Originally Posted by Max Wagner
Is it common to have a house pre wired with speaker wire that leads to lighting housings?
"Common" is a nebulous term.
From an audio perspective, I'll leave it to the audio experts to speak to the possible disadvantages of putting speaker and electrical wires in the same enclosure or raceway.
From an electrical code perspective the answer depends on the insulation rating of the speaker wire as compared to the lighting wires. According to NEC 300.3(C)(1), you can only have speaker cable in the same raceway or enclosure as a higher-voltage circuit if the insulation of the speaker cable is rated for the voltage of the higher-voltage circuit.
NEC 2008 300.3(C) Conductors of Different Systems
(C) Conductors of Different Systems.
(1) 1000 Volts, Nominal, or Less. Conductors of ac and DC circuits, rated 1000 volts, nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway.All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.
If the lighting is 120VAC lighting, and assuming you live in an area where the NEC is followed, then insulation of the speakers wires must be rated the same as the AC wires. If it's standard Romex, I believe that it will be 600 VAC.
However, if the ceiling fixtures are for LED's or other low voltage lighting, you might be OK, from a NEC perspective, having speaker wires in the same enclosure as the wiring for the lights.
Either way, unless the lighting fixture itself contains a speaker, the speaker wires are going to have to leave the enclosure and be run to wherever the speakers actually are.