atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Running a ground

Most phone systems now have the 3rd prong and ground to the same lug. It may be redundant, but you grounding the lug to the power ground is a direct path to ground, where as the ground in the plug may go through several other outlets, which can give a potential for high joint or other bad connections.

I try my best to make all grounds common, from the Telco to the electric, I want no difference in potential on my ground to any of my equipment.

The one thing you don't want to do is ground the lug to something other than the 3rd wire ground if they are tied together. Once again common ground.

We've been through this at least twice before. Yes, it's just for redundancy, something required by UL incase the line cord is pulled. Can't have all that premises wiring on one side of the system and the outside CO lines on the other without a ground.

My experience is that the supplemental ground should always be connected to the same point as the line cord ground. This ensures that there will never be a voltage differential between the two that will damage the equipment. You can never be certain that there will always be a zero potential between the receptacle ground that the system is plugged into and another point such as a cold water pipe or building steel.

Racks and enclosures should also be bonded to the same point that the equipment they contain is grounded to. I've seen in excess of 50 volts between the receptacle ground and building steel. In addition to a shock hazard it creates a dandy ground loop.

Secondary CO line protectors are another story if they are located with the equipment. You don't have to worry about a voltage differential there and you want a solid low impedance ground. So a cold water pipe, building steel or the electrical service ground is what you want and you want to use a substantial size wire.

-Hal

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Redundancy is good. So you are recommending against grounding the phone switch unit to the water pipe and building steel, is that right?

As a practical matter, how do we connect a ground wire from the phone switch to the line power grounding?

I have a question on cold water pipe:

Even if there was a plastic section, wouldn't it still work? Tap water generally conducts electricity because of the impurities. Distilled water doesn't conduct. Mythbusters proved it.

Your not serious Rob ?

I say no more our i might lose another star, and i don't have that many to lose :scratch:

While it's true that the impurities and minerals in water do conduct electricity, it's not consistent. The only way to get a consistent ground connection is through a true metallic connection.

Even if there was a plastic section, wouldn't it still work? Tap water generally conducts electricity because of the impurities.

No, it wouldn't work. Even salt water doesn't have a low enough resistance to act as a conductor in those cases.

But I have seen EC's put a ground clamp on plastic pipe...

As a practical matter, how do we connect a ground wire from the phone switch to the line power grounding?

see that big wing nut?

-Hal

I have seen gnd. clamp at outside demarc to plastic, as well as gas line.

They were using FM to convey the gnd. effect. :nono:

The way I read it was unless you could verify it was common to the electric ground.