sunhux,
Other than CO2, the options are Halotron I and FE-36. Halon has already been banned due to risk of damage to the ozone layer.
CO2 is an excellent agent for most electrical fires, but is not sufficient for Class A fires, because they tend to smolder and re-ignite when the gas dissipates (which it does quickly). It is a "clean" agent, typically causing no additional chemical damage. Large volumes are needed for effective use on a mixed-material fire, and you must watch for smoldering materials or other re-ignition sources.
Halotron I extinguishers, is also a clean agent which discharges as a liquid, has high visibility during discharge, does not cause thermal (unlike the cold generated by the rapid release of CO2) or static shock, leaves no residue and is non-conducting. It IS quite expensive compared to CO2.
FE-36 is another clean agent developed to replace Halon. It is is less toxic than both Halon 1211 and Halotron I and has no ozone-depleting potential (Halotron I is supposed to be phased out in 2015). It is also expensive.
Cheers,
LHerrou
