Hi Crutschow, Hero999..
Like Hero999 said, a Volt Free Contact, is just a pair of contacts supplied, for example, a building's Alarm/ Fire Alarm or Swipecard authorisation. They're used a lot on revolving doors, automatic doors etc. There is no voltage at the contacts, you supply your own.
I want to use it to pull a PortB pin low (Pullups on) on a PIC18F4550. I was just concerned, about stray interference etc. Worst case, the cable would be approx 20 metres long. I have done this before with PLC's, but never with a PIC.
Regards
John