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SCI Family

Products with SCIs have been gradually introduced into most manufacturer’s addressable fire detection products over the last few years to cater for the legislative requirements of some specific markets and regions, and to give extra flexibility when designing and installing fire detection systems.


Hochiki’s ESP addressable range supports a whole family of SCI-enabled devices.



System with SCIs







On a healthy addressable fire system, the voltage from the fire control panel is driven one way around the loop, both powering devices and carrying data.  But if a fire loop cable isidentally damaged by tools or other equipment, particularly if not mechanically protected by conduit, and the result of that damage is that the positive and negative conductors within the cable come into contact with each other, that vital voltage level drops.  This is a short-circuit and at this point this entire loop is instantly out of action, which of course puts the whole building and its occupants at risk.


Short-circuit isolators recognise the voltage drop and when they activate, they divert the loop voltage back along one of the conductors, maintaining the flow of power and data for the rest of the loop. 


At the same time, because it is programmed to recognise when it’s no longer receiving a return loop drive voltage, the fire control panel will automatically switch to driving voltage from both ends of the loop, using both conductors.





SCIs and Standards


In BS 5839 it is recommended that an isolator is only required once in every zone – and that a zone can be anything up to 2000 square meters.  In other words, it’s acceptable to lose a whole zone due to a short-circuit on the loop.


Whereas in some regions, the local standards might prescribe that at every device type change on the loop, you need to install an SCI.  This is the case for Germany for example, as dictated in their BS 5839 equivalent, the “DIN VDE 0833-2”.





Features & Benefits


  • Using devices with integrated SCIs will help to maintain loop voltage in the event of a cable short

  • SCIs are normally integrated into addressable devices ranging from sensors, call points, modules and sounders

  • SCI-enabled devices feature an LED to visually show when a device is isolating.  This is usually amber in colour, to differentiate it from polling (green) or alarm condition (red).



Hochiki's SCI-Enabled Products

Our SCI-enabled products offer flexibility and added system security, for a range of applications and region-specific requirements.

Learn more


Optical Addressable Smoke Sensor with SCI

An optical Smoke Sensor with SCI, which is fully compatible with Hochiki’s ESP Analogue Addressable Protocol.  The ALN-EN(SCI) incorporates Hochiki’s newest High Performance Chamber Technology removing the need to use Ionisation Smoke Sensors in the majority of applications.


Addressable Heat Sensor with SCI

A Heat Sensor, which is fully compatible with Hochiki’s ESP Analogue Addressable Protocol.  The ATJ-EN(SCI) incorporates a Variable Temperature heat element and a Rate of Rise heat element, both of which are controlled from the Control Panel, allowing either thermal element or both elements simultaneously to be active in making the fire decision.


Addressable Multi-Sensor with SCI

a Multi-Sensor, which is fully compatible with Hochiki’s ESP Analogue Addressable Protocol, and incorporates a thermal element and High Performance photoelectric smoke chamber.  The ACC-EN(SCI) has three modes, which are controlled from the Control Panel, allowing either the optical element or thermal element or both elements to be active in making the fire decision.


Addressable Base Sounder with SCI

An addressable loop powered Base Sounder with SCI, innovatively designed to give a range of tones and volumes with a maximum output of up to 98 dB(A) (±2 dB(A)) with low current consumption.  The unit is designed to fit onto the ESP range of mounting bases.


Addressable Manual Call Point with SCI

An addressbale Manual Call Point with integral short-circuit isolator, which is fully compatible with Hochiki’s ESP analogue addressable protocol.  The unit incorporates a bicoloured LED, showing red for communications polling and continuously lit when the unit is activated.  The LED will show amber when a short-circuit is present but will switch to red if the unit is then activated.


Weatherproof Addressable Manual Call Point

A weatherproof (IP67) Manual Call Point with integral shortcircuit isolator, which is fully compatible with Hochiki’s ESP analogue addressable protocol. The unit incorporates a bi-coloured LED which operates in the same way as the HCP-E(SCI).


Addressable Dual Input Module with SCI

A Dual Input Module designed to interface to a variety of inputs such as door contacts, sprinkler flow/door switches and plant equipment.  Also available as a DIN Rail mountable version; both models feature an integral short-circuit isolator.


Addressable Dual Relay Controller with SCI

A Dual Relay Controller designed to provide two general-purpose relay outputs, each output can be driven separately for control of such devices as dampers or for control of plant and equipment shutdown. The monitored input can be used for local power supply fault monitoring or as a general purpose input.


Addressable Dual Sounder Controller with SCI

A Dual Sounder Controller, which has been designed to provide two sounder outputs (that can be driven separately) with full fault monitoring.  The monitored input can be used for local power supply fault monitoring or as a general-purpose input.


Addressable Dual Zone Monitor

A Dual Circuit Zone Controller designed to allow up to 60 conventional detectors (30 on each zone) to be interfaced to Hochiki’s ESP analogue addressable system.  The unit provides full monitoring against malfunction or disconnection, together with a self-test feature through the ESP protocol, ensuring integrity at all times.


Addressable Mains Relay Controller with SCI

A Single Input/Output Module, which provides a single, mains-rated relay output for the control of such devices as dampers, extractors or plant and equipment shutdown. The monitored input can be used for local power supply fault monitoring or as a general-purpose input.


Addressable Plant Control Module

A loop-powered input/output module with four independent change-over relay outputs and four monitored inputs. The outputs feature N/O and N/C volt free contacts and can be driven separately under the control of the fire alarm panel, to be used for the control of devices such as dampers or for plant and equipment shutdown.


SCI Sensor Mounting Base

An SCI Sensor Mounting Base, which is fully compatible with the above range of SCI sensors. Its fourth terminal enables the SCI functionality for the attached SCI sensor (does not provide short-circuit isolation on its own).  The base is also capable of driving a remote LED if required.

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