Pre-Action & Deluge Systems
WSD delivers the electrical side of pre-action and deluge fire suppression systems for data centres, electrical switch rooms, archives, museums and other environments where accidental water discharge would cause more damage than the fire it was preventing. Detection design, control panels, cause-and-effect programming, suppression release integration and ongoing maintenance, working alongside the sprinkler contractor handling the mechanical pipework.
If you’re an M&E consultant, main contractor, sprinkler company or FM provider looking for a specialist electrical contractor to handle the detection and control side of a pre-action or deluge project, this page is for you.
What pre-action and deluge systems do
Both pre-action and deluge are sprinkler systems designed for environments where standard wet-pipe sprinklers carry too much risk of accidental discharge.
- Pre-action systems – the sprinkler pipework is dry under normal conditions. Water only enters the pipework when a separate detection system (typically fire alarm or aspirating smoke detection) registers a fire condition. A second event (heat-triggered sprinkler head activation, in a double-interlock configuration) then releases the water through the activated sprinkler. The result: a sprinkler system that won’t dump water on a server hall because a pipe joint failed
- Deluge systems – all sprinkler heads in the protected zone are open, and water is held back by a deluge valve. When detection identifies a fire, the deluge valve opens and all sprinklers in the zone discharge simultaneously. Used in high-hazard environments where rapid, total water coverage is the right response
Both system types depend completely on the detection and control side being designed, installed and integrated correctly. That’s where WSD comes in.
What WSD delivers on a pre-action or deluge project
We deliver the complete electrical scope:
- Detection design and installation – selecting and installing the right detection technology for the environment (addressable fire alarm, point smoke, beam smoke, aspirating smoke detection (VESDA), heat detectors, linear heat detection cable, flame detectors where appropriate)
- Control panels – selection, installation, programming, integration with the deluge valve or pre-action panel
- Cause-and-effect programming – matrix design and configuration so the right detection event triggers the right suppression response with the right interlocks
- Suppression release integration – electrical interface with the deluge valve, pre-action solenoid or gas suppression release
- Interlocks – door interlocks, audible and visual warning, plant shutdown, HVAC isolation, BMS reporting
- Commissioning – end-to-end functional testing across the detection, control and release matrix
- Maintenance – planned servicing of the electrical and detection side alongside the wider fire safety maintenance contract
The sprinkler company handles the mechanical pipework, valves and sprinkler heads. We handle the electrical, detection and control. The two scopes meet at the deluge valve or pre-action panel interface, which we co-ordinate jointly during commissioning.
Recent installs & upgrades.
A small selection of jobs we have delivered or maintain in this area.
Sherborne MRF Sprinkler Upgrade
Replacement of zone-check systems and upgraded pump controls across a 12,000 m² material recovery facility, completed in two phased weekend shutdowns.
Aldgate
Self-test emergency lighting retrofit across six floors, including monthly compliance reporting.
Central House
Networked addressable fire alarm system across 400+ devices, with graphics-panel monitoring and an ongoing maintenance contract.
Got questions? We've answered the common ones.
Quick answers on cover, callout times, accreditations and what working with us actually looks like. Still got a question? Get in touch.
What size of project do you take on?
Anything from a single-panel fire alarm install in a small commercial unit through to a multi-floor refit across a live multi-tenant building. Most of our work runs from focused fire alarm and emergency lighting packages up to six-figure suppression and pump room schemes for main contractors and M&E consultants.
Are you accredited?
Yes. WSD holds BAFE (SP203-1), NICEIC Approved Contractor and SafeContractor accreditations, and we are members of the FIA and BSI. Insurance: £5m public liability, £10m employers’ liability, £1m professional indemnity, £5m product liability. Certificates available on request.
What’s the difference between pre-action and deluge sprinkler systems?
Pre-action systems hold the sprinkler pipework dry and only admit water when a separate detection system identifies a fire. Sprinkler heads then activate normally when heat reaches them, in a double-interlock pre-action configuration. Deluge systems have open sprinkler heads throughout the zone, with water held back by a deluge valve. When detection identifies a fire, the deluge valve opens and all sprinklers in the zone discharge simultaneously.
Do you install the actual sprinkler pipework?
No. The mechanical sprinkler pipework, valves and sprinkler heads are typically installed by a specialist sprinkler company. WSD handles the electrical, detection and control side. The two scopes meet at the deluge valve or pre-action panel interface, which we co-ordinate during commissioning.
