Overview
IEC TS 62367:2004 - "Safety aspects for xDSL signals on circuits connected to telecommunication networks" - is a Technical Specification from the IEC that addresses the safety implications of having xDSL (DSL: Digital Subscriber Line) signals on circuits in equipment connected to a telecommunication network. It explains how xDSL signalling interacts with the safety requirements of the IEC 60950 family (information technology equipment - safety) and provides practical rules for classifying and assessing such circuits for compliance.
Key topics and requirements
- Scope and purpose: Clarifies safety considerations when xDSL (ADSL, VDSL, HDSL, SDSL, etc.) shares wiring with PSTN/ISDN or DC power-feeding.
- Circuit classification (Rule 1): Circuits carrying xDSL signals are to be classified as either TNV‑1 or TNV‑3 circuits based on their normal operating voltage.
- Voltage assessment (Rule 2): When assessing voltages against IEC 60950‑1 limits and when determining insulation working voltage, the a.c. xDSL signal component is regarded as zero and does not change the circuit classification.
- Signal characteristics (Annex A):
- Typical magnitudes: mean powers correspond to r.m.s. voltages of a few volts (worst-case ADSL example: ~3.31 V r.m.s. downstream, ~1.33 V r.m.s. upstream).
- Short-duration spikes: brief (~1 μs) spikes may reach higher peak values (document cites spikes with peaks up to ~30 V and statistical occurrence estimates: e.g., ~15 V spikes every seconds–minutes, ~20 V every hours, ~27 V every years).
- Crest Factor / Peak-to-Average Ratio (CF/PAR): CF typically ~5–6 for ADSL; distributions for multi‑carrier schemes (DMT) and single‑carrier (QAM) are discussed.
- Effects of line termination impedance and measurement considerations for xDSL parameters.
Applications - who uses this standard
- Product designers and manufacturers of CPE (customer premises equipment), modems, splitters, network termination units and other devices that connect to public telecommunication lines.
- Safety engineers and compliance officers responsible for ensuring IT and telecom equipment meets IEC 60950 series requirements when xDSL signals are present.
- Test laboratories and certification bodies evaluating insulation working voltages, TNV classification and safety compliance for DSL-capable equipment.
- Network equipment integrators and installers who need to understand safety implications of combining xDSL with PSTN/ISDN or power feeding.
Related standards
- IEC 60950 / IEC 60950‑1 - Information technology equipment - Safety (primary normative reference).
- ITU‑T recommendations such as G.992.1 (ADSL) are referenced in the TS for functional signal parameters and examples.
Keywords: IEC TS 62367, xDSL safety, DSL safety, IEC 60950, TNV circuits, crest factor, PAR, DMT, ADSL, VDSL, CPE, telecom safety.