I agree with Colin MCGeechan, it does help to have the green/yellow wire going to the chassis stud to comply with the "Approval agencies". I also think it is to do with the "Grade of Insulation" as specified in the standard, (page 125 third edition UL1950/CSA C22.2 950-95. without the green/yellow wire it would be difficult to have the secondary side to chassis ground/earth. This affects the electrical strength test voltage requirement.as well.
Maybe the green/yellow wire was there when the product you spoke about was approved and was removed after. Kevin Keegan International Approval Consultant K.E.S. & Associates Specialists in solving Product Integrity issues 1 Stonecroft Terrace Kanata, Ontario Canada Associate offices in U.K. & Australia Tel: 613 592-0820 Fax: 613 592-0820 Email: [email protected]
