Thanks for all the feedback everyone; I got restricted from replying after 5 posts in 24 hours (guess because I'm a noob?) Anyway, glad my predicament could provide some lively discussion!
To answer a few replies:
No. Nor would you (or your tenant) have any viable legal claim. Nothing in your post indicates that the fiber optic line wasn't working just fine until the contractor you hired caused damage. Why on Earth should the internet provider fix the contractor's damage for free?
Let me try an analogy here. I hire Fred to build a pole barn. Fred, being a paid contractor, is legally obligated to follow building codes for his work. But instead of using the 3/8" plywood for the roof decking as required by local codes, he cheaps out and uses 1/4" sheathing instead.
Next month I hire Alice to install a solar panel on the roof. When she steps on the roof, her foot goes through the flimsy decking.
Is Alice at fault here? The barn was "working" before she got there. Just because it's working, doesn't mean it was done correctly. In this case, Fred is at fault for not following the proper code. I'm not going to go after Alice to fix something that wasn't done correctly by Fred, even though technically she's the one who "broke" it.
That's what happened here. They didn't install it according to code, and therefore they're liable for it being damaged too easily. Much of the electrical and building codes are there exactly for this reason: to protect the next person who has to work on/around/near it, so that each tradesperson can assume that the work was done in a uniform, standard, safe way.
Here's a good summary of some of those rules:
https://www.ecmweb.com/national-ele...nec-and-optical-fiber-cable-and-raceway-rules
A couple key provisions here are that "you must install equipment and cabling in a neat and workmanlike manner", and for exposed cables "ensure the cable will not be damaged by normal building use". Routine repairs and maintenance fall under "normal building use".
Another point or maybe not, we are talking about fiber here, not copper wire. Do local wiring codes even apply if they haven't been updated for fiber?
That's a great question & was the part I was unsure of. The National Electric Code has rules for fiber optic but I didn't know if my state/locality adopted that part yet.
This work was clearly shoddy though. They had about a 10-foot length of the fiber optic hanging underneath the gutter without any support or brackets, then it ran from the gutter to the ground, again w/o support, then was halfway-buried along the side of the house until it got to the service box.
Getting an expert to admit that the job was not "installed in a workmanlike manner" under cross-examination (I had photos of the entire run) would certainly not have been difficult.
It would be highly unusual to use conduit behind siding. I spent a long time running fiber data cabling over the years. It doesn't sound like the break had anything whatsoever to do with the fact the cabling wasn't in conduit. It sounds like despite being "careful" he didn't know what he was doing an "stretched" the fiber. Next time, consult AT&T or a qualified person to move the ONT rather than letting some siding guy touch it.
Agreed for the part behind the siding & yeah it's a good point about letting the AT&T guy move it. But as I'm sure you're aware, they must also provide a length of free cable ("service pull") at the entry box, which wasn't done and is likely the reason why it was stretched.
A demand letter to ATT to fix it might possibly get something. They have the same problem- fix the low cost problem or pay an attorney a lot more. It may cost them less to just fix it and keep everyone happy.
Yeah, that was my plan.. send them a letter with photos of the unsecured wiring, specify the sections of the NEC which were violated, and ask that they refund my tenant for the repair.
However, after all that is said and done, it turns out the story has a happy ending. The AT&T guy showed up, took one look at the mess of an install & agreed it was done poorly, and wrote up the order in a way that the tenant wouldn't get charged for it, not even the dispatch fee.
Thanks again all, I really appreciate all the viewpoints!