Fire !

[empip]

http://www.interfire.org/features/electric_wiring_faults.asp

How do electrical wiring faults lead to structure ignitions? Presented in 2001.
"...This paper reviews the known, published information on this topic and then points out areas where further research is needed. The focus is solely on single-phase, 120/240 V distribution systems. It is concluded that systematic research has been inordinately scarce on this topic, and that much of the research that does exist is only available in Japanese..." Blimey, so we don't know too much then...

Click to read Selected parts of Fire investigation - John Twibell (£75.99'ish - phew !) Results / pics of some experimentation are interesting... For some people anyway.

 

[ban-all-sheds]

I've often seen it stated that when the Fire Service can't find the cause of a fire they just put "electrical" down.

 

[flameport]

A lot of 'electrical' fires are actually caused by appliances or people misusing them (nails instead of fuses, taped up extension leads, towels drying over the cooker etc.)

As for the report - mostly relates to USA items. The country where the power distribution system is designed so that when an overhead supply wire falls to the ground, it appears the same as a normal load to the protective devices.
This is why most of those videos on YouTube showing wires arcing away on the ground are from the USA.