110 LED light Danger

[GregOConnor]

I added a bank of 4 duplex receptacles to the top of my lxi. with three switches down in the bus. We run 10units of 800 watt powered speakers for events and use lights to illuminate sail flags when parked at other venues for my RV club. One of the switches and one dedicated plug is for the American flag light that we always fly when camped.
I tapped into the wires that run curbside behind the center cabinet. After install I checked the electrical outlets and used a homedepot shop light LED portable fixture. All was well but when I checked other receptacles,, no good. I then clicked the radio button switch on the shop light an the light came on. I went back to the last good receptacle and no light. It seems that the origional receptacle ( which I never touched) has reversed polarity and the shop light on off switch simply changes polarity and does not cut power. WTF I can only guess that they do this so users dont return lights that dont work on reversed polarity receptacles and switched extension cords. I plan to get my meter and check all the receptacles again. I am first surprised that ac power would make a difference I understand the principle with dc I guess they have some sort of ac to dc converter in the fixture?