Auxiliary services, such as cable, telephone, doorbell, furnace
	control circuits etc. are generally considered to be "class 2"
	wiring by both the CEC and NEC.

	What this generally means is:

		1) class 2 and house power should not share conduit or
		   termination boxes.
		2) class 2 and house power should be 12" apart in walls
		   except where necessary.
		3) cross-over should be at 90 degrees.
	
	While the above may not be strictly necessary to the code, it
	is advantageous anyways - paralleling house power beside telephone
	lines tends to induce hum into the telephone.  Or could interfere
	with fancier furnace control systems.

	With telephone wiring, twisted pair can alleviate these problems,
	and there are new cable types that combine multiple services into
	one sheath.  Consult your inspector if you really want to violate
	the above recommendations.