Sprinklers in the lift shaft head: the clause that switches your lift off

Sprinklers in the lift shaft head are one of the few design decisions that can leave a building with a lift that stops working, a fire service that does not operate, and nobody at the table who realised either was going to happen.

Two documents that have to be read together

The National Construction Code deals with sprinkler systems in lift installations. Where sprinklers are installed in a space housing lift electrical and control equipment, including machine rooms, secondary floors and sheave rooms, the heads have to be guarded against accidental damage in a way that does not impair them, and the system has to be capable of being isolated and drained without isolating other sprinklers in the building. The control valves have to be monitored.

The lift design standard deals with the same space from the other direction. The well, machine room and pulley rooms are for the lift. Fire detection and extinguishing equipment is allowed, but where a sprinkler system is used, activation is only permitted when the lift is stationary at a landing and the electrical supply to the lift and its lighting is automatically switched off by the fire or smoke detection system.

Read separately, both look manageable. Read together, they describe a sequence that has to be engineered, and it is that sequence that is routinely missing.

What the sequence actually has to do

Before a sprinkler in the shaft can operate, the fire panel has to signal the lift. The lift goes to the next available floor, opens its doors and lets people out. Once it is parked, power to the main circuit board is removed, including light and power circuits. If there is an automatic emergency supply, that has to be signalled and closed as well. Only then can the sprinkler system be permitted to activate.

That is not a wiring detail. It is an interface between the fire system, the lift controller and the emergency supply, and it has to be specified, built into the control system, commissioned and tested. It also means the lift will not restart on its own. Once the emergency has passed, somebody has to start it manually.

The consequence people miss

Here is the part that catches designers out. In buildings with an effective height of 12 metres or more, the Code requires fire service operation of the lift. Fire service operation means the brigade can take control of a lift and use it.

If the sequence above has switched the lift off, the brigade cannot use it. Those two requirements are pulling in opposite directions, and the design has to resolve which one wins, in writing, with the fire engineer and the fire authority involved. If the answer is that the lift shuts down, the builder and the fire engineer need to know that fire service operation will not function, and the fire authority needs to be part of that decision. It is a performance solution, and it needs to be treated like one.

And then there is the water

Whatever the paperwork concludes, if sprinklers discharge into a lift shaft head, the lift is going to be unreliable until it stops. Lifts are not designed to be rained on. Water, electronics and electrical systems have a long history of not getting along. Even a design that satisfies every clause has produced a lift that needs a technician, an inspection and probably some replaced equipment before it carries anyone again.

That is worth saying out loud to an owner at design stage, because the discussion afterwards tends to start from an assumption that a compliant system should have survived.

The checklist we work through

On every project, confirm with the builder or the project fire engineer whether sprinklers have actually been deemed necessary in the lift well or machinery space. Very often the answer is that they were drawn in by default and can come out.

If they are staying, get the positions. Check them against the clearances the lift design standard requires, before the pipework is installed rather than after. Confirm the isolation valve sits outside the well and the machinery space, and that the monitoring is there.

Then deal with the sequence. Who is writing the cause and effect. Who is wiring the signal from the fire panel to the lift controller. Whether the emergency supply is in the sequence. Who commissions it and who witnesses that test. And if the building needs fire service operation, what the resolution is and who has signed it.

Timing is the whole game

All of this is cheap at design stage and painful once the shaft is built. The control system changes are the easy part. The hard part is that the answer often needs the fire engineer, the fire authority, the builder and the lift contractor to agree, and by the time somebody notices the conflict, three of those four have demobilised.

The Australian Elevator Association covers the compliance references in its industry position paper on sprinklers in lift shafts. Consult your lift manufacturer or maintenance provider on the specific control system requirements for your equipment, because the sequencing capability varies.

General information only, not advice on a particular design. If sprinklers are proposed in your shaft head and you are unsure what has been resolved, that is a good time to ask.