How to Test and Repair a Smoke Detector Circuit

How to Repair Smoke Detector Wiring Problems: Hardwired Smoke Detectors with Battery Back Up, Testing and Troubleshooting a Hardwired Smoke Detector Circuit.

Troubleshooting Smoke Detector Wiring
Electrical Question: I have 2 hard-wired smoke detectors in the front hallways of a 3-storey house, 3 in the back hallways and 1 in the basement.

• I am using Firex i480 units sold by home depot.
• The one on the 3rd floor of the back hallway will not trigger the system, despite the fact that I have changed all the units.
• I have rewired the connections between the first floor and the second floor and again from the second floor to the third floor, but still the 3rd floor unit is not connected to the system, even though it is getting power (green light is on).
• It also appears to be at the end of the circuit which I am assuming started in the basement, where the breaker box is. I am stumped, and would appreciate any input.

Thanks a lot.

This home electrical repairs question came from: Jay, from Irvington, New Jersey.

Dave’s Reply:
Thanks for your electrical wiring and troubleshooting question Jay.

How to Repair Smoke Detector Wiring Problems

Application: Smoke Detector Circuit Wiring
Skill Level: Beginner to Intermediate – best performed by a Licensed Electrician.
Tools Required: Basic Hand Tools and Safe Ladder.
Estimated Time: Depends on personal experience and the number of smoke detectors and access to them.
Precaution: Smoke Detectors are required by code to be installed in specific areas of the home. Never remove or leave a smoke detector disconnected or never leave the smoke detector circuit power off.
Notice: Smoke detector type alarms should be tested frequently to make sure they are functioning correctly and the 9 volt battery should be replaced every year. Installing or upgrading electrical wiring should be done according to local and national electrical codes with a permit and be inspected.

• Hardwired Smoke Detectors with Battery Back Up
  • What is a Hardwired Smoke Detector System?
    • A hardwired smoke detector system is a 3-wire cable consisting of 3-insulated wires and one ground wire which connects all of the smoke detectors together.
    • Two wires are the 120 volt power supply and the extra wire is used for the Alarm Signal which causes all of the smoke detectors to go into alarm. the alarm wire on the smoke detectors is typically yellow.
    • The initial power supply for the smoke detector circuit is provided by a 2-wire circuit which is typically supplied by a lighting circuit.

• Testing a Hardwired Smoke Detector Circuit
  • With a hardwired smoke detector system you can press the TEST button on any smoke detector and this  should cause all of the smoke detectors to go into alarm all at the same time if the smoke detector wiring has been installed according to the electrical code for hardwired systems.

• Troubleshooting a Hardwired Smoke Detector Circuit
  • If one or more of the smoke detectors do not alarm when the others do and they are all wired together with the interconnected wiring then the wiring connections must be checked because there may be a loose connection.
  • If all the connections have been checked and the circuit still does not work then there may be a problem with the circuit wiring and this may be tested with a voltage tester with the power ON, or a continuity tester with the power OFF.
  • Testing an electrical circuit is best performed by an electrician.

More about Smoke Detectors

How to Wire Smoke Detectors

• How to Install Smoke Detectors

• Understanding smoke detector wiring. Smoke alarms provide the earliest warning of both fire and smoke.

Repair Electrical Wiring

• Troubleshooting and Repairing Electrical Wiring

• Licensed Electrician Reveals the Secrets of Successful Electrical Troubleshooting Methods used to solve the majority of the home electrical problems and wiring failures encountered.

The following may also be helpful for you:

Dave's Guide to Home Electrical Wiring: » You Can Avoid Costly Mistakes! « Here's How to Do It: Wire It Right with the help of my Illustrated Wiring Book Great for any Home Wiring Project. Complete Guide to Home Electrical Wiring Perfect for Homeowners, Students, Handyman, Handy Women, and Electricians Includes: Wiring GFCI Outlets Wiring Home Electric Circuits 120 Volt and 240 Volt Outlet Circuits Wiring Light Switches Wiring 3-Wire and 4-Wire Electric Range Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet How to Troubleshoot and Repair Electrical Wiring Wiring Methods for Upgrading Electrical Wiring NEC Codes for Home Electrical Wiring ....and much more. Learn more about Home Electrical Wiring with my Online Video Course: Basic Home Electrical Wiring by Example

Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.

Electrical Tips to Help You Wire it Right The Safest Way to Test Electrical Devices and Identify Electric Wires! The Non-Contact Electrical Tester This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use. The Quickest Way to Check for Faulty Electrical Wiring! The Plug-In Outlet Tester This is the first tool I grab to troubleshoot a problem with outlet circuit wiring. This popular tester is also used by most inspectors to test for power and check the polarity of circuit wiring. It detects probable improper wiring conditions in standard 110-125 VAC outlets Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency Lights indicate if wiring is correct and indicator light chart is included Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect Very handy and easy to use. Strip Off Wire Insulation without Nicking and Damaging the Electric Wire! The Wire Stripper and Wire Cutter My absolute favorite wire stripping tool that I have had in my personal electrical tool pouch for years, and this is the tool I use to safely strip electrical wires. This handy tool has multiple uses: The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation. The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets.. The wire stripper will work on both solid and stranded wire. This tool is Very Handy and Easy to Use.

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