We cable high-rise suites often, sometimes the contractors give us a ground terminal sometimes not. Today they did not.

My question is, is it OK to run a ground wire in the same conduit as the tie cable, so we can ground directly to a ground strip in the tel closet on the floor? Or is it better to have a seperate conduit for the ground?

My second question is what gauge ground wire should I use?

It would be nice to have more information. What is the ground for? What's the cable installation for?

-Hal

The ground would be strictly for the telephone system.

We're cabling voice and data.

Yes, you may run the equipment grounding conductor within the same conduit. You may also save yourself some time and trouble by bonding your system's equipment grounding terminal to the nearest piece of building structural steel, a metallic cold water pipe or the building's electrical grounding conductor.

You don't necessarily have to follow the same path that your tie cable pairs follow. You also don't have to run the "ground" wire that far. Look for any copper cold water pipe or iron framing member (not steel studs) and you will be fine for a grounding point.

Ed's correct about not grounding to the building's frame. That's just not good practice. As far as gauge goes, you are looking for >1/4 ohm from end to end of your ground cable, which simply means the longer the run the larger the gauge. 4 gauge copper has a resistance of .2533 ohms per 1000 feet but 6 gauge is .4023 ohms per 1000, so you could only go about 625 feet before you exceeded your 1/4 ohm limit.

Ed, I thought a cold water pipe was a no-no for grounding these days?

I thought a cold water pipe was a no-no for grounding these days?

Only because plastic (PEX) is being used a lot these days and rarely a section of copper will be replaced with it. If you are sure that the pipe gets back to ground it's probably better than building steel. First check for any AC voltage between the pipe and the electrical receptacle ground, if it's more than a couple of volts you don't want to use it. If none then check with the ohm meter. An analog meter like the "kick meter" is best for this. Nearly all digital meters have a high input impedance and will give a false voltage reading on open circuits when it's actually zero.

-Hal

Unless the cold water pipe switches to PVC at some point before entering the earth, it is an excellent ground.

Remember that it's the electrician's job to ensure that all metallic piping is bonded to the electrical service and to the building's steel structural members. This does NOT mean steel studs. Regardless, the electrician may do a perfectly fine job during the building's construction, but over time, plumbers come in and replace parts of the metallic piping systems with plastic. They don't have a clue as to the risk they are causing in doing this. They also aren't going to place a bonding jumper around the replaced piping; they just walk away with a check in hand once the water is running.

This is why you really can't trust any grounding point except the one that's used for the building's electrical service. Even that can be compromised due to hack repairs, but at least there's a good chance that the power company's ground at the pole or transformer will be good enough.

Perhaps the most popular misconception that can be made is that if you provide your own ground rod for the phone system, you'll have a good ground. Nothing could be farther from the truth. Doing so will actually invite problems AND is illegal under the NEC.

Since the phone system is usually plugged into a wall outlet by a 3-prong plug, I don't see how running a separate cable to the building's electrical grounding conductor would give a better ground. That third prong on the plug is supposed to go to the building's electrical grounding conductor. Can you explain this? Is it just for redundancy?

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

...removed post

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.

Even if a water line or building steel is common to the electrical ground (which it should be) that doesn't mean that there isn't a differential voltage between the two. Even if there isn't any voltage when you install the system there isn't any guarantee there will always be none. I have had a differential voltage crop up after more than two years that destroyed a system.

The only way to be sure you will have no problems is to ground your system to the same point that the line cord is connected to.

-Hal

I have talked to some alarm guys and they do not ground their alarm panels. Any reason that you know of why they don't?

Any reason that you know of why they don't?

Because they work fine without a ground? I haven't connected the supplemental ground on a Partner system in years since I had two destroyed.

-Hal

Check the outlet with a simple outlet tester for good ground and use one of these.

https://www.itwlinx.com/images/products/SurgeGateAC/M4.jpg

A "simple" outlet tester is not sufficient. As others have stated, you must use the electrical/building bond and ensure that you have a very low resistance between the system ground and the building ground.

I am not certain if it is NEC or not, but in my area the telephone ground is not allowed to exceed 5 ohms.

