It shall be unlawful for any person who obtains a permit under this subchapter to do any excavation of any kind which may create or cause a dangerous condition in or near any street, alley, sidewalk or public place of the city without placing and maintaining proper guard rails and signal lights or other warnings at, in or around the same, sufficient to warn the public of such excavation or work, and to protect all persons using reasonable care from injuries on account of the same.
('84 Code, § 23-12) Penalty, see § 10.99