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Dust in Electrical Equipment: A Hidden Hazard

Dust in Electrical Equipment: A Hidden Hazard

For a lot of people, dust is an inconvenience that just needs to be cleaned up. If you’re an electrician, though, you know that a significant amount of dust can be something much more dangerous. Under the right conditions, certain fairly common types of dust can actually catch fire. As if that wasn’t bad enough, there are even conditions in which the dust can explode!

Electricians need to take extra care when dealing with dust. While it may be tempting to just blow the dust out of certain pieces of equipment, if precautions aren’t taken, then something this simple can lead to a major blow-out. This danger is why flammable dust is used to define Class II hazardous locations by the National Fire Prevention Association.

Is Dust Really Flammable?

To answer this, stop and think about some of the most common types of dust that you encounter on the job. In many cases this dust is either made of powdered materials or is finely-ground sawdust. Some powdered dust isn’t very flammable; these materials aren’t likely to cause an explosion. If the material that the dust is made of is flammable, however, then that means the dust itself is flammable as well.

To make matters worse, each particle of dust has a very large surface area for its size. This means that almost the entire particle can burn at once, resulting in a very fast flash fire. This fire can spread from one dust particle to the next, burning through an entire room full of suspended dust particles in a matter of moments.

Dust in Electrical Equipment

This flammable dust presents a significant danger if it’s allowed to build up in electrical equipment. As dust collects inside the equipment, there’s also a possibility that the equipment itself could be damaged. Built-up dust can trap heat within the equipment, increasing the likelihood of components overheating or suffering from heat damage. If dust manages to collect on exposed wires or circuit boards, it also presents a danger of short circuit. Given that the short circuit would ignite some of the dust, this is a pretty bad position to be in.

The Dangers of Blowing Out the Dust

Collected dust can be difficult to remove, which is why some find it tempting to use compressed air to blow the dust out. Unfortunately, doing so creates two potentially significant problems.

First of all, blowing the dust out with compressed air circulates the dust into the air much more than other methods. This creates a much more ideal environment for a flash fire and also redistributes the dust so that it can collect elsewhere.

Second, the rapid movement of air over some surfaces can actually build up a slight static charge. If this charge is discharged onto nearby equipment, then it can create a small spark. Even though it isn’t a flame, that little spark could potentially be enough to ignite dust in the air and cause a flash fire or explosion.

Proper Dust Removal

Before removing any dust, affected equipment should be shut down and any power within their systems should be discharged. PPE should be equipped to ensure that you are as safe as possible when cleaning. OSHA requires that cleaning methods that do not generate dust clouds be used, with the most common being the use of a vacuum that’s approved for dust collection. Dust collection systems and high-quality filters can also be installed in the HVAC system to minimize dust buildup.

Have you ever seen a dust explosion, either in person or online?

ElectricianTalk.com

2 Comments

  • Very informative article. Although I have never witnessed a dust fire or explosion, I have often seen large deposits of dust buildup in many of the appliances I service. I will definitely think twice about using compressed air to remove any dust, thank you for clarifying that, I had no idea how much of a threat that could impose. Prevention of dust buildup could extend the longevity of electronics, from my experience this is the most overlooked area of maintenance.

  • Richard Tomkinson says:

    I didn’t witness it, but we got a contract one time to replace three 15KV switches and five 2,000KVA substations because of dust. The dust had built up over decades to the point it was causing arcing between the busses and tripping breakers. The on-call maintenance person was HVAC guy, not an electrician, and he kept resetting the breaker. Apparently, after he reset the breaker for the 4th time in one shift, it blew up. Massive hole in the front of the breaker can.

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