Ground rod in every light pole?

[winnie]

For protection from lightning, you are dealing with a huge number of variables and lots of random chance.

A ground rod at every pole _might_ help conduct a strike into the earth, but keep in mind that lots of the damage is done by the current spreading through the earth. A ground rod might be the path that currents in the earth enter the wiring, exiting at a different ground rod. These earth currents are a big reason that all ground electrodes must be bonded together, and why isolated ground electrodes (eg. separate ground rods for telephone and power) are a very bad idea.

For protection from shock, I'd like to see residual current detection such as @jaggedben suggests. Would probably need to have reliable EGC systems and lower sensitivity that GFCI to maintain safety while avoiding nuisance tripping, because I don't think a class A GFCI would be reliable on an extended outdoor circuit.

Jon

 

[don_resqcapt19]

Some kind of GFCI for the whole circuit, or what they call residual current device in most countries, would be pretty simple and effective.

With the longer distances, I would not be surprised if the normal leakage current exceed even the 30 mA trip for a RCD.

 

[hillbilly1]

With the longer distances, I would not be surprised if the normal leakage current exceed even the 30 mA trip for a RCD.

Especially at 480.

 

[Joethemechanic]

When I was a kid, parking lots were lit by incandescent lights on wooden poles with ariel wires on porcelain insulators. No grounding at all and nobody got a shock from touching the pole. And the parking lots were mostly not paved, just stone.

Our town even had a traffic signal mounted to a tree

It was a much better time

 

[garbo]

We're doing a parking lot where the electrical design shows 8' copper ground rod in every light pole. My questions are:
1. What is the function of this copper ground rod in every light pole? Is good, bad or doesn't matter install this ground rod in terms of electrical safety?
2. Isn't enough the EGC running with the circuits conductors feeding the light pole providing a ground fault current path to open the circuit in the event of ground fault?
In my understanding the ground rod is not necessary but some expert can clarify this or I'm missing something. Thanks

A few years ago at an IAEI continuing education class the instructor told us that installing to ground rods at any light pole was a waste of time & money. Nothing beats a properly sized ground wire from a panel.

 

[winnie]

Ehh. Just switch to fiber optic lighting. No conductors run to the poles at all

(Intended as a joke, but apparently an area of active research.)

-Jon

 

[petersonra]

Ehh. Just switch to fiber optic lighting. No conductors run to the poles at all

(Intended as a joke, but apparently an area of active research.)

-Jon

If you could get enough light to do any good it might make a lot of sense.

Much safer and no I^2R losses to worry about.

 

[tortuga]

A few years ago at an IAEI continuing education class the instructor told us that installing to ground rods at any light pole was a waste of time & money. Nothing beats a properly sized ground wire from a panel.

Could be, but the issue of energized poles, signs (as described in post #69) and even metal fences remains a NEC blind spot.
And distance is a huge factor.

 

[tortuga]

Two others claimed in lawsuit to be shocked at city park where boy was electrocuted

A 1993 civil lawsuit filed by the family of woman that claims she too was electrocuted at a city-owned park where a 12-year-old was killed in October states that there were two previous incidents in …

www.augustachronicle.com

 

[petersonra]

Could be, but the issue of energized poles, signs (as described in post #69) and even metal fences remains a NEC blind spot.
And distance is a huge factor.

So what? ground rods will not protect you from energized poles or fences.

 

[Benderofmiami]

I'm not sure how well they work a direct lightning strike is a lot of energy,but another layer of protection couldn't hurt ,and if its on the print you
can't get around it ,it's part of the job cost.

 

[tortuga]

So what? ground rods will not protect you from energized poles or fences.

I am not saying ground rods will not protect you from energized poles or fences I am saying EE's will.
Grounding and bonding is a place in the NEC where there is not a always 'prescriptive path', as they call it, for an average electrician to follow, rather 250.4 mandates a performance requirement for the person designing the system.
And I think thats a blind spot electrical contractors should be aware of.
Performance-based requirements provide an overall objective without mandating specifics for accomplishing that objective.

