We are going to install a new outdoor MLO subpanel to a conrete pole. It will get fed from a 208/120v 3 phase panel. The new panel will have 3 breakers in it serving a camera and lighting. Since it is not in a building or a structure, do we need to install a ground rod for this new subpanel?
Need a Ground Rod Installed?
- Thread starter rbeard
- Start date
- Status
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
yes, it is a structure. I believe you need two rods.
- Location
- Logan, Utah
I agree with jumper, this is indeed a structure and 250.32(A) requires a grounding electrode system installed at the pole.
If you use ground rods then 250.56 would require a single rod to have a resistance of no more than 25 Ohms or be augmented with an additional electrode.
Chris
If you use ground rods then 250.56 would require a single rod to have a resistance of no more than 25 Ohms or be augmented with an additional electrode.
Chris
I would double check the listing of your sub-panel. 225.36 requires that the disconnect required by 225.31 be suitable for use as service equipment. Most (if not all) MLO panelboards I have looked at require a "main" be installed to satisfy 225.36. This is based on the 2008 NEC.
Pete
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
NEC says it is a structure. Requires 2 rods
ivsenroute
Senior Member
- Location
- Florida
Yes, it is a structure
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Grounding electrodes are for lightning protection. Lightning will strike that concrete pole with or without your electrical panel installed.
Make sure you bond the camera coax per Article 820.
Make sure you bond the camera coax per Article 820.
mcclary's electrical
Senior Member
- Location
- VA
What did they install the panel on? Is it hanging in mid air floating by itself?,,,NO? It's actually screwed to something? Something manmade? Then thats' a structure. Even if it's a 4x4 with some cement
A lot of times the pool contractors will drive 2 pieces of 3/4" IMC a couple of feet apart and hang the pool panel on them using minis or unistrut to hang the panel on.
Personally, if I do the panel, I'd hang it on the house or block fence. Pipes rust and collapse.
Is every parking lot pole a structure? Is every lighted sign a structure?
Not here.
And then build a fence 12" in front of it
I hate pool guys.
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aftershock
Senior Member
- Location
- Memphis, TN
And then build a fence 12" in front of it
You owe me my beer, and a new keyboard.
- Location
- Massachusetts
Yes, they are absolutely structures to the NEC.
Well than you do not follow the NEC. :grin:
Electron_Sam78
Senior Member
- Location
- Palm Bay, FL
that local definition conflicts with article 100's definition of a structure. Unless the panels are planted in seed form then wired once they reach maturity they were built/manufactured/constructedsomewhere.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I tend to agree with the structure concept but that in itself creates other issues.
Let's look at a septic pump setup. Many of these units require 240v for the pump and 120v for the alarm. In some systems the alarm is tied to one leg of the pump-- problem-- yes. Since the 2008 we now have to have a dp breaker installed which would trip out the alarm on a short circuit or ground fault on the pump. Damn the alarm won't work. This makes this install illegal, at least around here.
Now run two circuits - a 240v circuit for the pump and a 120v circuit for the alarm. Problem again-- 225.30 unless one of the special conditions would apply (I didn't think it would). So if it's a structure, which I say yes to, then there is no legitimate way to wire the septic pump system.
I believe there must be an answer somewhere but as the NEC is written there isn't much that wouldn't qualify as a structure if it is detached from the building serving it. What is the intent-- who knows.
Let's look at a septic pump setup. Many of these units require 240v for the pump and 120v for the alarm. In some systems the alarm is tied to one leg of the pump-- problem-- yes. Since the 2008 we now have to have a dp breaker installed which would trip out the alarm on a short circuit or ground fault on the pump. Damn the alarm won't work. This makes this install illegal, at least around here.
Now run two circuits - a 240v circuit for the pump and a 120v circuit for the alarm. Problem again-- 225.30 unless one of the special conditions would apply (I didn't think it would). So if it's a structure, which I say yes to, then there is no legitimate way to wire the septic pump system.
I believe there must be an answer somewhere but as the NEC is written there isn't much that wouldn't qualify as a structure if it is detached from the building serving it. What is the intent-- who knows.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Yes, but don't require electrodes if supplied by single circuits.
- Location
- Massachusetts
You are correct, ................ of course the thread is about a feeder.
But the NEC does require disconnecting means at separate structures .......... unless say there was a specific exception to get around it.
Electron_Sam78
Senior Member
- Location
- Palm Bay, FL
is there an exception keeps a structure like a light pole fed by a single branch circuit from needing a GES?
And then build a fence 12" in front of it
Or put equipment right in front!! Just installed a panel for a pool job because the HO didn't want the pool contractor doing it. Have to say, what a disgusting, sloppy, disheveled person the pool "electrician" was. HO asked me what I thought of them. I smiled and told her, Mama said if you can't say nuthin' nice . . .
Electron_Sam78
Senior Member
- Location
- Palm Bay, FL
oops I meant a disconnect not a GES?
- Status