Wire Size
- Thread starter MW
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macmikeman
Senior Member
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- Planet macmikeman
Re: Wire Size
How about #12 guage for instance. Could be you need to run larger wire depending on distance from source to load, for things to run well though.
How about #12 guage for instance. Could be you need to run larger wire depending on distance from source to load, for things to run well though.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: Wire Size
Unless voltage drop were a factor, this could be wired with #14 THHN. You could use either a 20 or a 25 amp CB with the #14 THHN to provide short circuit and ground fault protection.
Unless voltage drop were a factor, this could be wired with #14 THHN. You could use either a 20 or a 25 amp CB with the #14 THHN to provide short circuit and ground fault protection.
charlie
Senior Member
- Location
- Indianapolis
Re: Wire Size
If you are looking at minimums and an inspector would be, you could get by with #14 NM cable. It is rated for 20 amperes in the 60? column and 240.4(G) applies to it (you are referred to it by 240.4(D)).
If you are looking at minimums and an inspector would be, you could get by with #14 NM cable. It is rated for 20 amperes in the 60? column and 240.4(G) applies to it (you are referred to it by 240.4(D)).
Re: Wire Size
charlie,
I agree and know you are correct, but, I wonder, in the real world, how often would that get redtagged?
Inspectors that care enough to come here would pick up on the "fine line"..not so sure about some others.
just wondering.........
charlie,
I agree and know you are correct, but, I wonder, in the real world, how often would that get redtagged?
Inspectors that care enough to come here would pick up on the "fine line"..not so sure about some others.
just wondering.........
marc deschenes
Senior Member
Re: Wire Size
Charlie , for de rating purposes you are allowed to use the 90 degree coulmn if the conductors are thhn , a #14 thhn is Rated at 25 amps. There should be no problem at all , unless there is an extremely high ambient temp involved or issues with the number of conductors in a raceway or as stated already voltage drop.
However , I am like the pilot who in the fog who does not trust the instruments ,
and would use #12 with an ampacity almost twice the required capacity. Good thing this wasn't a bid job !
Charlie , for de rating purposes you are allowed to use the 90 degree coulmn if the conductors are thhn , a #14 thhn is Rated at 25 amps. There should be no problem at all , unless there is an extremely high ambient temp involved or issues with the number of conductors in a raceway or as stated already voltage drop.
However , I am like the pilot who in the fog who does not trust the instruments ,
and would use #12 with an ampacity almost twice the required capacity. Good thing this wasn't a bid job !
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Wire Size
GENEM: You might want to revisit the articles that apply to motors, before firing anyone. This question has to do with an A/C motor.
GENEM: You might want to revisit the articles that apply to motors, before firing anyone. This question has to do with an A/C motor.
Re: Wire Size
Here's a little hypotheticle question on a motor circuit.
A Home Inspector inspects a home and cites a violation of #12 THHN conductors connected to a 50 amp breaker in the load center. This branch circuit is feeding a 3 HP 230 V single phase motor; all parts are listed for 75 deg C.
Is the Home Inspector correct in citing this as a violation?
(Hint; articles 240.6, 310.16, 430.22(A), tables 430.52, and 430.148)
Answer: Yes, he is right.
? Table 430.148 gives a 3HP motor an full load current of 17 amps
? 430.22(A) requires conductors be sized at 125% of full load current
? 17 x 125% = 21.25 amps
? Table 310.16, #12 THHN 75 deg C column = 25 amps
? Table 430.52 allows up to 250% for the inverse time breaker
? 17 x 250% = 42.5 amps
? Answer 40 amp breaker.
Roger
[ August 23, 2005, 10:14 AM: Message edited by: roger ]
Here's a little hypotheticle question on a motor circuit.
A Home Inspector inspects a home and cites a violation of #12 THHN conductors connected to a 50 amp breaker in the load center. This branch circuit is feeding a 3 HP 230 V single phase motor; all parts are listed for 75 deg C.
Is the Home Inspector correct in citing this as a violation?
(Hint; articles 240.6, 310.16, 430.22(A), tables 430.52, and 430.148)
Answer: Yes, he is right.
? Table 430.148 gives a 3HP motor an full load current of 17 amps
? 430.22(A) requires conductors be sized at 125% of full load current
? 17 x 125% = 21.25 amps
? Table 310.16, #12 THHN 75 deg C column = 25 amps
? Table 430.52 allows up to 250% for the inverse time breaker
? 17 x 250% = 42.5 amps
? Answer 40 amp breaker.
Roger
[ August 23, 2005, 10:14 AM: Message edited by: roger ]
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Wire Size
An exception to Table 430.52 allows you to go to the next higher standard size. So I would think that a 45 amp would be acceptable.
IMHO, a HI should not be citing a "violation." Rather, a HI should report a "concern," and should include a recommendation that a professional be hired to review the concern. But then, I don't think they are going to put me in charge of HIs.
An exception to Table 430.52 allows you to go to the next higher standard size. So I would think that a 45 amp would be acceptable.
IMHO, a HI should not be citing a "violation." Rather, a HI should report a "concern," and should include a recommendation that a professional be hired to review the concern. But then, I don't think they are going to put me in charge of HIs.
Re: Wire Size
Charlie, actualy the original answer to the question (before I edited it) was a 45 amp breaker, but it incorrectly referenced 240.4 as the reason.
