Ranges....a maximum overcurrent protective device?

[don_resqcapt19]

Yes the unit states 40 amp but does not state that is the maximum... That is my point. If the unit is 16 kw and was on a commercial setting then we could put this on a 70 amp overcurrent protective device.


So you are saying I can go 150% of the units nameplate

I have never seen a range that can be fed with 2 circuits... perhaps commercially

Yes, I believe the code permits the OCPD to be up to 150% of the nameplate, and I see that as a hard maximum, not permitting you to use the next larger standard size where the 150% value is not a standard size. Note that an overcurrent specification on the nameplate or in the instructions would prevail over the code rule of 150%.

As far as the two circuit rule, it only applies to "household type appliances", whatever those are, but no matter what they are, I think that rules out applying 422.11(B) to commercial ranges.

 

[wwhitney]

Would just like to point out that 422.11(B)'s language "having a maximum demand of more than 60 amperes calculated in accordance with Table 220.55" means, for 240V appliances, a rating of 28 kW or more.

If I understand Note 1 to the Table correctly, it is saying a 12 kW range has an 8 kW demand, while for 13 kW the demand is 1.05*8 kW; for 14 kW 1.10*8 kW, etc. So a 27 kW range has a demand of 1.75*8 kW = 14 kW, or at 240V a current of 14/0.24 = 58.3A. Now Note 1 says that procedure is only applicable up to 27 kW, so I guess a 28 kW range has a demand of 28 kW?

For 208V supplied ranges, you hit the trigger in the 422.11(B) language at 24 kW.

Cheers, Wayne

 

[macmikeman]

When we reach the point of having robot wives, people in apartment buildings are going to have problems with all those derated range oven circuits, because those robots will be trying to cook all at the same exact instant in time because of the software programming.............. lol..

 

[Mr. Serious]

Regarding the range running with all elements on at the same time: I don't see it as a problem that it pulls more than the OCPD rating in that condition, because the heating elements shut themselves off after heating up. So, such condition would only exist for a few minutes at most. The person cooking would almost never start all burners simultaneously, so by the time a third or fourth one is started, the first and second ones have already heated up somewhat, and will be in a state of cycling on and off to maintain the set temperature.

 

[hbiss]

The person cooking would almost never start all burners simultaneously, so by the time a third or fourth one is started, the first and second ones have already heated up somewhat, and will be in a state of cycling on and off to maintain the set temperature.

For burners, there is no thermostat involved, only a control that varies the duty cycle. When I had electric, the burners would be on full blast most of the time. So, it's conceivable that if the ovens are heating up and the burners are on the range would be drawing maximum current until the ovens temped which could be at least 15 minutes or more.

-Hal

 

[Mr. Serious]

I didn't know that. Although it seems that new ones built within the last 4 or 5 years should have a temperature limiter:

Electric Range & Cooktop - Coil Burner Sensi-Temp Technology

It says that the manufacturer is now required to provide temperature limiting. And, I think I've seen some older ranges that had the same thing.

Perhaps the duty cycle would still be high, even with the temperature limiter.

 

[Dennis Alwon]

The crazy thing is that you could put a 100 amp breaker on this range and still be compliant. That is odd to say the least and in the real world that wouldn't happen. I think the manufacturer of this particular unit used 40 amp because T. 220.55 allows a 16kw unit to be sized at 40 amps

5% for reach kw over 12-- 16-12 = 4
4 x 5%= 20%
8kw ( from table) * 1.2 = 9.6 kw

9.6 kw / 240 = 40 amps

 

[Mr. Serious]

Out of this whole thread, only one reply mentioned a receptacle, way back at the beginning:

I normally provide a 50A circuit and receptacle. Range cord is 50A anyway. There is no 40A receptacle and range cord. More than 50A what do you do? Hard wire?

All this talk about 80A or 100A breakers for a range, but you can't do that with a receptacle rated for 50A.

 

[Dennis Alwon]

Out of this whole thread, only one reply mentioned a receptacle, way back at the beginning:


All this talk about 80A or 100A breakers for a range, but you can't do that with a receptacle rated for 50A.

No but you can direct wire it.

 

[dalc4life]

220.55. 16kw (cooktop and not more than 2 oven) will be treated as 8KW. Then add .05 for for kw over that 12kw, which is 1.20. So you have 8X1.20=9.6KW. 9600/240=40amps. Thus 8AWG 40aOCD. Am I missing something here?

 

[dalc4life]

220.55. 16kw (cooktop and not more than 2 oven) will be treated as 8KW. Then add .05 for for kw over that 12kw, which is 1.20. So you have 8X1.20=9.6KW. 9600/240=40amps. Thus 8AWG 40aOCD. Am I missing something here?

I wanted to edit, but waited too long. This is RESIDENTIAL application and 220.55 Note 4 combined with Note 1 is where this calculation derives.

 

[david luchini]

Thus 8AWG 40aOCD. Am I missing something here?

He was asking how large of a circuit he could install. 16kw @ 240V is 67A.