---
title: Modification of Flameproof Enclosures
description: "Flameproof enclosures are supplied complete with all internal components fitted and certified as a single entity by a recognised test authority. The testing procedure will take into account the **free** **internal volume** after all the components have been fitted, the…"
url: "https://www.eicstech.com/kb/flameproof-ex-d/basics-on-the-modification-of-flameproof-enclosure/"
updated: "2022-06-01"
category: Explosion Proof Basics / Flameproof (Ex d)
---

# Modification of Flameproof Enclosures

Flameproof enclosures are supplied complete with all internal components fitted and certified as a single entity by a recognised test authority. The testing procedure will take into account the **free** **internal volume** after all the components have been fitted, the **temperature rise** (determined by the maximum power dissipation), **creepage and clearance distances**, and the **rise in pressure** as a result of an internal explosion using a gas/air mixture in its most explosive proportions.

The certification effectively “freezes” the design of the equipment so that **any unauthorised** **modifications will invalidate the approval/certification**. Therefore, the following points should be observed.

- **Replacement of components should always be exactly the same** as the original specified components in order to avoid infringement of the certification. A component larger or smaller than the original will affect the internal geometry of the enclosure. Pressure piling is a possibility if a larger component is fitted, and increased volume will result if a smaller component is fitted.

![modification to a flameproof enclosure](https://www.eicstech.com/wp-content/uploads/2022/06/improper-modifications-to-flameproof-enclosures.png)

- **Adding components is also forbidden**because of the possibility of increased explosion pressure as a result of pressure piling.

- **The removal of components must also be avoided** since an increase in the free internal volume will result. The original test results, prior to certification, would be compromised as a result of a modification such as this.

**Some other unauthorised modifications**

- Use of wrong size / type of hole sealing plug
- Use of wrong size / type of cable entry gland
- Misuse of constructional screws or bolts
- Attaching cable brackets using cover fixing bolts
- Drilling holes
- Adding / removing gaskets
- Using hardening sealants or tapes
- Changing layout of components
- Adding additional components
- Removing or omitting components