Sizing Stove Circuit which info correct?

[infinity]

Trevor, I know all this. I am just saying the NEC states we can do it but if the manufacturer says something else don't we have to follow their specs. It did say 55 amps. If it just said 13.3kw I would have no argument.

Do the manufacturers instructions state that you need to use a 55 amp circuit? If so then I agree with you but if not unless there's a code section that says to avoid using T220.55 and use the ampacity listed on the appliance I see no reason why you need to use the 55 amps.

 

[LarryFine]

Wouldn't one use the demand table for house load calculations, and the nameplate for the actual installed circuit sizing?

Of course, the actual appliance load is usually unknown when the house is being built, and can change when a new appliance replaces an old one.

 

[david luchini]

Wouldn't one use the demand table for house load calculations, and the nameplate for the actual installed circuit sizing?

The demand table applies to the branch circuit as well.

 

[Little Bill]

The demand table applies to the branch circuit as well.

I believe that note #4 is for branch circuits.

 

[ramsy]

I believe that note #4 is for branch circuits.

Example D1(a) shows a 12-kw Range calculation using 8,000 VA from Tbl.220.55

Calculation for Neutral:
Range: 8000 VA at 70% (see 220.61) 5,600 VA

Example D2(a) shows a similar 12-kw Range calculation at 12,000 VA for General Load, before application of demand factors.

The above, and other Examples further down are all using 8,000 VA for Range branch circuit, regardless of 12-kva nameplate

 

[JFletcher]

As long as its cord is not pinched on the exhaust blower motor, it should be good to go.

I have never seen a range that can simultaneously operate both top and bottom elements, so 55a is never going to happen.

If I have access to the range instructions, the branch circuit is getting sized according to that. 110.3(b)

highest real world use is going to happen for a large Thanksgiving or Christmas meal, with the oven on cooking a bird or ham, and all four burners up top on. The oven element duty cycle will be ~50%, two of the burners might be on high (100%), the other two turned down low for gravy and rewarming.

The overall duty cycle under its highest expected use would be 50% or less of name plate.

 

[kwired]

Then what does 13.3 kW rated mean exactly ? So, it will never approach 13.3kW ever full blast at Thanksgiving??

When you first turn "everything" on you will draw 13.3kW. But it won't last long enough to get into thermal trip range of the 40 amp breaker before things begin to cycle on temperature setting. Not saying you can't have a condition that will trip 40 amp breaker but is not too likely.

I have never seen a range that can simultaneously operate both top and bottom elements, so 55a is never going to happen.

.

Most ovens I have ever had "preheat" the oven using both elements until you get to maybe around 70-80% of set point. But again this doesn't last for very long and the breaker will hold even if overloaded to some extent. If you left the oven door open so that it never reaches that 70-80% then it may trip, but might take 30 minutes maybe even an hour before it does, just depends on where actual current/time is in relation to the trip curve for the breaker, and even a little on ambient temp at the breaker.

 

[LarryFine]

I have never seen a range that can simultaneously operate both top and bottom elements, so 55a is never going to happen.

I have, for two modes: pre-heating and self-cleaning.

 

[JFletcher]

I stand corrected...

 

[Dennis Alwon]

Here is my point

An a/c unit states the fla is 25 amps and max overcurrent protective device is 30 amps. Now according to the nec I can use an overcurrent protective device 175% of the fla meaning a 45 amp overcurrent protective device. Now the name plate states 30 amp but the nec states 45 amps.... I have to use the nameplate rating

440.22 Application and Selection.
(A) Rating or Setting for Individual Motor-Compressor. The
motor-compressor branch-circuit short-circuit and ground-fault
protective device shall be capable of carrying the starting
current of the motor. A protective device having a rating or
setting not exceeding 175 percent of the motor-compressor
rated-load current or branch-circuit selection current, whichever
is greater, shall be permitted, provided that, where the
protection specified is not sufficient for the starting current of
the motor, the rating or setting shall be permitted to be
increased but shall not exceed 225 percent of the motor rated load
current or branch-circuit selection current, whichever is
greater.

