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bluegoose42 07-05-2012 10:27 PM

Subpanel
 
I just bought a foreclosure and the previous owner cut the overhead cable from the house to the detached garage. The wire that's there is two #2 aluminum and a stranded bare aluminum. He cut it right at the weather head and left enough so that I can do a new splice and drop to the sub panel if it's the right kind of wire.

With every subpanel I've wired in the past I ran 2 hot conductors, a neutral, and a ground. I've never done any overhead wiring, but plenty of wiring within a building. The panel that's in the garage is in shambles and I can't even tell how it was hooked up originally, so I'll be replacing with a new 100 amp sub.

My questions:

Is it possible to wire a sub with the wire that's already in place? If so, how do you get 240 without the extra conductor?

If not, what type of wire do you use for an overhead application, as well as for the portion in the house until it leaves the house?
- The panel in the house is at the opposite end of where this line is currently run. So there's wire running from the house panel across the attic to a weather head, and then spliced to the overhead wire which runs to the garage.

Thanks in advance for any help you can offer

bluegoose42 07-05-2012 10:33 PM

Also, while I'm at it, the panel in the house is also a subpanel, because the main with the meter is a ranch panel on a pole about 75 feet from the house. The feeder comes in through the basement in 2" conduit and is 3 #2 aluminum, no bare ground. These were also cut where they enter the basement, so I need to splice them and continue the run to the panel in the house. I was planning on using the 3 existing wires as my 2 hots and neutral, and then running a ground rod from the panel for a ground. I tried to pull a ground through the conduit but there's no way that was happening.

Will this work without having a ground that goes back to the meter/main as long as I have a solid ground from the ground rod?

How would it have been hooked up originally that they only needed 3 wires? This house was built in 1974

Thanks again

J. V. 07-06-2012 09:57 AM

Prior to the 2008 code cycle, 3 wire feeders to unattached structures were compliant as you can see. The main panel/service panel/disconnect is on the pole and the new code cycle would require the house and the garage be fed with 4 wires like you are accustomed to installing.
The question I have is where does the feeder/service for the garage originate from? The house or the pedestal main service panel/disconnect on the pole? Is there a breaker for each feeder? Or is it possible they extended the service to the house and the garage? Lets make sure about what you actually have before we give any advice.
Open the the panel on the pole an see how the house is fed. Or is this panel on the pole actually a disconnect? A disconnect for both house and garage?
So look into each panel and disconnect on the property and see what they were thinking. Are these feeders or service extensions to the house and garage? Let us know.

bluegoose42 07-07-2012 12:57 AM

The feeder for the garage comes from the subpanel in the house.

I looked in the garage panel today too and saw that the wires are run 2 hots to the bus and the bare ground to a ground bar that has both grounds and neutrals.

I understand that under the current code cycle neutral and ground are supposed to be isolated. Because I'm just repairing what was already there, I can legally hook it up the way it was.

What is the down side to NOT isolating your neutral and ground?

k_buz 07-07-2012 06:22 AM

Quote:

Prior to the 2008 code cycle, 3 wire feeders to unattached structures were compliant as you can see.
This is simply not true. Prior to the 2008 NEC, ground rods were not required at detached structures. A separate ground and neutral have been required for a long time...much before 2008.

stickboy1375 07-07-2012 06:27 AM

Quote:

Originally Posted by k_buz (Post 959830)
This is simply not true. Prior to the 2008 NEC, ground rods were not required at detached structures. A separate ground and neutral have been required for a long time...much before 2008.

That simply is not true. :) Check out 250.32 (B)(2) in the 2005. 3 Wire feeders were allowed, you ALWAYS needed a grounding electrode, unless it was a single branch circuit. (a multi wire branch circuit shall be considered as a single branch circuit)

k_buz 07-07-2012 06:58 AM

You changed your mind since this?
http://www.diychatroom.com/f18/subpa...97/#post950338

I am going to have to look into this, maybe it was a state thing.

stickboy1375 07-07-2012 07:05 AM

Quote:

Originally Posted by k_buz (Post 959841)
You changed your mind since this?
http://www.diychatroom.com/f18/subpa...97/#post950338

I am going to have to look into this, maybe it was a state thing.

