Is supplemental grounding needed for small trailer mounted panel

[shade23]

I need to hookup four small, two wheel, rubber tired, pull trailers that will be used at an outdoor festival. They each have 120/208 volt, 200 amp panels and each panel supplies GFCI outlets. Each panel is supplied with a four wire supply cord, L1, L2, Neutral, Ground. The panel, all electrical, and the metal trailer are all bonded to the ground.
My question is should I supply a supplemental ground rod at each trailer. These trailers will be stationed in four different areas on a football field. I have researched and I have not found a clear answer.
Thank You!

 

[petersonra]

I did a quick pass thru article 525 and did not see anything that seems to require a grounding electrode system for trailers.

I don't see what you would gain by having a GES at each trailer.

 

[ActionDave]

I'm not sure what you mean by "bonded to the ground". At any rate, what is important is the wiring feeding the trailers and the panels. Ground rods have no value in a temp situation like this and I wouldn't waste any effort on them.

250.32?? or somewhere near there is the code section for temp, vehicle mounted generators.

 

[Craigv]

I'm not sure what you mean by "bonded to the ground". At any rate, what is important is the wiring feeding the trailers and the panels. Ground rods have no value in a temp situation like this and I wouldn't waste any effort on them.

250.32?? or somewhere near there is the code section for temp, vehicle mounted generators.

I think he means the feeder grounding conductor is bonded to the trailer frame and body.

NEC 2017: 525.30 States that trailer frames and metal parts thereof must be bonded.

It is silent about an electrode system for trailers. Therefore not required but can be installed if desired. So essentially the GES for the generator or the utility is the only one required. 525.32 requires the continuity of conductors be verified each time the portable equipment is connected.

 

[david]

You have a structure with a 200 amp panel being supplied by a feeder from a service or a panel being supplied by a gen. the question wasn’t whether two ground rods serve any purpose but does the code require earthing or not, the code is not silent on it .

ARTICLE 590 Temporary Installations 590.2 All Wiring Installations.
Other Articles. Except as specifically modified in this article, all other requirements of this Code for permanent wiring shall apply to temporary wiring installations.

525.3 Other Articles.
(A) Portable Wiring and Equipment. Wherever the requirements of other articles of this Code and Article 525 differ, the requirements of Article 525 shall apply to the portable wiring and equipment.

 

[petersonra]

You have a structure with a 200 amp panel being supplied by a feeder from a service or a panel being supplied by a gen. the question wasn’t whether two ground rods serve any purpose but does the code require earthing or not, the code is not silent on it .

I think you are missing the point. he asked whether a ground was required at the trailer. I see nothing that would require that. With some exceptions a GES of some sort is going to be required at whatever the source or service is, but not at the trailers.

 

[david]

I think you are missing the point. he asked whether a ground was required at the trailer. I see nothing that would require that. With some exceptions a GES of some sort is going to be required at whatever the source or service is, but not at the trailers.

Article 250.32 as other articles would apply because article 525 or article 590 is without specific requirement on the issue

i read there is some changes in defining structure and equipment in 2017 and i did not read in this thread the supply would be a vehicle mounted gen maybe i missed that i go back and re-read

 

[Craigv]

Article 250.32 as other articles would apply because article 525 or article 590 is without specific requirement on the issue

i read there is some changes in defining structure and equipment in 2017 and i did not read in this thread the supply would be a vehicle mounted gen maybe i missed that i go back and re-read

It really doesn't matter if the trailers, which are the OP's topic of question, are fed by portable gensets or a utility service...both of those sources will require a GES. The trailer feeders will have an equipment ground and a grounded conductor. The relevant code for festival power is Article 525, "Carnivals, Circuses, Fairs and Similar Events".

In Article 525, Part IV refers to 250.118 for equipment grounding conductors and to Article 250 Parts VI and VII for installation of equipment grounding conductors. It continues in 525.31:

"The equipment grounding conductor shall be connected to the system grounded conductor at the service disconnecting means or, in the case of a separately derived system such as a generator, at the generator or first disconnecting means supplied by the generator. The grounded circuit conductor shall not be connected to the equipment grounding conductor on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means."

There is no mention of a GES because the GES is covered by the articles covering portable generators and building services.

525.35 states: Wherever the requirements of other articles of this Code and Article 525 differ, the requirements of Article 525 shall apply to the portable wiring and equipment. Hence, the OP's trailers, which are fed by portable wiring and are portable.

 

[david]

I’m going to yield the position as I stated, however not based on the idea that article 525 trumps 250.32 rather based on the scope of the NEC the trailer in discussion is not a mobile home or a recreational vehicle therefore the trailer in discussion has no NEC requirements since it is a vehicle outside the scope of the NEC

A) Covered. This Code covers the installation of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways for the following:
(1) Public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings
(2) Yards, lots, parking lots, carnivals, and industrial substations

Not Covered. This Code does not cover the following:
(1) Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles

 

[petersonra]

I don't believe a trailer is an automotive vehicle.

 

[zbang]

I personally don't think they're needed but some inspectors do; when that comes up I pound in a rod and call it good.

I'll also toss in another variable- if the trailer/panel is "cord and plug connected" that makes it utilization equipment . I would not put much weight on that.

 

[david]

I don't believe a trailer is an automotive vehicle.

it is sold with a vehicle title and its not an RV or a mobile home

Trailer (vehicle) - Wikipedia
https://en.wikipedia.org/wiki/Trailer_(vehicle)
A trailer is an unpowered vehicle towed by a powered vehicle. It is commonly used for the transport of goods and materials. Sometimes recreational vehicles, travel trailers, or mobile homes with limited living facilities, where people can camp or stay have been referred to as trailers.

