Voltage Drop
- Thread starter eeeee
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I don't think the NEC makes reference to K. It varies with temperature.eeeee said:
R = C x (K/A)1000 = ohms per 1000 ft.
C = 1.02 for stranded conductors and 1 for solid.
A = cross setional area in cmil
K = 10.575 at 25C and about 12.5 at 65C. In your area it might be zero.
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
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- Service Electrician 2020 NEC
I've been using this formula for K.
K = R2 * CM
R2 = R1[1 + TCR(T2 - 75) From: NEC Tbl.8 Note 2.
TCR = Temperature Coefficient of Resistance, cu = 0.00323, al = 0.00330
T2 = new temperature, usually 60 or 90
CM = circular mils
Except for percentage adjustments in Tbl.8, Note 3, this formula does not differentiate between stranded and solid AWG. Tbl.8, Note 1, seems to assume normal-stranded wire for the chosen TCR's, unless differences between strands and solids was considered negligible.
To incorporate Bob's formula correctly for solid AWG, it looks like I could multiply my result above by 0.98 ?
K = R2 * CM
R2 = R1[1 + TCR(T2 - 75) From: NEC Tbl.8 Note 2.
TCR = Temperature Coefficient of Resistance, cu = 0.00323, al = 0.00330
T2 = new temperature, usually 60 or 90
CM = circular mils
Except for percentage adjustments in Tbl.8, Note 3, this formula does not differentiate between stranded and solid AWG. Tbl.8, Note 1, seems to assume normal-stranded wire for the chosen TCR's, unless differences between strands and solids was considered negligible.
To incorporate Bob's formula correctly for solid AWG, it looks like I could multiply my result above by 0.98 ?
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