

I guess by "whip" I was talking about the two metal hoses extending from the appliances. If that's not a whip, then forgive my ignorance. The cooktop is close to the j box and doesn't require an extension while the oven has about 6-7 feet of 10/2.

I know that the cu/al connectors need to be changed and I know that the BEST thing would be two separate breakers. What I'd like to know is can the two appliances go on one 50A, and can it be done legally and reasonably safely.

Thanks for the replies so far!
 
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Old 04-06-13, 12:03 PM
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Not a pro but what I think here we have code vs best practice. By code you can, best practice you shouldn't but to be the devil's advocate this is like plugging a lamp with a 18 gauge cord into a 20 amp circuit. It's done all the time and the explanation often given is the breaker protects the wiring not the device.

The real problem is you do not have a national code compliant 3-wire circuit. A national code compliant 3-wire circuit would be white, red, black, no ground. But you have white, black, ground. That would be code compliant only if both appliances were 240v only. If either appliance has a white wire in the whip it is 120/240 and the wiring is not national code compliant.
 
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Old 04-06-13, 02:23 PM
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I know that the cu/al connectors need to be changed and I know that the BEST thing would be two separate breakers. What I'd like to know is can the two appliances go on one 50A, and can it be done legally and reasonably safely.
Yes, but you'll almost certainly need to upgrade the cable to a 4-wire. Then you might as well make it a cable with (smaller) copper conductors. By that time you might as well run separate supplies.
 
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