Conduit fill Question
- Thread starter zappy
- Start date
- Status
electricalperson
Senior Member
- Location
- massachusetts
im sure with a number that small you can round down. i dont think the .0003 matters. as far as im concerned you are pretty exact to full on the 1 inch emt. dont worry
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
If I were to perform a formal calculation, and document the results, and apply my PE seal to the document, and if I came up with those two numbers, I would say that the conduit is not big enough. But then, I would not have come up with those numbers!
How so, you ask? I would ask in return, what value did you use for Pi? Did you use 3.14 (i.e., three significant digits), or perhaps did you use 3.1415926535 (a few more significant digits)? While I am at it, what values did you use for conductor diameters? And where did you get those numbers? Then, looking at your replies, I would expect to observe that at least one of the values you used had a degree of precision that is no better than two, or at most three, significant digits. You don't know the diameter of a wire to four significant digits! Therefore, it is mathematical and engineering nonsense to show a final result that has four significant digits. Your final result cannot have a degree of precision that exceeds that of your input numbers. What I am telling you is that you did not, in fact, get a final answer of 0.3463. You got a final answer of 0.346 at best, and it is possible that both the conduit size and the total fill values are both 0.35. I know that because your input information had no more than three signficant digits, and maybe only two.
Bottom line, you can use the 1 inch.
If I were to perform a formal calculation, and document the results, and apply my PE seal to the document, and if I came up with those two numbers, I would say that the conduit is not big enough. But then, I would not have come up with those numbers!
How so, you ask? I would ask in return, what value did you use for Pi? Did you use 3.14 (i.e., three significant digits), or perhaps did you use 3.1415926535 (a few more significant digits)? While I am at it, what values did you use for conductor diameters? And where did you get those numbers? Then, looking at your replies, I would expect to observe that at least one of the values you used had a degree of precision that is no better than two, or at most three, significant digits. You don't know the diameter of a wire to four significant digits! Therefore, it is mathematical and engineering nonsense to show a final result that has four significant digits. Your final result cannot have a degree of precision that exceeds that of your input numbers. What I am telling you is that you did not, in fact, get a final answer of 0.3463. You got a final answer of 0.346 at best, and it is possible that both the conduit size and the total fill values are both 0.35. I know that because your input information had no more than three signficant digits, and maybe only two.
Bottom line, you can use the 1 inch.
8awg thhn 0.0366 x3 = 0.1098
6awg 0.0507 x3 = 0.1521
10awg 0.0211 x3 = 0.0633
10awg 0.0211 x1 = 0.0211 (EGC)
Total 0.3463
1"EMT 0.346
Is there anything I did wrong?
Last edited:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
I do not think so. I get the same values. I think you are okay. The difference is minute. 3/10,000 of a square inch. I have no idea what charlie b is talking about in this app. Those values are straight from the Chapter 9 tables.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
If you round the numbers to three digits past the decimal, you're well under (relatively speaking).
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