Which manufacturers do you work on for pre-action and deluge?
Tyco, Viking, Reliable, Victaulic, and other LPCB and FM approved equipment.
Can you pair pre-action with VESDA?
Yes. VESDA aspirating smoke detection is one of the most common detection methods paired with pre-action sprinkler systems in data centres and similar high-value environments, often in a double-interlock configuration.
Do you cover the whole UK?
Yes, we deliver maintenance contracts and projects nationally from our Bromsgrove HQ. Most of mainland Britain is within a routine response window for reactive maintenance work.
Sites further from the Midlands may have slightly longer response windows for reactive call-outs; we can provide a map of typical response times by area during the initial survey if it’s relevant to your site.
Detail that often comes up.
Standards, integration, manufacturers and the questions we get asked most. Skim or dive in.
- Detection pairing
- Manufacturers
- Applications
- Who we work with
- Standards
Detection pairing
Detection selection depends on the protected environment, the speed of response required, and the level of asset protection the system has to deliver. The detection method is selected based on the level of asset protection required, the environmental conditions and the specific fire risks present within the building.
Addressable fire alarm systems
The standard for most pre-action installations
Point smoke detectors
For general detection in conventional environments
Beam smoke detectors
For large open volumes where point coverage would be excessive
Aspirating Smoke Detection (VESDA)
For very-early-warning in data centres, archives and similar high-value environments
Heat detectors
For environments where smoke detection isn’t reliable
Linear heat detection cable
For cable trays, conveyors, tunnels and other linear applications
Flame detectors
Where rapid flame detection is critical (typically industrial process environments)
Gas suppression release and control systems
For integrated multi-layer protection
Cause-and-effect fire alarm programming
Linking detection events to the appropriate suppression and shutdown actions
Talk to our team
We will walk through your project, scope the work, and quote against what you need.
Manufacturers
Our work is installation, integration and maintenance of the electrical components for systems built around equipment from leading manufacturers. All electrical systems are installed and maintained in accordance with the relevant British Standards, insurer requirements and project specifications.
Tyco
Including Tyco Fire Protection Products deluge and pre-action equipment
Viking
Including Viking SupplyNet and Viking Cellular Series equipment
Reliable
Reliable Automatic Sprinkler Company deluge and pre-action equipment
Victaulic
Including Victaulic FireLock deluge and pre-action systems
Other LPCB and FM approved equipment
Talk to our team
We will walk through your project, scope the work, and quote against what you need.
Applications
These systems are typically specified in environments where accidental water discharge could cause significant damage or where enhanced fire protection is required:
Data centres and server rooms
Electrical switch rooms and substations
Telecommunications facilities
Archives and document storage facilities
Museums and heritage buildings
Pharmaceutical and manufacturing facilities
Distribution and logistics warehouses
High-value commercial and industrial assets
Energy and infrastructure projects
Talk to our team
We will walk through your project, scope the work, and quote against what you need.
Who we work with
Our pre-action and deluge work is typically delivered as a subcontracted electrical scope on projects led by:
Main contractors
Managing the overall project delivery
M&E contractors
Who include the electrical fire detection in their wider M&E scope
Sprinkler companies
Who handle the mechanical scope and bring us in for the electrical
Facilities management providers
Managing existing buildings
End-user building owners
Commissioning specialist fire protection solutions directly
Talk to our team
We will walk through your project, scope the work, and quote against what you need.
Standards
WSD’s pre-action and deluge work is delivered to current British Standards and best practice:
BS 5839-1
Fire detection and fire alarm systems for non-domestic buildings (detection side)
BS 7273-1 and BS 7273-3
Code of practice for the operation of fire protection measures (the cause-and-effect side)
BS EN 12845
Fixed firefighting systems: sprinkler systems (the wider sprinkler standard context)
BS 7671
IET wiring regulations
BS 8519
Fire-resistant cable systems where applicable
LPCB and FM
Approved equipment throughout
Talk to our team
We will walk through your project, scope the work, and quote against what you need.
Assured, insured & compliant.
WSD holds the accreditations the industry treats as the minimum bar for serious commercial work. Backed by £5m public liability, £10m employers liability, £1m professional indemnity and £5m product liability cover. All work delivered to current British Standards.
Need a specialist electrical contractor for a pre-action or deluge project?
New install, retrofit, takeover or maintenance – we’ll engage at the right stage.