I have more complicated questions... But first I believe we need to agree on some facts, which I am honestly hazy on.
First > Depending on your scale > Which amperage is needed and optimized?
Nearly guessing here...
3 amps for N Scale
5 amps for HO Scale
10 Amps for G....
? Or is this even applicable today.
Here is the other shoe to drop.... If I have a large layout of over 400 square feet of track stretched around a 21 x 60 foot rectangle. Would it be best to start off at 10 amps and hope the power gets all the way around or use small 3-5 amp boosters for a N Scale layout expecting to run upwards of 12 trains at a time.
Thank you for listening,
As for fire... I have personally witnessed 12 volt wiring on a 10 amp circuit basically burst into flame as it shorted near a gasoline line. Prior to 1973, it was not unusual to find Manufacturers running 12 volt wiring through the same chase as a gasoline line. A major difference between the 1972 vs the 1973 BMW 2002. Once, I learned this fact many years ago, I tended to be careful in choosing any car made prior to 1973, I wouldn't own a pre-1973 BMW and rewired a 1963 Panel Truck to the wiring diagram of a 1973 BMW 2002. There was also a practice in use of the old days of varying wiring gauge, even in 110 volt circuits. Again a practice I tried to avoid and will replace a circuit with one type of gauge with fewer splices or connections. This maybe a factor more on a 10 amp circuit than a 3 amp circuit.
I also tend to separate wiring to type and other use. Such communication wiring being separated from power lighting. We have an additional consideration with DCC wiring.
The Construction methods of the day in the 1906 SF Earthquake place natural gas lines in the same pockets at the new to the day electrical wiring. It was fires and explosions which were the most fatal for San Francisco. Sort of like saying it was not the Hurricane but the flood which harmed New Orleans during Katrina then followed by lawlessness.
Meaning > There is a fire extinguisher near my layout and I am working on a fail-proof method of turning off all power to my layout - As I leave the room.