Does it matter if mains cables run close to signal cables?
Mains cables carry relatively high alternating currents that can be induced into audio cables running alongside them, even if the audio cable is well screened. The longer the distance the cables run alongside each other, the greater the amount of interference (usually hum) that will be induced into the signal cable. When audio and mains cables must cross, try to arrange the crossing to be at right angles, as this is the angle of minimum coupling.
