It looks as though you use the de-rating curve
http://www.rtie.com/ntc/surggard.htm
So for 7 amp NTC running outside of short duration peaks say an average 1/3
of 7 amps of mains 240V for driven amp and less than rated mains fuse then
125 degrees would be the operational maximum of the thermistor.
Would be nice to know a rule of thumb formula for real life "black body"
radiator/convector temperature and power consumption whether disc
thermistors or rod
resistors