Electrical Equipment and Products
Smoke Detectors

Prior to entering the fire scene, don appropriate PPE.

 

Detailed Procedure

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If the smoke detector to be collected is hardwired, at the electrical service panel:

1. Visually examine the electrical service to ensure all circuits are de-energized and electrical products can be safely collected.

2. Photograph the panel.

3. Sketch or diagram the scene and evidence to be collected, noting the circuit of interest.

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Proceed to the smoke detector collection site. Smoke detectors may bear fingerprints or trace evidence and therefore should be handled as little as possible and with gloved hands, avoiding contact with boundary surfaces as much as possible.

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To collect a hardwired smoke detector that is still attached:

1. Apply a non-contact voltage tester to the hardwired smoke detector as a presumptive test for the presence of electrical current. Use a multimeter as appropriate. If current is not detected, proceed.

2. To facilitate potential collection in the future, document which branch circuit overcurrent protection device supplied the subject hardwired smoke detector. 

3. Use the general to specific methodology to photograph the smoke detector in place. Continue photographing the collection process as you collect the smoke detector.

4. When you are ready to collect the smoke detector, don new, unused, clean latex or nitrile gloves and gather the containers and tools necessary. Typically, boxes or zip plastic bags are used.

5. If the detector is hardwired and still mounted, NFPA 921 recommends removing the entire detector assembly, including the electrical box and ceiling board, if necessary.

6. Mark the hardwired smoke detector or its remains to denote the orientation of the detector as found, for example up/down.

7. If the hardwired smoke detector is still attached, remove the entire assembly. Be careful when handling brittle wire and smoke detector parts to avoid damage.

8. Use color-coordinated zip ties, a permanent marker, or a paint pen, make witness marks on the conductors to be cut.

9. If the smoke detector is in middle of a string, label line side vs. load side. 

10. Use diagonal cutters to cut the conductors between the witness marks.

11. Remove the smoke detector and conductors. 

12. Use zip ties or a similar method to secure the smoke detector to a backer board to prevent damage or alteration. 

13. Secure the backer board inside an appropriately sized box or enclose in a zip bag to prevent damage to or alteration of the smoke detector.  

14. Seal the box or bag with evidence security tape. 

15. Label the box or bag. 

16. Initial and date the tape. 

17. Store the collected items in a secure location until you can transport them to the laboratory.

18. Transport the collected items to a climate-controlled, secure evidence storage facility consistent with your organization’s guidelines. If you will be shipping the evidence to a lab, consult the lab for advice on how to package for shipping so the evidence is not damaged in transit.

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To collect a detector that is battery-only or is hardwired but no longer connected:

1. Carefully excavate around the detector. Locate all components, including the body, horn, and battery. Sift the debris with various sized mesh screens, if necessary.

2. Use a multi-meter with DC capability to check the “as found” voltage of loose batteries and batteries in the smoke detector, if you can do so without damaging the detector. Do not remove the battery if it is still in the battery compartment of the detector.

3. If the detector is not hard-wired but is still mounted:

   1. Take a photo of the detector in place.

   2. Remove the smoke detector from its mount. 

   3. Photograph all sides of the detector. 

   4. Use zip ties or a similar method to secure the detector, battery, and any large pieces of remains to a backer board to prevent damage or alteration. Take care not to disturb any acoustic agglomeration marks around the horn.

   5. Place the backer board in the bottom of a similarly sized box. If necessary, secure the backer board to the box to protect the top of the device from contacting the boundary surface.  

4. Other smoke detector parts may be bagged and added to the box prior to sealing. See below for the process of collecting loose components.

5. Seal the box with evidence security tape. 

6. Initial and date the tape. 

7. Label the box or bag packaging with case information according to your organization’s SOP.

8. Store the collected items in a secure location until you can transport them to the laboratory.

9. Transport the collected items to a climate-controlled, secure evidence storage facility consistent with your organization’s guidelines. If you will be shipping the evidence to a lab, consult the lab for advice on how to package for shipping so the evidence is not damaged in transit.

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If collecting the smoke detector in a zip bag:

1. Use the taco method to protect the detector. Wrap cardboard or other protective media around the detector to form a protective taco-shaped wrapper. Avoid contact with the horn. 

2. Secure the wrapper with tape.

3. Place the wrapped detector in a zip bag. 

4. Zip the bag closed.

5. Seal the closure with evidence security tape. 

6. Initial and date the tape. 

7. Label the box or bag packaging with case information according to your organization’s SOP.

8. Store the collected items in a secure location until you can transport them to the laboratory.

9. Transport the collected items to a climate-controlled, secure evidence storage facility consistent with your organization’s guidelines. If you will be shipping the evidence to a lab, consult the lab for advice on how to package for shipping so the evidence is not damaged in transit.

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All parts of the smoke detector may be relevant, including the mounting bracket and wire harness (for hard wired units).  Collect these components in zip bags as well. Seal and label all collection bags as previously described.

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If parts of the smoke detector are loose:

1. Collect loose parts in a separate zip bag. 

2. Zip the bag closed. 

3. When collecting loose batteries, package and secure them to prevent shorting or further draining of the battery reserve. 

   1. Ensure that battery terminals do not contact conductive materials, as that can cause draining or shorting. Collect the battery in a zip bag.

   2. Place the sealed zip bag with the loose batteries in the box with the detector. Secure the bag to prevent movement.

4. All components and battery bags can be placed in the box or bag with the detector prior to sealing and labeling the box according to the procedure above.

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After you have collected a hardwired smoke detector, collect the branch circuit overcurrent protection device, if appropriate:

1. Apply a non-contact voltage tester to the panel as a presumptive test for the presence of electrical current. 

2. Use a multimeter as appropriate. 

3. Witness mark the overcurrent protection device on the circuit of interest to denote which one it is. 

4. Use zip ties or a paint pen to witness mark the branch circuit line. 

5. With diagonal cutters, cut between the witness marks. 

6. Pry the overcurrent protection device and the attached branch circuit wire piece out. Place in a zip bag and close. 

7. Label the bag according to your organization’s SOP. 

8. Seal the bag with evidence tape. 

9. Initial and date the tape.

10. Store the collected items in a secure location until you can transport them to the laboratory.

11. Transport the collected items to a climate-controlled, secure evidence storage facility consistent with your organization’s guidelines. If you will be shipping the evidence to a lab, consult the lab for advice on how to package for shipping so the evidence is not damaged in transit.

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If the smoke detector will also be examined for ignitable liquid residue, please consult the laboratory for the proper collection procedure. Consider taking a debris sample from the area around the smoke detector to be tested for the presence of ignitable liquids.

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Laboratory testing of smoke detectors:

Examination of smoke detectors in a laboratory environment may provide an opportunity to evaluate and document internal componentry utilizing light microscopy, x-ray, or computer tomography and may also allow determination of operability by examining the audible horn for evidence of acoustic agglomeration of soot.