Kev tawg pov thawj cov yeeb nkab fittings yog qhov tseem ceeb hauv qhov chaw muaj kev phom sij, ua hauj lwm kom muaj kev nyab xeeb ntawm cov hluav taws xob cables thiab cov xov hlau los ntawm cov chaw uas muaj kev tawg, tiv thaiv sparks thiab arcs los ua ignitions.