Wires are basic element for electricity transmission in buildings. Three types are most common - FR, FRLS and ZHFR or LSZH.
FR (Fire Retardant) wires are manufactured with a fire retardant PVC compound to offer extra safety and are widely used in homes. In offices, FRLS (Flame Retardant Low Smoke) wires are preferred and are safer alternative than FR. They cost typically 10% higher than FR wires. During short circuits/fire, FRLS compound restricts spread of blaze and smoke emission is less in comparison to the ordinary FR wires. Hence FRLS wires are recommended for commercial infrastructure as well as all public spaces. Next ZHFR (Zero Halogen Flame Retardant) or LSZH (Low Smoke Zero Halogen) wires have minimal smoke and are non-toxic. Recommended for Underground public spaces like Metro, etc.
At BestOfElectricals.com, top brands like Finolex, KEI, Havells, Polycab make FR, FRLS and ZHFR wires are available to buy online.