Induction Cooktop and Electric Oven on Same Circuit?

Status
Not open for further replies.
E

ESolar

Senior Member
Location
Eureka, CA Humboldt County
Occupation
Electrician/Contractor
NEC 220.55 allows a cooktop and two wall ovens on the same circuit. My understanding is that if there were only an electrical cooktop (or only an oven), it would require a separate circuit, but if there are both they can be combined on the same circuit. There is currently a 50 amp (circa 1994).

The 30" IKEA induction cooktop selected states separate 30 amp circuit in manual (that's not the UL listing, but the manual). The 4500 W IKEA oven selected states separate 20 amp circuit in manual (that's not the UL listing, but the manual). I assume that the stated separate circuit is for when the cooktop or oven are installed alone (e.g., one could have an induction cooktop and gas oven, or vise versa) and that combining them is allowed, regardless of statements in the manuals.
FYI they are they are UL 858.

What is required in this case?
 
ESolar said:
NEC 220.55 allows a cooktop and two wall ovens on the same circuit. My understanding is that if there were only an electrical cooktop (or only an oven), it would require a separate circuit, but if there are both they can be combined on the same circuit. There is currently a 50 amp (circa 1994).

The 30" IKEA induction cooktop selected states separate 30 amp circuit in manual (that's not the UL listing, but the manual). The 4500 W IKEA oven selected states separate 20 amp circuit in manual (that's not the UL listing, but the manual). I assume that the stated separate circuit is for when the cooktop or oven are installed alone (e.g., one could have an induction cooktop and gas oven, or vise versa) and that combining them is allowed, regardless of statements in the manuals.
FYI they are they are UL 858.

What is required in this case?
Click to expand...
You would need individual circuit protection for each appliance, if your intent is to feed both of them from the 50A circuit. Also, that circuit probably doesn't have a neutral present. Does either appliance require a neutral?


SceneryDriver
 
wwhitney said:
Seems like (2017) 210.19(A)(3) Exception 1 allows what the OP proposes without any OCPD beyond the existing 50A branch circuit OCPD.

Cheers, Wayne
Click to expand...
You're correct. I don't do much residential, so I missed that. What a weird exception to the tap rules.


SceneryDriver
 
SceneryDriver said:
You would need individual circuit protection for each appliance, if your intent is to feed both of them from the 50A circuit. Also, that circuit probably doesn't have a neutral present. Does either appliance require a neutral?


SceneryDriver
Click to expand...
There is a neutral (interesting because there is not one on their dryer)! Neither appliance requires a neutral unless required by code (i.e., they have diagrams for three-conductor wiring with neutral as ground). So - wire a small subpanel behind appliance with two breakers (20 and 30) or just use the 50 amp?
 
wwhitney said:
Seems like (2017) 210.19(A)(3) Exception 1 allows what the OP proposes without any OCPD beyond the existing 50A branch circuit OCPD.

Cheers, Wayne
Click to expand...
Thank you. There is the issue: if appliance calls for dedicated circuit you're supposed to have it. Is there any issue with using a small 50 amp two breaker subpanel located behind appliance (other than not being accessible to reset, which could be a problem.
 
The house I grew up in had the built-in oven and cook-top on the same circuit. The J-box was supplied by SE cable, and each appliance by 10-3 NM w/o grd. I have also seen range circuits supplied by two parallel 10-3 w/o grd cables.
 
ESolar said:
Thank you. There is the issue: if appliance calls for dedicated circuit you're supposed to have it. Is there any issue with using a small 50 amp two breaker subpanel located behind appliance (other than not being accessible to reset, which could be a problem.
Click to expand...
Unless you have 110.26 working clearance behind the appliance it is a problem. Most places that you could put it in the kitchen that are code compliant probably are not "woman of the house" compliant though.
 
kwired said:
Unless you have 110.26 working clearance behind the appliance it is a problem. Most places that you could put it in the kitchen that are code compliant probably are not "woman of the house" compliant though.
Click to expand...
I have noticed some oven options that are 30 amp. The cooktop is 30 amp. Yet NEC allows them to be wired to the same circuit. I get that it's code, but that seems like a potential issue. Any thoughts when the total rated amperge of the applicances exceeds the breaker (note that this would likely be the case for most installs where a double oven and cooktop are on the same circuit, which is commonly 50 amp)?
 
