Overhead wire for feeder.

[Owhark]

What wire is supposed to be used for an overhead feed to a sub panel in a separate structure? Also, based on my understanding of the NEC, ANY sub panel is supposed to be fed by 4 separate wires(L1, L2, N, G.) and that the neutrals and grounds are to be isolated from each other and not bonded. Am I correct?
Most manufacturers of 4 wire cable like quadruplex say it’s for 3phase services.

 

[ramsy]

North America has adopted fire codes for this kind of electrical work.

Which code cycle has your AHJ adopted?

 

[ptonsparky]

I've never had an issue using overhead quad cable as a single phase feeder. Nor have the inspectors. Just don't take it into the building.
That said, I live and work here. YMMV.
Ask your AHJ what they approve of.

 

[LarryFine]

I've never had an issue using overhead quad cable as a single phase feeder.

Same here. Make sure you know which conductor you choose as the neutral, and test for this at the load end when you're done to be sure anyway.

The brand my usual supplier carries has one, two, and three ridges molded on the insulation. I always use the one with three ridges as the neutral.

 

[Owhark]

I realy appreciate your guys replies. Thank you for your time! Thank you!

 

[Owhark]

Could I ask you to, explain why to use the 4 wire over head and not the 3 wire from and electrical theory point of view?
about the AHJ, they require all installs to be up to the 2017 NEC. But the inspectors themselves don’t usually know the code book and allow you to use 3 wire overhead and use the bare messenger wire as the neutral and not have a ground from the main to sub and just bond the neutrals and grounds in the sub. Most contractors around here just do it that way. But from my understanding of the Code book, you need 4 wires weather it’s underground or overhead and your neutrals and grounds are to be isolated from each other in the sub panel.

 

[hillbilly1]

I have found buying underground and overhead wire from our local poco much cheaper than from the supply house. And as far as overhead, they always have it in stock, and you don’t have to order it.

 

[tom baker]

The overhead wire POCO uses is not listed. This may or may not be an issue.

 

[wwhitney]

Could I ask you to, explain why to use the 4 wire over head and not the 3 wire from and electrical theory point of view?

If there ends up being an alternate metal path between the buildings (which often happens in the future even if it is not present at the time of the feeder installation), and that alternate metal path is connected to the EGC in each building (as is also common), then omitting the EGC and rebonding the neutral at the building supplied will put that alternate metal path in parallel with the neutral. Which is not good, it will be carrying part of the neutral current during normal conditions.

Whereas if you run a separate EGC in the feeder, the alternate metal path just ends up in parallel with the EGC. Which is OK.

Cheers, Wayne

 

[tom baker]

Could I ask you to, explain why to use the 4 wire over head and not the 3 wire from and electrical theory point of view?

Downstream of the service, EGC and neutrals are now separated. Starting in 2002 the NEC did not allow regrounding the neutral at separate buildings, if there was a parallel path. Neutral current could be on the parallel path, be it a water pipe, coax shield or the EGC. If you use triplex, you are combing the neutral and EGC onto the bare messenger.

 

[LarryFine]

I have found buying underground and overhead wire from our local poco much cheaper than from the supply house. And as far as overhead, they always have it in stock, and you don’t have to order it.

I wasn't aware they would even sell it (or anything)!

 

[LarryFine]

Could I ask you to, explain why to use the 4 wire over head and not the 3 wire from and electrical theory point of view?

I just posted this today in response to someone asking why we bond grounding systems to the neutral. See if it explains anything you're asking (read entire thread for context):

Bonding of Neutral bus and Ground bus at Main Panel.

Good day engineers, I've read that, bonding of neutral bus and ground bus shall only be done at the MAIN PANEL. As graphically illustrated in Sir Mike Holt books, the main panel which contains the Main disconnecting device is separated from the branch circuit protective devices (which is...

forums.mikeholt.com

But the inspectors themselves don’t usually know the code book and allow you to use 3 wire overhead and use the bare messenger wire as the neutral and not have a ground from the main to sub and just bond the neutrals and grounds in the sub. Most contractors around here just do it that way. But from my understanding of the Code book, you need 4 wires weather it’s underground or overhead and your neutrals and grounds are to be isolated from each other in the sub panel.

They're absolutely wrong and you're understanding is correct.

 

[dissonant]

I've never had an issue using overhead quad cable as a single phase feeder. Nor have the inspectors. Just don't take it into the building.
That said, I live and work here. YMMV.
Ask your AHJ what they approve of.

Can I ask why you say to not take it into the building?

 

[ptonsparky]

Can I ask why you say to not take it into the building?

Most of it is not Listed, if any, so it has not been tested for smoke, flame spread and whatever else for use in a dwelling.

 

[electrofelon]

I wasn't aware they would even sell it (or anything)!

Yeah me either. For the POCO's I deal with, it would be 2 frustrating hours on the phone and then getting turned down.

 

[kwired]

Same here. Make sure you know which conductor you choose as the neutral, and test for this at the load end when you're done to be sure anyway.

The brand my usual supplier carries has one, two, and three ridges molded on the insulation. I always use the one with three ridges as the neutral.

Haven't used a lot of quad but what I have used has at least a ridge on one conductor. For single phase 120/240 use that for the neutral the other two don't matter. For service on high leg delta use one with ridge for high leg. Will still need to verify rotation otherwise unless it has other identification.

 

[kwired]

The overhead wire POCO uses is not listed. This may or may not be an issue.

Often the underground isn't either or is only USE rated and can't enter a building.

 

[kwired]

Could I ask you to, explain why to use the 4 wire over head and not the 3 wire from and electrical theory point of view?
about the AHJ, they require all installs to be up to the 2017 NEC. But the inspectors themselves don’t usually know the code book and allow you to use 3 wire overhead and use the bare messenger wire as the neutral and not have a ground from the main to sub and just bond the neutrals and grounds in the sub. Most contractors around here just do it that way. But from my understanding of the Code book, you need 4 wires weather it’s underground or overhead and your neutrals and grounds are to be isolated from each other in the sub panel.

That was the general practice and was allowed before 2008 code (I believe it was 2008).

From a theory perspective would be better yet to separate current carrying and grounding/bonding conductor at the source rather than at the service disconnect. One step further would be for the utilities to not use grounded conductors as current carrying conductors, would be a big change to stray voltages that commonly end up occurring when there is any impedance in a particular grounded conductor path, which even with the low resistance of a conductor that still results in a little bit of voltage drop across the conductor and increases the more load the conductor is carrying.

 

[LarryFine]

Haven't used a lot of quad but what I have used has at least a ridge on one conductor.

Even lamp cord has one or more ridges on the wire intended to be used as the grounded conductor.

When I first started in electricity, the wire meant to be grounded was known as the "identified conductor."

 

[LarryFine]

From a theory perspective would be better yet to separate current carrying and grounding/bonding conductor at the source rather than at the service disconnect.

Not sure I agree. You'd want the ground-fault current pathway to be as short as practicable.

One step further would be for the utilities to not use grounded conductors as current carrying conductors, would be a big change to stray voltages that commonly end up occurring when there is any impedance in a particular grounded conductor path, which even with the low resistance of a conductor that still results in a little bit of voltage drop across the conductor and increases the more load the conductor is carrying.

In the old days, grounded vs not-grounded was debated for a while. Each has its advantages and disadvantages.