Electrical And Other
Maintenance Formulae

TO FIND
SINGLE-PHASE
THREE-PHASE
DIRECT CURRENT
Kilowatts
I x E x PF
1000
I x E x 1.732 x PF
1000
  I x E  
1000
KVA
I x E
1000
I x E x 1.732
1000
---------------
Horsepower (Output)
I x E x %EFF x PF
746
I x E x 1.732 x %EFF x PF
746
I x E x %EFF
746
Amperes when Horsepower is known
      HP x 746      
E x %EFF x PF
           HP x 746           
1.732 x E x %EFF x PF
  HP x 746  
E x %EFF
Amperes when Kilowatts is known
  KW x 1000  
E x PF
    KW x 1000    
1.732 x E x PF
  KW x 1000  
E
Amperes when KVA is known
KVA x 1000
E
KVA x 1000
1.732 x E
---------------
E = Volts     I = Amperes     %EFF = Percent Efficiency     PF = Power Factor
Other Useful Formulae

    BTUs x 777.5 = foot pounds
    BTUs x 3.93 ÷ 10,000 = horsepower hours
    BTUs x 2.93 ÷ 10,000 = Kilowatt hours
    BTUs per minute x 13.0 = foot pounds per second
    BTUs per minute x 1.76 ÷ 100 = Kilowatts
    BTUs per hour x 2.93 ÷ 10,000 = Kilowatts
    BTUs per hour x 2.98 ÷ 1,000,000 = Boiler horsepower
    (Celsius x 9 ÷ 5) + 32 = Fahrenheit
    Circular mils x 0.7854 = Square mils
    (Fahrenheit - 32) x 5 ÷ 9 = Celsius
    Foot pounds x 2.29 ÷ 1,000 = BTUs
    Foot pounds x 5.05 ÷ 10,000,000 = Horsepower hours
    Foot pounds x 3.77 ÷ 10,000,000 = Kilowatt hours
    Foot pounds per minute x 1.29 ÷ 1,000 = BTUs per minute
    Foot pounds per minute x 3.03 ÷ 100,000 = Horsepower
    Foot pounds per second x 1.82 ÷ 1,000 = Horsepower
    Horsepower x 42.4 = BTUs per minute
    Horsepower x 33,000 = Foot pounds per minute
    Horsepower x 550 = Foot pounds per second
    Horsepower x 0.746 = Kilowatts
    Horsepower boiler x 33520 = BTUs per hour
    Horsepower boiler x 9.80 = Kilowatts
    Horsepower hours x 2550 = BTUs
    Horsepower hours x 1,980,000 = Foot pounds
    Kilowatts x 56.9 = BTUs per minute
    Kilowatts x 3412 = BTUs per hour
    Kilowatts x 1.341 = Horsepower
    Kilowatt hours x 3412 = BTUs
    Kilowatt hours x 1.34 = Horsepower hours
    Square inch x 273,000 = Circular mils

Wire Gauges Information
Gauge AWG Ft. / Ohm @ 77 ºF Ohms / 1000 ft @ 77 ºF Ft / Ohm @ 149ºF Ohms / 1000 ft @ 149 ºF AMP @ 140 ºF Dia. in mils (1000th in) Dia. in mm Wt. in Lbs. per 1000 ft
0000
000
00		 20000
15873
12658		 0.050
0.063
0.079		 17544
13699
10870		 0.057
0.073
0.092		 195
165
145		 460.0
410.0
365.0		 11.684
10.414
9.271		 641.0
508.0
403.0
0
1
2
3
4		 10000
7936
6289
4975
3953		 0.100
0.126
0.159
0.201
0.253		 8621
6849
5435
4310
3425		 0.116
0.146
0.184
0.232
0.292		 125
110
95
85
70		 325.0
289.0
258.0
229.0
204.0		 8.255
7.348
6.544
5.827
5.189		 319.0
253.0
201.0
159.0
126.0
5
6
7
8
9		 3135
2481 1
968
1560
1238		 0.319
0.403
0.508
0.641
0.808		 2710
2151
1706
1353
1073		 0.369
0.465
0.586
0.739
0.932
55

40		 182.0
162.0
144.0
128.0
114.0		 4.621
4.115
3.665
3.264
2.906		 100.0
79.5
63.0
50.0
39.6
10
11
12
13
14		 980.4
781.3
617.3
490.2
387.6		 1.02
1.28
1.62
2.04
2.58		 847.5
675.7
534.8
423.7
336.7		 1.18
1.48
1.87
2.36
2.97		 30

