More and more questions come up about when field wiring should be replaced in a brownfield migration/modernization project. Everyone wants to minimize their installation costs, but it is becoming more of a necessity to take a close look at our field wiring/installation vs. assuming it is just ok. Here are a few things to be on the lookout for that may indicate field wiring should be replaced. Make sure to inspect and note condition and number of splices. Check wiring insulation for exposure to excessive heat, sunlight, chemicals, etc. Is the insulation brittle? What is the age of conductors? The total impedance of each critical loop should be verified, as new system specifications for hardware I/O may be different than the legacy system. These are just a few things to be on the lookout for, but would like to know what others have come across in this area.