Originally Posted by
pdisme
That is definitely too much and you were simply overloading the outlet.
The nice thing about Delta outlets is that they will self-reset if you unplug and plug back in. I have a Dell laptop with a 90 watt external power supply. If I have the laptop configured for 'high performance', as soon as I plug in, the outlet turns off. If I do the trick a previous poster mentioned and remove the battery so as not to activate the charging circuitry in addition to the laptop's own needs, the outlet stays on. If I first put the laptop in power save mode, then plug the power brick into it, it does not reset the outlet. So I believe the threshold the seat outlets will support is in the 70 to 80 watt range.
This ^^. Outlets on all the 764's and 330's auto-reset. I can't say about other planes. Anyway, 120 watts is too much. Maybe on one of the brand new 739's (when they come out).
Sometimes the planes have outlets in the galleys which are more well serviced and have higher amp ratings. You could also try the outlets in the bathroom if you are really in a pinch, but I think they are even more tightly clamped (30w?)