 

[infinity]

I don't believe a trailer is an automotive vehicle.

I’m going to yield the position as I stated, however not based on the idea that article 525 trumps 250.32 rather based on the scope of the NEC the trailer in discussion is not a mobile home or a recreational vehicle therefore the trailer in discussion has no NEC requirements since it is a vehicle outside the scope of the NEC

A) Covered. This Code covers the installation of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways for the following:
(1) Public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings
(2) Yards, lots, parking lots, carnivals, and industrial substations

Not Covered. This Code does not cover the following:
(1) Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles

I agree, and it's beyond the scope of the NEC.

 

[LarryFine]

Look at it as a large extension cord.

 

[Craigv]

I’m going to yield the position as I stated, however not based on the idea that article 525 trumps 250.32 rather based on the scope of the NEC the trailer in discussion is not a mobile home or a recreational vehicle therefore the trailer in discussion has no NEC requirements since it is a vehicle outside the scope of the NEC

A) Covered. This Code covers the installation of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways for the following:
(1) Public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings
(2) Yards, lots, parking lots, carnivals, and industrial substations

Not Covered. This Code does not cover the following:
(1) Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles

I beg to differ. Article 525 directly applies to the OP's trailers. (NEC 2017)

525.1 Scope. This article covers the installation of portable wiring and equipment for carnivals, circuses, fairs and similar functions, including wiring in or on all structures.

525.2 Definitions.

Portable Structures. Units designed to be moved including, but not limited to, amusement rides, attractions, concessions, tents, trailers, trucks, and similar units.

525.30 Equipment Bonding.
...
(3) Metal frames and metal parts of portable structures, trailers, trucks, or other equipment that contains or supports electrical equipment.


I can't imagine a way the OP's trailer, which contains or supports electrical equipment for use at an outdoor festival, is not directly covered by NEC and specifically Article 525.

 

[david]

VI. Equipment Grounding and Equipment Grounding Conductors
250.110 Equipment Fastened in Place or Connected by Permanent Wiring Methods (Fixed).
Exposed non–current-carrying metal parts of fixed equipment likely to become energized shall be connected to the equipment grounding conductor under any of the following conditions:

525.1 Scope.
This article covers the installation of portable wiring and equipment for carnivals, circuses, fairs, and similar functions, including wiring in or on all structures.

Article 525 is making applicable to potable wiring methods rules that article 250 states are applicable to fixed wiring methods

250.114 Equipment Connected by Cord and Plug.
Under any of the conditions described in 250.114(1) through (4), exposed non–current-carrying metal parts of cord-and-plug-connected equipment likely to become energized shall be connected to the equipment grounding conductor.

In article 525 the rules for portable cords apply whether the portable cord has a plug on it or not
VII. Methods of Equipment Grounding

250.130 Equipment Grounding Conductor Connections.
For Grounded Systems. The connection shall be made by bonding the equipment grounding conductor to the grounded service conductor and the grounding electrode conductor.

Nothing in 250.130 trumps or makes inapplicable 250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).

525.31 Equipment Grounding. Is saying the exact same rules that you find in article 250 that are applicable to fixed wiring methods

The same way 250.130 does not make 250.32 inapplicable 525.31 does not make 250.32 inapplicable

Article 525 does not change the scope of the NEC

The NEC is not Applicable to trailers or a fixed panel in a trailer article 525 is applicable to portable feeders to trailers or portable supplies (wiring methods) like an extension cord to portable equipment.

The internal wiring in a portable vending machine does not become subject to the NEC just because it is portable equipment being used in a Article 525 application

(B) Portable Wiring Inside Tents and Concessions.

Article 525 only addresses the portable wiring methods used in a Article 525 application

Sorry this is a long response
David

 

[jumper]

David, if you copy and paste

, the one at the end needs a “/“ added. [/QUOTE ].

 

[david]

David, if you copy and paste

, the one at the end needs a “/“ added. [/QUOTE ].

Thank you

 

[david]

.

Portable Structures. Units designed to be moved including, but not limited to, amusement rides, attractions, concessions, tents, trailers, trucks, and similar units.

If you consider Festoon lighting stung on the outside of a truck or outside and through a trailer verses a ceiling mounted fixed light fixture controlled by a permanent fixed light switch in a trailer that may help distinguish the portable wiring method in article 525

 

[petersonra]

I beg to differ. Article 525 directly applies to the OP's trailers. (NEC 2017)

525.1 Scope. This article covers the installation of portable wiring and equipment for carnivals, circuses, fairs and similar functions, including wiring in or on all structures.

525.2 Definitions.

Portable Structures. Units designed to be moved including, but not limited to, amusement rides, attractions, concessions, tents, trailers, trucks, and similar units.

525.30 Equipment Bonding.
...
(3) Metal frames and metal parts of portable structures, trailers, trucks, or other equipment that contains or supports electrical equipment.


I can't imagine a way the OP's trailer, which contains or supports electrical equipment for use at an outdoor festival, is not directly covered by NEC and specifically Article 525.

if IIRC, the post in question suggested this sentence from article 90 precluded the trailer from being covered by the code.

Not Covered. This Code does not cover the following:
(1) Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles

I suggested a trailer is not an automotive vehicle so the exclusion would not apply. that does mean that I think anything other than article 525 applies to the situation under discussion.

An automotive vehicle pretty much by definition has to have a built-in source of locomotion such as an engine. A trailer is thus not an automotive vehicle.

automotive
adjective
pertaining to the design, operation, manufacture, or sale of automobiles:
automotive parts.
propelled by a self-contained motor, engine, or the like.