40 — ElectriCalc Pro
Sizing Temperature-Adjusted
Derated Wires
A circuit was built with 60°C copper wire
connecting a 47,650 Volt-amp load to a
240 Volt, three-phase source. Ambient
temperature is 50°C. What is the derated
wire size required if eight current-carrying
THHN wires were installed in the race-
way?
Steps
Keystrokes
Display
Clear calculator
o o
0.
Set to 60°C
S 6
3Ø 60 Cu 0.
Enter Volt-amps
4 7 6 5 0 V
VA 47,650.
Enter Volts
2 4 0 U
VOLT 240.
Set to 50°C amb
5 0 S 2
AMB° 50. °C
Find adj. wire size
w
AWG 250 CU
Amb WIRE SIZE
Find derated
8 S P
D/R 500 CU
wire size
Amb WIRE SIZE
Display Wire
P
D/R 46.5
Ampacity Amb
WIRE A
Display Adjust.
P
ADJ 41. %
Factor
Amb
Display NEC Table
P
NEC 310.15
Set to 30°C
3 0 S 2 o
0.
and Clear
NOTE:
All Settings should be changed
back to default to avoid conflicts in
answers throughout the rest of this manu-
al. See “Settings” for a list of Permanent
Values/settings. Changing these settings
may affect your calculations.
