Coax Cabled Melting

[jarrodk]

I built a new house this past year, and ran two RG6 wires to each room from the basement. I also ran five (5) wires directly from the panel to the location of the satellite. Dish installers came out and hooked up the dish and receivers. About 3 months later (3 months ago), I lost reception. A tech came out, inspected everything (I of course ran the connection tests prior to him coming), checked the grounding connector (four wires coming into it), and found that the copper in the coax cable had melted. He cut the wire, placed a new connector on, and called it an abnormal, one-time occurrence. Needless to say, when I lost connectivity last night, I decided to check the grounding connections. The copper in the coax was again melted. Instead of calling a tech, I decided to purchase a crimper, a new grounding connector, and the coax ends (which cost me less than the service tech visit had they come out).

As I was replacing the connector, I noticed a pretty good spark coming off the RG6 metal sheathing when it touched the metal connector. I only noticed this with one of the four wires.

With my non-existent electrical background, I'm not sure if there is voltage coming through from the dish, from a receiver, etc. Any thoughts and what the problem could be, and if this should be my problem or Dish's problem? Thanks.

 

[RandallA]

The RG6 coming from the receivers has voltage. That's how the lnbs and some switches without PIs are powered by the receiver. When working on connectors always unplug the receivers so there is no power.

As far as the melting cooper, something else is going on with your ground. I would have an electrician check your wiring and ground, just to be on the safe side. A Dish Network will have only basic knowledge about electricity.

 

[8bitbytes]

As far as the melting copper, something else is going on with your ground. I would have an electrician check your wiring and ground, just to be on the safe side.

I second the testing of your house/outlet wiring and what your outside Dish is grounded to - something bad is going on there. Coax doesn't just melt!

 

[primetimeguy]

The copper is melting? Are you sure? I would think if the copper melted the entire jacket would be melted too!

 

[Jared Twomey]

Do you know if you have a DPP44 switch connected somewhere? If so that may explain why just the one wire is melting if there is a power inserter in that line.
But I second the possibility of a ground problem. There is 13-18 volts of dc power being passed through the coax from the reciever to the dish... you should not be melting rg6.
The only other thing I would maybe think is if it is actually rg59, or a really really really cheap rg6 with a really small conductor.

 

[dishdude]

Are you sure it isn't corrosion? It is possible there is a cut in the line and moisture has penetrated and migrated down to the connector, which is most likely the lowest point in the line.

 

[Splicer]

You may wish to check on the LNB. My best guess is that it is drawing way too much power, thus the the braid gets hot , softens the dielectric center conductor covering, center conductor also hot...VOILA!!! Burnt RG6...even if it is quad shield cable. You could use RG11 but that would still soften and melt inside the connector. But what I find amazing is...the receiver actually would put out that kind of amperage without burning itself up/out first.

*EDITED* for using the wrong word.

 

[bhelms]

It's not the voltage of itself that would cause melting, but rather power being dissipated through the conductor, and that is as much a function of the available current. The PI for the DPP44 puts out about 18 volts and IIRC is capable of about 2 amps max. current. If there was a near short (low resistance, but not zero) at the point where the melting is occurring then some part of those 36 available watts would be indeed dissipated at that focal point, maybe enough to cause heating and eventual melting of the insulators. But I don't see where there is anyway nearly enough power available to melt copper unless it is quite thin at that location for some reason.

jarrodk did not specify whether it's the inner conductor or the shield that's melting, but he did mention a spark produced (between the inner and outer conductors?) when attaching the connector, so I do suspect the problem is with improperly installed connectors that are providing some type of short, if not a dead short, at the point where the problem is occurring. This of course could also damage the voltage source, receiver or power insertor, over time.

But I am also worried that there is some other grounding problem in his electrical wiring, and a fault somewhere that is finding a path to ground through the coax. That could present dangerous voltages and currents that the coax should not be handling. This condition should be investigated immediately!

jarrodk - I recommend that you get an electrician in to look into the possibility that your electrical service has a floating ground and/or fault condition that is contributing to this problem. It will cost you a few bucks for an inspection, but that will either correct the (rather serious) problem or provide you piece of mind that it's not in your wiring. Show him exactly what you saw and did and he can render an educated guess. Report back and we can take it from there...