Honeywell
• 25
P
OWER
CABLING
4.1.1.4
Cable and fuse sizes, frames MR7 to MR9, North America
The recommended fuse types are gG/gL (IEC 60269-1) or class T (UL & CSA). The fuse volt-
age rating should be selected according to the supply network. The final selection should be
made according to local regulations, cable installation conditions and cable specification. Big-
ger fuses than what is recommended below shall not be used.
Check that the fuse operating time is less than 0.4 seconds. Operating time depends on used
fuse type and impedance of the supply circuit. Consult the factory about faster fuses. Honey-
well offers recommendations also for high speed J (UL & CSA ), aR (UL recognized, IEC
60269-4) and gS (IEC 60269-4) fuse ranges.
Table 17. Cable and fuse sizes (MR7 to MR9)
The cable dimensioning is based on the criteria of the Underwriters’ Laboratories UL508C:Cables must
be PVC-isolated; Max ambient tempe30°C, max temperature of cable s70°C; Use only
cables with concentric copper shield; Max number of parallel cables is 9.
When using cables in parallel,
NOTE HOWEVER
that the requirements of both the cross-sectional
area and the max number of cables must be observed.
For important information on the requirements of the earthing conductor, see standard Underwriters’
Laboratories UL508C.
For the correction factors for each temperature, see the instructions of standard Underwriters’ Labora-
tories UL508C.
Frame
Type
I
L
[A]
Fuse
(class T)
[A]
Mains, motor
and ground
cable, Cu
Terminal cable size
Main terminal
Earth terminal
MR7
230 18P
400 37P
75.0
72.0
100
AWG2
AWG9-AWG2/0
AWG9-AWG2/0
230 22P
400 45P
88.0
87.0
110
AWG1
AWG9-AWG2/0
AWG9-AWG2/0
230 30P
400 55P
105.0
150
AWG1/0
AWG9-AWG2/0
AWG9-AWG2/0
MR8
230 37P
400 75P
143.0
140.0
200
AWG3/0
AWG1-350 kcmil AWG1-350 kcmil
230 45P
400 90P
170.0
225
250 kcmil
AWG1-350 kcmil AWG1-350 kcmil
230 55P
400 110
208.0
205.0
250
350 kcmil
AWG1-350 kcmil AWG1-350 kcmil
MR9
230 75P
400 132
261.0
350
2*250 kcmil
AWG1-350 kcmil AWG1-350 kcmil
230 90P
400 160
310.0
400
2*350 kcmil
AWG1-350 kcmil AWG1-350 kcmil