Hide Phones in Desk Safe Compartments (Faraday Pockets)
A lockable desk compartment can keep a phone out of sight, while a tested RF-shielding pouch can reduce radio signals reaching it. Choose a pouch with test data for the phone’s relevant frequency bands, size the compartment for the pouch, and store the phone unpowered. Do not charge a phone inside a closed or shielded space.
An expert tip: choose the shielding product before you build the compartment. A pouch that barely fits can strain at its seams or fail to close as intended. I plan these projects as two separate tasks: secure storage for the phone, and verified RF shielding from a commercial product. A metal-lined drawer alone is not proof of signal blocking.
Planning the Storage Compartment and RF Requirement
A desk phone compartment needs to hold the phone securely, let the pouch close without strain, and keep the device away from heat and electrical equipment. A lock controls access; it does not provide RF shielding. Set those goals separately before selecting or modifying a desk.
Start by deciding what you need the compartment to do. If you only want the phone out of sight, a lockable drawer may be enough. If the phone must also be isolated from radio signals, use a commercial RF-shielding pouch or enclosure with documentation for its tested performance.
Shielding effectiveness describes how much a material or enclosure reduces radio-frequency energy over a stated frequency range. It is expressed in decibels (dB). Higher values indicate more reduction under the stated test conditions, but the result depends on frequency and how the product was tested.
What RF test data should you check?
A useful test report identifies the product tested, the frequency range, and shielding effectiveness in dB across that range. Compare the reported bands with the phone’s radios and the purpose of storage. Do not rely on a general claim such as “blocks signals” without supporting test details.
ASTM D4935 is a test method for measuring shielding effectiveness of planar materials. It does not set a universal pass level for a finished pouch, nor does it prove that a phone cannot connect when inside one. A pouch has seams and a closure, so material data alone may not describe the performance of the complete product.
| What to check | Why it matters | What to look for |
|---|---|---|
| Frequency range | Phones can use several radio bands | Test data covering the bands relevant to your phone and use |
| dB values by band | Performance may vary across frequencies | Results stated by frequency, not one unexplained figure |
| Test object | Flat material differs from a finished pouch | Data for the actual pouch or enclosure, if available |
| Closure and seams | Openings can affect shielding | Instructions for closing and using the product |
| Fit | A stressed closure may not work as intended | Room for the phone and case without pulling seams |
No single dB value can be treated as a universal guarantee that a phone will stop connecting. If isolation is important, consider the product’s documentation and test the closed pouch in its intended location. A phone’s signal indicator is not a calibrated shielding measurement.
Checking Device Fit, Drawer Travel, and Electrical Clearances
A fit check starts with the phone and its case, then adds room for the shielding pouch. Measure the desk’s usable interior, not just its outside dimensions. The compartment also needs to open and close without catching on slides, rails, wiring, or nearby equipment.
Measure the phone and case at their widest, deepest, and longest points. As a design allowance, make the clear internal compartment dimensions at least 10 mm larger in each dimension than the phone-and-case dimensions. This is a fit recommendation, not a code minimum. Then check that the actual pouch fits and closes without pressure on its seams.
Check the drawer and desk before cutting
Look inside the desk and note the drawer-slide position, structural rails, fasteners, and any visible wiring. Pull the drawer through its full travel and look for spots where a pouch could rub, fold, or get pinched. Do not cut a structural rail or drill where concealed wiring may be present.
If you cannot confirm what is behind a panel, pause and inspect the desk construction or ask a qualified professional. A phone-storage project does not require adding an outlet or cutting into a power supply. Keep the compartment separate from power supplies, electrical panels, and heat-producing equipment.
Electrical clearance rules apply to covered electrical equipment, not ordinary desk storage. NEC 110.26 addresses working space and access for covered equipment. Do not use a desk compartment to block that required space. If electrical work is added, follow the locally adopted code and use qualified help where needed.
Installing the Lockable Compartment and Shielding Product
Install the compartment with the fasteners and load limits specified by its maker. Keep the RF pouch removable, so you can inspect its closure and seams. Avoid adding charging hardware: a closed shielded compartment can hold heat, and charging inside it is not a safe storage plan.
A passive RF-shielding pouch generally does not need grounding. Do not connect it to building wiring or plumbing unless the product instructions and a qualified electrical design explicitly require that connection. A casual grounding connection is not a substitute for verified shielding data.
A careful installation sequence
- Survey the desk. Record the desk construction, slide geometry, phone and case dimensions, nearby wiring, and the location of heat-producing equipment.
- Select the pouch. Choose a commercial product with band-specific test information. Check its size, closure instructions, and stated temperature limits.
- Size the compartment. Allow at least 10 mm beyond the phone-and-case dimensions in each direction, then verify that the pouch fits without strain.
