What does 'cross phase' mean for a 3-phase electrical supply?

Answer 1

The following is pretty colorful but in reality you will see nothing as the safety equipment stipulated by the electrical code trips the circuit open before any serious damage is done. On a circuit that has tripped on a ground or phase fault the first thing to be done is isolate the circuit using lock out procedure. The trouble shooting equipment used is a megger. Once the fault is located and repaired, the circuit is re fused or the breaker reset, power turned on and an amperage reading is taken. If all the equipment is within the manufactures specifications the circuit is signed of as operational. To quote Billy Mays "KABOOM!". For any two or more phases to make mechanical contact in a three phase electrical system creates the ultimate dead short. This results in an immediate explosion with an arc flash brighter than the surface of the sun and a complete meltdown of the conductors and equipment. Simply put, you don't want to cross phases or allow them to make contact in any single or three phase system. This is the worst thing any electrician can do.