The Irish police force are currently considering going on strike. Have other police forces ever gone on strike? If so, what were the consequences for public safety?

I don't think this is comparable to the Irish police strike, but since the question is broad, I think this might fit in.

To answer your first question, yes, other police force has gone on strike. The Hong Kong Police Force (HKP) went to strike in 1977. There was about 2000 of them. They marched not so peacefully - and not for good reason either.

So, HKP had always been known for being terribly corrupt, so much that there's this saying that you would need to bribe them even in your death (because you got to have their "permission" to hold your funeral). In 1974, Hong Kong Independent Commission Against Corruption (ICAC) was established. Their first and primary target was HKP.

Long story short, ICAC moved fast and broke things. They prosecuted 272 persons of whom 145 were convicted. Just in the first three weeks, 140 policemen were arrested, including higher officials. Hundreds and thousands name followed through.

This provoked the anger of the remaining police forces, so in 28 October 1977, about 2000 policemen gathered in central Hong Kong. Dressed in civilian attire, they marched to the office of the Police Commissioner. They met the commissioner with a demand loud and clear: stop arresting police officers. But after realizing that meeting with commissioner wouldn't change anything, they go to their primary target. About 100 policemen went out and stormed the ICAC headquarter. They smashed the building, injured several ICAC officers, and threatened to burn down the HQ.

After the disastrous day, fearing that the policemen might go on another strike, in November 5 the Governor of Hong Kong issued amnesty for corruption committed before 1 January 1977 - which means, most of the corruption cases in Hong Kong. The pardon did not extend to higher-level officials, but it freed plenty of police officers nonetheless.

For your second question, since my study is limited to ICAC themselves, I don't know much how dire was the situation in 28 October. But in the next days mass media condemned the strike, dubbed it threatening the corruption eradication progress. Lots of support were given to ICAC, especially so after the governor issued amnesty.

I can't give you a more detailed reading but this is covered in Febari, Corruption Eradication Politics: Hong Kong ICAC and Indonesia KPK (2015). Book isn't in English though.