A flameproof enclosure’s effectiveness stems from its ability to contain flames within, walaupun apabila letupan berlaku di dalam selongsong peralatan elektrik. Penahanan ini dipastikan dengan menghalang nyalaan daripada keluar melalui pelbagai permukaan sendi.
Pematuhan kepada piawaian khusus mengenai jurang, panjang, and surface roughness of these joints is crucial. These gaps not only extinguish the flames but also cool them effectively. They reduce the temperature of the flames passing through to a level insufficient for igniting any bahan letupan mixtures that may be present outside the enclosure.