The builder stated I don't know what I'm talking about.

[Dan Harris]

I reported this for a breaker on an oven on a new home

" ELECTRICAL SYSTEM
Notes On The Main Service Panel
Panel Wiring
There was an over sized breaker in the main electrical distribution panel.
[ 50 amp Breaker is installed , With 40 Amp wiring For the Oven] "
_______________________________________


The builder told the customer if they are both 40 amps, it would cause the oven to trip???


Thoughts on this?

[chris mcintyre]

What are you calling 40 amp wiring?



The builder told the customer.........


Homeowners/customers often misinterpret information.

[John Arnold]

The builder told the customer if they are both 40 amps, it would cause the oven to trip???


He doesn't know anything. That's why they have anti-tripping devices!

[Dan Harris]

What are you calling 40 amp wiring?



Homeowners/customers often misinterpret information.

# 8 copper on a 50 amp breaker

[ken horak]

You are correct
#8 NM is only good for 40amperes.

Make a believer out of the builder by showing him article 334.80 in the NEC.
This is where it states that the ampacity of NM cable shall be determined in accordance with Article 310.15 and the ampacity shall be in accordance with the 60 degree conductor rating

Then show him 310.15 (2) (B) This tells you refer to Table 310.16

310.16 60 degree column under copper # 8 = 40 amperes

By showing him were it is written in the code book it should not only back up your report but should show the builder you know what your talking about.
If by chance you don't have the NEC, I'm sure someone here can cut and paste the articles into a PM or email to you. (I can if need be- let me know)

[H.G. Watson, Sr.]

You can view NFPA 70 (NEC) on line for free at nfpa.org the 2002, 2005 (which is incorporated into the IRC), and 2008 versions are readily available for viewing. You do have to sign up first (free) and use a valid email address (for verification) but thenceforth are free to view at anytime. It requires real-time d/l of the "viewer" which controls/limits you to view only mode, but you are free to type out on word pad, notepad, whatever program you wish what you read.

NFPA (http://www.nfpa.org)

Sign up/in, then navigate to the list of codes and standards, They are contained in a scroll box in the middle of the page. Scroll down (on the right of the box not the page) to NFPA 70 (which is the National Electrical Code). It will default you to the 2008 edition. If you need the 2005 or 2002 edition, you will see an option for that lower on the page. Then click on view the document, then agree to the terms and conditions, then open the document and allow the viewer to load (pop-ups and active x will need to be allowed for it to work). If you need more precise directions or a direct link after you've signed up, let me know (PM).

Its not as handy as having a viewable version, but quick and easy to access on the fly, wi-fi, etc.

[H.G. Watson, Sr.]

Here's a direct link to NFPA 70, the National Electrical Code (NEC) (forgot to mention earlier you will also have to allow cookies):

NFPA 70: National Electrical Code® (http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70&cookie%5Ftest=1)

It will default to the 2008 edition, they've changed their page a bit since I last visited, note the drop down box for the edition (defaults at 2008).

Change that to 2005 for the IRC, leave at 2008 if applicable for your jurisdiction, or change to 2002 edition if need be. (although earlier editions are listed in the drop down box, only these three are available for online view only mode).

When page self-refreshes (if you've changed from the 2008 default), or not, look about four topic lines lower see "VIEW THE DOCUMENT ONLINE (READ ONLY)" and see the clickable link just below that which will display: View 2002 edition online or View 2005 edition online or View 2008 edition online depending on what you selected on the drop down box above.

When you've clicked that link, the system will prompt you to sign in if you haven't already, then ask you to accept terms and conditions to view, then load the real viewer and display. Click on the table of contents icon for yet another box to pop up to navigate to the section, use the page turn arrows to further navigate and enjoy.

[H.G. Watson, Sr.]

Of course if there is a remote panel or fused or breaker disconnect between the main panel and the stove/oven itself and it is protected at correct rating for the conductors, the larger sized breaker/disconnect back in the service/main panel would be okay.

[Jerry Peck]

You are correct
#8 NM is only good for 40amperes.

Make a believer out of the builder by showing him article 334.80 in the NEC.

- 334.80 Ampacity.
- - The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60°C (140°F) conductor temperature rating. The 90°C (194°F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60°C (140°F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.
- - Where more than two NM cables containing two or more current-carrying conductors are installed, without maintaining spacing between the cables, through the same opening in wood framing that is to be fire- or draft-stopped using thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a) and the provisions of 310.15(A)(2), Exception, shall not apply.
- - Where more than two NM cables containing two or more current-carrying conductors are installed in contact with thermal insulation without maintaining spacing between cables, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a).


