Ground rods for solar light poles?

[Electron_Sam78]

It looks like article 690 requires a grounding electrode for photovoltaic systems. I don't see anything excluding parking lot poles with a system voltage of 24 Volts. So does this mean all my poles need to have a rod installed at each one and all metal parts bonded to it?

 

[jaggedben]

Theoretically, yes, you need to bond all exposed metal parts. Seems like there should be an exception for a 24V system but there isn't one. Only thing you might be able to go with is if these solar lights are a self contained product that come with instructions that don't mention grounding.

In the 2008 code, 690.47(D) could possibly be read to require a ground rod at each pole. That's probably a matter of interpretation. In the 2011 code there is no such section, and you could drive one rod at any of the poles and bond all of the parts to it, if you wish.

 

[Electron_Sam78]

Thanks. It also looks like I'm exempted from a system ground connection in section 690.41 so all I need to do is the ground rod and equipment bonding. :thumbsup:

 

[kwired]

I question whether or not the NEC even applies if this is a self contained unit. Is there any premesis wiring involved, such as maybe a line to additional units?

 

[Electron_Sam78]

No, there are no lines in or out. It's all self contained within the structure of the pole

 

[Electron_Sam78]

Technically it is a photovoltaic system even though it is a small one for a single specific purpose.

 

[Electron_Sam78]

The scope of 690 says that the PV systems covered may be interactive with other electrical power production sources or stand-alone, with or without...batteries. To me that sounds like solar light pole is included in the scope

 

[jaggedben]

kwired is right. It is arguable that if there is no field wiring then the device does not fit under the NEC, or that the NEC has nothing interesting to say about its installation. Although the scope section of 690 may seem to include any photovoltaic device, you've also got section 110.3(B), which says that listed or labeled equipment shall be installed according to the instructions.

So are these poles listed? And if so, what do the instructions say? Do they mention grounding or not?

If they are listed and do not require grounding in the instructions, you have an argument under 110.3(B) that grounding is not required. If that is the case, and if this installation going to be inspected, I would ask the AHJ ahead of time if they think it is necessary to follow the grounding rules in 690, or I would even request that they not be considered under the scope of 690. It's within their power to decide.

 

[kwired]

The scope of 690 says that the PV systems covered may be interactive with other electrical power production sources or stand-alone, with or without...batteries. To me that sounds like solar light pole is included in the scope

So the little solar powered landscape lights you get at Wal Mart for around $10 need to comply with art 690? I bet less than .00001% of any of them ever sold were ever even questioned if any electrical codes apply to their use or installation. I would be interested in seeing a permit application with some of those being the only item(s) to be installed.

I have a solar powered calculator - do I need a grounding electrode for it? If so where can I terminate it on the calculator?

There is thousands of PV powered cheap stuff out there that does not have sufficient energy levels to be much of an electrical hazard if something should fail, I don't think the NEC intended to cover these items, maybe they need a power level limitation stated someplace to clarify what 690 applies to.

 

[Electron_Sam78]

I'm sure the little landscape lights fall under the 110.3(B) section. HAHA @ the calculator :lol:.

I would have to say the parking lot lights do have "field wiring". The wires that run internally inside the pole from the array to the controller/batteries then back up the fixture head. They sure don't come pre-installed, I have to install them in the field. If you're talking about utility electrical grid wiring then a stand-alone solar generation system would be exempt from the NEC but it's not as outlined in the scope of 690.

Kwired, something failing within the PV system and energizing metal parts is not what driving a ground rod is there to remedy. You're referring to a grounded system where one wire of 2-wire PV system needs to be grounded as referred to in section 690.41. In that case the fault current could be cleared by the fuse operation. However, 690.41 specifically exempts PV systems under 50 volts from having to be grounded (one conductor of a 2-wire system being grounded). I am simply talking about complying with section 690.43 Equipment Grounding, where in order to have grounded metal equipment in a ungrounded system you would have to have a grounding electrode installed. This type of grounding is not for fault clearance but for high voltage contact clearance such as lightning or transmission line contact.

As far as the UL listing goes I'm not sure about it and the installation instructions don't mention anything about equipment grounding but there are tapped holes in the array with a grounding symbol stamped into the metal, the light fixture will have a grounding terminal or tapped hole as well and the pole has a grounding bracket.

And I am the AHJ in this case.

 

[Electron_Sam78]

..also there's 690.47(B) where it says that a dc system must have a GES installed in accordance with 250.169 for ungrounded systems.

