Minimizing fire risk with 3D Printers

So I always thought there was a risk of fire, You have a very hot head with a fragile sensor and in many cases, bad connectors with the wrong gauge. (My printer had a very bad connector that I had to replace)

Anyway with risks of burning filament, connectors and thermal runaway. (A serious risk if the sensor fails) 

While from my understanding, No one has died yet, Houses have burned down and pets have been lost. Failures are uncommon but potentially inevitable with all printers.

www.youtube.com/watch?v=xIA2yzb16Gk&feature=youtu.be

What is everyone's ideas on reducing the risk and if failure did occur, Automatically stop the printer and maybe stop any fire that occurs? 

I personally have prints lasting over 12 hours. Have one thats been running for 5 hours and another 13 left and well, I would personally like to know im safe having prints going on through the night. Im sure many others would like to feels safe too. Not to mention the number of people who dont even know of the risks.

Maybe keep plenty of smoke detectors near by? Or a camera system to keep an eye on them? Also constant and consistent maintenance never hurt anything. 

Hmmmm..... 

 How hard would it be to rig up an independent, temp controlled power cutoff?  

 that way, should temps get too far ( say for example 10-15 degrees ) over your normal printing temps, then ( depending how you set it up ) either power is cut to the heaters or power is cut to the entire printer... 

 

  Just a thought... 

 

The main issue is if the sensor dies or is dislodged from the head, Its not giving correct readings and there is a good chance, it will keep heating until it melts.

A large glass box containing/surrounding the printer will eventually stop any fire that is started due to suffocation of the flame. It obviously wont prevent the printer from being totally destroyed, but it will definitely stop your house from being totally destroyed.

Make a fuse, it's their job to prevent overloaded cables thus fires in apartments, so why not in a printer? A simple thread that melts when X temperature is surpassed in the head, cutting the power to the printer. No software bugs, purely physical and simple.

On commercial printers, a thermal fuse is placed directly on the hotend hot block, and the hotend is wired serially through that.

Instead of a questionable homemade thermal fuse, why not do it like the commercial printers, and attach a proper rated and certified thermal fuse directly to the heater block :)

Like this one: http://www.ebay.com/itm/1pc-KSD301-NO-300-C-10A-250V-Thermostat-Temperature-Switch-Bimetal-Disc-N-C-/310844802358?pt=LH_DefaultDomain_0&hash=item485fcb4536

Sadly thermal cutoffs aren't really available in ratings over 240°C, and a bimetal switch as above, will cool down and close the circuit again. It will add a significant layer of safety though, and could be wired to a latching relay carrying the printer current.

Hey i've seen one of these inside a waffle iron, it was used to turn the heater on and off. But really, this is any different than adding a second or third thermistor somewhere?