cook top

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olly

Senior Member
Location
Berthoud, Colorado
Occupation
Master Electrician
Can you use the tap rule to wire an electric oven and electric cook top if the original feed and breaker is 40a #6 al? How long can the tap be? (the oven and cook top are on different walls. Do you tap to both with #12. Or just to the cooktop with #12. Thank you very much!!!!!! This is residential.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Basically you can only apply the tap rules where there is OCPD appropriate to the wire size at the far end. Just having the rated load low enough does not count.
Install a fused discount at the end of the #12 and you might be OK.
 

JDB3

Senior Member
I am concerned about asking to feed an oven & cook-top with #12 , taped off a 40 amp feed. Unless they are gas units & smaller than any that I have seen, #12 @ 20 amps will not normally work !! :eek:hmy:
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Occupation
Electrician
I am concerned about asking to feed an oven & cook-top with #12 , taped off a 40 amp feed. Unless they are gas units & smaller than any that I have seen, #12 @ 20 amps will not normally work !! :eek:hmy:[/QUOTE

Agreed. How can you power an electric cooktop and an electric oven with a #12???? The oven would be 30 amps minimum and the cooktop close to that.
 
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James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
The oven would be 30 amps minimum and the cooktop close to that.

Single ovens don't use 30 amps, and don't need a 10 gauge circuit. Some single ovens require only a 15 amp circuit. GE Profile has offered one such oven for more than 15 years.

Cooktop by itself is probably going to be close to 40 amps, though.
 

kwired

Electron manager
Location
NE Nebraska
I am concerned about asking to feed an oven & cook-top with #12 , taped off a 40 amp feed. Unless they are gas units & smaller than any that I have seen, #12 @ 20 amps will not normally work !! :eek:hmy:
Read 210.19(A)(3) and exceptions, 210.23 and 210.24 and in particular 210.23(C). Been some changes in 2014 but I think the practical application is about the same- especially for multi-outlet circuits. A 12AWG tap is specifically permitted on a 50 amp circuit in table 210.24. Exception in 219.19(A)(3) states the length of the tap shall not be longer then necessary for servicing the appliance though. So you typically have a 40 or 50 amp conductor to the appliance location with a tap conductor in the whip to the appliance.
 

meternerd

Senior Member
Location
Athol, ID
Occupation
retired water & electric utility electrician, meter/relay tech
I installed a double wall convection oven and a 5 burner induction cooktop. I used separate 50A, #4 copper runs because the distance was pretty long. I used the panel adjacent to the meter instead of the sub, even though the sub was closer. Now wifey can use both ovens and all 5 burners at the same time if she wants. It was as pain to run the wire and I didn't want to have to go back and do it over. Maybe overkill, but not that much more expensive compared to the appliance cost. Breakers are lockable off.
 

kwired

Electron manager
Location
NE Nebraska
I installed a double wall convection oven and a 5 burner induction cooktop. I used separate 50A, #4 copper runs because the distance was pretty long. I used the panel adjacent to the meter instead of the sub, even though the sub was closer. Now wifey can use both ovens and all 5 burners at the same time if she wants. It was as pain to run the wire and I didn't want to have to go back and do it over. Maybe overkill, but not that much more expensive compared to the appliance cost. Breakers are lockable off.
It was overkill IMO, but can't argue over cost compared to cost of your units. What happens if you get a little VD? It takes just a little longer to cook. I bet same unit has a 208 volt rating and it will have even less heat output at that rating then @ 240 volts with only 5 or even10 volts of VD.

Plus how often are all five burners running at 100% plus both ovens @ 100%? Reality is you could probably have run 10 AWG and never noticed any difference in performance, and likely never had the load demand for long enough period to cause much for excess heating in the circuit either. But same kW in space heating appliances would be a different story.
 

electricman2

Senior Member
Location
North Carolina
Occupation
Retired Electrical Contractor
I'm doing a kitchen remodel right now that requires a 20 amp circuit for the oven and a 40 amp circuit for the cooktop. Pretty typical around here
 

kwired

Electron manager
Location
NE Nebraska
I'm doing a kitchen remodel right now that requires a 20 amp circuit for the oven and a 40 amp circuit for the cooktop. Pretty typical around here
NEC would permit both to be on a single 40 or 50 amp circuit, though many people prefer to run separate circuit to each appliance. I usually run separate circuits myself. I could see there being local code amendments that do require separate circuits though.
 

meternerd

Senior Member
Location
Athol, ID
Occupation
retired water & electric utility electrician, meter/relay tech
It was overkill IMO, but can't argue over cost compared to cost of your units. What happens if you get a little VD? It takes just a little longer to cook. I bet same unit has a 208 volt rating and it will have even less heat output at that rating then @ 240 volts with only 5 or even10 volts of VD.

