(A) No employee shall be required to enter into any confined space unless a confined space entry procedure, incorporating one of the following, is used (see appendix to this rule for recommended entry procedures):
(1) Air sampling shall be performed by qualified, trained personnel prior to and periodically during occupancy to determine that the atmosphere within the confined space contains an adequate quantity of oxygen (nineteen per cent), and any known or expected harmful atmospheric contaminants have been diluted to safe concentrations.
(2) A supplied-air respirator or self-contained breathing apparatus is provided and used.
(B) When the confined space has been exposed to, contained, or is likely to have combustible gases within its confines (such as sewage treatment plants), it shall not be entered unless the atmosphere contains a concentration of less than ten per cent of the lower explosive limit, (see rule 4123:1-5- 99.1 of the Administrative Code).
(C) Appropriate control measures, which may consist of forced or natural ventilation, use of personal protective equipment, a combination of these, or other effective control techniques, shall be instituted if tests under paragraph (A)(1) or (B) of this rule indicate that the atmosphere in the space to be entered contains:
(1) Any concentration of flammable vapor or gas ten per cent or greater of the lower explosive limit; and/or,
(2) A hazardous concentration of any known or expected toxic contaminants; and/or,
(3) Less than nineteen per cent oxygen.
(D) Means of safe entry and exit shall be provided for entering or leaving a manhole, vault or other similar underground area.
(E) Where electrical equipment is used in confined spaces subject to combustible atmospheres, the permanent fixtures to which the lamp socket and plugs are attached shall be the type approved for that location. All extension cords shall be made of heavy duty cord. All lamps shall be guarded.