Does coax ethernet work during power outages?

September 9, 2022 8:13 AM

My Comcast/Xfinity internet service is delivered via coaxial cable ethernet. If my router & PC are plugged into a backup power supply will I still have internet access during power outages? Or does your typical home power outage also shut off coax-supplied internet service?
posted by mono blanco to Computers & Internet (12 answers total)

There is electrically-powered equipment "out in the field" (hanging from overhead cables or located in ground-mounted enclosures) which needs power in order to keep your cable service working. So, it depends on whether the power to this equipment is out, not just whether the power to your house is out.

In most places [edit: speaking only about the US], the cable field equipment power supplies are backed up by batteries designed to run the equipment for 4 hours (plus or minus). In some areas with frequent power outages and/or reliability regulations from state or local government, larger battery banks and/or combustion generators are used to provide longer runtime during a power outage.
posted by Juffo-Wup at 8:17 AM on September 9, 2022 [2 favorites]

Best answer: Mine continues to work during a power outage, I have coax-in cable and internet; my wifi on battery backup in my house still works fine, and I can still watch cable TV on my battery-backuped cable box and TV. It's kind of disconcerting when all the lights go out but the TV is uninterrupted.

If the equipment on the other end of the wires/fiber has power, either due to the provider having backup power or the outage being local, then there should still be signal at your house.

But, YMMV depending on your service provider and how bad the power outage is.
posted by AzraelBrown at 8:31 AM on September 9, 2022

Best answer: YMMV, but I have kept up my xfinity connection during a localized power outage for a about two hours until my UPS batteries died. It worked well enough that I'm contemplating a larger UPS.

Though all bets are off depending on how large the power outage is and what's affected.
posted by RonButNotStupid at 8:33 AM on September 9, 2022

In my experience, even when power is out in my entire town, cable internet still works as long as you have power for your own modem. I don't know how long the cable company's backup power is good for, but certainly hours.
posted by ssg at 8:44 AM on September 9, 2022

Unless your router is an all-in-one modem+router, don't forget to plug your modem in the battery backup too.
posted by dlwr300 at 9:25 AM on September 9, 2022

My fiber internet's field equipment hut gained a small utility generator last year when there was a prolonged multi-day outage on that block, but generally there's service during brief interruptions. My home network's crazy layout means we have to have like 4 UPSes to keep it all powered, though.

It's not guaranteed like it was during the plain old telephone service era, but they seem to recognize they're still covering the same services and maybe need to meet the same criteria before it becomes a legal requirement?
posted by Kyol at 9:29 AM on September 9, 2022

In my area, the cable is tied to a local grid that had some sort of problem whenever there was severe weather. I made it about 2 months with cable before I switched to fiber like I had before as the grid went down so frequently. I don't know if they just had it powered by the local power company so lines would go down easily or what. The fiber being underground locally makes it a bit more robust in local power outage events.
posted by crunchy potato at 10:22 AM on September 9, 2022

As other said, it should work.

One wrinkle: if you have fiber going to a junction/converter box somewhere on or outside your house, and your coax actually comes from that box rather than coming from the curb or whatever, then make sure this box has a UPS too, in addition to anything you put on your modem.
posted by StrawberryPie at 3:25 PM on September 9, 2022 [1 favorite]

Yeah, StrawberryPie had my BUT because I live in an apartment and would bet that back in the closet is a fiber to cable converter thingy that I doubt is blackout power backed up. They don't have 18 cables running from the pole to apartments. Maybe they have a bit of a battery backed UPS in that closet but I doubt it.

Let me not tell you about managing 1k+ UPSs and the hair pulling nightmares of getting them all replaced on schedule. That's why I doubt there is one in the back room wiring closet of my apartment. Haven't tested, I just use a tethered phone for internet during outages.
posted by zengargoyle at 11:45 PM on September 9, 2022 [1 favorite]

If the ISP has proper battery backups, it will work, but I can tell you from personal experience that Spectrum does not necessarily have those.
posted by Candleman at 4:42 AM on September 10, 2022

When we have power outages, Comcast internet generally goes down as well. This is a residential neighborhood; areas with commercial service may have better luck.
posted by coldhotel at 5:01 AM on September 10, 2022

Some Comcast Xfinity Modems have an UPS option, that will stay on, but it is designed to stay on only to keep the VOIP working. Internet is not supposed to work during a power outage.
posted by kschang at 12:38 AM on September 12, 2022