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This website publishes administrative rules on their effective dates, as designated by the adopting state agencies, colleges, and universities.

Rule 4123:1-5-22 | Confined spaces.


(A) No employee will 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 will be performed by qualified, trained personnel prior to and periodically during occupancy to determine that the atmosphere within the confined space contains an adequate concentration of oxygen (minimum of nineteen and one-half per cent to a maximum of twenty-three and one-half per cent), and any known or expected harmful atmospheric contaminants have been reduced 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 will not be entered unless the atmosphere contains a concentration of less than ten per cent of the lower explosive limit.

(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, will 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 and one-half per cent oxygen.

(D) Means of safe entry and exit will 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 will be the type approved for that location. All extension cords will be made of heavy duty cord. All lamps will be guarded.

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Last updated September 1, 2023 at 9:25 AM

Supplemental Information

Authorized By: 4121.12, 4121.121, 4121.13
Amplifies: 4121.47
Five Year Review Date: 2/1/2027
Prior Effective Dates: 1/1/1986, 4/10/2011, 6/1/2016, 2/1/2022