I need to install new lighting and old cloth wiring has tested positive for ACM. I am not doing the work myself, I am hiring an electrician but I will let him know what I have found. Is there any special precautions he should take.
Turn off the breaker. Since older wiring often has faults or simply unmarked MWBCs (which cannot be detected by voltage testers), I suggest turning off the main breaker.
For the other risk, look into what Neil DeGrasse Tyson says about "political truths", i.e. if something is repeated often enough the human brain goes "must be true". And obviously, it isn't.
It turns out there actually is a health risk associated with asbestos, but you have to be a career laborer working around asbestos dust. Because of this, companies responsible for such laborers set up trust funds to pay out claims for affected workers. There's a tiny amount of legal work involved in getting a claim. As for publicizing the existence of these trust funds, they decided to leave that to the free market.
The result is dirty lawyers carpet-bombing media with ads trying to identify and retain anyone who worked with asbestos, so they can lock in potential clients, so they can collect a 1/3 contingency fee for ticking a few boxes on some forms.
The side effect of this "feeding frenzy" is triggering that "political truth" that Tyson speaks of. "Surely asbestos must be more dangerous than dioxin, since it gets more press!" ... Occasional, incidental exposure to non-dusty asbestos a few times in a lifetime is simply not a risk factor. At all.
If you really want to, you can wear any quality COVID-spread-prevention mask, and wipe down the work area afterwards.
Lawyers in my field are definitely guilty of what has been said here and elsewhere regarding the profession. What's the joke, what do you call a thousand lawyers at the bottom of the ocean? A good start. Badum bump.
The basic fact is no exposure to asbestos dust should be considered "safe." Your electrician (if he's licensed) will likely already have experience donning PPE for asbestos work. Frankly, I would advise taking precautions with any cloth wiring. But I also wouldn't pretend the sky is falling.
The latency of symptoms from asbestos exposure is decades, 20-to-50 years, and in the vast majority of cases stems from years of contact. At the same time, secondary exposure to asbestos is real. I have clients who were spouses and children of people who worked with asbestos.
Remember, better safe than sorry. Asbestos fibers don't dissolve. There's NO KNOWN safe level of exposure, but, again, it needs to be airborne. Just touching the wire won't hurt you, but taking a belt sander to it would suggest you're a few eggs short of a dozen.