Typically most fire marshal laws would require plenum cable.
"Plenum" is a fire code rating. It is sometimes identified by the designation "CMP" meaning a communications plenum rated cable. http://www.lockergnome.com/it/2005/04/01/what-is-plenum-cable/
at home under your bed
Recommended for HVAC
Type cmp, catvp cl3p, fplp P designates "plenum"
Cat6 is the current standard for new installations of ethernet cable. Depending on the space and certain building codes you need to decide between Plenum (CMP) or Riser (CMR). The difference being Riser cable is more durable, but puts out toxic fumes when caught on fire, so it is not suitable for spaces with open air flow. Dropped ceilings are generally considered Plenum spaces so therefore require plenum cable.
Plenum (OFNP - Optical Fiber Nonconductive Plenum) Source: www.extron.com/company/article.aspx?id=decipheringapp
Here in Louisville, KY General purpose runs for about 75$ a box and Plenum is $250.
Plenum
Plenum refers to a type of building and how its air is exchanged. When a bulding is on fire and the cable starts to burn it gives off toxic fumes and will kill you. Plenum cabling is coated differently for burning purposes.
Plenum rated cabling is required when used in an open ceiling return air environment. That is when the return air for the hvac units use the space between the ceiling of the first floor and the floor of the second floor as a return air plenum. The way to tell is if the return air vent has a duct attached to it. The duct will run to the air conditioning air handler. This condition IS NOT a plenum rated ceiling. However, if the return air vent does not have a duct, that means the air conditioning air handler is using the air space between floors as a plenum. This condition requires the use of plenum rated cabling. If plenum rated cable is exposed to flame, it does not give off toxic gases as it melts.
PVC/Riser grade versus Plenum grade Ethernet cableI found about half a 1000ft roll of Cat 5 Ethernet cable. As far as I understand, it's Space ShuttleCAT5e350MHz24AWG4 Twisted PairsSolid conductors