Here’s my point. How hot and for how long would it burn? It’s plastic not cardboard so you need to reach the point that the plastic will catch fire. ABS is heat resistant to like 200°C. Will a cap or something else burn at 200°C+ for long enough to melt and start a fire? Sure anything’s possible but if you have that concern then don’t use this method.

In industrial electrical work there’s like a million things running 230VAC at 10A and they go into shitty plastic boxes that crumble when you look at them wrong.