ECN Forum Forums Code Related Discussion NEC & other Code issues 3-wire subpanel?? I goofed.

I only picked 25 ohms as it is kind of a standard the NEC uses for ground rods.

As in one ground if not 25 ohms or less needs another ground rod added to it.

The grounds I have installed and tested have been more around 5 ohms.

Wouldn't a phone line or CATV line from that same pole to the house be another continuous metallic path?

Donnie

if memory serves street light poles once were in dispute , being in the structure realm and having to have disco's apply....

this could have been 225.32 ex 3's orgin

sure Donnie,
parrallel noodles are never discriminate

Guys
What is the difference if the meter is on the house or on a pedestal in the yard? The SE conductors only have to be 3 wire, (2 hots, 1 neutral). The meter is not considered service equipment, even if there is a disconnect at the meter pedestal, just a utility required measuring device. If you had the meter on the house fed via 3 wire from the pole, it would be a code compliant installation even when the TV & Tele underground wires are run in from the pole. So what changes when there is a meter in the middle of the yard? Nothing.
You could run a 4 wire feeder from the meter pedestal to the house, but it is not required. I have done it both ways. I prefer the feeder if money is not an object. Either method is fine as long as the neutral/ground issue is code compliant.

I do not think this changes anything here, the exception does not say a pole is not a structure.

The metallic paths have to be bonded at both structures or buildings to make this not possible.

It sure is something to think about, I do not see the cable TV line carrying much current for long.

Might make for bad reception.



[This message has been edited by iwire (edited 11-17-2003).]

Heres an article from this months IAEI Magazine addressing 3 wire vs. 4 wire feeders.

I'm sorry guys, but I think a pole is not a structure. A pole is neither built nor constructed. It is a tree minus the bark, and it is inserted into the earth. A garage is a structure. A house or building is a structure, a pole is not. Sorry.

I would require four wires to the structure. (the ONLY structure in this case )

Ryan,
I've built quite a few Service Poles! LOL

BTW. I vote for 4 wires. Pull the feeder out and repull it with a 4th wire.

[This message has been edited by txsparky (edited 11-17-2003).]

We have a little investor-owned utility out here in California called Pacific Gas & Electric. In more rural service areas, like the Sierra Nevada foothills, they often drop power to a customer-owned pole on the residential property, with a meter base and cutoff box (often a metermain panel) installed on the pole by the property owner.

The metermain is the service point, where the utility drop (or service lateral) neutral and the grounding electrode conductor are bonded. The pole is indeed a built object, in other words, a structure.

We run a three conductor feeder (2 hots & a neutral) to the house and treat the house panel as another "service" as far as system grounding configuration goes. We install a grounding electrode system (a Ufer in the foundation) at the house and bond the neutral and the grounding busses with an MBJ.

This is a major utility, and as far as I can see, it's a Code-compliant installation. I agree that if the phone co were to install their network interface device on the pole that's the point of service, you could have a metallic path between structures, and potential for a fault current on the phone line if a ground fault occurrs and the neutral of the feeder is compromised. This isn't an issue because the phone co runs their drop to the house itself.

Cliff

Ryan I am very interested in your logic here.

1)The code article in question says

"building or structure"

Why would they use the word structure if this was limited to buildings?

2)Electrical safety wise what is the difference?

How is this dangerous from a pole to a building but not from a building to building?

3)The pole did not grow there and have its bark stripped, workers brought it to the site and installed it.

The wires were attached to it, the meter base and disconnect where mounted to it.

It was constructed.

If you failed me on this I would have to go over your head. (Possible in this state, I do not know about yours)

You can only enforce the code, not what you prefer.

PS, I would prefer 4 wires too.

Bob


[This message has been edited by iwire (edited 11-18-2003).]