Registered: 10/05/04
Posts: 1622
Loc: City of North Port
No, you are correct. The section is very clear the minimum branch-circuit rating shall be 40A except for 20A taps off a 50-ampere branch circuit when the 3 or 4 conditions are met.
I think Ruben was just making a generalized statement that Article 220 is used to calculate loads for branch-circuits, feeders, & services & that Articles 110, 215, 230, & Chapter 4 are used to determine required conductor & overcurrent protection sizing; as applicable.
Yes I was. Due to a comment here that some people use 220.
Originally Posted By: ronwampler
As an inspector be aware that a sharp electrician may use Table 220.55 Note 4 to use a single 40 amp br. ckt. and tap connections to the cooktop and wall oven per 210.19(A). Tap rules have been around for a long time. I have inspected several industrial sites with taps and high-bay overhead drops. Please review 240.21(A) and look over part (B) and (C) for future reference.
Well, I have read all the cited code references and some I thought to check and have come to the conclusion to either use the manufacturer's instructions (if available - and a lot of times they do not recommend an overcurrent device) or simply take the KW rating of the unit and divide by 240v and require an overcurrent device that is the next standard per 240.6 in conjunction with 240.4(B). Many thanks for the input from all of you.
The last thing to look at in this is Note 4 of Table 220-55. It specifies using the nameplate rating of a cooktop or wall mounted oven when they are fed by a separate circuit.
This is the same note that allows you to combine them on one 50 amp circuit (tap)...
If you want to know the size of the branch circuit conductor use 422.10. The minimum at 40 amps 220.19(a)(3) or the table 220.55 for more than one range calculating feeder or service conductors. The overcurrent protection for a single range shall be sized per 422.11. The overcurrent protection may be sized at 150% of the circuit conductor requirements per 422.11(e)(3). That is how you could (depending on appliance) have a 40 amp rated conductor and a 60 amp breaker.
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Michael J Timpanaro Inspector/Plans Examiner/CEU Instructor Florida
The question is about cooktops and wall mounted oves with an individual branch circuit that are below 8 3/4 kw. 422.10 tells you to use 220.55 and when you do you really need to read note 4 because IF they are not ranges, you use the nameplate rating. 210.19(A)(3) says this but we all get caught up in the section for OVER 8 3/4 kw (allows for 40 amp max.) And I'm not sure 422.11(E)(3) is for cooktops & ovens because this section seems to have special rules for cooking equipment. I only say this because in the cases I read elsewhere in the code (and in 422), if anything, they LOWER the overcurrent protection, not increase it. I am pretty confident that the OC protection should be sized to the kw rating (next standard fuse/breaker size).
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