Just when you thought it was safe to go in the water...

[bdosborn]

How many times do you think a DIYer has wired a 120V circuit to a 12V in an RV because the wire colors are the same?

Bruce

[twisted lines]

On that note I wonder how many people learned a (valuable) lesson about twisting 3 black wires together under the house

[MtnDon]

light2.JPG

The picture makes it look like there are three wires, but there are actually only two...both red!

I touched it to a 9volt and it lights up both ways + and -

There are devices that include circuitry that makes the DC connection work either way. I have some lithium-ion cell chargers that don't care which way you connect them. The circuit electronics sort it out for you. Great idea to make it dummy proof.