LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I wouldn't go that light in a commercial kitchen. I'm still at the full 100a circuit.
Range calculation
- Thread starter retnoc
- Start date
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
I do not have my code book but unless this is being installed in an industrial environment, i believe the code book said 1 range shall be installed to the nameplate rating. HOWEVER, it also says for branch circuits supplying a range table 220.55 is permitted to be used.
Can you explain what is wrong here?
- Location
- Connecticut
- Occupation
- Engineer
220.55 says Electric Cooking Appliances IN DWELLING UNITS and Household Cooking Appliances USED IN INSTRUCTIONAL PROGRAMS.
This range is in a commercial kitchen.
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
220.55 isn’t excluded because of size of load being at 17300 VA but only gets excluded if this is being installed in an industrial or commercial setting such as a restaurant
The original post did not clarify if this was installed in a dwelling or not
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
The original post did not STATE this range being installed in a commercial location. More info needed
- Location
- Connecticut
- Occupation
- Engineer
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
Wire up to 17300 VA then. It’s best to go larger than minimum and post did not specify location initially so 17300. /208 = 83.17 i
Wire:
83.17 i x 125% (do we apply continuous load factor?) = 103.96 i = # 2 AWG THHN?
Breaker:
103.96i = 110 ampere breaker next size up
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
That’s not in the original post description but knowing that now i made a new calculation. I don’t have NEC code book on hand so I’m not sure if its accuracy
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
Is at a restaurant or thanksgiving it can exceed 3 hours at max load current
- Location
- Connecticut
- Occupation
- Engineer
The load of the range is 91A @ 208V, single phase. A 100A circuit would suffice.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
You know there are more posts and info than in just the OP. You need to read the whole thread before replying to just the OP.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
It could run for 10 hrs and still not be considered a continuous load. This is because it cycles on/off, so not full load the entire time.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The oven is thermostatically controlled so the range will never see the entire load for 3 hours straight.
Sorry - posted at the same time as Little Bill
- Location
- New Jersey
- Occupation
- Journeyman Electrician
That is not correct. An oven has a thermostat and cycles on and off. The range will not operate for 3 continuous hours at maximum current.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I'm thinking they used 91a to specify a circuit greater than 90a, a la HVAC MCA.
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
Yea I forgot about that. Ok so we never consider ranges continuous or use 125% factor?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Correct. In a dwelling using T220.55 you can actually reduce the branch circuit size according to the demand factor in the table.
Sparky Adam
Master Electrician
- Location
- Dallas, TX
- Occupation
- Operations Manager / Master Electrician
This is the most confusing discussion I've ever read on this subject.
Sorry, OP.
Sorry, OP.
TX+ MASTER#4544
Member
- Location
- Texas
- Occupation
- electrical Code instructor and mentor
Hello, retnoc.
Here's the way to calculate your household electric range.
Using the 2023 NEC Code. Section 220.55 refers to T.220.55 " ....for household demand factors and loads..."
See note Number 1 of that table for ".....Over 12 kW through 27kW...." You stated only one range at 12.3kW
Therefore we will have to use Column C titled... Maximum Demand (kW) (see notes) Not over 12 kW.
Therefore, your range is well over that rating so we must apply Note number 1of that table.
Referring again to that note, it says to increase Column C by 5 percent for every additional kilowatt of rating or major fraction thereof for the individual ranges exceeding 17.3 kW. (drop the 3 fraction).
Thus, 17 kW - 12kW = 5 kW at 5 percent 5% x 5Kw = .25 ( 5% for each Kw over 12kW per note number1)
One range from T.220.55 and column C is at 8 Kw.
Must increase that 8 Kw x .25 so multiply the 8 Kw x 1.25 = 10,000 Va or kW or 8,000 x 1.25 = 10,000 W or Va.
I put a number 1 in front of the .25 (1.25) thus the 1 is a hundred percent of the 8kW from Column C plus the 8,000 watts rating for one range.
Obey Ohm's Law, 10,000 watts/ 240 volts =41.66 amps or 42 amps.
Using romex or type NM and the ampacity from T.310.16 in the 60 degree column it requires a 6 AWG at 55 amps.
Table 240.6(A) list a standard size to be a standard 45 amp OCPD. Check Section 334.80 Ampacity.
As to why I did that, take a moment and read that section for using the 60 degree column of T.310.16, the final ampacity for type NM.
Thanks for reading
TX+ MASTER #4544
You need to read the other posts in a thread. The OP's installation is in a commercial kitchen so 220.55 does not apply.