 

[kwired]

Here is my point

An a/c unit states the fla is 25 amps and max overcurrent protective device is 30 amps. Now according to the nec I can use an overcurrent protective device 175% of the fla meaning a 45 amp overcurrent protective device. Now the name plate states 30 amp but the nec states 45 amps.... I have to use the nameplate rating

But an AC isn't the same as a range in many ways when it comes to selecting conductor size and OCPD. Most importantly it doesn't have any allowable demand factor that can apply to it. It can and will run at full rating for extended periods of time, the range doesn't run at full rating for very long even if you are trying to get all you can out of it.

 

[Dennis Alwon]

But an AC isn't the same as a range in many ways when it comes to selecting conductor size and OCPD. Most importantly it doesn't have any allowable demand factor that can apply to it. It can and will run at full rating for extended periods of time, the range doesn't run at full rating for very long even if you are trying to get all you can out of it.

That has nothing to do with it. Again, if the listing of the range is based on the 50 overcurrent protective device then that is supposed to be what is required. I already said it is absurd and ridiculous, and I don't agree with it but that is the way it reads to me.

 

[ramsy]

That has nothing to do with it. Again, if the listing of the range is based on the 50 overcurrent protective device then that is supposed to be what is required. I already said it is absurd and ridiculous, and I don't agree with it but that is the way it reads to me.

Unlike HVAC equipment name plates, there is no minimum or maximum fuse listed on cooking appliances.

 

[kwired]

That has nothing to do with it. Again, if the listing of the range is based on the 50 overcurrent protective device then that is supposed to be what is required. I already said it is absurd and ridiculous, and I don't agree with it but that is the way it reads to me.

What about the last sentence in 422.10(A) that says you can use table 220.55 for branch circuits/conductor selection for household ranges and cooking appliances?

Note 1 of the table tells you what to do if over 12kW range - and range in the OP only being 1.3 kW more than 12 still leaves the resulting demand factor under 40 amps, in fact it only adds 65 watts to the 8 kW base that is good up to 12 kW.

 

[Chamuit]

I bought a gas stove. :rotflmao:

 

[Dennis Alwon]

What about the last sentence in 422.10(A) that says you can use table 220.55 for branch circuits/conductor selection for household ranges and cooking appliances?

I am not arguing what the code states. I know what it states... I don't know how to express what I am saying any differently because you keep going back to what the code states. The code also states to use the manufacturers instruction.

 

[ramsy]

..The code also states to use the manufacturers instruction.

I thought code was a minimum standard, and adding more room for expansion, or safety, or preference, or nameplate, is fine.

 

[kwired]

I am not arguing what the code states. I know what it states... I don't know how to express what I am saying any differently because you keep going back to what the code states. The code also states to use the manufacturers instruction.

Which is a CYA instruction from them plus helps leave a way out of honoring warranties, but now I see what you are getting at and have little more to say on that, I think

How many of us read every instruction on pretty much any common household appliance? How many times do we just install a 14-50 receptacle (with 40 or 50 amp circuit) and never know what specific appliance will be plugged in? I think code should be what applies in this situation and instructions should be written to comply with code, for that matter shouldn't listing standards align themselves with code?

 

[Dennis Alwon]

Which is a CYA instruction from them plus helps leave a way out of honoring warranties, but now I see what you are getting at and have little more to say on that, I think

How many of us read every instruction on pretty much any common household appliance? How many times do we just install a 14-50 receptacle (with 40 or 50 amp circuit) and never know what specific appliance will be plugged in? I think code should be what applies in this situation and instructions should be written to comply with code, for that matter shouldn't listing standards align themselves with code?

I totally agree.. as I stated earlier. It is like some hydromassage tubs that state you have to run a #6 bond back to the panel. Yeah right