3 WAY SWITCHES EXPLAINED IN SIMPLE TERMS, HOW AND WHY THEY WORK, WHAT ARE THE 4 DIFFERENT WIRES USED IN 3 WAY SWITCHES, WHAT ARE THE BLACK SCREWS FOR AND WHAT ARE THE GOLD SCREWS FOR, SIMPLE DIAGNOSTIC PROCEDURE TO DIAGNOSE INCORRECT WIRING IN 3 WAY SWITCHES, MULTIWIRE BRANCH CIRCUITS, WHAT ARE THEY AND ARE THEY LEGAL- QUESTION EXPLAINED FROM LAST VIDEO WITH NEC CODE REFERENCES