Unseen Threats: Tracing the Real Sources of EMI/RFI

 Why modern systems still glitch

Even well-designed facilities - data centers, labs, SCIFs, and medical suites can suffer unexplained errors, intermittent failures, or degraded performance. The usual suspect isn’t the hardware itself but the electricity feeding it. Unfiltered power lines and stray electromagnetic signals can quietly compromise reliability and safety.

Where EMI / RFI actually comes from

EMI and RFI aren’t mysterious. They originate from two broad sources:

Natural

  • Lightning, solar activity and geomagnetic events

  • Atmospheric electrical phenomena

Man-made

  • Power conversion equipment, switching supplies, and drives

  • Motors, generators, and large transformers

  • Wireless transmitters, routers, and radio equipment

  • Poorly shielded electronics or cable runs that act like antennas

Why shielding and filtering matter: A practical perspective

Experts observing field failures note two recurring facts: 

(1) shielding alone is often insufficient, and 

(2) proper filtering at power entry points dramatically reduces problems. This is where robust EMI/RFI filters become essential.

EMI in secure environments

In secure facilities, EMI is more than a performance issue—it’s a security threat. Electromagnetic emissions can unintentionally carry data outside controlled areas. TEMPEST-grade EMI filters, such as those used in high-assurance defense projects, are engineered to block these emissions while maintaining power quality. This same principle applies to SCIF/TEMPEST filters, which combine noise suppression with low reactive power draw to support efficiency in secure power systems.

Practical mitigation checklist (what engineers actually do)

  • Filter at the power entry — install facility-grade power filters to stop conducted noise. See examples in the facility filter overview: Facility Power Filters.

  • Use proper shielding — metal enclosures or conductive coatings for plastic housings.

  • Segregate cabling — separate power, control, and RF cables; avoid parallel runs.

  • Grounding & bonding — low-impedance, continuous grounding paths reduce common-mode noise.

  • Test and measure — spectral scans and conducted-emissions tests reveal real problems before failures occur.

Standards and product choices — what to watch for

If you need solutions that meet tight requirements, look for filters and products designed to comply with recognized standards (MIL-STD, UL, DO-160). For rugged and defense applications, Military/COTS EMI Power Line Filters are better option.

Location: Southern California, CA, USA

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