Could a power outlet be ruining hair straighteners?
124V is on the high side of "normal" for a U.S. outlet. Most appliances should be able to handle that voltage, but some will not, at least not long-term. It's not so much voltage as amperage; the current flowing through a wire will create heat (the "toaster effect"). However, voltage determines amperage: I=V/R, so as V increases and R (resistance) stays constant through a circuit, I (current) will also increase.

There are voltage regulators you can buy for your entire house's wiring. These regulators are basically a smaller version of the big grey can transformer on the power pole outside (or the big green box down the street or in someone's back yard); they will "step down" the power from the incoming line just that little bit more to put it between 110 and 120V, which is the "butter zone" for U.S. electrical.

When shopping for your next hair-straightener, look for one that is rated for 125V, or at least 120V. Appliances are commonly rated for 110V, which is the low side of U.S service voltage and may not handle a "hotter" electrical region.