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Posted By: jes Communications entrance ground safety - 06/17/08 10:28 AM
Does anyone have a reference to safe practices for a service person working on the entrance protector ground for cable or phone systems? Recent situation where the electrical service neutral was open. Neutral current was returning via the common bonding between electrical system and cable system grounds. Troubleshooter for cable system removes ground wire from protector. Big mistake. Received shock and house now had no neutral return path. Fire ensued.
Looking for any work practices or safety standards that would support more care on the service persons part. Have talked to some folks who use clamp-on ammeter to look for just this problem but that's not universal it appears.
Posted By: earlydean Re: Communications entrance ground safety - 06/17/08 12:29 PM
NFPA 70E Section 410.10
Here's a story related to this. My dad and a (idiot of a) coworker were sent out to a doublewide trailer whose owner said their HBO was tiling. They show up, and my dad just refuses to get out of the truck, since the lights are flickering and dimming. So, while he calls the POCO since he knows what the problem is, his coworker goes up to the trailer and knocks on the door. Old aluminum sided-trailer, he gets shocked and thrown back 25 feet. Now, I guess in an attempt to warn the homeowners, he does it again, and wakes up by the tree, again. Now my dad puts a pair of insulated gloves on, finds the pedestal, and turns the power off. He looks at the cable ground, and what do you know, it's black and burned quite nicely. He disconnects the one cable just as the POCO shows up. Their guys open the pedestal, say everything is fine (mind you the HO is now hovering over everyone's back now that the power and the HBO is out), and they close the pedestal and turn the breaker on. Big arc from the two pieces of cable until my dad moves it aside. POCO guy says "Okay maybe there is a problem..."

Moral of the story? One, don't touch a house with AL siding if the lights are flickering. Two, it also uses the cable itself (although the fact the cable was "grounded" to one of the siding screws didn't help.) Three, people don't pay any attention to anything but the TV. Four, there are some good, competent cable techs out there, so long as they are the older vets from the pre-monopoly (read: Comcast!) era.

Ian A.
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