If they are in violation of OSHA regulations, you can report them and refuse the work. There are whistleblower laws that prohibit them from firing you in retaliation. They might violate those laws and fire you anyway for blowing the whistle or for refusing unsafe non-compliant work. If they do, you could get a lawyer and pursue a wrongful termination suit. Depending where you are, municipalities get sued all the time and lose a lot and pay substantial settlements. Juries are not too sympathetic to municipalities. The bureaucrats that work for the city / township / borough don't care that much, it's not their money.
Municipalities often don't have a real squared away HR department that tells them how to do things without getting sued. If pushed, the municipality could decide to just outsource work on that switchgear to contractors and pay whatever OSHA fines they have to for work done to date. If they do that, they might decide they can get rid of one electrician to offset that cost - that might be you. That might cost them much more, but government employess couldn't possibly care less. So you'd be out of a job and no lucrative lawsuit to pursue. Then six months later they might decide to restructure their maintenance department, bring that work back in house, and hire someone for a slightly different position - one that you're not qualified for, but their cousin just so happens to be a perfect fit.
Go to a lawyer. Get a LETTER registered and sent to the appropriate entity
You might want to consult with a lawyer in advance in case they take retaliatory action. The lawyer can advise you about dotting your i's and crossing your t's when you refuse work so that you have a a strong case in case they do fire you in retaliation. You can also have the lawyer contact them in writing as
@LGLS said above. Sometimes people will clean up their act when you shine a light on things. If they know there's a lawyer involved, they know there's a chance they may have the headache of defending a lawsuit, even if the money doesn't come out of their pocket. They may very well decide that buying an arc flash suit to shut you up is less trouble and again, not their money.
Also very important, the lawyer can advise you if push comes to shove and you sue them, what it would cost you to pursue this kind of lawsuit, what your odds are of winning, how much you'd stand to win, and how long it would take before you see your money. The municipality's (or their insurance company) could offer a very small settlement and if you don't settle, drag out your case as long as they can.
If you get fired, right or wrong, win or lose, the next day you'll have to find another job and explain to prospective employers that you were fired for refusing unsafe work.
A lot of small government bureaucrats are good at getting rid of people they don't like without firing them and without getting themselves in trouble. Just doing whatever they can to make sure your job is as miserable as possible. Be prepared to get called in on Thanksgiving for bullshit, getting the worst truck, getting the worst jobs, getting no overtime, etc.
All that said, this is the most important thing:
First and foremost, if you don't feel safe, refuse the work.