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NEMA Size Starters for Single-Phase Motors

Size of
Controller		 Continuous
Current
Rating
(Amperes)		 Horsepower
at 115V at 230V
00
0
1
1P
2
3		 9
18
27
36
45
90		 1/3
1
2
3
3
7½		 1
2
3
5
7½
15

Reference: NEMA ICS2-1993, Table 2-4-2.

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Derating Factors for Conductors in a Conduit

Number of
Current
Carrying
Conductors		 Percent of Values in
Tables Adjusted
for Temperature
If Necessary
4-6
7-9
10-20
21-30
31-40
41 & Above		 80
70
50
45
40
35

Reprinted with permission from NFPA 70-1996, National Electrical Code,® copyright © 1996,  National Fire Protection Association, Quincy, Massachusetts 02269.

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Temperature Classification of Insulation Systems

Insulation Systems*

Temperature Classification
Class A
Class E**
Class B
Class F
Class H
Class N		 Class 105
Class 120
Class 130
Class 155
Class 180
Class 200		 105°C
120°C
130°C
155°C
180°C
200°C		 221°F
248°F
266°F
311°F
356°F
392°F

 

*IEEE Std. 117.
**Used in European equipment.

Insulation systems are arranged in order of their insulation level and classified by a letter symbol or by a numerical value.
The numerical value relates to the temperature classification of the insulation system.
The temperature classification indicates the maximum (hot-spot) temperature at which the insulation system can be operated for normal expected service life.
In general, all materials used in a given insulation system should be rated for temperatures equal to, or exceeding, the temperature classification of the system.

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Resistance Temperature Detectors (RTDs)

Metal Characteristic TRC (W/W/°C)*
Copper 10.0W @ 25°C .00427
Platinum 100W @ 0°C .00385
Nickel 120W @ 0°C .00672

 

*TCR is the Temperature Coefficient of Resistance.

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Thermocouple Junction Types

Junction Type Thermocouple Materials
E Chromel-Constantan
J Iron-Constantan
K Chromel-Alumel
T Copper-Constantan

 

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