UL-Formulierung

Hallo Leute,

ich habe bei UL folgende Formulierung gefunden:

Polarity, as applied to contacts and terminals is a term which is used 
to describe the relationship between the load and line connections to a 
multicircuit switch.

When two or more sets of contacts are so connected in a circuit that a 
short circuit will not occur when all of the terminals of these contacts 
are made electrically common,  these contacts are said to be connected 
to the same polarity.

When a short circuit will occur, these contacts are said to be of 
opposite polarity.

Irgendwie verwirrt mich die Formulierung mit den Polaritäten (speziell 
bei uns geht es um Relais-Kontakte und das Schalten von Wechsel- oder 
Drehströmen). Und wozu ist das gut?

Ciao
ein ULGequälter