Applying NEC to temporary portable solar power

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Hi all,

(Mods: I am not asking for advice on how to execute my job, I am asking for others' interpretation of code application, safety protocols and input about their purpose.)

This is my first post on the forum, which I had to join after seeing so much good insight. (And yes I have read through discussions similar to my topic.)

I work for a small California based OEM integrator/manufacturer and we design, build, sell, and rent fully self contained portable solar AC/DC systems (some have wheels directly mounted, others are trailer based). With temporary, wheel based, off-grid, low capacity, and a combination of use applications that vary from day to day, how do you regulate this plug and play devices? Our expertise in our niche runs deep, but one thing I continually struggle with is what codes and regulations apply to our various niche applications. Specifically, the conversation about grounding continues to be a grey zone for me. I understand the NEC requirements for grounding and bonding, and I also grok the reasons why they are both needed. But if you can't fit the equipment into an NEC definition, how does the NEC apply in terms of getting an event permit signed at a temporary event? And whether NEC applies or not, does the practice of using a GEC rod actually make anyone safer? Especially when talking about smaller systems capable of producing 2kw-10kw AC max...

Having been in the event industry for a long time I have seen a number of California municipalities treat temporary structures and electrical equipment as though they are permanent and fall under the standards of the building industry, which is rather ridiculous IMO.

My post here is to flesh out and get current code references relating to grounding in the following case scenario:
Single day event, public park, needs temporary event power. The event is environmentally focused, and is opting to use portable solar generator equipment rather than combustion generators. The power will be distributed in the same way that it would be if combustion generators were in use, with UL listed cords plugs and receptacles. The difference being that the source power is harnessed via PV, battery, and inverter. The PV system is designed using UL listed components, but is not itself UL listed.

According to my interpretation, if NEC applies a grounding rod must be driven for each separately derived unit. Which is fine, but what if this were a parking lot or street intersection with no access to earth?

The AWJ is asking for "detailed grounding documentation from the generator manufacturers" to prove grounding. I can do this, even though a diagram doesn't prove grounding only a field test would. Nonetheless I find this request to be erroneous due to a poor understanding of the equipment. They are not generators first of all... and even if they were, has anyone ever heard of a temporary permit requiring such a level of detail from a portable gas/diesel generator supplier? Seems like this AWJ is just trying to justify their high Silicon Valley pay!

Also in practical terms, isn't the point to give current from lightning or a high voltage line somewhere to go, not to prevent a shock hazard resulting from a fault in the circuit. Is that not what circuit breakers are for? Since we aren't dealing with grid line voltage and there isn't any contact with other power systems, this leaves lightning as the only real reason to sweat any of this. If lightning were to strike, wouldn't it more likely strike the massive tent with metal framing next to the small trailer? If lightning is a concern, isn't a lightning rod much more effective at abating danger? Or perhaps lightning arrestors in the inverters? These are thoughts that make me doubt that GECs would even provide much protection at all... Am I totally off here?

In ten years of event production I have never dealt with such rigamarole for an event permit. Usually the fire inspector has some basic safety questions and requirements, but in this case I am also dealing with a building inspector who clearly doesn't understand portable solar power and it's application to temporary event power.
 
Welcome to the forum Traverse.

I see no sense in driving ground rods for a one day event, for a one week event for that matter.


Thanks Dave.

We can agree on that, but the AWJ does not. In fact, this same event was held in a parking lot last year, which has a skin underneath that cannot be pierced. In prelim permit approval, my statement that all systems were chassis grounded seemed enough to cut it, but the site inspector insisted that earth grounding be present in any electrical system. The lunatic wanted me to run 100s of feet of wire to attach to these stadium sized light poles and ground to them. When I pointed out that it creates a trip hazard that could only be mitigated with tons of cable ramps that are unavailable and in short supply, he ended up telling me to do something so useless that it blows my mind. He had me mount the grounding conductor to a concrete form stake and then nail the form stake on it's side using 4" construction nails to the asphalt surface. To "ground" the system. It was the only way to get the sign off on this single day event... Knowing it to be a completely useless exercise... I did it. Laugh away.

I am dealing with the same AWJ dept for the same event only at a park this year. At the end of the day they hold all the green stamp power and their interpretation of the code matters more than mine, but the more equipped I am with concrete data and specific code references the better prepared I am to handle such idiocy.
 
