Quantifying Lethal Currents: Re-Evaluating Safety Standards For Low-Voltage Devices

The Core Issue – Outdated Safety Standards

Existing safety standards for low-voltage electrical devices have not been substantially updated in decades, meaning they do not account for changes in device design and usage. The outdated standards base permissible current limits on outdated models of lethal electrical thresholds in the human body.

For example, IEC 60479 parts 1 and 2, which provide effects of current passing through the human body, have not been updated since the 1990s. Yet our understanding of electrophysiology and electrically induced harm has advanced considerably thanks to new research and computational models. Emerging evidence suggests conventional testing methods underestimate lethality risks from modern device failure modes.

By re-evaluating safety margins to reflect new evidence on the likelihood of ventricular fibrillation and cardiac arrest, updated standards could improve safeguards against electric shock casualties while still enabling innovation in compact, low-voltage devices.

Modernizing the Testing Methodology

Existing testing methods also contribute to the obsolescence of safety standards. Conventional testing emphasizes voltage thresholds using dated equipment and electrode placements that crudely approximate real-world scenarios.

Next-generation testing protocols should incorporate improved fidelity through more realistic electrode positioning, waveforms, and pathways. Computational modeling and in-silico approaches can supplement physical tests with better spatial and temporal precision at lower cost and ethical impact.

Testing methods should evaluate risks from emerging device use cases like wearables and inserts. Safety margins and risk assessments ought to adapt as environments, users, and uses evolve over upcoming decades of disruptive technological change.

Accounting for New Failure Modes

Alongside testing methodology limitations, existing standards overlook risks from evolving failure modes in modern low-voltage devices. The drive toward miniaturization with microelectronics introduces reliability challenges as components become tightly packed and heat dissipation gets constrained.

We must re-evaluate assumptions that low voltages intrinsically limit shock hazards and thermal failures. Updated standards should require manufacturers to demonstrate adequate insulation, fusing, connectors, and quality control for risks like dendrite formation, hot spots, and arc tracking.

As electronics permeate user environments via IoT and wearables, we must account for use hazards like moisture ingress, mechanical stress, and radiofrequency interference that could precipitate unpredictable device failures.

Updating Safety Margins

With improved device testing and risk assessments, we can quantify updated safety margins using statistical methods to constrain the aggregate shock casualty risk to acceptable levels. Probabilistic analysis should set new margins based on computational models gauging population-level variability in electrical harm thresholds.

Ideally updated standards would limit the probability of lethal shocks to less than 1 in 10,000 device-hours or mandate redundancy to meet five- or six-sigma reliability. Reflecting modern evidence, revised margins may necessitate 50% lower maximum current limits compared to conventional guidelines.

Standards will evolve from imposing blunt thresholds toward continuous assurance that emerging device designs and use cases provably operate within quantified risk boundaries.

Impact on Device Design

To meet stricter safety margins under modernized standards while preserving compact form factors, device manufacturers will adopt creative solutions both within and around core electronics.

Tighter constraints on maximum operating voltages and currents will drive more aggressive derating of components. Designers may turn to thinner insulation materials, advanced connectors, and innovative busbar geometries to curb leakage currents.

Safety mechanisms like fuses, varistors, and isolation circuits will become more tightly integrated and multi-layered to limit voltages and fault currents. Compensating components will help meet thermal dissipation needs as form factors continue shrinking.

Beyond hardware adjustments, robust quality assurance infrastructure and sophisticated embedded firmware will play larger roles in predictive failure analysis and hazard mitigation under new risk-based paradigm.

Conclusions

Updating decades-old safety standards is crucial and timely given that emerging risks from evolving low-voltage devices are otherwise unaccounted for under the outdated guidelines still commonly used today.

Through proactive evaluation of revised testing methods and risk models, standard-setting bodies have the opportunity to preemptively constrain dangers to human life as the modern tech ecosystem grows more pervasive.

The path forward requires cross-disciplinary collaboration to implement continuous safety assurance via rigorous device evaluation and design paradigms limiting aggregate risk based on state-of-the-art harm thresholds quantified through improved computational models.