Applies to
- Products / Models: CHQ-DIM2(SCI), CHQ-SZM2(SCI), CHQ-DZM(SCI), CHQ-DSC2(SCI), CHQ-DRC2(SCI), CHQ-PCM(SCI), CHQ-MRC2/MRC2-FS(SCI), CHQ-SIM, (including /DIN and /M variants, and the earlier CHQ-DIM, CHQ-SZM and CHQ-DSC modules); APS-CZ4; EK-WL8-OUT. EOL parts: 10 kΩ, 6K8, LCMU (1270070-00) with 47 µF capacitor, TE-RH-E (16702730-00), 1 kΩ 2 W (CHQ-DSC2(SCI) sounder EOL)
- Firmware / Version: Not applicable
- Region: Not applicable
- Standards: BS EN 54-17 (short-circuit isolators), BS EN 54-18 (input/output devices); intrinsically safe variants additionally covered by BASEEFA certification
Direct answer
Fit the end-of-line (EOL) component that the specification sheet gives for that particular input: 10 kΩ (10k ohm) ±5% on a CHQ monitored input, and 6K8 (6.8 kΩ / 6k8 ohm) ±5%, the LCMU active EOL with its 47 µF capacitor or the TE-RH-E Zener EOL on a CHQ-DZM(SCI) conventional detection zone (a CHQ-SZM2(SCI) zone takes the TE-RH-E only). Install it at the far end of the monitored cable, so that an open circuit changes the measured resistance and is reported as a fault. Values differ by product, so confirm the value against the exact ordering code before fitting.
Requirements and purpose of EOL resistors
- An EOL resistor enables the input to detect open-circuit faults on the cable. If the cable is cut or disconnected, the input or zone detects the resulting change in resistance and reports a fault.
- Fitting the EOL is not on its own enough on every module. On the CHQ-DIM2(SCI) the resistive input monitoring only works when the module runs in enhanced mode and the fire alarm control panel supports that mode; on a panel that does not, the module falls back to compatibility mode and the inputs are not monitored at all. Confirm panel support before relying on an EOL to detect open circuits.
- The value depends on what is being monitored, not on the module family. On Hochiki CHQ modules the monitored input EOL is 10 kΩ (10k ohm) ±5%. Conventional detection zones differ by module. A CHQ-DZM(SCI) zone offers three EOL options: a 6K8 (6.8 kΩ / 6k8 ohm) ±5% resistive EOL, an active EOL (the LCMU, part 1270070-00, fitted with the 47 µF ±20% 35 V capacitor) or the TE-RH-E Zener EOL device. A CHQ-SZM2(SCI) zone uses the TE-RH-E Zener EOL only, and neither the 6K8 resistor nor the LCMU is an option on it. An APS-CZ4 conventional zone board uses 6K8 on its detection inputs and 10K on its sounder outputs. Sounder circuits on addressable modules are different again: a CHQ-DSC2(SCI) sounder output takes a 1 kΩ ±5% 2 W EOL while its monitored input takes the usual 10 kΩ ±5%. An Ekho EK-WL8-OUT output needs a 5.6 kΩ (5k6 ohm) EOL. Always take the value from the specification sheet for the exact ordering code.
- The EOL and operational resistors are supplied with the module — do not discard them. On intrinsically safe variants such as CHQ-DZM(SCI)-IS the supplied EOL resistors form part of the BASEEFA certification, so a substitute of the same nominal value is not automatically acceptable; verify that any replacement meets the certification requirements for the installation.
Typical configurations and placement
- Install the EOL resistor at the end of the monitored circuit (i.e., at the end of the cable, typically where it is connected to a relay/contact or for zone monitoring at the last device).
- If a monitored input is unused, the preferred method is to fit the EOL component across the terminals so the input reads healthy. Some modules can also disable input monitoring in hardware, but the switch is not the same on every module. On the CHQ-DRC2(SCI), CHQ-DSC2(SCI) and CHQ-MRC2(SCI) it is switch 8 of the 8-way DIL switch: monitoring is disabled with the switch UP on a Smart-Fix module and DOWN on a DIN module, because the two housings use opposite switch orientations. On the CHQ-PCM(SCI), switch 8 is not used at all and must be left OFF; monitoring is switched for two inputs at a time on a separate two-way DIL switch, and even with monitoring off the input still needs about 470 Ω across it to activate. Do not apply this to other products: on Hochiki addressable manual call points (MCP-DPS, SCP-DPS, SCP-W) DIL switch 8 selects polling mode, not monitoring. Check the installation instructions for the exact ordering code before moving any switch.
Common wiring pattern for a monitored input when connected to a relay contact
The diagram below shows the recommended wiring layout for a monitored input connected to a relay contact, with the EOL resistor placed at the far end of the cable loop.
For whether a module needs an auxiliary 24 V DC supply, and for the line continuity options on a conventional zone, see Loop Power vs External PSU: Powering and Wiring Notes.
When to contact technical support
- The input still reports a fault after the EOL resistor is correctly fitted and checked.
- You are not sure which EOL value or resistor part number applies to a specific module or conventional zone board.
- The installation is intrinsically safe (e.g. CHQ-DZM(SCI)-IS) and you cannot confirm that the fitted EOL resistor meets the BASEEFA certification requirements.
Safety note
This article is general guidance for Hochiki Europe products. Design, installation, commissioning, maintenance and modification of fire detection and alarm systems should be carried out by, or under the responsibility of, a competent person in accordance with the applicable standards (for example BS 5839-1 in the UK). Statutory requirements imposed by the relevant enforcing authority also apply. Always refer to the current product manual and data sheet for the exact model before carrying out any work.
References
- CHQ Modules (Inputs) Installation Instructions, 2-3-0-778
- CHQ-DZM(SCI) Instructions, 2-3-0-1731
- CHQ-DZM(SCI)-IS Instructions, 2-3-0-1366
- CHQ-DRC2(SCI) Installation Instructions, 2-3-0-2802
- APS-CZ4 Conventional Zone Detection Board Operation Manual
- EK-WL8-OUT Specification
Last reviewed: 2026-10-06 — Reviewed by: Hochiki Europe Technical Support