Lock-on device

Last updated: September 2026

What it is for

A fire alarm panel that can be switched off casually will eventually be switched off casually. The lock-on device makes de-energising the panel a deliberate act: somebody has to remove hardware, not just flip a handle while chasing a tripped circuit two positions over.

It works with the other two halves of the same requirement, not instead of them. The circuit is dedicated, so nothing else on it gives anyone a reason to touch the breaker. The disconnecting means is permanently marked and red, so it is identifiable at a glance by somebody who has never been in the building and is working under pressure. And it is lockable in the ON position, so the identification is backed by something physical.

Take any one of the three away and the other two stop doing their job.

Where the Canadian requirement comes from

Section 32 of the Canadian Electrical Code, CSA C22.1, adopted in Ontario as the Ontario Electrical Safety Code. Section 32 is supplementary: it amends the general rules rather than standing alone, and it covers local fire alarm systems, permanently connected smoke and carbon monoxide alarms, and fire pumps. In Ontario the operative edition is the 2024 OESC, in force 1 May 2025.

Be careful with the rule number. The dedicated circuit and red lock-on requirement is commonly cited to Rule 32-108, and that citation comes from Canadian secondary trade guides whose code edition is not always stated, not from code text we have read. The same caution applies to 32-100 for conductors and 32-102 for wiring methods and separation. The only Section 32 rule numbers we can point at in a government source are 32-200, for dwelling unit smoke and carbon monoxide alarms, and 32-304, for fire pump service boxes, both confirmed in Alberta's STANDATA interpretation. Treat the requirement as solid and the number as needing a check. The wider walkthrough is in powering a fire alarm system under Section 32.

The opposite rule, one floor up

Worth holding beside it, because the two get confused. A dwelling unit smoke alarm is not allowed a lockable disconnect: Ontario Building Code Article 3.2.4.20, Sentence (9), requires smoke alarms to be permanently connected and to have no disconnect switch between the overcurrent device and the smoke alarm.

So the panel gets a disconnect you can lock on. The smoke alarm gets no disconnect at all. Same building, opposite solutions to the same worry.

What goes wrong

Three failures, and all three are visible on inspection.

Never fitted. The commonest by a distance. The breaker is right, the marking is right, and the lock-on was on somebody's list.

Fitted, then removed. A renovation, a panel change, a service call, and the clip goes in a pocket and never comes back.

The circuit is shared. The panel arrived after the panel schedule was finalised, so it landed on a spare with something else already on it. A lock-on device on a shared circuit protects the wrong thing.

Who checks it

The Electrical Safety Authority inspects the electrical side, and the fire or building authority inspects the CAN/ULC-S524 side. Two documents, two inspectors, two sign-offs, and you can pass one while failing the other.

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