 

[ggunn]

..also there's 690.47(B) where it says that a dc system must have a GES installed in accordance with 250.169 for ungrounded systems.

GES?

 

[jaggedben]

This type of grounding is not for fault clearance but for high voltage contact clearance such as lightning or transmission line contact.

If you're concerned about these issues, then by all means ground your poles. If you want to do it for those reasons then it scarcely matters if the NEC requires it.

 

[PWDickerson]

I recently installed a 12v stand-alone solar lighting system at a bus shelter. I asked the AHJ if ground rods would be required, and he said no, and referenced 250.162(A).

 

[kwired]

I would have to say the parking lot lights do have "field wiring". The wires that run internally inside the pole from the array to the controller/batteries then back up the fixture head. They sure don't come pre-installed, I have to install them in the field. If you're talking about utility electrical grid wiring then a stand-alone solar generation system would be exempt from the NEC but it's not as outlined in the scope of 690.

That does clarify things - some. If it is all in one assembly - even if you have to field assemble some of it, it may still not be premesis wiring but rather a self contained, (probably listed), piece of equipment. If it had a wind turbine or other a gas powered generator yet was self contained would you apply NEC? Now if the power source were on one structure or component and you ran conductors to other structure or separate components you have premesis wiring and NEC is likley going to apply to field wiring unless it is "plug and play" type connection and listed as such.

As far as lightning - why is a light pole that has no wiring running to any other structures any different than having a flagpole with no wiring to other structures? You can install a ground rod if you want, but you also don't have to. Depending on construction of pole and base, the base could supplement the rod more than the rod supplements the base.

 

[Electron_Sam78]

GES?

Grounding Electrode System

If you're concerned about these issues, then by all means ground your poles. If you want to do it for those reasons then it scarcely matters if the NEC requires it.

That's what grounding (installing a grounding eletrode system) is for. It certainly is not for providing a low impedance path back to the transformer to clear unintentional energizing of non-current carrying metal parts. That's what the equipment grounding conductor is for or in the case of a two-wire dc system it would be the reason for grounding the system (aka driving a ground rod and attaching the negative wire to it) as stated in 690.41. That just happens to be exempted in this case since the poles are less than 50 volts. I assume because the power levels are so low an enregized pole at 24 volts wouldn't cause any harm.

I recently installed a 12v stand-alone solar lighting system at a bus shelter. I asked the AHJ if ground rods would be required, and he said no, and referenced 250.162(A).

I believe your AHJ missed the context of that section. 250.162(A) refers to a grounded SYSTEM which means that one wire of a dc system must be grounded (for example the negative wire attached to a ground rod). That section has nothing to do with equipment grounding aka the grounding of exposed non-current carrying metal. The same thing is addressed, with almost the same wording, for PV systems in section 690.41

That does clarify things - some. If it is all in one assembly - even if you have to field assemble some of it, it may still not be premesis wiring but rather a self contained, (probably listed), piece of equipment. If it had a wind turbine or other a gas powered generator yet was self contained would you apply NEC?

Yes, the NEC covers generator installs, even portable ones i believe.

Now if the power source were on one structure or component and you ran conductors to other structure or separate components you have premesis wiring and NEC is likley going to apply to field wiring unless it is "plug and play" type connection and listed as such.

I think you are mistaken. The pole is a structure as defined in article 100. If there were a grid connected elecrical panel installed on the pole then it would have to comply with 250.32 for buildings or structures supplied by feeders or branch circuits.

As far as lightning - why is a light pole that has no wiring running to any other structures any different than having a flagpole with no wiring to other structures?

Because this is the National ELECTRICAL code.

You can install a ground rod if you want, but you also don't have to. Depending on construction of pole and base, the base could supplement the rod more than the rod supplements the base.

Not in this case

 

[Electron_Sam78]

I know this isn't the grounding and bonding forum but since it's being talked about and there's obviously confusion about what grounding is for and the difference between a grounded system, equipment grounding, equipment bonding, and effective fault current path I thought I'd insert it.

Here's an informative look at grounding, bonding , and fault current path that helps explain the difference of each really well and tell why they are necessary. http://www.tirebiter.net/downloads/ludecke.html

 

[kwired]

I know this isn't the grounding and bonding forum but since it's being talked about and there's obviously confusion about what grounding is for and the difference between a grounded system, equipment grounding, equipment bonding, and effective fault current path I thought I'd insert it.

