Chiller Wiring Standards

LOUDA Chiller Wiring Current Standards

Estimation mnemonic:

Multiply 2.5 by 9, then subtract one for each higher wire size.

Thirty-five times 3.5, with pairs subtracting 0.5.

Conditions may change, with adjustments applied; at high temperatures, a 10% discount applies to copper upgrades.

The number of conductors in the conduit is two, three, or four; at full load, the current rating is reduced by 10%, 20%, or 30%, respectively.

Note:

(1) This section’s mnemonic does not directly state the current-carrying capacity (safe current) for various insulated wires (rubber‑ and plastic‑insulated). Instead, it expresses this capacity as “the cross-sectional area multiplied by a certain factor,” determined through mental calculation. As shown in Table 5‑3, the multiplier decreases as the cross-sectional area increases. “Multiply by nine for sizes 2.5 mm² and below; for larger sizes, subtract one from the next higher size” means that for aluminum‑core insulated wires with cross sections of 2.5 mm² or less, the current‑carrying capacity is approximately nine times the cross‑sectional area. For example, a 2.5 mm² wire has a current‑carrying capacity of 2.5 × 9 = 22.5 A. For wires 4 mm² and above, the relationship between current‑carrying capacity and the cross‑sectional area multiplier progresses sequentially upward: the multiplier decreases by one for each successive wire size—namely, 4 × 8, 6 × 7, 10 × 6, 16 × 5, and 25 × 4.

“Thirty-five times three point five, pairs grouped with a reduction of zero point five” means that for 35 mm² conductors, the current-carrying capacity is 3.5 times the cross-sectional area, i.e., 35 × 3.5 = 122.5 A. For conductors 50 mm² and larger, the multiplier relationship between current-carrying capacity and cross-sectional area changes: every two wire sizes form a group, with the multiplier decreasing by 0.5 for each subsequent pair. Specifically, 50‑mm² and 70‑mm² conductors have a current-carrying capacity equal to 3 times their cross-sectional area; 95‑mm² and 120‑mm² conductors have a capacity equal to 2.5 times their cross-sectional area, and so on. “If conditions change, apply an adjustment factor; at high temperatures, reduce copper capacity by 10%.” The above mnemonic applies to aluminum‑core insulated wires installed openly under ambient conditions of 25°C. If such wires are installed openly in areas where the ambient temperature remains above 25°C over the long term, calculate the current-carrying capacity using the method described above, then further reduce it by 10%. When copper‑core insulated wires are used instead of aluminum, their current-carrying capacity is slightly higher than that of equivalent‑size aluminum wires; you can estimate it by increasing the wire size by one rating based on the aluminum‑wire calculation. For example, the current-carrying capacity of a 16 mm² copper wire can be calculated as if it were a 25 mm² aluminum wire.

If it is a copper-core wire:

1.5 square millimeters can handle a maximum current of 12–13.5 A.

2.5 square millimeters can handle a maximum current of 16–18 A.

A 4-square conductor can safely carry a maximum current of 32–36 A.

6 square meters can accommodate a maximum current of 48–54 A.

If it is an aluminum-core wire:

1.5 square millimeters can handle a maximum current of 6 A to 6.75 A.

2.5 square millimeters can handle a maximum of 8–9 A.

A 4-square conductor can safely carry a maximum of 16–18 A.

A 6-square‑meter area can safely handle a current of 24–27 A.

These values are not exact; the specific numbers depend on the temperature.

Permissible long-term current according to the national standard:

4 square is 25–32A.

6 square is 32-40A

At an operating temperature of 30°C, the current-carrying capacity under long-term continuous operation at 90% load is as follows:

1.5 square millimeters — 18A

2.5 square millimeters — 26A

4 square millimeters — 26A

6 square millimeters — 47A

10 square millimeters — 66A

16 square millimeters — 92A

25 square millimeters — 120A

35 square millimeters — 150A

Power P = Voltage U × Current I = 220 V × 18 A = 3960 W

Wire load current values specified in GB 4706.1-1992/1998 (partial)

Copper-core wire: .. Copper conductor cross-sectional area .. Permissible continuous current .. 2.5 square millimeters (16A–25A) ..

4 square millimeters (25A–32A) .. 6 square millimeters (32A–40A)

Aluminum-core wire: Aluminum conductor cross-sectional area… Permissible continuous current… 2.5 square millimeters (13 A to 20 A)

4 square millimeters (20A–25A) .. 6 square millimeters (25A–32A)

///Example illustration:////

1. Each computer consumes approximately 200–300 W of power (about 1–1.5 A); therefore, ten computers require a copper‑core wire with a cross-sectional area of 2.5 mm² for power supply; otherwise, a fire could occur.

2. A 3-horsepower air conditioner consumes approximately 3,000 W (about 14 A), so each unit requires its own dedicated 2.5‑mm² copper‑core power cable.

3. Nowadays, the service entrance wiring typically consists of 4‑mm² copper conductors; therefore, the total current drawn by simultaneously operating household appliances should not exceed 25 A (equivalent to 5,500 W). Replacing the internal wiring with 6‑mm² copper conductors is pointless, since the cable entering the meter remains 4‑mm².

4. In older homes (built 15 years ago), the service‑entrance wiring typically consisted of 2.5‑mm² aluminum conductors; therefore, the total current drawn by all appliances operating simultaneously should not exceed 13 A (equivalent to 2,800 W).

5. The household appliances with relatively high power consumption are: air conditioner 5A (1.2 HP), electric water heater 10A, microwave oven 4A, rice cooker 4A, dishwasher 8A, washing machine with drying function 10A, and electric water boiler 4A.

In fires caused by electrical power sources, 90% are attributable to overheating at connection points; therefore, all connections must be soldered. For contact components that cannot be soldered, use 5–10…

Must be replaced annually.

(For example, outlets, circuit breakers, etc.).

……… The long-term current allowed by the national standard.

4 square is 25–32A

6 square is 32–40A

。。。。。。。。。。。。。。

In fact, these are all theoretical safety values; the actual limit values are even higher.

The maximum allowable power for 2.5 mm² copper wire is 5,500 W; for 4 mm², it’s 8,000 W, and for 6 mm², 9,000 W—no issues there.

A 40A digital meter can easily handle 9,000 W without any issues. A mechanical meter rated at 12,000 W won’t burn out either. 00