I'm in the midst of a giant electrical project in the van.

I want use use a GFCI outlet powered off the inverter I'm using.  The
inverter is the cheap/compact "modified sine wave" type.  I read somewhere
that many brands of GFCI outlets wouldn't work with these, but that Pass and
Seymour GFCI's would.  Sure enough, the P&S GFCI outlet I got works fine
running off the inverter, in the sense that it gives power and trips when
the trip button is pressed.

However, there is a slight buzzing sound coming from the outlet when it has
power.  The buzzing stops if you trip the outlet with the test button.  I'm
assuming that the choppy output wave of the inverter is causing the noise.
The P&S technical support guy I spoke to agreed, and seemed to think that
everything was ok so long as the outlet trips when the button is pressed.

I'm concerned about whether the buzzing is something to be worried about
otherwise.  It's faint enough that you don't really hear it unless you get
down on all fours right next to the outlet.  But is the vibration creating
an unsafe situation?

Any advice would be greatly appreciated.

-Wes

(I plan to describe the whole electrical project and post pictures when I
finish, hopefulyy by Sunday.)