hot comcast cable.

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stew

Senior Member
k And t house built in around 1920 or so. new tenant in upper unit which is fed by its own panel and service. went to plug the comcast cable together and blew off the cable end. Cant figure out where the voltage may be getting into the comcast system . only happens if the tv is plugged in. somehow there is a voltage loop that i cant see coming from somewhere. The only thing thats been done in the unit is thier was a very recent plumbing retrofit. not sure if they used copper or pvc. Even with that said I still cant figure out where this voltage comes from. any brilliant ideas?
 

hurk27

Senior Member
Lost service neutral, and this shows up even more when you only have a 120 volt service, the cable is connected at the pole MGN and bonded at the house, I have seen one almost cause a fire when the demark melted right off the back of the house, because all the neutral return was going through the cable.
 

hurk27

Senior Member
you might also want to check the receptacle polarity where the TV is pluged into, make sure its not a bootlegged neutral to ground 3-prong on a ungrounded system, run an extention cord to a known good receptacle and check between this cord and the recptacle to make sure the hot is on the hot side of the recptacle, if its on the neutral side and they have jumpered the EGC to this neutral it will now be hot, the cord on the cable box is a 3-wire and will put that 120 volt hot at the cable shield.
 

stew

Senior Member
bad neutral never crossed my mind thanks. this is a service with seu tapped to the utility conductors and attached to the side of the house pretty ratty at best. also one fuse seems to run the entire unit or at least most of it. the other fuses arent doin anything. leads me back again to your suggestion of bad neutral.
 

cadpoint

Senior Member
Location
Durham, NC
Is there a good 3 prong plug in bath room, or where ever that plumbing service was done? I'd checked for a voltage from prong to water pipes and if cast pipe on that as well, all pipes could go out of the house as a source well except HW pipe...

If the TV wall backs up to the drain wall, the plumber smoked the wiring, or rubbed something open...

JWAG...
 

stew

Senior Member
Checked the neutral balance and right on half and half with range lites etc working. Decided to scab in a clean circuit and guess what, my tic tracer now doesnt lite up on the comcast ground shell!! As soon as i plug the tv into the old circuit the shell lites my tester up like a christmas tree. (did this with just the cablle connnected to the tv and loose from the wall connection). Plug the tv into a clean grounded temp circuit and all is well. Found out also from the owner that the house was just reroofed. Got a hunch that maybe the roffers inadvertently may have damaged the circuit somehow.I am currently up grading this system with 2 new panels and a 2 pak meter service. Have talked the owner into replacing at least most if not all of the kt stuff. May leave the switch legs intact but thats about it.
 

hurk27

Senior Member
Checked the neutral balance and right on half and half with range lites etc working. Decided to scab in a clean circuit and guess what, my tic tracer now doesn't lite up on the comcast ground shell!! As soon as i plug the tv into the old circuit the shell lites my tester up like a Christmas tree. (did this with just the cable connected to the TV and loose from the wall connection). Plug the TV into a clean grounded temp circuit and all is well. Found out also from the owner that the house was just re-roofed. Got a hunch that maybe the roofers inadvertently may have damaged the circuit somehow.I am currently up grading this system with 2 new panels and a 2 pak meter service. Have talked the owner into replacing at least most if not all of the kt stuff. May leave the switch legs intact but thats about it.


Thats why I brought this out in my second post, I have seen where someone changed out the old two prong recepts to 3 prong but because of the old cloth covered wire couldn't tell which was neutral and got it backward and used what they thought was a neutral but was in fact a hot to bond the EGC to, same set up, Comcast tech said he had a foreign voltage on the grounding which turned out to be the grounding conductor was tied into the hot as was the neutral was on the small blade of the receptacle. now tracking down this connection will be fun.:grin:

Edited to add: Oh just to point out using the neutral is against code and very dangerous for this very reason! a very good way to get someone electrocuted touching a hotted EGC. not implying it was your work but people need to know this.;)
 
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qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Sorta retired........
Thats why I brought this out in my second post, I have seen where someone changed out the old two prong recepts to 3 prong but because of the old cloth covered wire couldn't tell which was neutral and got it backward and used what they thought was a neutral but was in fact a hot to bond the EGC to, same set up, Comcast tech said he had a foreign voltage on the grounding which turned out to be the grounding conductor was tied into the hot as was the neutral was on the small blade of the receptacle. now tracking down this connection will be fun.:grin:

Edited to add: Oh just to point out using the neutral is against code and very dangerous for this very reason! a very good way to get someone electrocuted touching a hotted EGC. not implying it was your work but people need to know this.;)

I'm with Hurk, I've seen it myself. bootleg was in the box tv was hooked to so it was rather easy to correct.......
 

ronaldrc

Senior Member
Location
Tennessee
I got a service call about 10 yrs. ago a the man said he got the crap knocked out of him when he set
his alum. ladder against the gutter to clean them.

But to make a long story short the hot circuit in his cable converter box got in contact with the cable box chassis
or the metal enclosure.It had made all the guttering and metal soffix 120 volt to ground.

Most metal enclosure with electronics inside just have a capacitor from the circuit board common to the metal enclosure. The electronics will work just as well with it hot as long as it doesn't see enough voltage drop to hurt it.
 

chris1971

Senior Member
Location
Usa
Had it where the exterior connection of the #12 ground wire for the cable was melting. Final outcome was that the POCO had a bad connection of the neutral in the triplex which was laying on a pine tree branch. The bare neutral rubbed on the branch until it wore through.
 
T

taylorp

Guest
. . . . Have talked the owner into replacing at least most if not all of the kt stuff. May leave the switch legs intact but thats about it.

Stew: You might want to review the 2011 NEC on switch legs. As I understand it, the 2011 code will require a neutral to be present at the switch location if the switch controls a lighting load that uses a neutral. Sorry, I am waiting for my 2011 NEC to arrive in the mail.

I think it says this:

(2011 NEC)

404.2 Switch Connections.
(C) Switches Controlling Lighting Loads. Where switches control lighting loads supplied by a grounded general purpose branch circuit, a grounded circuit conductor shall be provided at the switch location. [ROP 9-95]

We adopted this practice late last year because of all the electronic switching devices now being sold, which require an "ungrounded" conductor in the switch "leg" in order to work properly.

This info might save you from doing double work later on.

Someone who has an actual copy of the 2011 NEC may correct me if I am wrong on this subject.
 
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