Building Design and Construction Handbook - Merritt - Ventech!

15.39
Horsepower
TABLE 15.3 Protection of Three-Phase 208-V Motors and Circuits (Continued)
Size and class
of motor
Ampere
rating Class
Branch circuit
protection*
Maximum
size fuse
permitted
by the
code
Timedelaycartridge
or lowpeak
fuse
that can
be used
Ordinary
service
Motor-running protection†
Size of time-delay-cartridge
or low-peak fuse
Maximum size
Heavy
service
40�C
motor
All other
motors
Size of fused switch
or fuse holder
Maximum
size
switch
that can
be used
Size that
can be
used with
time-delaycartridge
or lowpeak
fuses
Minimum
size of
starter:
NEMA
size
Minimum
size and
type of
wire:
AWG
or
MCM
Minimum
size of
conduit:
diameter,
in
10 28.6 1 90 45 30 35 40 35 100 60
2 70 45 30 35 40 35 100 60
3 60 45 30 35 40 35 60 60 2 8 R 3
⁄4
4 45 45 30 35 40 35 60 60
15 42.3 1 125 60 45 50 50 50 200 60
2 110 60 45 50 50 50 200 60
3 90 60 45 50 50 50 100 60 2 6 R 1
4 70 60 45 50 50 50 100 60
20 55 1 175 90 60 70 70 70 200 100
2 150 90 60 70 70 70 200 100
3 110 90 60 70 70 70 200 100 3 4 R 11 ⁄4
4 90 90 60 70 70 70 100 100
25 68 1 225 100 70 80 90 80 400 100
2 175 100 70 80 90 80 200 100
3 150 100 70 80 90 80 200 100 3 2 R 11 ⁄4
4 110 100 70 80 90 80 200 100
30 83 1 250 125 90 100 110 100 400 200
2 225 125 90 100 110 100 400 200
3 175 125 90 100 110 100 200 200 3 1 R 11 ⁄2
4 125 125 90 100 110 100 200 200
40 110 1 350 175 110 125 150 150 400 200
2 300 175 110 125 150 150 400 200
3 225 175 110 125 150 150 400 200 4 0 RH 2
4 175 175 110 125 150 150 200 200
50 132 1 400 200 150 175 175 175 400 200
2 350 200 150 175 175 175 400 200
3 300 200 150 175 175 175 400 200 4 00 RH 2
4 200 200 150 175 175 175 200 200