table 310 b 2 b
- Thread starter shputnik
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- New Jersey
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- Journeyman Electrician
Do you mean T310.15(B)(2)(b)?
kwired
Electron manager
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- NE Nebraska
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- EC
That is my guess.
Note the headings of T310.15(B)(2)(a) and (b) - one says for ambient temps other then 30 deg C the other says for other then 40 deg C.
Most of our conductor selecting comes from T310.15(B)(16) which the values in that table are based on an ambient of 30C, but you use T310.15(B)(2)(a) for adjustments if other then 30C ambient.
Some of the tables are based on 40C ambient - T310.15(B)(2)(b) is for adjustments involving those tables when the ambient is other then 40C.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
No. First simple fact effecting the outcome of the calculation is the adjustment factor of 1.00 is for 30 degrees in one table and 40 degrees in the other.
if I had a room with a 45 degree Celsius ambient temperature...which correctional table do I use? 310.15B2a or 310.15B2b?
im confused appreciate your feedback
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
What kind of conductor are you using? Most common applications are all conductors from 310.15 (B) (16), which that table is based on 60, 75 and 90 degree rated conductors used at an ambient temp of 30C. You will not use (B)(2)(b) for adjustments to conductors selected from (B)(16)
Table (B)(17) is also based on 30C ambient - I believe most the other ampacity tables are based on 40C. If you have an application that uses one of those other tables then you use the adjustment factors from (B)(2)(b) if you have other then 40C ambient.
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