You have to keep in mind, one thread was describing a sub panel located within the same structure, this thread is discussing a detached structure.

As I stand, you could never run a 3 wire feeder and re bond the neutral at a sub panel within the same structure, with detached structures, you could run a 3 wire feeder, re bond the neutral, as long as there were no continuous metallic paths bonded to the grounding system in each building or structure involved.

This is off the 2005 NEC, which my state is on, I still run a 4-wire feeder to remote structures even though I don't have to by code.

k_buz 07-07-2012 07:19 AM

That is a good point, and I didn't notice that difference. I will have to check into this as I (personally) can't remember ever bonding the neutral in a detached sub.

I will agree and retract my previous post about it needing to be 4 wire.

bluegoose42 07-07-2012 11:39 PM

Okay, so I found a thread that talked about why the neutral and ground are isolated and that all makes sense.

However, I am still going to temporarily repair the damage with the existing 3 wire feeds until I can do it right this fall.

So, what I gathered from the other thread was that for a detached structure with no metal connection to the other building, the 3 wire feed would have two hots connected to the bus, and the 3rd wire is attached to the neutral bar, which is then bonded to the panel, correct? And then the a ground rod is required, which is also connected to the bonded neutral bar NOT the ground bar, correct?

So, then the ground rod is a protection from lighting but not actually an equipment ground ??? So how is your equipment grounded??

Also, the overhead wire that is currently in place to the garage is two insulated conductors and one bare stranded aluminum. The bare aluminum is spliced to insulated conductors at both weather heads before entering each panel. Is that okay? Seems like it should be insulated the whole way, but it was obviously working that way for a long time, so I'm just wondering about that also.

Thanks again for the input

zappa 07-08-2012 05:56 AM

Quote:

Originally Posted by bluegoose42 (Post 960449)
Okay, so I found a thread that talked about why the neutral and ground are isolated and that all makes sense.
However, I am still going to temporarily repair the damage with the existing 3 wire feeds until I can do it right this fall.

Code violation. How about doing it right the first time? String the proper number of wires so you don't create more work for yourself later.

Quote:

So, what I gathered from the other thread was that for a detached structure with no metal connection to the other building, the 3 wire feed would have two hots connected to the bus, and the 3rd wire is attached to the neutral bar, which is then bonded to the panel, correct? And then the a ground rod is required, which is also connected to the bonded neutral bar NOT the ground bar, correct?
Close. The ground rod goes to the ground bar which needs to be electrically bonded to both the neutral and panel. This information pertains to a 3-wire system, not a 4-wire like you will be converting to. The neutral bond gets removed in a 4-wire and the neutral will be floating by itself.

Quote:

So, then the ground rod is a protection from lighting but not actually an equipment ground ??? So how is your equipment grounded??
The equipment gets grounded through the neutral. This information pertains to a 3-wire system, not a 4-wire like you will be converting to.

Quote:

Also, the overhead wire that is currently in place to the garage is two insulated conductors and one bare stranded aluminum. The bare aluminum is spliced to insulated conductors at both weather heads before entering each panel. Is that okay? Seems like it should be insulated the whole way, but it was obviously working that way for a long time, so I'm just wondering about that also.
It's normal for the neutral to be uninsulated in certain cases. Look at the overhead feeding your house or other homes that have overhead.

Thanks again for the input

.....

bluegoose42 07-08-2012 11:36 AM

Quote:

Originally Posted by zappa (Post 960529)
Close. The ground rod goes to the ground bar which needs to be electrically bonded to both the neutral and panel. This information pertains to a 3-wire system, not a 4-wire like you will be converting to. The neutral bond gets removed in a 4-wire and the neutral will be floating by itself.
.....

So to electrically bond the ground bar to the neutral I would just connect them with a piece of wire?

zappa 07-09-2012 05:26 AM

Quote:

Originally Posted by bluegoose42 (Post 960777)
So to electrically bond the ground bar to the neutral I would just connect them with a piece of wire?

The manufacture of the panel provides the proper bonding strap. But since you are buying a new panel and using a 4-wire system this strap gets left out in a sub-panel. This is the only correct way to repower your garage.


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