40A range w/ 52A "rating"

[malachi constant]

Looking at appliance cuts this morning, very fun. (Yeah right.) We are installing a GE range. Says "Breaker size: 40A". Says "kW rating: 10.7 @ 208V". Do the math...

10700 VA / 208V = 51.4A. That's bigger than the breaker.

A 40A breaker is good for 40A * 208V *0.8 = 6656 VA. Am I correct it is fair to use this smaller number in the load calculations?

 

[steve66]

Are you sure its not a 3 phase range?

 

[raider1]

The branch circuit load can be calculated in accordance with Note 4 from Table 220.55.

Also a range is not a continuous load.

Chris

 

[malachi constant]

It's available in 240V or 208V. (Incidentally, the 40A 240V model is rated at 14.2 kW - in other words 59.2 amps.)

It's a residential model. I can't imagine this is a three phase unit. We only have 208V/1P available in a given unit, so it wouldn't work. I've always seen 40A/2P units installed in units.

GE JB680SP if you want to look it up.

 

[malachi constant]

The branch circuit load can be calculated in accordance with Note 4 from Table 220.55.

Also a range is not a continuous load.

I'm using 220.82 - optional calculation for dwelling unit. Does table 220.55 apply?

I'm not familiar with this table. 220.55 says this we CAN use this table to calculate data, but not that we must. Looks like if we do use it then per the table header in my case only column C applies, so I could use 8kW.

I'd always assumed breaker limitations trumped nameplate rating. Is this not the case? Is it not correct that a 40A breaker is only rated for 80% of its listing - i.e. 32A? Why can't this number be used?

This one is coming out left field. Glad I posted the question, I figured the answer was a lot more straightforward than its turning out to be.

 

[ibew501ed]

220.55 text says
Where two or more single-phase ranges are supplied by
a 3-phase, 4-wire feeder or service, the total load shall be
calculated on the basis of twice the maximum number connected
between any two phases.
FPN No. 1: See Example D5(A) in Annex D.


and as stated note 4 says
Branch-Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55. The branch circuit
load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance.

 

[augie47]

Basic question here. I keep seeing references to 220.*** which is for load calculations, but 210.19 states 3) Household Ranges and Cooking Appliances. Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 8? kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
Would this not mean Art 220 is for calculating loads, but when it comes to installing the circuit 210.19 would require a circuit adequate to meet the actual (nameplate) load ?

 

[JAMAN]

It may be a misprint on the spec sheet. If you scroll down to the bottom of the website where it says "Power/Ratings" it is listed as 7.9KW at 208V. Check it out.

http://products.geappliances.com/ApplProducts/Dispatcher?REQUEST=SpecPage&Sku=JB680SPSS

 

[steve66]

Basic question here. I keep seeing references to 220.*** which is for load calculations, but 210.19 states 3) Household Ranges and Cooking Appliances. Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 8? kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
Would this not mean Art 220 is for calculating loads, but when it comes to installing the circuit 210.19 would require a circuit adequate to meet the actual (nameplate) load ?

A logical argument, but I don't think that was the intent for two reasons:

1. The note Radier refered to specifically says the "branch circuit load" can be calculated for one range based on the table. So they are very specific in saying that's not just the load to use in calculating feeder sizes, but also for branch circuits.

2. For the 8.75 KW range with the minimum branch circuit size of 40 amps: At 208V, a 8.75KW range would draw a little more than 40 amps. Of course, a larger range would draw even more. So that's a specific example of where a range can have a smaller branch circuit than its real nameplate load.

I realized that ranges weren't continuous loads, but I never realized there was a specific note that allowed a branch circuit sized smaller than the nameplate rating.

 

[steve66]

It may be a misprint on the spec sheet. If you scroll down to the bottom of the website where it says "Power/Ratings" it is listed as 7.9KW at 208V. Check it out.

http://products.geappliances.com/ApplProducts/Dispatcher?REQUEST=SpecPage&Sku=JB680SPSS

If the spec says 10.7 KW at 208V, then yes, that is probably a misprint. It looks like it draws 10.7 KW at 240V, and 7.9 KW at 208V.

Using the higher rating, this is a range over 8.75 KW (like in Augies Post), so per the paragraph Augie mentioned, 40 amps would be the minimum branch circuit size.

And a 40 amp circuit also works for table 220.55 and the note that Raider posted. 10.7 KW at 240 Volts = 44 amps, and 0.8 times 44 is 36 amps. So again, a 40 amp circuit would be right.