Plus how often are all five burners running at 100% plus both ovens @ 100%? Reality is you could probably have run 10 AWG and never noticed any difference in performance, and likely never had the load demand for long enough period to cause much for excess heating in the circuit either. But same kW in space heating appliances would be a different story.

Nameplate said 40A min. Rated 240 only. Made by Miele and Bosch. Maybe European are a bit different. Definitely high end (at least they cost a lot!)
I figured that the electronics was happier at full voltage, especially on the induction. Once in a while the cooktop "locks up" and the touch controls won't work. Takes cycling the breaker. Nice not cycling the oven too, because setting the clock back up after an outage (no battery backup) is a bit of a hassle.

All 5 burners and both ovens? Not that unusual around Christmas and Thanksgiving. Happy wife, happy life!

The old stove was gas burners, convection electric oven on a 20A 240 ckt, so couldn't be used. Maybe just my utility background...I'm used to wrestling with BIG wire!:D
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Single ovens don't use 30 amps, and don't need a 10 gauge circuit. Some single ovens require only a 15 amp circuit. GE Profile has offered one such oven for more than 15 years.

Cooktop by itself is probably going to be close to 40 amps, though.

I have seen many single ovens that require a 30 amp circuit. Perhaps the newer units have gone to 20 amps

IMO, itr is not compliant to tap off the 40 amp circuit unless the tap is part of the appliance whips. For instance a single wall oven and a cooktop may be allowed to be tapped off the 40 amp circuit if the whips enter the same jb as the 40 amp branch cir.
 

JDB3

Senior Member
I try to find the name plate rating before wiring. Though not always possible, due to owners not having picked out appliances. AND, at times, the owners decide to go with different units. Therefore I run separate runs for the appliances, & try to error on plenty.
 

kwired

Electron manager
Location
NE Nebraska
Nameplate said 40A min. Rated 240 only. Made by Miele and Bosch. Maybe European are a bit different. Definitely high end (at least they cost a lot!)
I figured that the electronics was happier at full voltage, especially on the induction. Once in a while the cooktop "locks up" and the touch controls won't work. Takes cycling the breaker. Nice not cycling the oven too, because setting the clock back up after an outage (no battery backup) is a bit of a hassle.

All 5 burners and both ovens? Not that unusual around Christmas and Thanksgiving. Happy wife, happy life!

The old stove was gas burners, convection electric oven on a 20A 240 ckt, so couldn't be used. Maybe just my utility background...I'm used to wrestling with BIG wire!:D
I guess full voltage depends on some factors. Around here no load voltage is typically much closer to 250 instead of 230 that may be listed on appliances so some voltage drop is normally not much of a problem - especially in the average dwelling. Plus there is a good chance the unit is also rated for 208 volts, just at a lower output rating. Now your European made unit likely is rated 240 volts - that is what they have over there, and the induction part may throw a curve ball in there as well. (I really know little about induction cooking units, and have never even used one.)

Otherwise if talking resistance heating units, there is slim chance of all surface elements and all oven elements drawing 100% rating for long enough period of time to trip the branch circuit overcurrent device. I'd guess same would go for induction, at some point the cooking surface/pan/etc. will reach a setpoint and then the heat source will be cycled. Older design heat elements can run continuously on high setting - but you usually have to turn them down at some point or you will have burned whatever it is you are cooking.
 

rt66electric

Senior Member
Location
Oklahoma
Tap rules were made for industrial applications instead of residential romex install

Tap rules were made for industrial applications instead of residential romex install

I tend to think that the wire size should match the breakersize upto the appliance.

Most appliances significantly downsizes the internal wiring(probably due to cost of materials) but increases the temp rating of the insulation.

The reduced wire size acts like a fuseable link ( not to mention the tiny spade connectors) .

Appliances(stove, dryer) are built similar to a fusebox ,in that, if a wiring fire does occur, then, the appliance enclosure contains the heat, flame,and amount of combustionable material to a point where it does not spread outside of the unit.

The smaller the internal wiring, then the less, amount to burn, The wire act like a fuse to quickly extingish or break the circuit without generating heat

Back to dwelling wire size matching the breaker...
If half the appliance is located a sizable distance away from the first half, then a sizable portion/length of wire is subject to physical damage or a direct short in the second half appliance. If a direct short occurs on a 12ga wire protected by 50 amp breaker, then the 12ga wire may become a runaway heating element inside a dwelling wall.

