During an arc flash explosion, anyone who is within range will be exposed to a loud bang similar to a bomb going off. Decibel levels can reach up to 160 and I've often heard this would be comparable to standing next to a jet fighter airplane during takeoff.
In order to ensure protection from the high level of sound, an electrical worker is required to wear ear plugs as part of their arc flash PPE. Usually, these ear plugs are made of foam and when you think about what happens to foam when it's exposed to extreme levels of heat you might think twice before putting them in your ears while working on electrical equipment. I'm here to tell you that this thinking is flawed and you always want to wear ear plugs for this type of work.
Will my ear plugs melt?
Most foam ear plugs will melt when exposed to enough heat energy. Some start to melt at around 5-10 cal/cm2 and some not until 50-60 cal/cm2. Silicone ear plugs seem to be your best bet as they proved to not melt even at energy levels greater than 50 cal/cm2. But here is the kicker...
None of them will melt if properly covered
The reason why this entire discussion is a little unnecessary is because when ear plugs are worn underneath the protection of a properly rated arc flash hood or balaclava they will never melt. This is really all you need to know.
If you were exposed to an arc flash of 50 cal/cm2 and you were not wearing an arc flash hood or balaclava to protect the sides and back of your head and neck then you are going to have much greater problems than a 1-inch piece of foam stuck in your ear.
There should never be a time when you are exposed to an arc flash that you would not be wearing both ear plugs and arc flash head protection. If you've got the correct protection for the arc flash heat energy than you will never have to worry about your ear plugs melting.
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