Once a outdoor distribution system is designed, sealed and stamped by an licensed Electrical Engineer it can be presumed that meets the performance-based requirements of 250.4 and the if the electrician installs it according to the drawings they are absolved of liability and its on the 'errors and omissions' policy of the EE.
Also as the designer you can require field testing of your designs to ensure the contractor installed it as you specified.
And of course if there is no EE it is the contractors liability.

 

[petersonra]

I'm not sure how well they work a direct lightning strike is a lot of energy,but another layer of protection couldn't hurt ,and if its on the print you
can't get around it ,it's part of the job cost.

No different than the contract requiring the EC to paint the conduit. Anything can be added to the contract that is in addition to the code requirements.

 

[petersonra]

I am not saying ground rods will not protect you from energized poles or fences I am saying EE's will.
Grounding and bonding is a place in the NEC where there is not a always 'prescriptive path', as they call it, for an average electrician to follow, rather 250.4 mandates a performance requirement for the person designing the system.
And I think thats a blind spot electrical contractors should be aware of.
Performance-based requirements provide an overall objective without mandating specifics for accomplishing that objective.

Once a outdoor distribution system is designed, sealed and stamped by an licensed Electrical Engineer it can be presumed that meets the performance-based requirements of 250.4 and the if the electrician installs it according to the drawings they are absolved of liability and its on the 'errors and omissions' policy of the EE.
Also as the designer you can require field testing of your designs to ensure the contractor installed it as you specified.
And of course if there is no EE it is the contractors liability.

Actually, there is a requirement that the average electrician has to follow as far as bonding goes. You are required to install an effective ground fault path. You can't blame anyone else if you don't do that. There might be someone else to share the blame, but you are responsible to make sure there is an effective ground fault path. I have never run across a permit application that says you can make an installation that is non-compliant just because the engineer says so.

250.4 (A)
(3) Bonding of Electrical Equipment. Normally non–current carrying
conductive materials enclosing electrical conductors
or equipment, or forming part of such equipment, shall be
connected together and to the electrical supply source in a
manner that establishes an effective ground-fault current path.

Effective Ground-Fault Current Path. An intentionally
constructed, low-impedance electrically conductive path
designed and intended to carry current under ground-fault
conditions from the point of a ground fault on a wiring system
to the electrical supply source and that facilitates the operation
of the overcurrent protective device or ground-fault detectors.

 

[tortuga]

You are required to install an effective ground fault path. You can't blame anyone else if you don't do that.

Once an EE has sealed a drawing for say a outdoor lighting system a contractor should submit a RFI to clarify the EE's drawings meet the performance requirement in 250.4. Then if there is a electrocution due to energized pole, fence sign pole etc it would be on the engineer.
See Supreme Court of Virginia Case, William Gordon Associates Inc V. Heritage Fellowship United Church Of Christ (2016).

 

[petersonra]

Once an EE has sealed a drawing for say a outdoor lighting system a contractor should submit a RFI to clarify the EE's drawings meet the performance requirement in 250.4. Then if there is a electrocution due to energized pole, fence sign pole etc it would be on the engineer.
See Supreme Court of Virginia Case, William Gordon Associates Inc V. Heritage Fellowship United Church Of Christ (2016).

I think this is something for someone with some legal expertise to determine, and even then it is probably different in different states. I took a quick peak at the case you cited and it appears to be a case of grossly deficient design work, not one of a contractor failing to meet code.

 

[tortuga]

I think this is something for someone with some legal expertise to determine, and even then it is probably different in different states. I took a quick peak at the case you cited and it appears to be a case of grossly deficient design work, not one of a contractor failing to meet code.

I completely agree. The case is highlighting the difference between prescriptive code compliance, building it 'to the prints', and performance code compliance. Designers have a bigger role in performance code compliance. The NEC is mostly prescriptive.

 

[mtnelect]

In my view, every contractor needs to have an attorney on retainer. I challenged a general contractor for progress payments on a retail building. It took me 5 years and 5 different attorney firms to a settlement in the hallway outside the court room on the day of the trial. So, you have a dispute, how long will you have to wait for justice ?

 

[mtnelect]

Just a side note, all the settlement money went to the attorneys' !

 

[ptonsparky]

Just a side note, all the settlement money went to the attorneys' !

Of course!