I would like to ask Earl a question. If you had one 12-2 romex cable loaded to 18 amps going thru drilled holes by itself, or 5 12-2 romex cables going thru the same set of drilled holes where the total load of the 5 cables combined was 18 amps, which situation do you consider more likely to become overheated? I am not trying to be funny with this, I just do not believe bundling of romex in at least residential situations is the problem. The actual problem starts when conductors get overloaded.
