weak current line; low-voltage signal line
Technical term for wiring that carries low-power signals, such as intercom, telephone, or data lines, as opposed to power lines.
Weak current lines must be wired separately from power lines.
The intercom's weak current line may be broken.
Compound of 弱 (weak) + 電 (electricity) + 線 (line). The term is a straightforward technical coinage.