Low voltage is a term we commonly see in the Explosion Hazardous world, although it is not actually an explosion protection topic. This is, however, a hot topic for confined spaces which may or may not have Ex-rated areas, but almost always include an increased risk of electrocution.
When we talk about low voltage, what we are actually referring to is technically classified as ‘extra-low voltage.’ According to the international standard IEC60364-4, anything below 50VAC (or 120VDC) is extra-low voltage, or what we commonly call just ‘low voltage.’
The IEC60364 standard uses the ‘extra-low’ term because it also addresses ‘high voltage’ (over 1000VAC) used, for example, in electricity transmission, and ‘low voltage’ which covers, for example, typical mains voltages in the 110-200VAC range.
In a confined space, anything conductive becomes an immediate risk if there is electrical current in the area. That is the risk addressed by low voltage equipment. But it is worth repeating: low voltage is not the same as explosion protection. Ex-certified equipment can be high, low or extra-low voltage. Low (extra-low) voltage in itself is not inherently safe to use in Explosion Hazardous Areas.