Arc blasts are an ever-present danger around electrical equipment. Unlike your high school reunion blast from the past, this is not the kind of blast you want. If you aren’t particularly worried about arc blasts, consider these facts:
- The temperature generated by an arc blast is four times hotter than the sun’s surface. It vaporizes anything in its path, even your blast suit.
- The pressure wave can kill just by percussion, even if you’re sufficiently away from it to not be incinerated. Your blast suit cannot protect you from this.
- The blast can force molten steel (from switchgear) and copper (from conductors) through your skin and into your bones and organs.
You can reduce the odds of an arc blast, but you must also be prepared if one happens. Among the PPE requirements are earmuffs, not just foam earplugs; the percussion, even if you’re not directly in its path, can permanently destroy your hearing.
To reduce arc blast risk:
- Before opening a service gear breaker, shut off the smaller loads (the branches) and work your way up the distribution to each feeder. As much as is humanly possible, never open or close a breaker under load.
- Part of removing loads is to de-energize the connected equipment and lock/tag it out. Ground it if possible.
Use test equipment rated for the energy level you would expect to encounter if the equipment were energized. Connect one lead at a time.
Source: Mark Lamendola | Mindconnection