Judged on measured fire performance, HFFR (halogen-free flame retardant) is the highest common domestic grade. It resists flame, produces little smoke, and releases essentially no halogen gas when burning.
That matters because most fire deaths are caused by smoke and toxic gas rather than flame. Ordinary PVC insulation releases hydrogen chloride when it burns — poisonous to breathe and corrosive to equipment.
Genuine HFFR wire is certified under IS 17048:2018, where BIS certification is mandatory. Ask for the halogen figure: 0.5% or below indicates genuinely halogen-free, while "low halogen" means reduced but still present.
APAR's halogen-free grade, Anushakti Fire Protekt EBXL HFFR, publishes an oxygen index of ≥ 31%, smoke density ≤ 10% and acid gas ≤ 0.5%.