- Fit the compartment. Use the compartment maker’s specified fasteners and load limits. Do not cut structural rails or drill into suspected wiring.
- Test movement. Open and close the drawer several times. Check for rubbing, pinching, and interference with slides or nearby equipment.
- Store the phone unpowered. Do not charge it in the pouch or in a closed compartment.
There is no universal code-specified airflow rate, or CFM, for an unpowered phone-storage compartment. That does not make heat irrelevant. Follow the phone and pouch makers’ temperature limits, and keep a phone that is hot, swollen, or damaged out of the compartment. Follow the device maker’s battery-safety guidance.
Verifying Fit, Closure, and RF Performance
Verification means checking the physical installation and the shielding product separately. The drawer should travel smoothly, the phone should fit without pressure, and the pouch should close as directed. RF performance should be judged from product-specific test evidence and, when required, a suitable test of the closed setup.
Practical checks after installation
- Fit: Place the phone and case in the pouch. Confirm that the closure operates normally and the seams are not stretched.
- Retention: Place the pouch in the compartment and move the drawer through its full travel. The pouch should not slide into a pinch point.
- Locking: Close and lock the compartment. Check that the lock works without forcing the drawer or compressing the pouch.
- RF evidence: Review the test report for the actual pouch or enclosure, including frequency range and dB results.
- Location check: If RF isolation is required, test the closed device and pouch in the actual location using a suitable method. A signal bar or “no service” display alone is not a calibrated test.
A phone may behave differently across locations and network conditions, so one observed result does not prove a pouch’s shielding effectiveness. Do not treat a single call attempt or signal indicator as a pass/fail certification. If the intended use requires a defined performance level, seek a test method and acceptance criteria suited to that use.
Planning case studies: two common desk layouts
The examples below are planning scenarios, not documented installation claims. They show how the same checks apply to different desks.
Scenario 1: A shallow desk drawer. The phone fits, but the pouch is thicker than expected and catches on the slide. The right next step is not to force the drawer. Measure the full travel path, compare the pouch’s folded size with the available space, and select a better-fitting compartment or pouch.
Scenario 2: A desk beside electrical equipment. The planned compartment would cover access to equipment. Keep the phone compartment away from that space and preserve applicable working clearance. If the desk layout cannot do both, change the storage location rather than blocking access.
Conclusion: Choose the Pouch Before the Compartment
A reliable setup starts with a lockable, well-fitted compartment and a commercial RF pouch whose test information matches your needs. Measure the phone and case, allow at least 10 mm per dimension, and confirm the pouch closes without stress. Keep the phone unpowered, avoid heat and electrical hazards, and verify drawer movement after installation.
FAQ
Does a metal desk drawer block phone signals?
A metal drawer is not proof of RF isolation. Seams, gaps, and openings can affect shielding, and performance can vary by frequency. Use a documented commercial pouch or enclosure if signal reduction matters, and review test data for the actual product.
Does a Faraday pouch need to be grounded?
A passive RF-shielding pouch generally does not require grounding. Do not connect it to wiring or plumbing unless its instructions and a qualified electrical design specifically require it. Grounding by itself does not establish that the pouch meets a particular shielding level.
How much larger should the compartment be than the phone?
As a design allowance, make the compartment’s clear interior at least 10 mm larger in each dimension than the phone and case. Then confirm that the pouch also fits and closes without seam stress. This is a practical fit recommendation, not a code requirement.
What shielding value should I look for?
There is no universal dB threshold that guarantees a phone will stop connecting. Review shielding effectiveness by frequency band and check that the report applies to the actual pouch or enclosure. Match the data to the phone’s relevant bands and your intended use.
Does ASTM D4935 certify a complete phone pouch?
No. ASTM D4935 is a test method for measuring shielding effectiveness of planar materials. It does not set a universal pass level for a finished pouch or guarantee that a phone cannot connect inside it. Look for test information about the complete product.
Can I charge a phone inside a shielded compartment?
No. Do not charge a phone inside a closed or RF-shielded enclosure. Heat can build up, and a shielding product may limit heat escape. Store the phone unpowered and follow the phone and enclosure makers’ instructions.
Should I test the pouch by checking the phone’s signal bars?
Signal bars are not a calibrated shielding test. They can change with location and network conditions, so they do not provide a dependable pass or fail result. Use product test data, and arrange a suitable test if a defined performance level is required.
What should I do with a hot or swollen phone?
Do not place a hot, swollen, or damaged phone in the compartment. Keep it out of the pouch and follow the device maker’s battery-safety guidance. If you are unsure how to handle it safely, seek guidance from the manufacturer or an appropriate repair professional.
(This article was written by one of our staff writers, Andrew Fairchild. Visit our Meet the Team page.)
