225 ILCS 705/18.17

In a gassy mine, permissible junction or distribution boxes shall be used for making multiple-power connections in working places or other places where dangerous quantities of methane may be present or may enter the air current, except that where nonpermissible junction or distribution boxes are in use, or on order, on the effective date of this section or the date such mine became a gassy mine, whichever is later, their use may be continued until such time as replacements are made.