25

20		 102.0
91.0
81.0
72.0
64.0		 2.588
2.305
2.053
1.828
1.628		 31.4
24.9
19.8
15.7
12.4
15
16
17
18
19		 307.7
244.5
193.8
153.6
121.8		 3.25
4.09
5.16
6.51
8.21		 266.7
211.4
167.8
133.2
105.5		 3.75
4.73
5.96
7.51
9.48

--		 57.0
51.0
45.0
40.0
36.0		 1.450
1.291
1.150
1.024
0.912		 9.86
7.82
6.2
4.92
3.90
20
21
22
23
24		 96.2
76.3
60.6
48.1
38.2		 10.4
13.1
16.5
20.8
26.2		 84.0
66.2
52.6
41.7
33.1		 11.9
15.1
19.0
24.0
30.2

--		 32.0
28.5
25.3
22.6
20.1		 0.812
0.723
0.644
0.573
0.511		 3.09
2.45
1.94
1.54
1.22
25
26
27
28
29		 30.3
24.0
19.0
15.1
12.0		 33.0
41.6
52.5
66.2
83.4		 26.2
20.8
16.5
13.1
10.4		 38.1
48.0
60.6
76.4
96.3

--		 17.9
15.9
14.2
12.6
11.3		 0.455
0.405
0.361
0.321
0.286		 0.970
0.769
0.610
0.484
0.384
30
31
32
33
34		 9.5
7.5
6.0
4.7
3.8		 105
133
167
211
266		 8.3
6.5
5.2
4.1
3.3		 121
153
193
243
307

--		 10.0
8.9
8.0
7.1
6.3		 0.255
0.227
0.202
0.180
0.160		 0.304
0.241
0.191
0.152
0.120
35
36
37
38
39
40		 3.0
2.4
1.9
1.5
1.2
0.93		 335
423
533
673
848
1070		 2.6
2.0
1.6
1.3
1.0
0.81		 387
488
616
776
979
1230

--		 5.6
5.0
4.5
4.0
3.5
3.1		 0.143
0.127
0.113
0.101
0.090
0.080		 0.095
0.0757
0.0600
0.0476
0.0377
0.0200


