Correct me if I'm wrong but last time I checked the yellow and green wire is the earth. Well it is with regards electrical wiring. Just have a look inside the power points and light switches in your house (provided it's not to old). (or best yet look on the web).
There's definitely two earths which makes me think you are just shorting the system.
Appears as the Virgin Islands originally put this article together so I have also asked them for a explanation.
Regards
Andrew

