Specifying a Seismic Shutoff System — A Guide for Engineers and Architects
When a building project requires seismic gas isolation, the specifying engineer or architect is responsible for defining what the system must do, which standards it must meet, and how it integrates with the wider building services design. Getting the specification right at concept stage avoids substitution problems, consent delays, and commissioning issues later.
This guide covers the key decisions and documentation relevant to specifying the Solid State Seismic Shutoff — MK6 for New Zealand building projects.
Regulatory trigger points
The primary regulatory reference for gas installations in New Zealand is the Gas (Safety and Measurement) Regulations 2010 (updated 13 November 2025), supported by NZS 4219 (Seismic Performance of Engineering Systems in Buildings). The requirement for seismic gas isolation is most commonly triggered by:
- Building consent conditions for new commercial construction in seismic zones
- Compliance schedules for buildings with specified systems
- Insurer requirements for high-value or high-occupancy buildings
- Territorial authority requirements for public buildings, hospitals, and schools
Where seismic isolation is required, the specification should reference both the regulatory trigger and the applicable standard — not just the product.
What to specify
A complete specification for a seismic shutoff system should address:
Detection and response
Specify the minimum performance requirements: response time, sensitivity range, and relay output configuration. The MK6 fires its output relay within 10 milliseconds of the trigger threshold being exceeded and holds the relay for 8 seconds after the last exceedance — covering aftershock sequences without requiring manual intervention between shocks. Five sensitivity settings are available (0.012g to 0.200g), field-adjustable via DIL switch.
Power supply
Specify whether the installation requires the AC or DC variant:
- AC variant — 230 V, 50 Hz, with internal NiCad battery providing up to 24 hours backup on mains failure
- DC variant — for connection to an external no-break power supply. No internal battery. Suitable for sites requiring continuous operation independent of mains power.
Output configuration
The MK6 provides two independent relay outputs (OMRON LY2, rated 10A at 230 VAC / 3A at 24 V DC resistive). Specify which output connects to which downstream device — gas shutoff valve, BMS digital input, machine emergency stop — and confirm contact ratings against the load.
Mounting and location
The unit must be mounted on a large mass of concrete in intimate contact with the earth — typically in the building foundations. The installation location should be identified on services drawings at consent stage, not left to the installing contractor. A poorly located unit — on a lightweight partition or isolated from the building structure — will not detect seismic acceleration reliably.
Documentation the MK6 provides
For consent and compliance purposes, the following documentation is available:
- Product specification sheet (dimensions, power, relay ratings, sensitivity settings)
- User manual covering installation, commissioning, wiring diagrams, and maintenance schedule
- Event counter — provides a tamper-evident record of all activations, including test triggers
The event counter is particularly relevant for compliance schedules: it provides an auditable log of activations without requiring additional data logging hardware.
Coordination with other disciplines
Seismic shutoff systems sit at the intersection of mechanical (gas), electrical (power supply and wiring), and structural (mounting location) disciplines. Early coordination avoids the common problem of the unit being installed in an accessible but structurally inappropriate location. The mounting point should be identified by the structural or civil engineer, not selected on site.
For projects integrating the MK6 into a BMS or PLC, the relay output wiring should be included in the electrical services drawings. The unit requires only a standard digital input — confirm input voltage and contact type with the BMS supplier at design stage.
Getting specifications support
We can provide product documentation, wiring schematics, and specification language for inclusion in project documents. If your project has specific integration requirements — unusual power supply, multiple outputs, remote monitoring — contact us at enquiry stage.
Solid State Seismic Shutoff — MK6 — full specifications →