No code requirement that I'm aware of but I'm not familiar with Canadian codes. Might also be a TELCO practice. What do they consider a "telephone ground"? That normally means the primary protectors and I can see the reasoning there. I don't think anybody cares about the KSU ground.

-Hal

1864, that's a rebranded Panamax surge protector. We always use them but if you are using the ground bus on it to connect the ground from the system that's no better than the line cord itself. That's because the line cord on the Panamax strip can be pulled just as easily. The system suplemental ground must be permanently connected.

-Hal

Hal

"That's because the line cord on the panamax strip can be pulled just as easily"

"can be pulled " help me out here,thats the same as can be used ?

I'm missing your statement some how.

Explain, thanks.

I thought I covered the reason for the supplemental ground above. The supplemental ground on the KSU is required by UL in case the line cord gets disconnected from the wall receptacle. When that happens the system and station wiring are not protected if something happens to the CO lines from outside.

The reason the ground cannot be taken from the ground on a surge protector like that Panamax is because that too is connected to ground with a line cord. Disconnect that cord and you are in the same boat.

That Ditek unit is permanently installed by virtue of a screw that replaces the wall plate screw. Surge and overvoltage wise I'll agree that it doesn't provide the protection that the Panamax does but there is nothing to stop you from using a Panamax after that.

-Hal

I always try to run my ground for the ITW Linx c.o. and station surge protectors and the ksu/pbx ground to the ground bar of an electrical panel. From my understanding from an phd electrical engineer is that a common ground for the entire building is best. I can get the two dollar explanation if anyone is interested. Since I started that practice, I've not had one fuse or protector fail. And all my systems are undamaged. Prior to that practice, I had one system get hit twice in a week. Ended up replacing the system...twice!

Al Dukes
:toast:

Please get the five dollar explanation. I need the explanation with the picture of the nuts and the bolts and the numbered instructions. I need Grounding for Dummies.

...the ground bar of an electrical panel... From my understanding from an phd electrical engineer is that a common ground for the entire building is best.

That is the best case scenario IF the electrical panel is the service entrance panel. About the only time you are going to be able to do that is with a residential type install. If you are on the third floor of an office building about all you can hope for is a conduit coming out of a sub panel. That may be just fine until some sparkie puts a neutral on a ground bus someplace, and it doesn't even have to be in that panel.

The advice given here is real world from people who do this kind of work. Who you going to believe, a Post Hole Digger or us?

-Hal

I don't know if it's for dummies, but look at the FAQ's in the Outside Plant category.

In this case I ended up putting a ground clamp on the nearest copper pipe and grounding my system to that.

Maybe running a ground from the backboard to the TELCO. grounding strip via conduit should be when you are cabling a large area where many phone systems could be installed.

In this case I ended up putting a ground clamp on the nearest copper pipe and grounding my system to that.

Well, like I said, I don't recommend that. It depends on how your particular equipment is designed as to whether or not it can be damaged by a voltage between the line cord ground and the supplimental ground.

-Hal

I will call my dad tonight and get the nuts and bolts. He gave a great explanation and has a phd in electrical engineering.

Will post tomorrow, I hope.

Al Dukes
:toothy:

My install documents which I require to be signed by the customer include environemental conditions which the customer is responsible to meet. This includes providing a true earth ground for the system aux ground at the system location. It also specifies a dedicated circuit with a dedicated ground for power. These are clearly stated as the customers responsibility, and liability in writing, and verbally in the project management meeting. They sign off on this document, and that unless they recieve a seperate quote, accept that quote, and schedule that work prior to the equipment being installed from my company that they will be responsible to provide any and all environmental conditions as stated in the document.
If you do not have the proper equipment, expertise, and experience to test the ground, then do not contract to provide that service, plain, and simple. The customer can get an EC in to take care of it if they do not have staff that can do so. On the final sign off include the environemntal conditions in the document as the customers liability, and that they accept that condition.

Now, do your best to give them the ground yourself so you can show due diligence even though it was not in your scope of work, but their scope. The middle screw of the faceplate of the power outlet is exactly what the previous post mentioned in reference to the Ditek unit with the wing nut as a good common ground according to codes..