I believe that I have figured this out. Someone please confirm. Table 220.55 answers all of these questions. In Note 4 of the Table it states that for a cooktop and wall mounted oven(s) (up to two) in the same room you add the name plate ratings and treat as one appliance. For example, a 7.3KW oven and an 11KW cooktop gives us an equivalent 18.3KW appliance. Then Table 220.55 is to be used. For one appliance > 8.75KW and less than 12KW, the maximum demand to use is 8KW. However, we are greater than 12KW. In this case, the demand shall be increased by 5% for each KW greater than 12KW (one can round down for fractions less than 0.5KW, see Note 1). Rounding 18.3KW to 18KW gives us 6KW over the 12KW limit, which increases the demand by 30%. Therefore the demand is 8KW x 130% = 10.4KW. The associated ampacity is 10,400/240 = 43.3 amps. Therefore a 50 amp circuit is fine. The NEC thought is that the case where all five burners are on max power boost and the Oven is maxed for cleaning at 800 degrees would likely never occur. But even if it did, you would trip the breaker.
 
ESolar said:
I believe that I have figured this out. Someone please confirm. Table 220.55 answers all of these questions. In Note 4 of the Table it states that for a cooktop and wall mounted oven(s) (up to two) in the same room you add the name plate ratings and treat as one appliance. For example, a 7.3KW oven and an 11KW cooktop gives us an equivalent 18.3KW appliance. Then Table 220.55 is to be used. For one appliance > 8.75KW and less than 12KW, the maximum demand to use is 8KW. However, we are greater than 12KW. In this case, the demand shall be increased by 5% for each KW greater than 12KW (one can round down for fractions less than 0.5KW, see Note 1). Rounding 18.3KW to 18KW gives us 6KW over the 12KW limit, which increases the demand by 30%. Therefore the demand is 8KW x 130% = 10.4KW. The associated ampacity is 10,400/240 = 43.3 amps. Therefore a 50 amp circuit is fine. The NEC thought is that the case where all five burners are on max power boost and the Oven is maxed for cleaning at 800 degrees would likely never occur. But even if it did, you would trip the breaker.
Click to expand...
Yes that is kind of the basis for allowing them on a common supply circuit, you still limited (somewhere in art 210 I believe) to maximum of 50 amp circuit for this but can use the demand factors for calculating ampacity needed.

At same time if an individual appliance has as part of listed instructions that it must be protected by a 30 amp overcurrent device - it shouldn't be allowed on that 50 amp circuit without some additional overcurrent protection. I think there may be more chance of such instruction these days than there used to be on such appliances.
 
kwired said:
Yes that is kind of the basis for allowing them on a common supply circuit, you still limited (somewhere in art 210 I believe) to maximum of 50 amp circuit for this but can use the demand factors for calculating ampacity needed.

At same time if an individual appliance has as part of listed instructions that it must be protected by a 30 amp overcurrent device - it shouldn't be allowed on that 50 amp circuit without some additional overcurrent protection. I think there may be more chance of such instruction these days than there used to be on such appliances.
Click to expand...
Suppose that the applianaces do specify an OCPD. Is this allowed: 50 amp OCPD on main panel (wire is 6 aluminum 75 C). Subpanel accessible near range with additional OCPDs, that combined might exceed the 50 amps (e.g., two 30 amp OCPDs, with wire to appliances sized accordingly)?
 
ESolar said:
Suppose that the applianaces do specify an OCPD. Is this allowed: 50 amp OCPD on main panel (wire is 6 aluminum 75 C). Subpanel accessible near range with additional OCPDs, that combined might exceed the 50 amps (e.g., two 30 amp OCPDs, with wire to appliances sized accordingly)?
Click to expand...
Note that the appliances will meet the 220.55 criteria. It seems like this approach would satisfy NEC and provide the appliance required additional OCPD protection.
 
ESolar said:
Suppose that the applianaces do specify an OCPD. Is this allowed: 50 amp OCPD on main panel (wire is 6 aluminum 75 C). Subpanel accessible near range with additional OCPDs, that combined might exceed the 50 amps (e.g., two 30 amp OCPDs, with wire to appliances sized accordingly)?
Click to expand...
As long as you can get the demand factor to come out at or below the 50 amps, yes. The two 30 amp circuits still will each need 30 amp conductor regardless what demand factor for individual appliance comes out to. The appliance whip may have smaller conductor but first was listed that way, second very well is a higher temp insulation therefore has higher ampacity anyway.
 
So hopefully one last question on this. If I put in a 50 amp subpanel on the existing range circuit, and the demand allows it, can individual circuits for the (1) cooktop (11000 VA, 30 amp), (2) oven (4800 VA, 20 amp), (3) lighting (600 VA,15 amp) and (4) range hood (240 VA, 15 amp) be run off that subpanel, or would it be limited to only the "heating element" appliances? Note that the 220.55 computed combined maximum demand for the (1) cooktop and (2) oven is 9,520 VA and the total for the four devices is 10,360/240 = 43 Amps, less than 50 amps.
 
Status
Not open for further replies.
Top