Truck died goin down road replaced battery light flashing same day tested alternator at 2 stores both say good fuse is good battery dead again???

Yes my husband is an electrician so all have been checked. Could this be the key switch lost gages then power replaced battery tested alternator ???

A defective ignition switch can cause problems like this, but it's usually pretty obvious, if you wiggle it and it quits, that's a good indicator.