I would think that an attic mounted antenna is a very low FIRE hazard, since any arc-over is probably going to be contained within either an Indoor Balun...or if using an Outdoor Balun (with DC continuity between 300-ohm and 75-ohm windings) then it will arc over either within the Preamp (if used) or the coax itself. But I wouldn't rule out an arc over between the antenna and a nearby wood strut...or worse case, flammable blown-in insulation material (which unfortunately is probably not illegal).
All you need is a Gas Tube Discharge Coaxial Protection Device (which is usually screwed into a Coaxial Grounding Block for attachment of the Grounding Wire). It will discharge when the static electricity reaches the relatively low spec voltage, which is MUCH lower than the (unknown) breakdown voltage in the usual air gap Grounding Block. Run the Ground wire to a convenient power box or copper water pipe. Since it's INDOORS, the full NEC compliant install to protect against direct lightning hits isn't required.....cuz the house is going to take the full brunt of the blow anyway:
The discharge device needs to have DC continuity to the antenna elements, which means you need to use a Balun which has DC continuity between the 300-ohm input and 75-ohm output. Most INDOOR Baluns do NOT have this capability, so use OUTDOOR Baluns from C-M, Philips or RCA (there may be others) and MEASURE IT just to make sure.... For the same reason, the device needs to be placed between the Balun and a Preamp (if used). If NOT using a Preamp, it could be placed anywhere along the Coax, as long as DC continuity isn't blocked by a Cable-type RF Spllitter (SAT-type RF Splitters have DC PASS on one or both ports).Edited by holl_ands - 7/22/13 at 9:23pm