The meaning and selection of NH fire-resistant cable models-Instrument Network

NH fire-resistant cableSelection precautions

Based on the specific characteristics of fire-resistant cables, designers should pay attention to the following issues when designing and selecting:

(1) When fire-resistant cables are used in cable tunnels with dense cables, cable interlayers, or in flammable places such as near oil pipes and oil depots, Class A fire-resistant cables should be selected first. In addition to the above situations and when the number of cable configurations is small, Class B fire-resistant cables can be used.

(2) Fire resistant cables are mostly used as power supply circuits for emergency power sources, requiring normal operation during a fire. Due to the rapid increase in ambient temperature during a fire, in order to ensure the transmission capacity of the power line and reduce voltage drop, for circuits with long power supply lines and strictly limited allowable voltage drop, the cross-section of fire-resistant cables should be enlarged by at least one level.

(3) Fire resistant cables cannot be used as high-temperature resistant cables.

(4) To reduce the probability of cable joint failure in fire accidents, the number of joints should be minimized as much as possible during installation to ensure the normal operation of the line in a fire. If branch wiring is required, fire protection measures should be taken for the joints.

1. Model composition

The models of flame-retardant and NH fire-resistant wires and cables consist of two parts: the product combustion characteristic code and the relevant wire and cable models, as shown in the figure

Fire resistant cable model

2. Combustion Characteristics Code Table

code name	name
Za	flame retardant
ZA	Flame retardant Class A
ZB	Flame retardant Class B
ZC	Flame retardant Class C
ZDb	Flame retardant Class D
omit	There is halogen
W	halogen-free
D	low smoke
U	low toxicity
N	fire-resistant
NJ	Fire resistant and impact resistant
NS	Fire resistant with water spray
	A Z is a single flame retardant and is only used for products with halogen-free substrates. If the substrate contains halogens, Z is omitted. B ZD is a bundle combustion type D, suitable for products with an outer diameter of no more than 12mm or finer.