Can you use a mix of wired sounders and wireless Heat / Optical sounders?

Direct answer

Yes. EK-WL8-HS and EK-WL8-OS can be used alongside wired ESP sounders in the same system. An EK-WL8-TRH translator places the Ekho devices on the same Hochiki ESP loop as the wired devices, and each combined sensor/sounder takes two loop addresses. The constraint is acoustic rather than electrical: the wireless and wired sounders offer different tone sets, so the tones have to be chosen deliberately on both sides. BS 5839-1 recommends that all fire alarm sounders within a building have similar sound characteristics, unless particular conditions such as an area of high background noise make this impracticable, and that the fundamental frequencies produced by fire alarm sounders lie in the range 500 Hz to 1,000 Hz, although the same recommendation accepts frequencies outside that range where background noise would mask them.

Applies to

Products / Models: EK-WL8-HS, EK-WL8-OS, EK-WL8-SND, EK-WL8-OV (Ekho hybrid wireless devices); EK-WL8-TRH (Ekho translator); wired ESP sounders such as CHQ-WS2, CHQ-WBS2, YBO-BS and YBO-BSB2
Firmware / Version: All versions
Region: UK / Europe
Standards: BS 5839-1 (system design); BS EN 54-3 (sounders); BS EN 54-25 (radio links); BS EN 54-5 (EK-WL8-HS), BS EN 54-7 (EK-WL8-OS, EK-WL8-OV); BS EN 54-23 (EK-WL8-OV visual alarm device)

Choosing the tones

All the sounders concerned are approved to BS EN 54-3. That standard verifies the sound output at the frequencies and sound patterns declared by the manufacturer; it does not itself specify or approve a particular tone. Matching the sound across a mixed wired and wireless system is therefore a design decision, not something the approval settles for you.

The alarm sound is a system-level setting: the operating mode of all sounders in a fire condition is selected once, either on the EK-WL8-TRH or in the Ekho Configuration software. Setting it in the configuration software is preferable, so that the system configuration data stays under control. Because the setting is shared by every sounder on the system, there are two practical ways to keep the wired and wireless devices similar.

Option A — two-tone (dual tone) signal

Two Ekho devices can give a two-tone warning. The EK-WL8-OV, a smoke sensor with a built-in voice annunciator and visual alarm device, plays 925 Hz and 628 Hz alternating every 250 ms as its default message 1. That is the same signal as Tone 1 on the wired ESP sounders, and the EK-WL8-OV stays synchronised with the other devices on the system to within 50 ms. The EK-WL8-SND wireless wall sounder has a two-tone setting selected on the unit that is close to Tone 34 on the wired sounders, and its output level is adjustable, but that setting is not synchronised with the other sounders; where sounders are installed in proximity, take that into account in the design. The sounders built into EK-WL8-HS and EK-WL8-OS use much higher frequencies in their two-tone mode and no volume adjustment is described for either device in its installation manual, so they do not suit this option.

The EK-WL8-OV follows the message setting on the translator, which is separate from the alarm sound setting that drives the tone sounders, so its signal is selected independently of Option A or Option B.

ESP Sounder Tone 1 = EK-WL8-OV Default message 1

(Duty cycle: 925 Hz / 628 Hz, 0.25s each)

ESP Sounder Tone 34 ≈ EK-WL8-SND Dual tone

(Duty cycle: two tones alternating every 0.25s)

Option B — 1 kHz signal

Keep the tones built into EK-WL8-HS and EK-WL8-OS and set the system to the 1 kHz continuous or 1 kHz pulsed alarm sound, then set the wired ESP sounders to a comparable tone — for example Tone 25 or Tone 39 on a CHQ-WS2. This keeps every sounder on the system synchronised and within the fundamental frequency range that BS 5839-1 recommends. Check the sound pressure level before you rely on this option: on the 1 kHz settings the sounders built into EK-WL8-HS and EK-WL8-OS give a minimum of 77 dB(A) to 89 dB(A) at 1 m depending on the measurement angle, roughly 10 dB less than they give on their 3 500 Hz settings, and there is no volume adjustment on either device. Figures for every setting are in How do Ekho wireless sounder tones compare with wired ESP sounder tones? The samples below let you hear how close the result is.

ESP Sounder Tone 25 ≈ Ekho Pattern No. 8

(Duty cycle: continuous tone)

ESP Sounder Tone 39 ≈ Ekho Pattern No. 9

(Duty cycle: 1s On / 1s Off)

When to contact technical support

Contact Hochiki Europe technical support to confirm the tone and volume settings for a specific mix of wired and wireless sounders, if the sound pressure levels or the sound characteristics required by the design cannot be achieved on site, or if you have not completed Ekho training. Formal training is required to design, install and commission Ekho systems. For warranty terms and the returns procedure, see Warranty, Returns & Support.

References

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.

Last reviewed: 2026-10-07 — Reviewed by: Hochiki Europe Technical Support