INSTALLATION, OPERATING AND TROUBLESHOOTING INSTRUCTIONS FOR MODEL A75D / A75DE –
THREE PHASE
Page 11 of 20
POWER CABLING FORMULAS
SIZE
AWG.
AREA
CIR.
MILS
SIZE
AWG.
MCM*
AREA
CIR.
MILS
SIZE
MCM*
AREA
CIR.
MILS
18
1620
1
83690
600
600000
16
2580
1/0
105600
700
700000
14
4110
2/0
133100
750
750000
12
6530
3/0
167800
800
800000
10
10380
4/0
211600
900
900000
8
16510
250
250000
1000
1000000
6
26240
300
300000
1250
1250000
4
41740
350
350000
1500
1500000
3
52620
400
400000
1750
1750000
2
66360
500
500000
2000
2000000
*DENOTES ALL SIZES LARGER THAN =0000 ARE EXPRESSED IN MCM.
TABLE OF CONVENTIONS
CMA = Cross section of wire in circular MIL area
A = Ultimate drain in amperes
LF = Conductor loop feet
MAX AMP = Maximum allowable amperes for given voltage drop
AVD = Allowable voltage drop
K = 11.1 Constant factor for commercial (TW type) copper wire
(KS5482-01)
= 17.4 for aluminum (KS20189)
Calculating Wire Size Requirements
CMA
=
A X LF X K
AVD
Calculating Current carrying capacity of wire
Max Amp
=
CMA X AVD
LF X K
Source: Handbook 100-National Bureau of Standards
NOTE: All Wire #6 and larger is stranded.
