# Why is HV Discharge dangerous in Hazardous Zones?

**URL:** <https://forumautomation.com/t/why-is-hv-discharge-dangerous-in-hazardous-zones/13355>\
**Category:** Electrical\
**Tags:** voltage, risk\
**Created:** [July 3, 2025, 4:15pm UTC](https://forumautomation.com/t/why-is-hv-discharge-dangerous-in-hazardous-zones/13355 "2025-07-03T16:15:23Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [July 3, 2025, 4:15pm UTC](https://forumautomation.com/t/why-is-hv-discharge-dangerous-in-hazardous-zones/13355/1 "2025-07-03T16:15:23Z")

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## What is High-Voltage Equipment Discharge?

[url= [High Voltage Pressure Testing Procedure (HV Pressure Test)](https://forumelectrical.com/high-voltage-pressure-testing-procedure-hv-pressure-test/)][color=#1E00A3] **High voltage (HV)** [/color][/url] equipment discharge is the unintended release of the electrical energy in the form of:

- Partial Discharge,
- Corona Discharge,
- Arc Flash,
- Dielectric Breakdown.

These discharges can be caused by insulation failure, air gaps, moisture, or aging equipment, and they frequently result in sparks, electrical arcs (or) high-temperature surfaces.

## Why is it important in Hazardous Environments?

Hazardous regions are those in which combustible gasses, fumes, or dust are prevalent.

In such conditions, even a small spark from an HV discharge can cause an explosion.

Typical hazardous areas:

- Petrochemical plants
- Refineries
- Grain silos
- Chemical processing zones
- Underground mines.

## Risk Types

| **Discharge Type** | **Risk in Hazardous Area** |
| --- | --- |
| Corona Discharge | Can ignite gas-air mixtures |
| Partial Discharge | Leads to long-term insulation failure, potential flashover |
| Arc Flash | High temperature (up to 20,000°C), explosion risk |
| Electrostatic Discharge | Sparks in flammable atmosphere |

 ![image](https://cdn.forumautomation.com/original/2X/1/1d10055678bc915e31b5b4e012cae5c515ca70a2.jpeg)

## Key Safety Measures

### Zoning and Classification

- To classify hazardous zones, use IEC 60079 or NEC 500/505 (Zone 0, 1, 2, or Class I Division 1/2).
- Utilize explosion-proof (or) intrinsically safe equipment in classified areas.

### Proper Grounding and Bonding

- Prevent electrostatic buildup and discharge.
- Use of flameproof high-voltage equipment
- Utilize Ex-d, Ex-e, or Ex-p-protected HV panels & switchgear.

### Regular Inspection and Testing

- Partial Discharge (PD) Testing
- Insulation Resistance Tests
- Thermographic scan for hotspots

### Environmental Control

- Dehumidifiers & air purging devices are used to avoid moisture and dust collection.
- Control of the Maintenance Work
- Permit-to-Work (PTW) systems.
- Use of inherently safe tools.
- No live testing unless in a safe zone.

## Standards

| **Standard** | **Description** |
| --- | --- |
| **IEC 60079 Series** | Equipment use in explosive atmospheres |
| **IEC 62271-200** | High-voltage switchgear and control gear |
| **NFPA 70 (NEC)** | Electrical installations in hazardous locations |
| **IS/IEC 60079 (India)** | National adaptation of IEC hazardous area standards |

Discharges from high-voltage equipment provide considerable ignition threats in combustible conditions. Proper design, equipment selection, zoning & maintenance practices are essential for avoiding catastrophic explosions or fires.

When developing or maintaining high-voltage systems in hazardous regions, always involve qualified workers and strictly adhere to applicable requirements.