The SZ1-K (AS+) and RZ1-K (AS+) cables are identical

During these last years the SZ1-K (AS+) and RZ1-K (AS+) cables have been manufactured in tandem although with different design criteria. Both exist on the market, the two being appropriate for and equating to the same uses.

The meaning of the concept High Security Cables (AS+) must always be regarded within the context of cables with exceptional performance, not only in resistance to the spread of fire but moreover in its guaranteed performance in extreme cases of fire.

The (AS+) cables complement the installations where a high level of flame-resistance is required. During a possible fire, they permit continued operation of the non-independent security services and the service circuits with centralised independent sources.

ITC-BT 28, subsection 4 f

If we refer to the texts of Spain’s Low Voltage Electro-technical Regulations, in ITCBT 28, which regulates the safety circuits of public gathering locations with regards to:

- Detection and alert
- Evacuation methods
- Protection and Fire-fighting systems
- and other installations where it is necessary to maintain the circuit’s integrity during a fire.

It shows that the appropriate cables for these uses should be in accordance with the fire testing described under the norm UNE-EN 50200 (842 ºC for 90 minutes).

The keys to completing this test entail not only the selection of good halogen-free flame-retardant materials but also in design aspects that, in each case, guarantee fulfilment of these requirements.

Differences between the cable types SZ1-K (AS+) and RZ1-k (AS+)

During these last years the SZ1-K (AS+) and RZ1-K (AS+) cables have been manufactured in tandem although with different design criteria. Both exist on the market, the two being appropriate for and equating to the same uses.

The key differentials in their designs are:

- SZ1-K (AS+): The insulation is made of special silicon that while burning maintains itself as a “solid insulating layer” around the conductor, maintaining the cable’s performance without short-circuiting.

- RZ1-K (AS+): The insulation is composed of a special mica tape on top of the conductor and a layer of reticulated polyethylene (XLPE) over the mica tape. Even if XLPE burns, the mica tape assumes the behaviour of an insulated layer due to its great dielectric resistance, in addition to its great resistance to flames over 950 ºC.

The (AS+) cables, both the SZ1-K (AS+) and the RZ1-K (AS+), are distinguished by the orange colour of the outer sheath so as to not confuse them with the RZ1-K (AS) types, with the green outer sheath.

At Top Cable S.A. the fire-resistant cable is called the Toxfree ZH (AS+), with a range of available sections for all needs, in the two cable types.