Originally Posted By: joetedesco
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Originally Posted By: lkage
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| joetedesco wrote: |
|
http://www.iaei.org/magazine/99_d/simmons.htm |
Is there a way to understand/check this without a code book handy?
NEC Section 240-3(d) requires that the ?overcurrent protection? must not exceed 20 amperes for a No. 12 conductor unless otherwise specifically permitted in Sections 240-3(e) through (g). Section 240-3(g) permits air conditioning circuit conductors to be protected in accord with Parts C and F of Article 440. Section 440-21 specifically states that the provisions of Part C are ?in addition to or amendatory of the provisions of Article 240.? For example, the air conditioner nameplate marking indicates a ?Maximum Fuse or Circuit Breaker Size? of 40 amperes. The minimum supply circuit ampacity is 24-amperes. In this case the nameplate on the air conditioner is marked for a Maximum Fuse or Circuit Breaker Size of 40 amperes, which will satisfy the requirements. Consequently, if no derating for ambient temperature is required, No. 12 conductors having an ampacity of 25 amperes are acceptable to supply this unit.
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"I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei
Originally Posted By: joetedesco
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http://www.ieisa.com/
–
Joe Tedesco, Massachusetts
Home Inspector Provider
www.joetedesco.org
necmeister@gmail.com
www.nachi.org/tedesco.htm
www.nachi.org/tedesco2.htm
www.nachi.org/illinoislicense.htm
www.nachi.org/jtarticles.htm
Originally Posted By: pabernathy
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Hmm…I will post a free copy of the NEC 2002 in PDF…just have to find it…lol
You can then use the online NEC updates to view the changes as I posted in a previous subject.
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Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com
Originally Posted By: pabernathy
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Joe,
I believe the next time I will be speaking is in Northern VA in Feb. I do not teach " seminar" full time and my talks are mostly on certain topics like AFCI and so on. I kinda base it depending on the situation at hand.
For example the last one I did was on changes from 1999 to 2002 NEC and going over the changes but that was to the apprentice program down here. I am not a full time instructor because I own an electrical contracting business and it takes most of my time...many of my jobs are 1 hour away so I leave early daily for them as my crew would simply FREAK OUT if i missed yelling at them.
I will most certainly see you get notified when I am in Northern VA...but I do not travel the " circuit " as you say...lol....I will leave that for the old veterans like yourself as I have too much money on the contracting table to sink my teeth into.
As for attending one of your seminars....would simply LOVE it...if you are in the VA area let me know...I will except a FREE invite...thehehehe
Someday I may decide to teach full time but I have to be honest with you....It does not pay nearly as much as the last electrical contract I had...lol.....so at 36...I am working as much as I can..., I left the "NIGHT" job of teaching AC/DC Theory and NEC last year to build my contracting business bigger.....and do more HI work as well...lol
If you are in the area....most certainly drop by.......
--
Paul W. Abernathy- NACHI Certified
Electrical Service Specialists
Licensed Master Electrician
Electrical Contractor
President of NACHI Central Virginia Chapter
NEC Instructor
Moderator @ Doityourself.com
Visit our website- www.electrical-ess.com
Originally Posted By: srowe
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| Quote: |
| NEC Section 240-3(d) requires that the ?overcurrent protection? must not exceed 20 amperes for a No. 12 conductor unless otherwise specifically permitted in Sections 240-3(e) through (g). Section 240-3(g) permits air conditioning circuit conductors to be protected in accord with Parts C and F of Article 440. Section 440-21 specifically states that the provisions of Part C are ?in addition to or amendatory of the provisions of Article 240.? For example, the air conditioner nameplate marking indicates a ?Maximum Fuse or Circuit Breaker Size? of 40 amperes. The minimum supply circuit ampacity is 24-amperes. In this case the nameplate on the air conditioner is marked for a Maximum Fuse or Circuit Breaker Size of 40 amperes, which will satisfy the requirements. Consequently, if no derating for ambient temperature is required, No. 12 conductors having an ampacity of 25 amperes are acceptable to supply this unit. |
Basically, you go by the "Min. supply circuit ampacity " as to what size branch circuit can be used. In other words, you can go against everything that has been taught as far as the properly sized branch circuit for a 40 amp breaker as it appears that the manufacturer states its ok to use a 12 awg wire for a 40 amp breaker.
Is this the way everyone else understands this?
Thanks!
Originally Posted By: bbadger
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I agree with your thoughts Shawn.
In the case of a unit marked like this the overcurrent protection for the circuit is provided inside the unit.
The breaker at the panel is not intended to protect against an overload, it is there for short circuit (line to line) or ground fault (line to ground) protection.
Originally Posted By: lkage
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| Quote: |
| For example, the air conditioner nameplate marking indicates a ?Maximum Fuse or Circuit Breaker Size? of 40 amperes. The minimum supply circuit ampacity is 24-amperes. In this case the nameplate on the air conditioner is marked for a Maximum Fuse or Circuit Breaker Size of 40 amperes, which will satisfy the requirements. Consequently, if no derating for ambient temperature is required, No. 12 conductors having an ampacity of 25 amperes are acceptable to supply this unit. |
I thought No. 12 conductors had a maximum ampacity of 20 amps not 25 amps.
Originally Posted By: bbadger
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| lkage wrote: |
| I thought No. 12 conductors had a maximum ampacity of 12 amps not 25 amps. |
Speaking very generally about dwelling units wired with NM cable.
10, 12 and 14 are rated 30, 25 and 20 respectively.
If you are in a house that uses wire in conduit the ratings will be
35, 25 and 20.
The difference is the temperature rating of the conductors.
NM must be based on 60 Celsius, pipe and wire usually based on 75 Celsius.
Now here is the thing, those are the ampacity ratings of the conductors but....
