Fire
Fire safety is important with any electrical or electronic assembly.
Theory
There is a lot to say here. I will just include some things that stand out to me.
Generally, electronic devices should be in metal boxes. From the Amp Hours episode 357-an-interview-with-rick-altherr Your server hardware product is not truly shipped until it has caught fire at a datacenter. I.e. it is possible for computers and servers to start on fire. Appliances can also start on fire, such as refrigerators: https://en.wikipedia.org/wiki/Grenfell_Tower_fire#Refrigerator
It is possible to design for hazardous environments where you don't want any part of the circuit able to get hot enough to combust flammable powders or gas. e.g. See Amp Hour 635-low-power-connected-devices-with-andrea-longobardi.
Therefore, all design of electronic and electrical work must take fire into consideration. It is important to design devices for fire safety. It is also important to design placement and location of devices for fire safety.
Predict Where Fire Will Go
Fire moves very fast, and it is generally not possible for a human to intervene. Therefore, you must predict where a fire is likely to start, and where it will go, once it starts (before anything occurs). By doing this, you can eliminate or at least minimize domino effects.
Links
Burn Tests
Ethernet Cable
Tests coming soon.
Nylon Cable Glands
These were reasonably self extinguishing. They did not burn well.
Cable gland burn test.
PLA
Tests coming soon.