When open flames must be used in manholes, the following precautions must be taken to protect against the accumulation of combustible gas:

1. (1) A test for combustible gas must be made immediately before using any open flame device.
2. (2) A fuel tank (e.g., acetylene) may not be in the manhole unless in actual use.

3. (3) Open flames must not be used within ground tents or on platforms within aerial tents unless:

   1. (a) The tent covers are constructed of fire resistant materials; and
   2. (b) Ventilation is provided to maintain safe oxygen levels and avoid harmful buildup of combustion products and combustible gases.

[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, and 49.17.060. WSR 20-20-109, § 296-32-23534, filed 10/6/20, effective 11/6/20. Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 49.17.060, and chapter 49.17 RCW. WSR 17-20-069, § 296-32-23534, filed 10/2/17, effective 1/1/18.]