11
taBle 1.
Allowable Ampacities of Insulated Conductors
Not More Than Three Conductors in Raceway or Cable or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F)
Size
Temperature Rating of Conductor
Size
60°C
(140°F)
75°C
(167°F)
85°C
(185°F)
90°C
(194°F)
60°C
(140°F)
75°C
(167°F)
85°C
(185°F)
90°C
(194°F)
AWG
MCM
TYPES
RUW, T
TW, UF
TYPES
FEPW
RH, RHW
RUH,
THW,
THWN,
XHHW
USE, ZW
TYPES
V, MI
TYPES
TA, TBS
SA, AVB
SIS, =FEP,
=FEPB,
=RHH,
=THHN,
=XHHW*
TYPES
RUW, T
TW, UF
TYPES
RH, RHW
RUH
THW,
THWN
XHHW,
USE
TYPES
V, MI
TYPES
TA, TBS,
SA, AVB
SIS,
=RHH,
=THHN,
=XHHW*
AWG
MCM
COPPER
ALUMINUM OR COPPER-CLAD ALUMINUM
18
16
14
12
10
8
......
......
15
20
30
40
......
......
15
20
30
45
......
22
25
30
40
50
21
22
25
30
40
50
......
......
......
15
25
30
......
......
......
15
25
40
......
......
......
25
30
40
......
......
......
25
30
40
......
......
......
12
10
8
6
4
3
2
1
55
70
80
65
85
100
115
130
70
90
105
120
140
70
90
105
120
140
40
55
65
75
50
65
75
90
100
55
70
80
95
110
55
70
80
95
110
6
4
3
2
1
0
00
000
0000
150
175
200
230
155
185
210
235
155
185
210
235
120
135
155
180
125
145
165
185
125
145
165
185
0
00
000
0000
250
300
350
400
500
255
285
310
335
380
270
300
325
360
405
270
300
325
360
405
205
230
250
270
310
215
240
260
290
330
215
240
260
290
330
250
300
350
400
500
CORRECTION FACTORS
Ambient
Temperature
°C
31-40
41-50
51-60
61-70
71-80
For ambient temperatures over 30°C, multiply the ampacities shown by the appropriate correction factor to determine the maximum
allowable load current.
Ambient
Temperature
°F
.82
.58
......
......
......
.88
.75
.58
.35
......
.90
.80
.67
.52
.30
.91
.82
.71
.58
.41
.82
.58
......
......
......
.88
.75
.58
.35
......
.90
.80
.67
.52
.30
.91
.82
.71
.58
.41
86 –104
105–122
123–141
142–158
159–176
= The load current rating and the overcurrent protection for these conductors shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10
AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum.
taBle 2.
standard kw Inputs
standard
kw
ratings
Immersion
heaters***
number of 50a contractors
full load current In amperes
single phase
three phase
no. of
wattage
208V
240V
480V
208V
240V
277V
480V
208V
240V
480V
3
6
9
12
15
1
3,000
1
6,000
1
9,000
1
12,000
1
15,000
1
1
1
14.4
28.8
43.3
57.7
72.1
86.5
115.4
144.2
173.1
216.3
N/A
N/A
N/A
N/A
12.5
25.0
37.5
50.0
62.5
75.0
100.0
125.0
150.0
187.5
225.0
250.0
N/A
N/A
10.8
21.2
32.5
43.3
54.2
65.0
86.6
108.3
130.0
162.5
194.9
216.6
N/A
N/A
6.3
12.5
18.8
25.0
31.3
37.5
50.0
62.5
75.0
93.8
112.5
125
156
188
8.3
16.7
25.0
33.3
41.6
50.0
66.6
83.3
99.9
124.9
149.9
166.7
208.4
250
7.2
14.4
21.7
28.9
36.1
43.3
57.7
72.2
86.6
108.3
129.9
145
181
217
3.6
7.2
10.8
14.4
18.0
21.7
28.9
36.1
43.3
54.1
65.0
72
90
108
18*
24
30
1
18,000
2
12,000
2
15,000
2
2
36*
45
54
2
18,000
3
15,000
3
18,000
3
3
2
60**
4
15,000
4
4
75**
5
18,000
5
5
3
90**
5
18,000
* 208V models use one additional immersion heater.
** Available on 50 gallon models or larger.
*** Each immersion heater contains three electric elements.
