Should I be worried about this? (Burned cable)

Our cable went out Thursday night, when we replaced an old TV with a new one. The cable guy showed up the next day, said he thought it was probably a short, not related to the new TV. Our cable wire is fastened along the wall, on the floor, underneath our carpet along the entire periphery of our living room.

He pulled up the carpeting, and what he found was this. In case it’s not clear from the picture, the casing on the cable was melted off, what was left of it was bubbled up, and there was charring on the wood floor underneath the cable. Clear evidence that it had been burned (not chewed), and that said burning had apparently happened while it was sitting there underneath our carpet.

Cable guy said he’d never seen anything like it and couldn’t imagine what had caused it. He was so intrigued he took a picture to show to his boss. The section of cable in question was located about two feet away from an electrical outlet, in front of a window near our front door. There were no obvious heat sources anywhere near it and never have been as long as I’ve lived there.

The cable was replaced so we have our TV and internet again, but I’m not sure this is something I should just forget about. I’m concerned this may be an ongoing fire hazard and am thinking about reporting it to my landlord.

What could have possibly caused something like this? Could it in any way be related to the new TV? It went out exactly, and I mean exactly when we made the switch. We’d been having touchy internet prior to that but nothing like a complete cable failure.

Most importantly – could this happen again? If so, how do I prevent it?

Thanks!

Christy

Might want to consider this advice which might also apply to your scenario if you have a hot ground looking to earth itself.

Looks like lightning damage.

Came in through the cable and discharged through the floor. You’re supposed to be protected by a grounding block outside of your home that has a screw connection and two female “F” connectors. The screw is for a wire that is supposed to go to a good ground - copper water pipes or a grounding rod. But usually the cable company installers don’t know a good grounding location from a bad one.

For instance, they might have connected to an outside faucet. But if you have plastic piping in your home (Pex), the brass faucet is not a ground connection, and a grounding rod should be used instead. There is one that your electrical panel connects to already.

My first thought was what is called an “open neutral” which is where the neutral connection in your home has lost its connection to earth ground. This is basically what the guy in astro’s link is describing, though he incorrectly calls it a “short”. This can be very dangerous and can electrocute people or cause your house to burn down, so you should get a qualified electrician (not a cable TV guy) to take a look at it ASAP.

My second thought was lightning damage, as gaffa said. An electrician can check that out too while he’s there.

My third thought is that someone has the wiring completely backwards at some point in your house and the cable’s “ground” connection inadvertently connected hot to neutral until something (in addition to the cable insulation) burned out. An electrician should be able to find that kind of fault too.

You are very lucky your new TV wasn’t toasted.

Since there is a landlord involved, tell him that an electrical engineer (me) has reviewed your symptoms and thinks that an on site inspection by a qualified electrician is a very good idea under the circumstances. That should give you enough leverage to have your landlord spring for an electrician’s service call.

ETA: If the landlord gives you grief about paying for an electrician, send me a PM and I will send you a letter (in writing on real paper, not an e-mail) with my signature on it that you can give to your landlord.

This is a violation of code – wiring should never be placed underneath carpet. And what happened to you is one of the reasons for this requirement.

That was my first thought, too.

Did you just get the newest digital receivers from Comcast? What I am getting at is this: Is your cable box brand new or recently replaced with the newest ones from Comcast?

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my guess would would be it was carrying high current for a long time like an open neutral as mentioned.

lightning can do some spectacular and strange things in a home. though i would expect that if a lightning strike would have melted the jacket it also would have damaged the braid and put burn marks on it and the floor material.

Wow, that is a really thoughtful and generous offer, thanks. I’m away on Spring Break but I’ll have my husband contact the landlord ASAP. I had a feeling this was probably serious business.

Our cable box was installed last August, when we moved into the apartment. So, probably not.

A quick way to check for either of these is to buy an electrical outlet tester. This will plug into an outlet, and little lights on it will light up to tell you if it’s OK, or what is wrong with it. It should cost less than $5 at any hardware store.

You may also wanna check at AVS Forums, it’s a free forum and a lot of techs and engineers post and read there

Are you sure about this? My impression was that anything under 24V was exempt from NEC.

That said, it *should *be a violation.

You should be very happy that you didn’t die in a house fire. You came very close to having no home. Don’t ever put cables under a carpet.

Yes, I’m very happy I didn’t die. I didn’t put the cables under the carpet, I moved into an apartment last August which already had cable installed and had no idea it could be a violation of code or a fire hazard until this thread.

Landlord has been called. I don’t know how long they will take to move on this, but they are sending someone out to take a look.

Good.

under normal circumstances a signal wire/cable under a carpet might not be a violation of code or a hazard, though it would be a bad move because you will possibly damage the wire/cable by walking on it and loose your signal.

it would be possible as discussed that a fault in your power wiring (which you would have noticed if you had set top rabbit ears antenna because the set wouldn’t work or had plugged a lamp in at that location) that caused your cable system coax to become a power conductor which is hazardous especially running under carpet (if it was above the carpet and visible someone may have seen this hazard earlier).

so if you had a power fault like the open neutral there are circumstances that it could have been discovered earlier and circumstances where a fire is your first indication of a problem.

keep us posted.

Just to follow up, make sure you check the ground for the cable. Look at how the cable connects to the building. In virtually every case, it’s the lowest wire on the pole (the top is power, then telephone, then cable). It will attach to the building, there will be a “drip loop”, then the wire comes down the wall and to exposed “splitters” or into a locked box. The cable for the various apartments comes out of that as well as a ground wire. The ground wire should be connected to a metal pipe that connects to the group - the electrical ground of the building.

The problem is that cable TV guys generally don’t know what makes a good ground and they connect to anything that looks like metal, not much worrying about where it ultimately goes. But this wire is to provide a path for lightning to take if it strikes the cable. If the ground wire is not connected to a good path to ground, it’s going to find some path - in this case through your floor.

Personally, I would trace that wire and whatever it is connected to to make sure it winds up in the ground. If it’s not a direct route, I’d drive a grounding rod into the ground and connect the grounding wire to that. As long as there is not any lightning at the very moment you have it disconnected, it’s perfectly safe to move it.

Little update…

Maintenance manager called today.

‘‘That burned cable–let me guess. It was by the window near the front door?’’

‘‘Why, yes. How did you know?’’ (We hadn’t told him where the problem was.)

He said last year, before we moved in, they were replacing windows in our apartment using a blowtorch, and an ember fell on the carpeting in exactly that spot. He seems very certain this is what caused the burned cable, says he was present when it happened, and, without knowing where the burned cable was found, he was able to guess its location. He was willing to come out and take a look just to be on the safe side, but was confident it wasn’t a faulty wiring problem or anything dangerous.

So… I think I feel a little better now.

Thanks for all your input and support here. It is greatly appreciated.

Ya learn something new everday, as my dear sainted Mom used to say. I’ve replaced many a window, but have yet had to pull out the blowtorch.

Why didn’t you notice the burned carpet when you moved in?

My dearly departed uncle used thermite. Nothing cuts you a hole better than thermite he’d say. Slicker than a hot knife through butter.