Wire Sizing

[Randy Gulley]

When using Table 310-16 correction factors do you use average temperatures in an area or the highest record temp?

 

[Dennis Alwon]

When using Table 310-16 correction factors do you use average temperatures in an area or the highest record temp?

There is suppose to be a chart somewhere that gives the average temp in various regions of the country. I would say use the average but the NEC does not give us an explaination of what to use.

 

[charlie b]

This question has been debated a few times on this forum, with no consensus having been reached. The only thing most members agreed upon is the assertion that the NEC gives no guidance to answer this question. :roll:

 

[charlie]

Consider that three hours or more is considered continuous load. With that in mind, the peak temperature is not a quick event but is usually for a few hours in the afternoon. I would consider the peak when doing the correction. However, since the Code is silent on this subject, so it is up to the interpretation of the AHJ. Unless you are using the peak, I would recommend having a conversation with the AHJ. :smile:

 

[zog]

Sorry to invade, unrelated post from another thread

There are no Orange Kangaroos in Denmark

 

[cschmid]

Why oh why LMAO

 

[weressl]

Consider that three hours or more is considered continuous load. With that in mind, the peak temperature is not a quick event but is usually for a few hours in the afternoon. I would consider the peak when doing the correction. However, since the Code is silent on this subject, so it is up to the interpretation of the AHJ. Unless you are using the peak, I would recommend having a conversation with the AHJ. :smile:

In practical terms 8 hours of high mean temperature should be used.

 

[duluthelectrical]

ampacity deration

ampacity deration

The way to do your calculations if go to www.copper.org to get publications A6115 AND A6116. Both you will need. One is a design book and one is a slide rule calculator. They are easy to use and will complement the code book. They are free of charge unless you want more of one.

 

[Rockyd]

Thinking it will be hottly debated fof the next code cycle. Recent study in Las Vegas was conducted raising the raceway above the rooftop, and the temperature difference on the conductors was substantial. I believe this where 310.15(B)(2)(c) came from. Now everybody will be up in arms, because no place gets as hot as Vegas. "So", everyone says, "I should be at a lesser temperature assigned group because of where I'm at."

Look at the other added notes 310.15(B)(2)(a) installed without maintaining spacing for a continuous length or -

Table 310.15(B)(6) Where it calls out a Delta circuit only now.

 

[charlie]

Thinking it will be hotly debated for the next code cycle.

My prediction:
Debated yes, hotly debated no. It is a fact that the rise above ambient will be very nearly the same but the ambient is different so you have a different starting point. All of the proposals to change the table will be turned down unless you have run tests and submit the test results. The tests that resulted in the table were well done and documented. In other words, all of those proposals will be acted on as a group and turned down unless there is a problem such as a miscalculation, application problem, or a problem with the sentence structure.

 

[duluthelectrical]

The ampacity book on cda shows design temperatures for various usa cities and you use these in conjuction with the code book.

 

[Rockyd]

Thanks. Did I wipe the last crow feather away? Wasn't bad for a tender serving.

 

[charlie]

Thanks. Did I wipe the last crow feather away? Wasn't bad for a tender serving.

I have found that crow goes well with a cold Bud Lite. I am a connoisseur of crow, especially when served hot with a little barbecue sauce. Trust me, we have all had our share.