Group:
US Calif here. Do the wiring regs require that Cable and Telco services are bonded to the electricity ground. It seems that my telco has it's own ground (a wire disappears into the earth!), and the catv service is bonded to an electrical conduit (but not the the ground stake itself). Any advise for getting them changed to comply with wiring regs at no cost?
Cheers
Den
Yes. Article 800 of the NEC (national electric code).
Good luck. The telco does whatever the hell it wants because they only answer to the Public Utility Commision, and they know the PUC doesn't care about residential grounding. The local electrical inspector also has some jurisdiction, but he won't want to get involved. Perhaps he has no real enforcement authority over the phone company? I went through all this a couple of months ago. I ended up grounding the NID myself, and I had to argue with the telco billing office for about 20 minutes when they tried to charge me for a service call when they sent someone out who just told me "I checked with my supervisor and we don't do that" and left.
BTW, bonding to the metal *service conduit* is specifically allowed by the NEC and is about as good as bonding to the grounding electrode system, so your CATV is likely OK.
Best regards, Bob
Yes
It seems that my telco has it's own
Trust me the Telco did not drive an ground rod. They bonded to something already there when they showed up. Maybe just lower on the riser. Which could be bad for you if they removed the tape protecting the conduit. Put an ohm meter on the wire for the Telco and the ground for the electrical service or the catv ground. If it reads less than 5 ohms "forget about it." If it is less than 25 ohms it might need some investigation. Over 25 start digging.
Numbers sited are just educated guesses. Personally I have never checked/measured one.
Call 'em and ask. The NEC now mandates bonding to the electrical service ground, but if your installation was before the change (1996?) then the change won't happen until the line is serviced for some reason. Locally, both cable and telco will do this anytime there needs to be work on the connection, even if it's a test for fuzzy picture/bad sound.
Jeff
This is far from a new change. It has been in the code since 1975 for sure,
800.13(b)(5) (the oldest book I have) and it was not new then.. The language and location in the code may have moved around but the requirement that all grounding electrodes on a premisis be bonded together has been consistantIn article , snipped-for-privacy@aol.com (Greg) writes: | >The NEC now mandates bonding to the electrical | >service ground, but if your installation was before the change (1996?) | | This is far from a new change. It has been in the code since 1975 for sure, | 800.13(b)(5) (the oldest book I have) and it was not new then.. The language | and location in the code may have moved around but the requirement that all | grounding electrodes on a premisis be bonded together has been consistant
The thing that changed around 1996 was the ability to use the grounded metal water pipe for the interconnection of grounding electrodes beyond a few feet from the pipe's entrance to the building. Before the change you could drive a local ground rod for your antenna or communications protector and connect both the protector and the rod to any convenient grounded water pipe. After the change you could still connect the antenna or communications protector to any convenient grounded water pipe, but not if it had a local ground rod. The local ground rod now requires its own #6 or larger bonding wire to the system ground (e.g., another bonded grounding electrode, the EGC, etc.) much like any other grounding electrode in the grounding system. Since this can mean stringing a #6 wire half way around a house in some cases, the requirement may act to discourage the use of an (otherwise good IMHO) local ground rod. :(
From some comments I've read here it appears that post-1999 code may no longer allow the antenna or communications protector to be connected to any handy grounded water pipe anymore (even if there is no local grounding rod). That would put things back on an equal footing, though I suppose you are still permitted to use thinner wire if there is no local ground rod.
Dan Lanciani ddl@danlan.*com
I had a similar experience. I have a 625ft run of D.E.B. telephone cable from their service box to my residence. I had several modems go bad during thunderstorms so I called them to check the grounding. The ground point was the service box and they would not drive a ground rod at the residence. Case closed from their viewpoint. I drove my own ground rod and connected it to their cable. Problem solved - no damage for the last 2 years now. Bob S.
Hi, Here in Calgary, Alberta where I live all cables are underground and grounding is altogether to electrical ground. No separate grounding. Tony
You should know that the actual wire pair just isn't bonded to anything. It does go through a protection network that would dump voltage surges to ground but in normal operation neither wire is grounded. One of the two is connected to "ground" via a coil at the central office and the other is connected to -48 volt batter via another coil.
Most telephone lines enter underground and the cable is shielded. This SHIELD is bonded to the electrical ground and for this reason, the network protection box is placed within a foot or two of the electrical power service. And the NEC and the utility rules call for connection to the electrical service ground.
At the interconnection point between your house and the utility cable, there are surge protectors that must be grounded, otherwise they are useless against a high-voltage spike that comes in simultaneously on both wires.
The electrical code and FCC regulations require connection of this ground terminal to the house's grounding electrode system, but the telco ignores the rules because the local building inspector can't enforce them and the public utility commission won't enforce them.
Been there, done that, Bob
This is one of those cases where you can simply do it and stop worrying about whether the telco/cableco is right or wrong. Buy a couple clamps and some 6 ga solid and bond them. You can just call it a cheap insurance premium. The utilities are certainly not going to pay you if your electronics all go up in smoke during a thunderstorm because of a ground shift between the electrodes.
If you go back through the archives of the various electronics and home groups you will see lots of arguments about surge protection but one thing that is consistant between all of them is that you need a good single point grounding system.
Quite true. I guess I didn't make my point clear enough. Also, any antenna grounding or lightning rod system is to be bonded to the power line ground. Ditto for "cable TV" (that's the one that often isn't grounded. Also, often the TV "dish" isn't bonding to the power ground. They all should be bonded together.
They are going to be bonded together anyway. The problem is if you don't give it a short, low impedance ground path at the electrodes the path is through your equipment. Most blown up PCs TVs and such is not because you had a surge. It is because you had 2 surges, one on the power and one on the signal path. Any differences got reconciled in the equipment where they meet.
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