Quoting chrysler1978@xxxxxxxxxxx: > Simply said, current flow causes heat, end of story. > > Brad Hogg <----also a qualified electronics engineer. > Winnipeg, Manitoba Often, the story can be more complex that it appears. What DB is saying (and it makes sense to me) is that a localized increase in resistance can be small enough to not reduce the current by much (you need to remember, the current depends on the TOTAL resistance of the WHOLE circuit, if the total resistance is significant, a small local increase in the resistance will leave the current flow largely unaffected). Then, if you focus on that small portion of the circuit with increased resistance, it sees virtualy the same current as before, and more heat generated due to higher R. If the wire is insulated, this heat may have nowhere to go, so it will keep on heating it up. Let's push it a bit further. This heat could increase R further, making things worse, till the insulation goes, and the short occurs, and there is your increase in current! Those simple discussions can be helpful to understand simple things like that, which can help us diagnose problems. And the more "wrong" we happen to be, the more we can benefit from them... D^2