I investigate numerous fires involving Transportation. Currently, I am in the middle of an investigation where a manufacturer is utilizing an electrical plastic type junction box as a junction box for electrical connections. There has been electrical occurences within the boxes causing excessive heat, arcing, etc. The bottom line? The boxes have melted, protective wiring insulation has ignited, and fire has spread from the boxes. Had a metal type junction box been utilized, the electrical occurences possibly could have remained within the box, but then there is still the issue of the protective wiring insulation igniting outside of the box.