UL 60079-6 2020 pdf download – Explosive atmospheres – Part 6: Equipment protection by liquid immersion “o”.
4.2.2 Requirements for Level of Protection “ob” Electrical circuits and components, when liquid immersed in accordance with this standard, are considered to be not ignition capable in normal operation and during expected malfunctions, and shall be assigned a Level of Protection “ob” (EPL Gb or Mb). A liquid level indication according to 4.7 is required. Switching devices protected by liquid immersion level of protection “ob” shall comply with the following additional requirements: a) When a sealed enclosure is employed, the enclosure shall comply with the overpressure test in 6.1.1 using four times the prescribed pressure. b) Electrical equipment containing switching devices operated in the protective liquid, rated at 2 kVA per contact or less, are permitted without further test. Where the switching device is rated above 2 kVA per contact, neither pressure increases nor excessive decomposition products shall invalidate the type of protection as demonstrated by tests in accordance with 6.1.5. c) The equipment shall be suitable for a prospective short circuit current of 32 kA unless marked with a lower value. 4.2.2DV.1 DR Modification ofClause 4.2.2, thirdparagraph to addthe following NOTEafter item c): NOTE The National Electrical Code®, (NEC®), ANSI/NFPA 70, may limit the use of increased safety terminations to 10 kA available short circuit current. Disconnectors and manual tap selectors, above 1 000 V, shall be lockable and provided with a warning according to 7 i). In addition, information on their use shall be included in the instructions. 4.2.3 Requirements for Level of Protection “oc” Electrical circuits and components, when liquid immersed in accordance with this standard, are considered to be not ignition capable in normal operation or in the case of regular expected occurrences, and shall be assigned a Level of Protection “oc” (EPL Gc).
4.4 Creepage and clearance Electrical circuits and components intended to be immersed in the protective liquid shall meet the relevant industrial requirements for creepage and clearance distances in air before being immersed in the protective liquid. If the relevant industrial standard gives options for pollution degree, pollution degree 2 shall be assumed. 4.5 Liquid containment enclosures 4.5.1 General The chemical resistance against the protective liquid shall be documented by the manufacturer. NOTE It is not a requirement of this standard that conformity to the chemical resistance against the protective liquid be verified. The enclosures shall be subjected to the type tests as specified in Clause 6 for sealed and unsealed enclosures respectively.