cooktop / oven

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Re: cooktop / oven

Roger, it's my contention that a neutral is required and it shouldn't be any smaller than 70percent leading to a range recepticle. Seems like 210.19 A 3 ex 2 addresses this by saying, "The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall mounted oven, or a counter mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range 8.75kW or more rating has been computed according to Column C of Table 220.19 but shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 awg."

Your comment that a neutral isn't required would seem to contradict the code section I cited.

JimWalker's comment seems to be a slightly different scenario. Sounds like there was nowhere to terminate a neutral to in a cooktop and the inspector insisted on seeing 4 wires entering and leaving the closest jbox where his taps fed from.

a.wayne3@verizon.net, what was your inspector's verdict?

Earlier when I asked about the branch circuit ampacity...I didn't realize ovens are continuous loads. Shows you how often electricians crank up the oven for 3 hours or more, huh?

Some conversations where discussing the theory concerning if a neutral would carry a load or not. I was able to borrow my friends 1999 NEC handbook and it offers the following comment on ranges: "On modern ranges the heating elements of the surface units are controlled by five-heat unit switches, The surface-unit heating elements will not draw current from the neutral unless the unit switch is in one of the low-heating positions. This is also true to a greater degreee as far as the oven-heating elements are concerned, so the maximum current in the neutral of the range circuit seldom exceeds 20A. Because of that condition, Exception No. 2 permits a smaller-size neutral than the ungrounded conductionrs, but not smaller than No. 10."

NECBuff...the title of article 220 is "Branch, Feeder, and Service Calculations." On a new installation I believe you would still need a neutral as well as a ground. Why wouldn't this be a requirement of 210.19 A 3 ex 2 if for no other reason?

[ July 11, 2004, 11:04 AM: Message edited by: chris68 ]
 
Re: cooktop / oven

Chris, There is only one place that I am aware of in the NEC that requires a neutral be provided where it is not actually used for equipment. That is in 250.24(B) for services.

There is no requirement to provide a neutral for any appliance that does not use a neutral.

If the cooktop does use a neutral we are we required to provide both a neutral and a EGC.

220.22 does not require a neutral at any appliance.

Bob
 
Re: cooktop / oven

Originally posted by chris68:
can we agree that you adjust a feeder's neutral calculation when determining ampacity for a range?
Click to expand...
We can agree the NEC allows adjusting the neutral ampacity for a range, it does not require that you do so.

What is 70% of 0? ;)
 
Re: cooktop / oven

Chris, one of the things that I stress for the guys who take my classes when reading the NEC, is to always look back to the 'PART' they are in when reading an Article/section. I also stress reading the 'Scope' of the article as it tells you what the Article covers.
Part I General
220.1 Scope. This article provides requirements for computing branch-circuit, feeder, and service LOADS.
Part II of Art 220 is for Feeders and Services.
220.22 is specifically for feeder and service load calculations, not for the purpose of wiring specifics. The 3rd sentence of 220.22 starts out "For a feeder or service supplying...". Most ranges are not supplied with a feeder, but a branch circuit.
If the range (as in one case in this thread) does not require a neutral conductor, there is no reason (or requirement) to install a neutral conductor.
250.140, and .142(B) exception 1, apply to existing installations and not to new work.

In todays economy and the 'dog eat, dog world' we live in competition is fierce, and any edge one in business can gain from using the NEC to their advantage should be permitted as good business sense. That is why understanding and using the NEC is good not only to defend oneself from the 'rogue' inspector, but is good for business as well ;) .

Pierre
 
Re: cooktop / oven

Chris68, in order to have a three wire circuit all three wires would have to connect to the equipment.

If infact the unit was straight 240v with nowhere to connect a neutral, you would be allowed to reduce it to as small as you would like, say to nothing. :D

The truth is as already stated, there is no requirement for a feeder or a branch circuit to have a neutral.

Roger
 
Re: cooktop / oven

Seems like 210.19 A 3 ex 2 addresses this by saying, "The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall mounted oven, or a counter mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range 8.75kW or more rating has been computed according to Column C of Table 220.19 but shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 awg."

Your comment that a neutral isn't required would seem to contradict the code section I cited. This section specifically states it's talking about a branch circuit.
 
Re: cooktop / oven

Chris nowhere does that say you must install a neutral in an installation. It only tells you what can be done if you do. For a 120/240 (hot/hot/neutral/equipment ground) appliance new installtion you would need one. For a straight 240v (hot/hot/equipment ground) there is no need or requirement or any reason to install one. It really is that simple. I think you are looking way to hard at this and overthinking it.
 
Re: cooktop / oven

"...shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 awg."
 
Re: cooktop / oven

"I think you are looking way to hard at this and overthinking it."

I've been accused of that before. Can you please tell me why my quoted article wouldn't apply?
 