This is where it states that the ampacity of NM cable shall be determined in accordance with Article 310.15 and the ampacity shall be in accordance with the 60 degree conductor rating

Then show him 310.15 (2) (B) This tells you refer to Table 310.16

- 310.15 Ampacities for Conductors Rated 0–2000 Volts.
- - (A) General.
- - - (1) Tables or Engineering Supervision. Ampacities for conductors shall be permitted to be determined by tables as provided in 310.15(B) or under engineering supervision, as provided in 310.15(C).
- - - - FPN No. 1: Ampacities provided by this section do not take voltage drop into consideration. See 210.19(A), FPN No. 4, for branch circuits and 215.2(A), FPN No. 2, for feeders.
- - - - FPN No. 2: For the allowable ampacities of Type MTW wire, see Table 13.5.1 in NFPA 79-2007, Electrical Standard for Industrial Machinery.
- - - (2) Selection of Ampacity. Where more than one calculated or tabulated ampacity could apply for a given circuit length, the lowest value shall be used.
- - - - Exception: Where two different ampacities apply to adjacent portions of a circuit, the higher ampacity shall be permitted to be used beyond the point of transition, a distance equal to 3.0 m (10 ft) or 10 percent of the circuit length figured at the higher ampacity, whichever is less.
- - - - FPN: See 110.14(C) for conductor temperature limitations due to termination provisions.
- - - (B) Tables. Ampacities for conductors rated 0 to 2000 volts shall be as specified in the Allowable Ampacity Table 310.16 through Table 310.19, and Ampacity Table 310.20 and Table 310.21 as modified by (B)(1) through (B)(6).
- - - - FPN: Table 310.16 through Table 310.19 are application tables for use in determining conductor sizes on loads calculated in accordance with Article 220. Allowable ampacities result from consideration of one or more of the following:
- - - - - (1) Temperature compatibility with connected equipment, especially the connection points.
- - - - - (2) Coordination with circuit and system overcurrent protection.
- - - - - (3) Compliance with the requirements of product listings or certifications. See 110.3(B).
- - - - - (4) Preservation of the safety benefits of established industry practices and standardized procedures.


310.16 60 degree column under copper # 8 = 40 amperes

Just showing where Ken got it from.

Which means that either:
- a) The builder needs to install wiring rated for the 50 amp breaker so the breaker will not trip off.
- b) The builder will have to explain to his buyer why the 40 breaker he is required to install to protect the wiring keeps tripping off whenever the buyer is cooking.

That argument from the builder is like going to the doctors off and bending your arm up behind you back and saying "Dr., my arm hurts whenever I do this." and the doctor responds with "Then don't do that." (i.e., Builder don't do that - install properly sized wiring.) :D

[H.G. Watson, Sr.]

Of course if there is a remote panel or fused or breaker disconnect between the main panel and the stove/oven itself and it is protected at correct rating for the conductors, the larger sized breaker/disconnect back in the service/main panel would be okay.

Would still apply if exists. Perhaps that's what the builder is referring to "tripping" at the oven (make sure there isn't an integral or intermediate protection exisitng at 40 amps).

[Dan Harris]

Other than knowing it's a 1800' track home, I don't remember the job.
I'm assuming it's a standard builder free standing range.

[H.G. Watson, Sr.]

Oh so it wasn't an oven. I haven't seen the pull outs a range yet but ya never know with some of the higher end stuff and new tech. Point being if there was an intervening properly sized protection closer to the "oven" as previously identified, now range, at the correct limit, it would suffice.

Pictures usually help to jog my old memory {of course taking the picture in the first place of noted deficiencies (like the panel labeling info on the oven or range) has to have happened first :) }.

Hope you or someone find the links useful for on-line view only free & fast access for any purpose.

[Dan Harris]

Oh so it wasn't an oven. I haven't seen the pull outs a range yet but ya never know with some of the higher end stuff and new tech. Point being if there was an intervening properly sized protection closer to the "oven" as previously identified, now range, at the correct limit, it would suffice.

Pictures usually help to jog my old memory {of course taking the picture in the first place of noted deficiencies (like the panel labeling info on the oven or range) has to have happened first :) }.

Hope you or someone find the links useful for on-line view only free & fast access for any purpose.

I'm assuming if I wrote oven on the report, the breaker was labeled "oven" I have seen them labeled as a range or oven.

[H.G. Watson, Sr.]

Self-discipline, notation, recordation and precise language; not the only one who has promoted the idea. Can't speak to your own assumptions or methods or the particulars of the instant example and draw no conclusions, you'd know best. An oven is not a range nor vice versa, although one may contain and perform the functions of the other.

P.S. "Track home" vs. "tract home".:p

[Steve Lowery]

Ignore this, Just getting rid of Brian's nagging header.

[Dan Harris]

Ignore this, Just getting rid of Brian's nagging header.

Brian figured out a way to get us to post. :)

[Tim Spanos]

an 8awg insulated cu thwn conductor is rated at 50 amps so if wiring was installed in a raceway and not cable the conductor is protected in accordance with its ampacity as long as there is no more than 1 circuit installed in raceway and the temp rating of the breaker is rated for 75 degree wiring......so If its in pipe with one circuit the wire is protected if its in cable than it is not protected.....