Dedicated circuit

A dedicated circuit is a branch circuit that supplies the fire alarm control unit and nothing else, with a disconnecting means that is permanently marked, red, and lockable in the ON position. It comes from Section 32 of the Canadian Electrical Code, adopted in Ontario as the Ontario Electrical Safety Code, whose 2024 edition, the 29th, came into force 1 May 2025. The point of it is that nobody can kill power to the panel while troubleshooting something unrelated, and that switching it off has to be a deliberate act rather than a casual one. The rule numbers commonly cited for it come from Canadian secondary sources rather than code text we have read, so verify the number against your own copy before putting it in a compliance document.

What the requirement actually is

Three things, and all three get checked.

Dedicated. The circuit supplies the fire alarm control unit and nothing else. Not the corridor receptacle that was convenient, not the janitor's closet light.

Red and permanently marked. The disconnecting means is identifiable at a glance by somebody who has never been in the building before and is working under pressure.

Lockable in the ON position. The lock-on device makes de-energising the panel a decision rather than an accident.

The reasoning is obvious once you have seen the failure. A panel sharing a circuit with anything else gets switched off by whoever is troubleshooting that other thing, and the building runs unprotected until somebody notices the dead panel or the monitoring station calls.

Why a 24 volt system gets Class 1 treatment

Every instinct built from ordinary control wiring says a fire alarm circuit is low voltage, low current, treat it lightly. The Canadian code closes that door explicitly. Rule 16-010 requires that circuits to safety control devices, where failure would introduce a direct fire or life hazard, be treated as Class 1 regardless of voltage or power limitation. A fire alarm system is exactly that kind of device.

So none of the Class 2 relaxations apply. Not the lighter wiring methods, not the loose separation. This is one of the sharper divergences from American practice, where fire alarm circuits are commonly installed power limited under a different rule set, and it is why American guidance on this does not transfer. The rest of Section 32 is set out in the guide to powering a fire alarm system.

The rest of the circuit

The dedicated supply is only half of it. Fire alarm conductors are copper, insulation rated not less than 300 V, and must be kept entirely independent of all other wiring, which means no shared raceway, box or enclosure except at the defined connection points. A fire alarm cable passing through a junction box holding line voltage, with no splice made, is still a failure: the rule is about occupancy of the enclosure, not about whether you connected anything. Conductor sizes, flame ratings and what to read off the jacket are in the fire alarm cable guide.

Which edition applies, and which rule numbers we could not confirm

In Ontario the operative document is the Ontario Electrical Safety Code. The 2024 OESC came into force 1 May 2025, it is the 29th edition, and it contains the 26th edition of the Canadian Electrical Code Part I plus Ontario amendments. Some sources, ESA's own pages included, call it the 28th edition; the OESC glossary entry settles the number and explains where the confusion comes from.

The dedicated circuit and red lock-on requirement is commonly cited to Rule 32-108. That number comes from Canadian secondary guides whose code edition is not always stated, not from code text we read, and the same caution applies to 32-100, 32-102 and 16-010. Alberta's STANDATA 18-CECI-32 is a government source and confirms Rule 32-200 for dwelling unit smoke and CO alarms and Rule 32-304 for fire pump service boxes. Treat the requirements above as solid and the numbers as needing a check against your own book.

What fails on site

The failure modes are predictable and all three are visible on inspection: the panel ended up on a shared circuit because it arrived after the panel schedule was finalised, the lock-on device was never fitted, or it was fitted and removed during a renovation and never put back. None of that affects the standby power calculation, which assumes the primary supply is there and working.

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