Re: cooktop / oven

Reading through 2002 Stallcup's Electrical Design Book page 11-64 says the following:

"A new branch-circuit installation for ranges, cook tops, ovens, clothes dryers, including junction boxes or outlet boxes that are part of the circuit shall be permitted to be bonded and grounded with an equipment grounding conductor. However, an isolated grounded (neutral) conductor shall also be installed. For further information concerning this type of installation, see 250, 114, 250.134, and 250.138. (See Figure 11-104)"

I've cited 3 references: 2002 Code, 1999 McGraw-Hill's Handbook, and now 2002 Stallcup's. Can anyone insisting a neutral isn't necessary on a new installation provide an excerpt from something supporting their arguments?

[ July 11, 2004, 01:09 PM: Message edited by: chris68 ]
 
Re: cooktop / oven

Seems like 210.19 A 3 ex 2 addresses this by saying, "The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall mounted oven, or a counter mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range 8.75kW or more rating has been computed according to Column C of Table 220.19 but shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 awg."

Your comment that a neutral isn't required would seem to contradict the code section I cited. This section specifically states it's talking about a branch circuit.
Click to expand...
Chris, if there is not a neutral connection at the equipment you would use a two wire branch circuit, not a three, so this section would not be applicable.
 
Re: cooktop / oven

Can anyone insisting a neutral isn't necessary on a new installation provide an excerpt from something supporting their arguments?
 
Re: cooktop / oven

Originally posted by chris68:
Can anyone insisting a neutral isn't necessary on a new installation provide an excerpt from something supporting their arguments?
Click to expand...
Chris we are not going to find something in the NEC that says "You do not need to run a neutral"

More importantly though, other than 250.24(B) you will not find anything that says we must run a neutral.

The change from three wire to four wire branch circuits for ranges has nothing to do with the neutral, ranges that used a neutral always had to have an insulated neutral.

The change affected the grounding of ranges and dryers. We used to be able to use the neutral as the grounding means, now we must provide a separate equipment grounding conductor.

None of the articles you have referenced require a neutral, only what to do with one if you run it.

Can we look at this another way?

I mostly work in buildings that have 3 phase services. Say I am feeding a 208 volt single phase cook top.

Would you say I have to bring over all three phases even though one would be capped off and unused?

Where does the NEC tells us the answer to this?

Don't worry about being stubborn many of us here are. :)
 
Re: cooktop / oven

Originally posted by chris68:
could you please provide me with more information on a 2 wire range circuit?
Click to expand...
It would be 2 wire plus ground, same as you would bring to a piece of 240 volt baseboard heat.
 
Re: cooktop / oven

"Chris we are not going to find something in the NEC that says "You do not need to run a neutral""


Ok, provide anything, SOMETHING...doesn't have to be NEC Code.
 
Re: cooktop / oven

Chris go ahead and run a three wire branch circuit if it makes you happy. The rest of us will stay more competitve and install what is neccesarry and code compliant.

Would you run a neutral to a 240v water heater?

If the cooktop is rated for straight 240v with a factory whip of a black, red, and EGC, what would you do with this neutral you have wasted money, time, effort, and natural resources installing.

You would spend more money on a wire nut to cap this conductor that is doing nothing. :roll:

Roger
 
Re: cooktop / oven

On June 21, 2004 7:57pm iaspiretowire asked, "Where in the code does it state that the branch circuit for a cooktop / oven for new construction has to have 4 wires (2 hots, 1 neutral, and 1 ground wire)? Thanks.

On June 21, 2004 8:16pm roger replied, "If there is no need for a neutral the NEC doesn't require one for this.
But what you are looking for can be found in 250.140"

On June 21, 2004 8:44pm iaspire to wire questioned roger's decision by asking, "wont you allways have a neutral for the low settings on a cooktop appliance?"

On June 21, 2004 8:58pm roger replied, "All the cooktops I'm familiar with require a neutral, but this is not an NEC requirement, the seperation of the neutral (if present) and EGC in new installations is however."

It would seem Roger is saying a neutral isn't required. Iwire is saying a neutral has and will always be required. It now sounds like iwire is agreeing with me that a seperate ground is now required.

"More importantly though, other than 250.24(B) you will not find anything that says we must run a neutral."

Seems like 210.19 A 3 ex 2 addresses this by saying, "The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall mounted oven, or a counter mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range 8.75kW or more rating has been computed according to Column C of Table 220.19 but shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 awg."

Roger, it sounds as if you and iwire do not agree on a wiring method for a new range installation.

PLEASE SOMEONE POST A REFERENCE OF SOME KIND (ANYTHING) SPECIFICALLY ALLOWING 3 WIRE RANGE CIRCUITS ON NEW CONSTRUCTION. I have provided 3 references, I challenge anyone to do the same.
 
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