A quick and usually reliable way to tell if a set is "hot" chassis: look at the tube numbers. If they all (or almost all) start with a 6 then it should be okay. (that means all the tube filaments are wired in parallel) In a hot chassis they are wired in series, like Christmas tree lights, and they will not all be the same voltage (don't ask me to explain why!) You can have tubes starting with all sorts of numbers and if they are jumbled up like that you can bet it's hot. The vast majority of 5 tube radios are hot chassis, known as the All-American Five. Most common used 3-12 volt tubes plus a single 35v and a single 50v. Probably what your RCA is. You just need a little extra respect when working on them while plugged in. (Touch the chassis while warming your feet on the baseboard heat, as I did at age 12, and suddenly YOU will be plugged in! This did not kill me
but it also did not encourage me to do it again!)
Oops! I stepped on you a little, Retro!