I do agree that a 45 amp breaker is the correct answer using the exception you mention.
Now, I think you would be good choice to keep HI's inline.
Roger
[ August 23, 2005, 12:04 PM: Message edited by: roger ]
Charlie, actualy the original answer to the question (before I edited it) was a 45 amp breaker, but it incorrectly referenced 240.4 as the reason.
I do agree that a 45 amp breaker is the correct answer using the exception you mention.
Now, I think you would be good choice to keep HI's inline.
Roger
[ August 23, 2005, 12:04 PM: Message edited by: roger ]
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: Wire Size
It this application he would have done nothing wrong. If he were wiring according to the AC mentioned in the original post than why should he be fired for following the code? As others have mentioned it seems like it's his boss that needs some code review.
peter d
Senior Member
- Location
- New England
Re: Wire Size
I suspect this thought process is why I see so many AC units wired with conductors sized to the maximum breaker size. :roll:
Re: Wire Size
I have had to redo two jobs because the AHJ (two different ones) demanded the motor ckt did not apply till the point of local disconnect or from an MCC. According to code I would have to say this is wrong but in both cases the AHJ would not change. So if it comes down to which is right--I will go with the ignorance of the inspector and play it safe. An oversize conductor is a lot cheaper than the labor to do it over to suit the AHJ. That is the reason for my original post and that is still what I tell my guys. If they want to take it up with the AHJ they can do it on thier own time. By the way--I am still a little upset with having to redo the jobs. By the way-we are speaking of motors here- if it is an a/c check 440.6 for conductor size.
[ August 24, 2005, 10:33 AM: Message edited by: GENEM ]
I have had to redo two jobs because the AHJ (two different ones) demanded the motor ckt did not apply till the point of local disconnect or from an MCC. According to code I would have to say this is wrong but in both cases the AHJ would not change. So if it comes down to which is right--I will go with the ignorance of the inspector and play it safe. An oversize conductor is a lot cheaper than the labor to do it over to suit the AHJ. That is the reason for my original post and that is still what I tell my guys. If they want to take it up with the AHJ they can do it on thier own time. By the way--I am still a little upset with having to redo the jobs.
By the way-we are speaking of motors here- if it is an a/c check 440.6 for conductor size.[ August 24, 2005, 10:33 AM: Message edited by: GENEM ]
peter d
Senior Member
- Location
- New England
Re: Wire Size
If a so-called inspector is ignorant of the most basic things like sizing conductors for a motor, I wouldn't listen to a word he said. Furthemore, if this inspector is ignorant, he may not be very safe at all!
I don't think going along with someone's ignorance is the best idea.
If a so-called inspector is ignorant of the most basic things like sizing conductors for a motor, I wouldn't listen to a word he said. Furthemore, if this inspector is ignorant, he may not be very safe at all!
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: Wire Size
Holding an employee "at fault" for following the code is wrong.
On that note, it's your decision whether to challenge authorities. Your decision to give in should be respected. You are there, you know who you are dealing with. If it's your company, work should be done to your taste. Not ours.
If there is no reasoning with The Man, you can't go far with arguing. That sucks, but that's life. It's up to each of us to set that level of tolerance for people's inability to adapt, or take input.
The issue I see is,
This is an unfair statement. If you canned someone for doing this, you're wrong. If he "did not know what he did wrong" then obviously the "don't contest inspectors under any circumstances" rule in your company was not very plain.
240.4(D), referencing (G) specifically explicitly excludes A/C's from the rule.
Holding an employee "at fault" for following the code is wrong.
On that note, it's your decision whether to challenge authorities. Your decision to give in should be respected. You are there, you know who you are dealing with. If it's your company, work should be done to your taste. Not ours.
If there is no reasoning with The Man, you can't go far with arguing. That sucks, but that's life. It's up to each of us to set that level of tolerance for people's inability to adapt, or take input.
marc deschenes
Senior Member
Re: Wire Size
Peter , I agree , I would ask him to demonstrate what code was violated , politely of course . If he were to pull the "do you know who I am " crap , I would file a complaint with everyone from the Mayor to the Governor.
Genem , Instead of canning aa worker that knows more than those who sit in judgement of him ,Perhaps you should just tell him to always use a larger wire size than required , as long as he works for you.
As I said ,I would also more than likely run a #12 but I understand a # 14 thhn is rated for this application. You stated that this journeyman would be fired especially if he did not know what he did wrong . What did he do wrong ??
Nothing . That is a lousy reason to be fired if you ask me .
Peter , I agree , I would ask him to demonstrate what code was violated , politely of course . If he were to pull the "do you know who I am " crap , I would file a complaint with everyone from the Mayor to the Governor.
Genem , Instead of canning aa worker that knows more than those who sit in judgement of him ,Perhaps you should just tell him to always use a larger wire size than required , as long as he works for you.
As I said ,I would also more than likely run a #12 but I understand a # 14 thhn is rated for this application. You stated that this journeyman would be fired especially if he did not know what he did wrong . What did he do wrong ??
Nothing . That is a lousy reason to be fired if you ask me .
electricmanscott
Senior Member
- Location
- Boston, MA
Re: Wire Size
You're fired!! What did I do wrong? I don't know
You're fired!! What did I do wrong? I don't know
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