Separate Structures

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iwire

iwire

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I have to install four - 30 amp, 208 volt, single phase circuits from a panel in a building to a 4" x 6" wood post mounted along a sidewalk.

These circuits will be run in one PVC raceway from the building out 150' to the wood post. The circuits will feed four NEMA L6-30R outlets mounted on the post.

Do I need to install grounding electrode(s)? ;)
 
Re: Separate Structures

Better install four posts. :D

You can't supply a structure with four branch circuits, unless you're working on one of the items listed in 225.30(A)-(E).

Is that what you're wanting to hear? :D

Edit: In the event you install the four posts, by 250.32(A), exception, you don't need grounding electrodes. :D

[ April 25, 2005, 08:02 AM: Message edited by: georgestolz ]
 
Re: Separate Structures

If I understand your question no you dont need ground rods and should not put them in.You are just installing receptacles on posts that post is not a seperate building or structure.250.32 is for seperate buildings.
 
Re: Separate Structures

If you are supplying (4) L5-30 receptacles, then you are just installing receptacles. The Equipment Grounding Conductor that you will run inside the PVC is your ground.
If you were to install a sub panel with the (4) outlets located on this same post the were fed via this sub panel, then you may have something to think about.
Some may claim that you call this a 'separate' service and will require bonding and ground rods (since it comes out of the ground, yet this is not a seperate building/structure).
Others will say that this is just a sub panel, and there is no bonding. Therefore, you do not install ground rods but run a EGC to the panel and run all 'grounds' to that.
What are you working with: Equipment Grounding Conductors, or Grounding Electrode Conductors? That should help you answer what you need.
 
Re: Separate Structures

Structure. That which is built or constructed.
Click to expand...
Is the post a "structure" based on the NEC definition. That is the question that must be answered first.
Don
 
Re: Separate Structures

A building or structure can only be supplied with a single or multiwire branch circuit. For more than one branch circuit you would need a feeder.
A feeder requires a disconnecting means and grounding electrode system.
See the rules in 250.32 and 225.30
Wouldn't it be easier to install one feeder, and a small panel than 4 separate circuits?
 
Re: Separate Structures

Bob
You are in compliance with 230.71 Maximum Number of Disconnects at the other structure so the way I read your question the answer is here:

250.32 Buildings or Structures Supplied by Feeder(s) or Branch Circuit(s).
(A) Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with 250.50. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.

Exception: A grounding electrode shall not be required where only a single branch circuit supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the conductive non?current-carrying parts of equipment. For the purpose of this section, a multiwire branch circuit shall be considered as a single branch circuit.
This exception wouldn?t count here as there is more than one circuit.

(E) Grounding Electrode Conductor. The size of the grounding electrode conductor to the grounding electrode(s) shall not be smaller than given in 250.66, based on the largest ungrounded supply conductor. The installation shall comply with Part III of this article.

250.66 (A) Connections to Rod, Pipe, or Plate Electrodes. Where the grounding electrode conductor is connected to rod, pipe, or plate electrodes as permitted in 250.52(A)(5) or (A)(6), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.

250.58 Common Grounding Electrode.
Where an ac system is connected to a grounding electrode in or at a building or structure, the same electrode shall be used to ground conductor enclosures and equipment in or on that building or structure. Where separate services, feeders, or branch circuits supply a building and are required to be connected to a grounding electrode(s), the same grounding electrode(s) shall be used.
Two or more grounding electrodes that are effectively bonded together shall be considered as a single grounding electrode system in this sense.

With out doubt, you already knew this but I am glad that you ask. Now can I ask you to return the favor and answer a question for me? Am I right?

edited to add out in, with out doubt
:)

[ April 25, 2005, 06:45 PM: Message edited by: jwelectric ]
 
Re: Separate Structures

So, unless we meet one of the exceptions under 225.32, we have to have a disconnect on the post, even if there is only one branch circuit serving it?
And the disconnect must comply with 225.36 and 225.38?
 
Re: Separate Structures

Did you build or construct the wooden beam? No!! Well you still have to ask AHJ to be safe. That's just not right.

frank
 
Re: Separate Structures

Wow, of course I was kidding with my first post. I would have never thought this situation would be an issue over a grounding electrode having to be installed. Personally, if I had done this job I wouldn't have even considered a ground rod may be required. I have never seen one in similar installs. Are there any inspectors on the forum that would consider a 4"x6" post a structure? Are there any here that would insist on a grounding electrode??
 
Re: Separate Structures

Interesting points by many.

I will get back to this tomorrow.

Tom, Possibly I can ignore 225.30 as this 'post' is not served by the branch circuits?

The post is not there now, we will be installing the post. IMO that makes it a structure per the NEC definition. :p
 
Re: Separate Structures

The NEC should be changed as far as this requirment goes. in the case of a single pole or other type of support that could not inhabit human beings, and is fed only by feeders or branch circuits,it should not require a grounding electrode or disconnect.
This is one of those requirments that is the cause of people thinking that a grounding electrode make the pole or support safer. As Mike Holt has pointed out a EGC ran with the supply conductors will make for a much safer installation than a grounding electrode will ever do!
As far as the disconnect goes if there is only receptacles on the support then the receptacles should be able to serve as the disconect for any equipment that is pluged into them.
If there is equipment hard wired upon the support or pole then this equipment should have a disconnect.
Exception 1. Meter fittings

Ok now where do we put it? :roll:
 
Re: Separate Structures

I would consider a 48" backyard swimming pool a structure,yet I've never seen the pump recpt. with a disconect and GES used,even if 2 or 3 circuits are involved. I would think that this situation would take presidence over a 4x6 piece of wood.

JMO frank
 
Re: Separate Structures

The pool has an article all to it and all the requirements are contained with-in 680. If there was no 680 I would think that we would be sinking rods in the ground for them. I think the rods would be a lot easier than that #8 grid for liner pools.
 
Re: Separate Structures

BOB,

As a licensed Electrician you may not build this structure,you must be a Licensed Constuction Supervisor in order to obtain the building permit required to perform this function.Am I wrong??? They build them we wire them.

frank
 
Re: Separate Structures

Hi Bob and Don,

In my opinion: (based on the 2005 NEC)

1.)The post is a separate structure according to the NEC.
2.)This means that you must run a feeder to the post (because of the 4 circuits) and provide a means of disconnect. 3.)Provide overcurrent protection for the 4 receptacles.
4.)You also must supply one of the grounding electrodes listed in 250.52(A)(4) through (A)(7).
 
Re: Separate Structures

I have a hard time seeing this as a 'structure'.
If you run power out to a fence post in your back yard and install a gfi, you do not need to first hit a disconnect.
I have a hard time seeing JUST a 4x6 post as a structure.
Especially if you install this post solely for the installation of your (4) Recepts.
If this post is only for you, and not for anything else (supporting or structural), then this post is just part of your mounting assembly.
 
Re: Separate Structures

Originally posted by milwaukeesteve:
I have a hard time seeing this as a 'structure'.
Click to expand...
Personally I agree.

That said, would you agree that when the NFPA provides a definition in article 100 that is the definition we must use?

Here is the 2002 NEC Article 100 definition of structure.

Structure. That which is built or constructed.
Click to expand...
Given the NEC definition and the fact the post did not grow there I would say it is a NEC structure.

Look at this from another direction.

A light pole to the NEC is a 'structure' this is shown clearly by the exception that allows the disconnect to be located elsewhere on the property.

225.32 Exception No. 3: For towers or poles used as lighting standards, the disconnecting means shall be permitted to be located elsewhere on the premises.
Click to expand...
Bob
 
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