Cable sizing according CSA
Calculation method according CEC part 1, table 2: allowable ampacities for not more than 3 copper
conductors in raceway or cable (based on an ambient temperature of 30 °C (86 °F). Correction factors for
other temperatures table 5A.
Maximum allowed current in function of the ambient temperature, based on a 75 °C (167 °F)
cable temperature
Ambient temperature
Cable section
(AWG or kcmil)
30 °C (86 °F)
40 °C (104 °F) 45 °C (113 °F) 50 °C (122 °F) 55 °C (131 °F)
10
< 35 A
< 31 A
< 29 A
< 26 A
< 23 A
8
< 50 A
< 44 A
< 41 A
< 38 A
< 34 A
6
< 65 A
< 57 A
< 53 A
< 49 A
< 44 A
4
< 85 A
< 75 A
< 70 A
< 64 A
< 57 A
3
< 100 A
< 88 A
< 82 A
< 75 A
< 67 A
2
< 115 A
< 101 A
< 94 A
< 86 A
< 77 A
1
< 130 A
< 114 A
< 107 A
< 98 A
< 87 A
1/0
< 150 A
< 132 A
< 123 A
< 113 A
< 101 A
2/0
< 175 A
< 154 A
< 144 A
< 131 A
< 117 A
3/0
< 200 A
< 176 A
< 164 A
< 150 A
< 134 A
4/0
< 230 A
< 202 A
< 189 A
< 173 A
< 154 A
Calculation method for CSA
• Single supply cables (3 PE - configuration (1)):
• Add 10 % to the total compressor current (I
tot
Pack or I
tot
FF from the tables)
• Install the prescribed fuse on each cable
• Parallel supply cable (2 x 3 2 PE - configuration (2)):
• Add 10 % to the total compressor current (I
tot
Pack or I
tot
FF from the tables) and divide by 2
• Multiply the ampacity of the cables with 0.8 (see CEC Part 1 table 5C)
• Install fuses of half the size of the recommended maximum fuse size on each cable.
• When using 2 x 3 phase + 2 PE as in (3):
• Add 10 % to the total compressor current (I
tot
Pack or I
tot
FF from the tables) and divide by √3
• Multiply the ampacity of the cables with 0.8 (see CEC Part 1 table 5C)
• Fuse size: the recommended maximum fuse size divided by √3 on each cable.
• Size PE cable:
• For supply cables up to AWG8: same size as supply cables
• For supply cables larger than AWG8: use maximum allowed ampacity of the selected supply
cables and compare with value in table below (see CEC Part 1 table 16)
< 100 A: use AWG8
< 200 A: use AWG6
< 400 A: use AWG3
Always check the voltage drop over the cable (less than 5 % of the nominal voltage is recommended).
Example of supply cable calculation:
I
tot
= 128 A, maximum ambient temperature is 45 °C,
recommended fuse = 150 A
Instruction book
90
2920 7101 41
Summary of Contents for CPC 40 G
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