Here's an informative look at grounding, bonding , and fault current path that helps explain the difference of each really well and tell why they are necessary. http://www.tirebiter.net/downloads/ludecke.html

I don't have any confusion over what grounding and bonding are for.

My question is whether or not the luminaire and its supply is a premesis electrical system or just a stand alone piece of equipment. There are all kinds of self powered equipment out there that NEC does not apply to, what makes this one different? It could have a cord for recharging a battery, but the only thing the NEC would apply to is installation of the receptacle it gets plugged into.

 

[Electron_Sam78]

I don't have any confusion over what grounding and bonding are for.

My question is whether or not the luminaire and its supply is a premesis electrical system or just a stand alone piece of equipment. There are all kinds of self powered equipment out there that NEC does not apply to, what makes this one different? It could have a cord for recharging a battery, but the only thing the NEC would apply to is installation of the receptacle it gets plugged into.

I agree with you that certain things don't get covered by the NEC. We just have to look at article 90 for that list.

Just for clarification, the word "stand-alone" refers to a power generation system that is not tied into the utility power grid. The NEC does apply to these kinds of installations whether it is a portable generator or a photovoltaic system. If you're talking about a prepackaged item that all you have to do is stick in the dirt after you take it out of the package then yes as was mentioned before, if it is UL listed then you would follow the directions for installation according to section 110.3(B). [I wonder does the UL inspect the manufacturer's installation instructions for the purpose of complying with the NEC and other codes?] However, with the solar lights I'm installing, I am pouring a 2 foot diameter concrete pier foundation and installing 20'x5" steel poles. Then the multi-part PV lighting system is being installed onto and within that pole. This kind of install (the pole at the very least) is considered a structure as defined by article 100. If this were a grid tied parking lot light it would be required to have a GES installed per section 250.32 unless, as the exeption states, it is supplied by only one branch circuit AND it also has an equipment grounding conductor run with the other circuit conductors. Also, in the case of the solar light and pole the applicable code section requires that equipment (not the system) be bonded together and grounded. I have yet to see anything in the code that exempts PV systems due to size or singularity in purpose.

As a side note pertaining to this job, I dug the foundtaion holes yesterday and today and installed the rebar. I decided to extend a section of rebar up into the pole cavity to use the foundation as a CEE as allowed in section 250.52(A)(3). No rods required. :thumbsup:

 

[kwired]

I agree with you that certain things don't get covered by the NEC. We just have to look at article 90 for that list.

Just for clarification, the word "stand-alone" refers to a power generation system that is not tied into the utility power grid. The NEC does apply to these kinds of installations whether it is a portable generator or a photovoltaic system. If you're talking about a prepackaged item that all you have to do is stick in the dirt after you take it out of the package then yes as was mentioned before, if it is UL listed then you would follow the directions for installation according to section 110.3(B). [I wonder does the UL inspect the manufacturer's installation instructions for the purpose of complying with the NEC and other codes?] However, with the solar lights I'm installing, I am pouring a 2 foot diameter concrete pier foundation and installing 20'x5" steel poles. Then the multi-part PV lighting system is being installed onto and within that pole. This kind of install (the pole at the very least) is considered a structure as defined by article 100. If this were a grid tied parking lot light it would be required to have a GES installed per section 250.32 unless, as the exeption states, it is supplied by only one branch circuit AND it also has an equipment grounding conductor run with the other circuit conductors. Also, in the case of the solar light and pole the applicable code section requires that equipment (not the system) be bonded together and grounded. I have yet to see anything in the code that exempts PV systems due to size or singularity in purpose.

As a side note pertaining to this job, I dug the foundtaion holes yesterday and today and installed the rebar. I decided to extend a section of rebar up into the pole cavity to use the foundation as a CEE as allowed in section 250.52(A)(3). No rods required. :thumbsup:

I still don't see it as being premises wiring just a piece of equipment that happens to have wiring within it and is powered by on board components. Your car is also a piece of equipment powered by on board components and has wiring within it.

And yes I know the NEC does not apply to an automobile in general.

I believe you mentioned earlier the portable generator - What in the NEC covers a portable generator? The portable generator itself is likely a listed product also. When you connect it to a premises wiring system is when NEC comes into play.

I don't see the NEC applying. Is it a good idea to provide a grounding electrode for it - maybe. If lightning strikes it does it make much difference if there is a grounding electrode or if there isn't one? I really doubt it. If lightning strikes a pole connected to a premises wiring system can a lightning strike follow that premises wiring to other structures? Definitely.