---
title: 'Intrinsic Safety - Ex i'
url: 'https://hazardex.com/protection/ex-i'
markdown: 'https://hazardex.com/protection/ex-i.md'
date: '2026-09-16'
description: "Ex i EN\_60079-11 Explosive atmospheres.  Equipment protection by intrinsic safety \"i\" Based on removing the ignition source by reducing the power in the circuit consequently also reducing heating to below ignition levels it was the 'safest' form of protection1 and with one exception2 th…"
taxonomy:
  category:
    - docs
---

# Intrinsic Safety - Ex i

[](#)  [ Hazardex ](https://hazardex.com/)     [ Protection Concepts ](https://hazardex.com/protection)      Intrinsic Safety - Ex i    

###### Ex i EN 60079-11 Explosive atmospheres.  Equipment protection by intrinsic safety "i"

![Ex e Triangle](https://hazardex.com/user/images/triangle-e.svg)

Based on removing the ignition source by reducing the power in the circuit consequently also reducing heating to below ignition levels it was the 'safest' form of protection[1](#fn:1) and with one exception[2](#fn:2) the only method used for Category 1G i.e. Zone 0.

Unlike all other protection methods intrinsic safety is the system concept, not just an individual entity but a combination of interconnected entities.

 **Intrinsically safe circuit**
A circuit in which any spark or any thermal effect produced in the conditions specified in IEC 60079‑11, including normal operation and specified fault conditions, are not capable of causing ignition of a given explosive gas atmosphere.

![Simple I.S. circuit](https://hazardex.com/user/images/is/simple-circuit.svg)Assuming a device is not self-contained i.e. portable then there will be at least two items (plus cable) to form an intrinsically safe circuit commonly referred to as a IS.loop.

Each item in the loop can be one of 4 types:

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| [Associated Apparatus](https://hazardex.com/ex-i/associated) | [Simple Apparatus](https://hazardex.com/ex-i/simple) | [Certified Equipment](https://hazardex.com/docs/type-cert) | [Cables](https://hazardex.com/ex-i#cables) |
|---|---|---|---|
| Contains both IS and Non-IS circuits | Basic 2 terminal devices e.g. switches | Certified equipment | Connecting Cables |

As Intrinsic Safety is a system concept each of the entities together in the the complete loop must be documented to confirm integrity in the form of a [Descriptive System Document](https://hazardex.com/docs/dsd)

For more detailed information please see refer to the specific [Intrinsic Safety](https://hazardex.com/ex-i) section.

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Notes

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1. Intrinsic Safety with 2 fault conditions i.e. Ex ia is the highest level of protection. [↩](#fnref1:1)
2. The 2014 edition of EN 60074-1 introduced the concept of Ex da, (EPL 'a') Flameproof technique for Category 1G. Only Gas detection sensors equipment can be certified Ex da [↩](#fnref1:2)

[🔝](#top)

 [ ](https://hazardex.com/protection/ex-n) [](https://hazardex.com/protection/ex-t)

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## Navigation

- Parent: [Protection Concepts](https://hazardex.com/protection.md)
- Previous: [Non-Sparking - Ex n](https://hazardex.com/protection/ex-n.md)
- Next: [Protection by Enclosure - Ex t](https://hazardex.com/protection/ex-t.md)