Andrew,
Ottawa has an on call system where 2 investigators/ fpos are scheduled each week (from a pool of 8). Each investigator get 12 hours straight time for carrying the pager, plus time and a half once they are called. System has some kinks but seems to work… Some of our city employees get up to 20 hours a week for being on call/ carrying a pager… You may want to check to see if your city has electricians or other trades on call..