Common explosion protection types for electrical equipment are shown in the table, as well as combined protection types formed by the combinations listed within the table.

Example: Ex demb indicates that the explosion protection types of the electrical equipment include Flameproof (d), Increased Safety (e), and Encapsulation (m), representing a hybrid explosion protection structure.

Risks in Confined Spaces

1. Oxygen concentration below 19.5% (oxygen deficiency) or above 23.5% (oxygen enrichment);
2. Flammable gas or vapor is above 10% of its Lower Explosive Limit (LEL);
3. The ambient air concentration of any toxic contaminant exceeds the Permissible Exposure Limit (PEL) allowed by OSHA – Occupational Safety and Health Administration;
4. The concentration of combustible dust mist in the air is sufficient to obscure vision within a distance of 5 feet or less.
5. Any ambient atmosphere that is Immediately Dangerous to Life or Health (IDLH), which may pose a threat of immediate loss of life, cause irreversible, immediate, or serious health effects, or cause eye irritation, allergies, or other conditions that could affect a person's ability to escape.