Electrical Wire Gauge Comparison Table

Circ. Mils Equivalent
Circ. Mils		 Awg.
Size		 Metric
Wire
Size
mm2		 Stranding/ Wire
Dia. per Strand		 Approximate
Overall Diameter
in mm in mm
-
1020
-
1620
1620
-
-		 987
-
1480
-
-
1974
1974		 -
20
-
18
18
-
-		 0.50
-
0.75
-
-
1.0
1.0		 1/.032
7/.0121
1/.039
1/.0403
7/.0152
1/.045
7/.017		 1/.813
7/.307
1/.991
1/1.02
7/.386
1/1.14
7/.432		 .032
.036
.039
.040
.046
.045
.051		 0.81
0.91
0.99
1.02
1.16
1.14
1.30
2580
2580
-
-
4110
4110		 -
-
2960
2960
-
-		 16
16
-
-
14
14		 -
-
1.5
1.5
-
-		 1/.0508
7/.0192
1/.055
7/.021
1/.0641
7/.0242		 1/1.29
7/.488
1/1.40
7/5.33
1/1.63
7/.615		 .051
.058
.055
.063
.064
.073		 1.29
1.46
1.40
1.60
1.63
1.84
-
-
6530
6530
-
-		 4934
4934
-
-
7894
7894		 -
-
12
12
-
-		 2.5
2.5
-
-
4
4		 1/.071
7/.027
1/.0808
7/.0305
1/.089
7/.034		 1/1.80
7/.686
1/2.05
7/.775
1/2.26
7/.864		 .071
.081
.081
.092
.089
.102		 1.80
2.06
2.05
2.32
2.26
2.59
10380
10380
-
-
13090
13090		 -
-
11840
11840
-
-		 10
10
-
-
9
9		 -
-
6
6
-
-		 1/.1019
7/.0385
1/.109
7/.042
1/.1144
7/.0432		 1/2.59
7/.978
1/2.77
7/1.07
1/2.91
7/1.10		 .102
.116
.109
.126
.1144
.130		 2.59
2.93
2.77
3.21
2.91
3.30
16510
16510
-
-
20820
20820		 -
-
19740
19740
-
-		 8
8
-
-
7
7		 -
-
10
10
-
-		 1/.1285
7/.0486
1/.141
7/.054
1/.1443
7/.0545		 1/3.26
7/1.23
1/3.58
7/1.37
1/3.67
7/1.38		 .128
.146
.141
.162
.144
.164		 3.26
3.70
3.58
4.12
3.67
4.15
26240
26240
-
33090
41740		 -
-
31580
-
-		 6
6
-
5
4		 -
-
16
-
-		 1/.162
7/.0612
7/.068
7/.0688
7/.0772		 1/4.11
7/1.55
7/1.73
7/1.75
7/1.96		 .162
.184
.204
.206
.232		 4.11
4.66
5.18
5.24
5.88
-
-
52620
66360
-
-		 49340
49340
-
-
69070
69070		 -
-
3
2
-
-		 25
25
-
-
35
35		 7/.085
19/.052
7/.0867
7/.0974
7/.100
19/.061		 7/2.16
19/1.32
7/2.20
7/2.47
7/2.54
19/1.55		 .255
.260
.260
.292
.300
.305		 6.48
6.60
6.61
7.42
7.62
7.75
Circ. Mils Equivalent
Circ. Mils		 Awg.
Size		 Metric
Wire
Size
mm2		 Stranding/ Wire
Dia. per Strand		 Approx.
Overall Diameter
in mm in mm
83690
-
105600
133100
-
167800
167800		 -
98680
-
-
138100
-
-		 1
-
1/0
2/0
-
3/0
3/0		 -
50
-
-
70
-
-		 19/.0664
19/.073
19/.0745
19/.0837
19/.086
19/.094
37/.0673		 19/1.69
19/1.85
19/1.89
19/2.13
19/2.18
19/2.39
37/1.71		 .332
.365
.373
.419
.430
.470
.471		 9.43
9.27
9.46
10.6
10.9
11.9
12.0
-
-
211600
-
250mcm
300mcm		 187500
187500
-
237.8mcm
-
-		 -
-
4/0
-
-
-		 95
95
-
120
-
150		 19/.101
37/.072
19/.1055
37/.081
37/.0822
37/.090		 19/2.57
37/1.83
19/2.68
37/2.06
37/2.09
37/2.29		 .505
.504
.528
.567
.575
.630		 12.8
12.8
13.4
14.4
14.6
16.0
350mcm
-
400mcm
-
-
500mcm
500mcm		 -
365.1mcm
-
473.6mcm
473.6mcm
-
-		 -
-
-
-
-
-
-		 -
185
-
240
240
-
-		 37/.0973
37/.100
37/.104
37/.114
61/.089
37/.1162
61/.0905		 37/2.47
37/2.54
37/2.64
37/2.90
61/2.26
37/2.95
61/2.30		 .681
.700
.728
.798
.801
.813
.814		 17.3
17.8
18.5
20.3
20.3
20.7
20.7
-
600mcm
700mcm
750mcm
750mcm
-		 592.1mcm
-
-
-
-
789.4mcm		 -
-
-
-
-
 300
-
-
-
-
400		 61/.099
61/.0992
61/.1071
61/.1109
91/.0908
61/.114		 61/2.51
61/2.52
61/2.72
61/2.82
91/2.31
61/2.90		 .891
.893
.964
.998
.999
1.026		 22.6
22.7
24.5
25.4
25.4
26.1
800mcm
800mcm
1000mcm
1000mcm
-		 -
-
986.8mcm
-
1233.7mcm		 -
-
-
-
-		 -
-
500
-
625		 61/.1145
61/.0938
61/.1280
91/.1048
91/.117		 61/2.91
91/2.38
61/3.25
91/2.66
91/2.97		 1.031
1.032
1.152
1.153
1.287		 26.2
26.2
29.3
29.3
32.7
1250mcm
1250mcm
1500mcm
1500mcm
-		 -
-
-
-
1578.8mcm		 -
-
-
-
-		 -
-
-
-
800		 91/.1172
127/.0992
91/.1284
127/.1087
91/.132		 91/2.98
127/2.52
91/.1284
127/.1087
91/.132		 1.289
1.290
1.412
1.413
1.452		 32.7
32.8
35.9
35.9
36.9
-
2000mcm
2000mcm		 1973.5mcm
-
-		 -
-
-		 1000
-
-		 91/.147
127/.1255
169/.1088		 91/3.73
127/3.19
169/2.76		 1.617
1.632
1.632		 41.1
41.5
41.5