Electrical Design Guide
‑27‑
Table 3–1 Reduction coefficient of conductor current‑carrying density
Number of Cables in the Same Duct Current Reduction Coefficient
＜ 3 0.7
4 0.63
5–6 0.56
7–15 0.49
● Do not bundle power cables and signal cables together or route them through the
same duct. Power cables and signal cables must be separated by at least 30 cm to
prevent interference.
● Use a grounding cable with the same cross‑sectional area as the main circuit
cable. If the cross‑sectional area of the main circuit cable is less than 1.6 mm
2
, use
a grounding cable with a cross‑sectional area of 2.0 mm
2
.
To comply with the EMC standards, use shielded cables. Shielded cables are divided
into three‑conductor shielded cables and four‑conductor shielded cables, as shown in
"
Figure 3–6
"
on page 27
.
If the conductivity of the three‑conductor cable shield is insufficient, add an extra PE
cable. Or use a four‑core shielded cable, with one core being the PE wire. The shield
of the shielded cable is comprised of cooper braids to suppress radio frequency
interference. To enhance the shield performance and conductivity, the braided
density of the shield must be greater than 90%.
Figure 3‑6 Recommended power cables
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