Fire Prevention: How Much Voltage Can My Circuit Handle At Home?

Many old buildings or homes lack the amount of smoke detectors required by national fire codes. When installing multiple smoke detectors, knowing how much voltage your circuit can handle is important.

Smoke alarms should be placed on every floor of your home or building, and in every sleeping area or bedroom. Buildings with a square footage greater than 1,000 sq. feet, require one smoke alarm per 500 square feet.

Most modern smoke detectors are wired to intercommunicate. This kind of wiring guarantees that when one alarm in the building is triggered, all alarms will go off. Generally, a smoke detector will have three wires, with three different functions. The black wire accepts the power supply, while the white/yellow wire is neutral. The third wire is red and connects all of the detectors together.

It is always important, when installing any electrical device, that you know the voltage of the product as well as the amount of power your circuit can handle. This will be listed on the owner’s manual. The number of devices you can connect to a signal circuit is based on the voltage of the circuit and the current rating of the devices connected to it. You must add up the current draw of all the devices and make sure the total does not exceed the rating of the circuit you want to connect.

For example, depending on the size of the building, the amount of smoke detectors allowed by your circuit may differ. If one smoke detector has a current rating of 9 volts, and you have a 120-volt circuit, then your circuit can only handle about 10 smoke detectors at a time. On the other hand, a 240-volt circuit can handle up to 21 smoke detectors at a time.

*Please Note* It is not a good idea to exceed 80% of the circuit’s rating to give some room for expansion, and adding of square footage.