Brendan,
I'm beginning to realize that the AFCI (at least from what I gather from the above tech) is intended to operate on a narrower set of fault conditions than I had assumed earlier.
Don(resqcapt19) describes the "glowing connection". I've seen far too many heat destroyed connections. Connections whose conductive metal to conductive metal resistance is not as low as it should be. When current flows through the connection, current supplying a legitimate down-stream load, the watts of heat released in the connection will be the current squared times the resistance. This heat moves out into the surrounding metal and insulations at a rate determined by their physical properties. The parts "fill up" with heat with gradual temperature rise because much of the heat is able to move on into air and other surrounding materials. But, at a point, the parts are "full", and if more heat is being created in the resistance of the connection than can be sloughed off into the surround, the temperature of the connection starts shooting up extremely fast. Physics calls this point the Black Body Radiation Limit. Our real world connection gets to this limit quicker than the theoretical. The connection "glows" at circuit normal load current levels. High temps are attained that result in destruction of the connection that creates the heat that generates the high temps. Circular, huh? At some point the connection may so degrade as to result in contact with either ground or the other side of the circuit, and there is a parallel fault or a ground fault that the AFCI can "see". Up to this point, the AFCI is blind to what's happening. Am I right? This is in a dwelling bedroom with 15 or 20 amp overcurrent branch circuit protection, a load that might be a space heater, and the AFCI starts "looking" above 50 amps, so the connection that is glowing, where ever it is, cord and plug contacts, wire nuts, terminal screws, hot or neutral, remains invisible while heat is released.
Do actuarials exist for this scenario?
