Opinion by

It is the duty of all parties using a highly dangerous agent, to use care commensurate with the danger, in order to prevent injury to persons or property exposed to its influence: Fitzgerald v. Edison Electric Illuminating Co., 200 Pa. 540. Cities are not excepted from the rule, and the fact that the agent is used or supervised under the police power does not excuse negligence in such use: Mooney v. Luzerne Borough, 186 Pa. 161. The cases deciding that municipal corporations are not liable for errors of judgment or discretion, rest on entirely different principles.

The wire in this case was a police call wire and broke as early as eight o’clock in the morning. The fact of the break was known to the police officials presumably at or near that time, and according to the evidence certainly as early as nine o’clock. The wire was very lightly charged and not in itself dangerous, but it was a naked wire and strung on poles in close proximity to other wires, some of which carried strong and dangerous currents of electricity. The fact of the break, therefore, was notice that it might become dangerous, and imposed the duty of examination. Whether that duty was properly met under all the circumstances, the lapse of time, the condition and population of the neighborhood, the urgency of the possible danger, etc., was a question for the jury.

The evidence as to the ordinance, police regulations, etc., though not important, was not incompetent. It merely tended to make more clear and definite the responsibility for due care which existed outside of them.

The father saw the wire on the pavement as he went to work in the morning and knew that his son would shortly pass the same place on his way to school. He testified that he avoided stepping on the wire though he did not know whether it was dangerous or not. This was the act of a prudent man. Whether he ought further to have returned to his house which was close *514at hand, to warn his son, was not so clear a duty that the court could declare it as a matter of law. It was a question of reasonable prudence or contributory negligence which was properly left to the jury.

Judgment affirmed.