 

[JAMAN]

I was always under the impression that the manufacturer's requirements and/or nameplate overruled the NEC. Don't remember is this in the NEC somewhere or I was told this.

 

[raider1]

I was always under the impression that the manufacturer's requirements and/or nameplate overruled the NEC. Don't remember is this in the NEC somewhere or I was told this.

110.3(B) requires us to install equipment in accordance with the equipments listing and labeling instructions.

I don't see where there are any instructions that require the installation of a circuit larger than a 40 amp circuit.

Is it not correct that a 40A breaker is only rated for 80% of its listing - i.e. 32A? Why can't this number be used?

A standard breaker is not listed to run at 100% of a continuous load, but for a non-continuous load the breaker can be loaded up to 100%.

A range is not a continuous load so therefore a 40 amp breaker can supply a 40 amp range load.

Chris

 

[sparks27]

12.6 kw oven

12.6 kw oven

I"m dealing with a similar situation as well. This resident at a retirement community had a contractor install a combo oven/stove and used the existing 40 amp stovetop circuit. # 8 TW .wire. Maint Dept did prev maint on panel and found burned bus bar. looked for kw. rating and its 12.6 kw @240v comes to 52.5 A looking at 08 nec. says use nameplate rating to rate circuit size. 220.55 table note 4 this should be 60A and #6 thhn. this panel is a zinsco 1965? yikes!

 

[ibew501ed]

Basic question here. I keep seeing references to 220.*** which is for load calculations, but 210.19 states 3) Household Ranges and Cooking Appliances. Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 8? kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
Would this not mean Art 220 is for calculating loads, but when it comes to installing the circuit 210.19 would require a circuit adequate to meet the actual (nameplate) load ?

I have a code calc book (2005) that clearly shows that a 17.6 kw range conductors are calc using 220.55 note 4 and note 1
note 1 = 8 kw +30% = 10.4 kw
10.4 kw / 240v =43.33 amps
#8 thhn
branch circuit min 45 amps

That is my understanding of ranges 210.19a3 sets the minimum at 40 amps

 

[malachi constant]

I am not so interested in sizing the branch circuit. The nameplate data says 40A, that's how I'll spec it.

I'm more interested in sizing the panel load and the service load. In this case these are being installed into a new apartment building, approximately 50 total apartment units. The service is 208V/3P/4W to the building, 208V/1P/3W to each dwelling unit. I am using Part IV optional feeder and service load calculations.

For the individual dwelling unit panel 220.82 applies. Paragraph (A) states this section can be used to calculate feeder and service loads in-lieu-of Part III. Skip to (B)(3), the range nameplate data should be added in full and then if applicable can be derated at 40% (per paragraph 220.82(B)). So assuming the information on the following link is correct, I should use 7.9 kVA at 208V. http://products.geappliances.com/ApplProducts/Dispatcher?REQUEST=SpecPage&Sku=JB680SPSS

For the service panel (meter stack) which feeds all the units 220.84 applies. All parts of (A) are met. Skip to (C)(3), the range nameplate data should be entered in full and then the appropriate derating factor can be applied per Table 220.84.

So in both cases I am not using Table 220.55, as that is in part III and I am in Part IV optional which excludes this table. I must use the nameplate rating, and cannot take 80% of 40A as I had originally assumed.

I'm pretty sure that is the correct procedure, but let me know if you see something fishy.

(Thanks JAMAN for catching the conflicting information on the manufacturer's website. I'll use the 7.9kVA value as it intuitively makes more sense.)

 

[LarryFine]

The nameplate data says 40A, that's how I'll spec it.

And, what size/type of wire?

 

[malachi constant]

And, what size/type of wire?

I'll bite. 3#8 CU (or 3#6 AL) + ground. Based on the 60-degree C column for anything under 100A. Don't have time to look it up but I believe the third wire is a code (and/or manufacturer) requirement for ranges. Am I missing anything with respect to the wire size?

 

[Dennis Alwon]

Looking at appliance cuts this morning, very fun. (Yeah right.) We are installing a GE range. Says "Breaker size: 40A". Says "kW rating: 10.7 @ 208V". Do the math...

10700 VA / 208V = 51.4A. That's bigger than the breaker.

A 40A breaker is good for 40A * 208V *0.8 = 6656 VA. Am I correct it is fair to use this smaller number in the load calculations?

The building is a residence so why are you calculated this. Read what Chris Raider posted. Use T.220.55 col.3. 10.7 amp range is treated as a 8kw range.. 8000/208= 38.46. 40 amp breaker works just fine.