Fireproof wires and cables are usually divided into two types: fire-resistant wires and cables and flame-retardant wires and cables, which are the general term for wires and cables with fire resistance performance. The following describes how to distinguish between these two types of cables.

1、 Fire resistant wires and cables

According to the national experimental standard (GB 12666), fire-resistant cables can be divided into two levels: NHA and NHB; In general product naming, NHA is usually represented by GNH and belongs to the category of high fire-resistant cables. NHB is represented as NH in general refractory products.

Fire resistance refers to the ability to maintain a certain period of operation under flame burning conditions, that is, to maintain the integrity of the circuit. This type of cable has a certain power supply capacity in the flame for a certain period of time.

Fireproof cables are actually another type of fire-resistant cable. It is composed of copper as the conductor core, seamless copper tube as the sheath, and inorganic mineral magnesium oxide as the insulation material.

Due to the overall composition of inorganic materials, the entire fireproof cable is neither combustible nor flame retardant. And it can withstand fire. The test shows that after burning in a flame of 800-900 ℃ for 2 hours, the cable has been running normally with power on. After burning in a flame of 1000 ℃ for 30 minutes, it is still intact and continues to operate normally. The normal working temperature is generally 250 ℃, which can operate safely and reliably.

Fire-resistant cables can continue to operate (transmitting current and signals) in the event of a fire, and their inherent flame retardancy is not included in the assessment. Flame retardant cables quickly stop working in the event of a fire, and their function is to be flame retardant and self extinguishing without spreading. Maintain normal operation of fire-resistant cables for 180 minutes in flame combustion at 750~800 ℃.

2、 Flame retardant wires and cables

Flame retardant cables can be classified into three levels according to the national experimental standard (GB 12666): ZRA, ZRB, and ZRC. In general product naming, ZRA is usually represented by GZR and is referred to as high flame retardant cable or oxygen barrier cable or high flame retardant oxygen barrier cable. ZRC stands for ZR in general flame retardant products.
Flame retardancy refers to blocking and delaying the spread of flames along wires and cables, so that the fire does not expand. This type of cable has self extinguishing performance after catching fire.

The oxygen barrier flame retardant technology mainly involves filling a layer of inorganic metal hydrate between the cable insulation core and the cable outer sheath. It is a non-toxic, odorless, halogen-free white gel. Oxygen barrier flame-retardant cables can be applied to low, medium, and high voltage power cables, control cables, and communication cables without changing the cable structure and original material parameters, and can be flame-retardant Class A.

Halogen-free flame-retardant cables have the advantages of low toxicity, low smoke, and halogen-free compared to halogen-containing flame-retardant cables. The flame retardant level is not high and is basically Class C. The reason is that the oxygen swallowing fire extinguishing energy efficiency of halogen free radicals is greater than the degradation temperature energy efficiency of non halide flame retardants.

Flame retardant cables maintain the electrical and physicochemical properties of ordinary cables while also possessing self-extinguishing properties, which means they are not easy to burn. When the cable catches fire due to certain reasons or is ignited by an external source, the cable will no longer continue to burn after the fire is extinguished, or the combustion time is very short (within 60 minutes), or the flame extension length is very short.

Note: Currently, most of the implementation is based on the GA 306.1-2007 standard