IMHO this should be treated as any other small portable generator used at an event, eg. a little honda on the back of a food truck.

The important thing is bonding to create a proper ground fault path, including an EGC run with circuit conductors and bonding of any metal which might become energized.

Grounding is only for stabilizing voltage relative to earth potential and for protection from lightning. If in a given situation it is required for another small portable generator than it should be required for your solar powered system.

-Jon
 
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According to my interpretation, if NEC applies a grounding rod must be driven for each separately derived unit. ...
...

I'd like to know why either you or the authority you're dealing with think so.

Show me anything in 250.20 or 250 Part VIII that applies to your systems. Note that you are not supplying 'premises wiring [or] premises wiring systems'.

And see 250.34. I presume that for a single day event all loads are cord-and-plug-connected.

While I believe that the NEC applies, I don't believe that the NEC requires your systems to be grounded.
 
I'd like to know why either you or the authority you're dealing with think so.

Show me anything in 250.20 or 250 Part VIII that applies to your systems. Note that you are not supplying 'premises wiring [or] premises wiring systems'.

And see 250.34. I presume that for a single day event all loads are cord-and-plug-connected.

While I believe that the NEC applies, I don't believe that the NEC requires your systems to be grounded.


I somehow mistyped that. I agree with you, but the local authority doesn't. In fact I just received notification that "8' ground rods will be required, all but 6" to 8" of the rod shall be driven into the ground."

Should I ask the AWJ to "Show me anything in 250.20 or 250 Part VIII that applies to these systems. Note that you are not supplying 'premises wiring [or] premises wiring systems'."??

What drives me nuts is that they are not merely asking for the rod to be driven, which in itself is no big deal, but they are requiring "Detailed grounding documentation from the generator manufacturers". This to me is harassment. Sure the units are not UL listed, but I am fairly sure nor are most generators. I have never in my life heard of such a request for an event permit. And all for what? Protection from lightning? For an event lasting for half of a day no less!
 
IMHO this should be treated as any other small portable generator used at an event, eg. a little honda on the back of a food truck.

The important thing is bonding to create a proper ground fault path, including an EGC run with circuit conductors and bonding of any metal which might become energized.

Grounding is only for stabilizing voltage relative to earth potential and for protection from lightning. If in a given situation it is required for another small portable generator than it should be required for your solar powered system.

-Jon

The units all have a ground neutral bond, unless there is an external power source feeding it, in which case the bond is automatically removed due to the aux power source having it's own bond.

Metal chassis components are all bonded to ground as well, but unless a ground rod is driven there is no earth ground. Mind you these are trailer and wheel based systems that function during transport, so earth ground isn't always present. How would one create a ground fault path on a boat, or an airplane? Chassis ground for small standalone portable systems should be entirely sufficient.
 
The units all have a ground neutral bond, unless there is an external power source feeding it, in which case the bond is automatically removed due to the aux power source having it's own bond.

Metal chassis components are all bonded to ground as well, but unless a ground rod is driven there is no earth ground. Mind you these are trailer and wheel based systems that function during transport, so earth ground isn't always present. How would one create a ground fault path on a boat, or an airplane? Chassis ground for small standalone portable systems should be entirely sufficient.
Your set up is good and your understanding is correct. I think the closest code section that covers your application is 250.34 which says no grounding electrode is required.

I would say you have a portable generaror, just not a gas variety. You are also correct that generators don't have to be ul listed.

What do these guys do when the carnival comes to town or the renaissance fair sets up?
 
Your set up is good and your understanding is correct. I think the closest code section that covers your application is 250.34 which says no grounding electrode is required.

I would say you have a portable generaror, just not a gas variety. You are also correct that generators don't have to be ul listed.

What do these guys do when the carnival comes to town or the renaissance fair sets up?

Thank you Dave. I have visited 250.34 and agree that it is as close as it gets in terms of relevance.

I am an event power service provider and work in a large number of local jurisdictions. In this case it is a city permitting department. This city is also home to some of the world's largest companies and it's building and fire permitting departments seem to be doing everything they can to justify their wage. As you can see in my other comment the "grounding" they made me do last year was an absolute joke. The unfortunate thing is if they insist on their own interpretation there is precious little I can do about it. Nonetheless, I just wrote them asking to explain to me exactly why my systems don't qualify under 250.34

We'll see what they say.