240.4(D) tells us that most times we will ignore those ampacity ratings.
| Quote: |
| 240.4(D) Small Conductors. Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum after any correction factors for ambient temperature and number of conductors have been applied. |
Clear as mud.
Originally Posted By: lkage
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| bbadger wrote: | ||||
Speaking very generally about dwelling units wired with NM cable. 10, 12 and 14 are rated 30, 25 and 20 respectively. If you are in a house that uses wire in conduit the ratings will be 35, 25 and 20. The difference is the temperature rating of the conductors. NM must be based on 60 Celsius, pipe and wire usually based on 75 Celsius. Now here is the thing, those are the ampacity ratings of the conductors but.... 240.4(D) tells us that most times we will ignore those ampacity ratings.
Clear as mud. |
Thanks, Bob. I appreciate your help. 
Is that (240.4 D) why we've learned to call out 14 guage wire on a 20 amp breaker as overfused?
...and what do 240. E through G say? Any rule of thumb that would help us?
Originally Posted By: bbadger
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| lkage wrote: |
| Is that (240.4 D) why we've learned to call out 14 guage wire on a 20 amp breaker as overfused? |
Yes, 10, 12, and 14 AWG are actually rated higher than we generally get to use them because of 240.4(D).
| lkage wrote: |
| ...and what do 240. E through G say? |
That is an excellent question as contained in those sections are the rules that let us wire HVAC units differently.
(E) Tap Conductors.
(F) Transformer Secondary Conductors.
I do not think most HIs need worry about (E) and (F).
Then there is (G)
(G) Overcurrent Protection for Specific Conductor Applications. Overcurrent protection for the specific conductors shall be permitted to be provided as referenced in Table 240.4(G).
The table goes on to list many items , the only ones that have impact in a typical home have to do with motors and motor operated appliances such as an HVAC unit.
For circuits feeding motors I can ignore 240.4(D) and use the wire at its rating.
Also for circuits feeding motors you may well see a breaker rated much higher than the wires are rated. This has to do with the motor having overload protection and the need to deal with high start up currents.
I have left out a great number of details here the point is that 60 amp breaker connected to 10 AWG feeding a HVAC unit may well be fine.
Feel free to ask questions.
Originally Posted By: Greg Fretwell
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If you think of 240.4(D) as basically protecting receptacles against whatever the customer might plug in it makes sense.
The times when you don't have to use this is when overload protection is separately provided (like a motor with internal thermal protection) and when it is a known load.
310.16 is only giving you short circuit protection.
The other "small conductor" branch circuits tend to serve outlets that the user can overload like receptacles and lamp holders. The installer/designer has no control in what may plug or screw in. (just look at what happens in the next few weeks 
240.4(D) builds in that 80% safety factor we all talk about in the allowable branch circuit O/C device.
Originally Posted By: lkage
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Thanks, guys, for paticipating here. Your help is much appreciated.
Originally Posted By: jhagarty
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| joetedesco wrote: |
| Joe. Stop posting. You were banned for a year. |
Will the Moderator please stop the deletion of posts that provide Benefit, Education and Resources to the Membership.
The Moderator's personal views and need for deletion are out of bounds and provide no resourcefulness to the Membership.
I suggest the anonymous moderator review COE Article 3 and the intended application of that article. Or is the Moderator not subject to the COE?
Originally Posted By: gbeaumont
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| jhagarty wrote: | ||
Will the Moderator please stop the deletion of posts that provide Benefit, Education and Resources to the Membership. The Moderator's personal views and need for deletion are out of bounds and provide no resourcefulness to the Membership. I suggest the anonymous moderator review COE Article 3 and the intended application of that article. Or is the Moderator not subject to the COE? |
Joe, I don't often agree with the moderation of this board, or the actions of our ESOP committee, but in this instance I believe that Joe T is in the wrong and being childish in his attempts to curry favor with our members dispite his being banned from the board.
IMO he is showing exactly the same lack of respect to the ESOP committee that he showed to our members at large, this is what led to his suspension.
Regards
Gerry
Originally Posted By: jhagarty
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Gerry:
You are entitled to your opinion as I am to mine.
The continued deletions by an Anonymous Moderator of threads providing value and education produces more harm to the current Membership.
Originally Posted By: Blaine Wiley
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Joe,
ESOP determined in their findings that Joe Tedesco was not to post on this board and his membership was revoked for a year. He is able to reapply after one year if he complies with the terms of his revocation.
I am not anonymous, nor is anyone else with the ability to enforce the decision of ESOP.
Joe's posts will continue to be deleted until otherwise directed by a vote of the ESOP committee. I suggest you hold your breath.
Originally Posted By: jhagarty
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| bwiley wrote: |
|
Joe, ESOP determined in their findings that Joe Tedesco was not to post on this board and his membership was revoked for a year. He is able to reapply after one year if he complies with the terms of his revocation. I am not anonymous, nor is anyone else with the ability to enforce the decision of ESOP. Joe's posts will continue to be deleted until otherwise directed by a vote of the ESOP committee. I suggest you hold your breath. |
Blaine:
This was a Member Driven Organization where each Member was entitled to have and express their opinion.
If the SOP or COE has been modified to reflect that NACHI Membership must Regurgitate the Pablum you spew, please post the Link.
Until that time, I am entitled to my opinion just as you are to yours.
Neither is right or wrong as it is the opinion expressed by a duly qualified Member of this Organization.
| bwiley wrote: |
|
I suggest you hold your breath. |
Not likely I will comply.
Originally Posted By: Blaine Wiley
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Last time I checked, the ESOP committee was comprised of members.
Originally Posted By: bkelly1
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| bwiley wrote: |
| Last time I checked, the ESOP committee was comprised of members. |
Elected ?