How do I politely explain "You can't use an old 2 wire 120 VAC Run without a Ground"

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ggunn said:
"Several innocent people have said with good intentions, "Why can't you just Ground at the Pump or Lamp to a Nearby Ground Rod?" At times this invites every Civil engineer and idle idiot to pipe up."

I didn't read that as him speaking to a specific civil engineer. It's a swipe at civil engineers, for sure, but I'll hazard a guess that the OP doesn't know all that much about laying out highway rights of way, either.
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Gunny, I am not trying to spar with you here. Remember, I am one those crazy persons who LIKE train drivers.
 
Thank you very much for the answers. I was hoping to have something that goes right to the physics of the matter. This is really a great forum.
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charlie b said:
The “normal” flow of current starts at the panel, goes through the breaker, travels along the “hot” (i.e., ungrounded) conductor, to and through the load, travels along the “neutral” (i.e., grounded) conductor to the neutral bar at the panel, and at that point we can say that it has returned to its source. Now I will address your questions. Let’s say we are talking about a light pole.

Suppose there is a failure internal to the light pole, such that a live wire comes into contact with the metal exterior parts. The current path I described above is still in effect, and the light is still operating. But now there is a second current path. It starts the same way, going through the breaker and the hot conductor. Once inside the light fixture, the current will flow along the faulted wire to the metal pole, from there to the wire you have attached to the case and also attached to the local ground rod. The current will travel along that wire, to the ground rod, into planet Earth, along the dirt to the location of the building’s grounding electrode system, into and up that system’s ground rod, up the grounding electrode conductor to the neutral bar inside the main panel, and at that point we can say that it has returned to its source. The amount of current that will flow along this path is limited by the resistance of this path. Others have already talked about this. The result is that the amount of current that this fault path adds to the total current seen by the breaker will not be enough to trip the breaker. That is why the suggestion made by the several innocent people whose intentions are good is absolutely guaranteed to fail.

It is also important to note that with the local ground rod in place, and with the fault I describe above, if a person touches the pole, it will create yet again another current path. In addition to current flowing from the metal pole to the local ground rod, current will flow through the person’s hand, along the body to the feet, into the dirt, and back to the source via the building’s ground rod. Once again, this extra current will not be enough to trip the breaker. But it will be enough to kill the person.

The only way to make this installation safe is to install an equipment grounding conductor, as others have already mentioned.
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ActionDave said:
Explain that attaching metal light poles to ground rods does NOTHING TO MAKE THEM SAFE. What is needed is a proper Equipment Grounding Conductor back to the breaker or fuse to clear a fault and show them this graphic

View attachment 19588
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Not really. We've had that for years and years and still no progress. Just Google. Sooooo many accidents because of lack of, or poor, light pole grounding. Just because a ground wire is run doesn't mean it's safe. There are many non-electricians that service these parking lots. My most basic complaint is NOT HAVING the handhole covers in place! There are so many instances where the handhole cover isn't even present - too many accidents specific to light poles!

What you say is 100% true, but in real life there needs to be more protection over and above just having the required equipment grounding conductor.

Class C GFCI protection? Perhaps?
 
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Trying to explain such a thing to a customer that has no technical knowledge can be challenging.

One could politely present the facts. The fact is that the 3 wire with ground cable is a newer method that has been proven to be so much safer over the years, it is required by the electrical codes and has been for a long time.

Most people understand that, and at that point their concerns are usually turned toward being forced to be safe by the government, rather than any technical aspects of an equipment grounding conductor.
 
Installer said:
While working on some other equipment, I think I have I have stumbled upon one or two old 2 wire 120 VAC Runs with a Hot and Neutral and no Ground running through a building to a Pump and or some Light Poles.
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You do realize that metal raceways and some metal sheathed cables are permitted to be used as the equipment grounding conductor? should you happen to have that situation.
 
Installer said:
How do I politely explain "You can't use an old 2 wire 120 VAC Run without a Ground" to some well meaning people.

While working on some other equipment, I think I have I have stumbled upon one or two old 2 wire 120 VAC Runs with a Hot and Neutral and no Ground running through a building to a Pump and or some Light Poles.
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kwired said:
You do realize that metal raceways and some metal sheathed cables are permitted to be used as the equipment grounding conductor? should you happen to have that situation.
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I hadn't thought of that.:)

I would hazard to guess the op already knows that, but in case he does not.....

Op: Any of the of methods listed in 250.118 will suffice for an EGC.
 
user 100 said:
I hadn't thought of that.:)

I would hazard to guess the op already knows that, but in case he does not.....

Op: Any of the of methods listed in 250.118 will suffice for an EGC.
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If you are going by code, NM without a ground wire is no longer a Chapter 3 wiring method. See 334.108, a grounding conductor is required to be included in the cable. Pulling it through metal raceway won't make it legal.
 
user 100 said:
I hadn't thought of that.:)

I would hazard to guess the op already knows that, but in case he does not.....

Op: Any of the of methods listed in 250.118 will suffice for an EGC.
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The fact he mentioned a pump and light poles - got me thinking he may not necessarily be talking old NM cable with no EGC, and possibly overlooking metallic wiring methods as an EGC. I could be wrong but want him to consider that if he hadn't.
 
Wouldn't this be like requiring ground rods to be driven at every receptacle?

There's already an adequate safety system in place with effective ground fault current path! The ground rod does nothing because it's such high resistance!

My company continues to put ground rods at every light pole out of habit and nobody wants to listen. It's amazing how guys can shut off their mind and just repeat things they've done in the past.


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JacobiusWrex said:
Wouldn't this be like requiring ground rods to be driven at every receptacle?

There's already an adequate safety system in place with effective ground fault current path! The ground rod does nothing because it's such high resistance!

My company continues to put ground rods at every light pole out of habit and nobody wants to listen. It's amazing how guys can shut off their mind and just repeat things they've done in the past.


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Nothing wrong with adding "supplemental electrodes" such as the rods at each light pole. There can be situations where there may be some benefit, but for most light poles there isn't much to gain to make it worth the cost.

Equipment grounding conductors are still necessary whether you drive the rod or not.
 
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