Edit: Carnival? I don't know. Fortunately I don't work in their jurisdiction often. They are the worst. It's not like I'm new at this. I've just never had to deal with such zealousness. I can't imagine they ask other event productions to supply "proof of grounding from generator manufacturers" as part of their application. BTW Dave, your comment on another similar thread, "Even then a ground rod does precious little to make things safer. Chant and wave your favorite sacred object to bless the trailer would be just as helpful" had me laughing pretty good.
 
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Largest companies in the world. Santa Rosa?

Who the heck is up there?

No. I am based in Santa Rosa, but I am dealing with the City of Mountain View, both a building inspector and fire marshall. The event client is Google and the venue is a park owned by Google near the Googleplex. Does the charade make sense now?
 
Thank you Dave. I have visited 250.34 and agree that it is as close as it gets in terms of relevance.

I am an event power service provider and work in a large number of local jurisdictions. In this case it is a city permitting department. This city is also home to some of the world's largest companies and it's building and fire permitting departments seem to be doing everything they can to justify their wage. As you can see in my other comment the "grounding" they made me do last year was an absolute joke. The unfortunate thing is if they insist on their own interpretation there is precious little I can do about it. Nonetheless, I just wrote them asking to explain to me exactly why my systems don't qualify under 250.34

We'll see what they say.

Edit: Carnival? I don't know. Fortunately I don't work in their jurisdiction often. They are the worst. It's not like I'm new at this. I've just never had to deal with such zealousness. I can't imagine they ask other event productions to supply "proof of grounding from generator manufacturers" as part of their application. BTW Dave, your comment on another similar thread, "Even then a ground rod does precious little to make things safer. Chant and wave your favorite sacred object to bless the trailer would be just as helpful" had me laughing pretty good.

You have the unfortunate circumstance of coming in to contact with a class of people I have come to label as Dirt Worshipers.

I intend to lavish them with as much ridicule and scorn as I can till the practice stops. At its least it is an annoyance and at its worst its a major distraction from real understanding of what makes an electrical system safe.
 
No. I am based in Santa Rosa, but I am dealing with the City of Mountain View, both a building inspector and fire marshall. The event client is Google and the venue is a park owned by Google near the Googleplex. Does the charade make sense now?

Yes. I spent a lot of my youth up your ways and was caught off guard. Thinking when did Santa Rosa get so big? Southbay is a who different ball game.

I am in SF at the moment.
 
Hi all,

(Mods: I am not asking for advice on how to execute my job, I am asking for others' interpretation of code application, safety protocols and input about their purpose.)

This is my first post on the forum, which I had to join after seeing so much good insight. (And yes I have read through discussions similar to my topic.)

I work for a small California based OEM integrator/manufacturer and we design, build, sell, and rent fully self contained portable solar AC/DC systems (some have wheels directly mounted, others are trailer based).

Are you with Sustainable Waves, maybe?
 
]Mind you these are trailer and wheel based systems that function during transport, so earth ground isn't always present. How would one create a ground fault path on a boat, or an airplane? Chassis ground for small standalone portable systems should be entirely sufficient.

Hey, even the ISS is grounded... https://en.wikipedia.org/wiki/Plasma_contactor

Basically they spray ions out of electrode systems to prevent static charging of the space station chassis.

Maybe you could get a few of the plasma contactors and have them spraying ions into the air for your grounding :)

Seriously, what is called a 'ground fault path' is created by bonding, not by sticking electrodes into the soil. As you have described, you are already well bonded which IMHO is the protection required. My apologies if by saying 'ground fault path' I implied anything other than proper bonding. I should have said 'low impedance fault current path'.

-Jon
 
No. I am based in Santa Rosa, but I am dealing with the City of Mountain View, both a building inspector and fire marshall. The event client is Google and the venue is a park owned by Google near the Googleplex. Does the charade make sense now?

I'm trying to remember if Mountain View has electrical inspectors, or just building inspectors. Perhaps you can find someone to appeal to who has actual knowledge of the electrical code.
 
Hey, even the [International Space Station] is grounded... https://en.wikipedia.org/wiki/Plasma_contactor ...
This is the kind of detail that undermines the space-travel deniers. Were the space program merely Hollywood fiction, we would never know that a plasma contactor (and a million other special-purpose technologies) was needed, and it would never have been invented.
 
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