Contacts and electrical · Updated 2026-09-28
Withstanding Voltage vs Working Voltage in Connectors
Datasheets often list a voltage in bold. It is usually the dielectric withstanding voltage (DWV) — the test voltage the insulation must survive for a short time (often one minute) without breakdown. It is not the voltage you should run the connector at.
Three different numbers
- Dielectric withstanding voltage: a short-duration proof test between adjacent contacts and between contacts and shell.
- Working (rated) voltage: the continuous voltage the connector is designed to carry, with a safety margin below the test voltage.
- Insulation resistance: measured at a DC test voltage (for example 500 VDC); shows insulation quality, not a voltage limit.
Service ratings
Many connector families group insert arrangements by service rating. Examples:
| Family | Rating | Test voltage | Working voltage |
|---|---|---|---|
| 38999 type | M / N / I / II | 1300 / 1000 / 1800 / 2300 Vrms at sea level | set by your design margin |
| MIL-DTL-5015 type (HMS31, VG31) | Instrument / A / D / E / B / C | 1000 to 7000 V | 200 to 3000 VAC |
Altitude and environment
At low air pressure the air gap between contacts breaks down more easily. That is why 38999 ratings drop to 800–1000 Vrms at 21,000 m (mated). Humidity, contamination and condensation also reduce the safe voltage.
Choosing a working voltage
- Start from the working voltage your system needs, including transients.
- Select an arrangement whose service rating gives a comfortable margin.
- Consider altitude, humidity and pollution in the enclosure.
- For high-voltage power, use a connector designed for it — J599HV has 3500 V withstanding voltage and large creepage distances.
Send us your voltages and environment and we will confirm the rating.