Exposed wiring should match the breaker size. Just as a 14ga wire is not allowed to be tapped off a 12 ga circuit.
 

kwired

Electron manager
Location
NE Nebraska
I tend to think that the wire size should match the breakersize upto the appliance.

Most appliances significantly downsizes the internal wiring(probably due to cost of materials) but increases the temp rating of the insulation.

The reduced wire size acts like a fuseable link ( not to mention the tiny spade connectors) .

Appliances(stove, dryer) are built similar to a fusebox ,in that, if a wiring fire does occur, then, the appliance enclosure contains the heat, flame,and amount of combustionable material to a point where it does not spread outside of the unit.

The smaller the internal wiring, then the less, amount to burn, The wire act like a fuse to quickly extingish or break the circuit without generating heat

Back to dwelling wire size matching the breaker...
If half the appliance is located a sizable distance away from the first half, then a sizable portion/length of wire is subject to physical damage or a direct short in the second half appliance. If a direct short occurs on a 12ga wire protected by 50 amp breaker, then the 12ga wire may become a runaway heating element inside a dwelling wall.

Exposed wiring should match the breaker size. Just as a 14ga wire is not allowed to be tapped off a 12 ga circuit.
Did you read the code sections I mentioned in post #6?

Appliances built like a fusebox? Look at the typical dwelling unit dishwasher - and tell me why they can't change listing requirements for those appliances instead of mandating GFCI protection for these appliances like they did in 2014 because of past fire problems that supposedly a GFCI will detect the failure that happens with them:(
 

rt66electric

Senior Member
Location
Oklahoma
Good point ....
"Appliances built like a fusebox? I should have said "inside a metal enclosure"

" Look at the typical dwelling unit dishwasher " ..... I agree with you,but,
Dishwashers are not included in this discussion

I interpret 210.23(C) in that the appliance taps are part of a listed assembly. Usually the 50 amp junction box supplies one unit, and then, it supplies the other unit.

"the oven and cook top are on different walls." Meaning Altering the assembly.
Would you take a #6 50amp circuit to j-box in the attic, then, run a #12 to a stove top ?? and then another #12 from the j-box to the oven???

More info is needed on the load requirements of the second unit.

and I would never use #6 alum as a branch circuit conductor...

In a this remodel situation, I would
(A) refeed everything from the panel using copper,
or
(B) run #8/3 copper from one location to the other with emphasis on good AL/CU screw type connectors
 

kwired

Electron manager
Location
NE Nebraska
Good point ....
"Appliances built like a fusebox? I should have said "inside a metal enclosure"

" Look at the typical dwelling unit dishwasher " ..... I agree with you,but,
Dishwashers are not included in this discussion

I interpret 210.23(C) in that the appliance taps are part of a listed assembly. Usually the 50 amp junction box supplies one unit, and then, it supplies the other unit.

"the oven and cook top are on different walls." Meaning Altering the assembly.
Would you take a #6 50amp circuit to j-box in the attic, then, run a #12 to a stove top ?? and then another #12 from the j-box to the oven???


More info is needed on the load requirements of the second unit.

and I would never use #6 alum as a branch circuit conductor...

In a this remodel situation, I would
(A) refeed everything from the panel using copper,
or
(B) run #8/3 copper from one location to the other with emphasis on good AL/CU screw type connectors
To the bolded question:
No. With the 50 amp circuit you need to run the #6 (NM cable, could be #8 for other wiring methods) to near one appliance and then continue with 50 amp conductor to a point near the other appliance. Like I mentioned earlier Exception in 219.19(A)(3) states the length of the tap shall not be longer then necessary for servicing the appliance, so that means the junction box where each appliance tap begins is going to be very near the appliance, typically in the same space or an adjacent space right next to it.
 

rt66electric

Senior Member
Location
Oklahoma
I think we agree.

OP"............... (the oven and cook top are on different walls. Do you tap to both with #12. Or just to the cooktop with #12. Thank you very much!!!!!! This is residential............"

I would not run #12 from one wall to the other.
 
cook top branch feeder

cook top branch feeder

Just wondering if have been living in the dark ages. I work in an area that I have to keep up with 2005-2014 codes in different municipalities. I was turned down for the first time today for running a 6/2wg to a cook-top that is only rated 240v. Blk Wht and bare ground from the cook-top. Inspector says the feeder has to be a 4-wire. Can someone tell me where in the code I can find this requirement.

Thx
 
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