Air pressure in electrical box?

Just curious. We have a standard green electrical box outside of the library I work at. It has the usual cautions about electricity. What I don't understand is why it has a sticker saying "Caution: Relieve Tank Pressure" on it. Is there usually high air pressure in an electrical box? Or are some kids sticking random stickers on the box? Just a minor curiosity. Never looked inside one to know.

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  • fuzzy
    Lv 6
    7 years ago
    Favorite Answer

    in a hazardous area electrical circuitry can pose an explosion hazard (sparks & explosive atmosphere are an exciting combination) In these cases sometime the wiring is enclosed in a sealed pressurised enclosure to keep the explosive gases away from any potentially arcing electrical components. I doubt that your library falls into this category but the box may well have been left over from another job (or some random sticker fitter has struck)

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