ECN Forum Forums Code Related Discussion NEC & other Code issues AFCI on smokes?

Mikesh, I suppose it comes down to two things: vocabulary, and design.

First, it is important to distinguish between "smoke detectors" and "fire alarm systems." The common household units, that have the sensor as well as the horn contained within, and where each unit has its' own battery back-up, is a "smoke detector."

The fancy systems that wire back to a little red panel, and are usually coupled with burglary alarms and monitored by an alarm company, are 'fire alarm systems.'

The distinction is critical, as our alarm code prohibits a fire alarm system from being GFCI or AFCI protected, and they are required to have a dedicated circuit.

Smoke alarms, by contrast, can be powered by any circuit - at least, in theory. However, these 'smokes' are required to all sound when one goes into alarm. In practice, this is accomplished by placing them on a dedicated circuit, and running an additional wire between the units so they can communicate.

Since we are required to have 'smokes' in every bedroom, and bedrooms were the first place AFCI's were required ... the 'smoke' circuit also was AFCI protected.

Code issues aside, we also have a trade practice of placing lights on a different circuit from the receptacles. There are two reasons for this preference: the first is that it is simply easier to have the sundry lights, even serving multiple rooms, and their switches on their own circuits. A secondary reason is the desire for a tripped breaker (serving an appliance) to not leave you in the dark.) Often, lights will be on a 15 amp circuit, while receptacles will be on 20 amp circuits.