5 conductor 4wire plus ground/messenger needed overhead building feeders

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fmtjfw said:
Some triplex has ACSR bare conductor, lots has AL bare conductor.
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That AL bare conductor has a steel strand in the center for support - which is what ACSR is Aerial Cable Steel Reinforced.

Aluminum would not survive long without reinforcement - some short runs maybe are the exception. Otherwise the aluminum doesn't have the strength to support the load, and withstand additional load added by wind, snow and ice, etc.
 
iwire said:
It is not a NRTL listed conductor type so we cant use it. If the manufacturers spent the money to have it listed we could use it.
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I continue to disagree with you on this issue. In my opinion triplex and quadplex are very clearly "identified" for the purpose and permitted by sixth list item in Table 396.10(A). Note that is the only list item in that table that does not have an NEC article reference.
Identified (as applied to equipment). Recognizable as suitable for the specific purpose, function, use, environment,
application, and so forth, where described in a particular Code requirement.
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You could do what I saw between power poles just outside of the SeaTac airport. The had run a messenger cable between poles, lashed PVC conduit to the messenger and pulled medium voltage conductors through the conduit. I have no idea why they did it that way.
 
Smart $ said:
Where in the code?
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IMO here ....

338.10(B)(4)(b) Exterior Installations. In addition to the provisions
of this article, service-entrance cable used for feeders or
branch circuits, where installed as exterior wiring, shall be
installed in accordance with Part I of Article 225. The cable
shall be supported in accordance with 334.30. Type USE
cable installed as underground feeder and branch circuit
cable shall comply with Part II of Article 340.
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334.30 Securing and Supporting. Nonmetallic-sheathed
cable shall be supported and secured by staples, cable ties,
straps, hangers, or similar fittings designed and installed so
as not to damage the cable, at intervals not exceeding 1.4 m
(41?2 ft) and within 300 mm (12 in.) of every outlet box,
junction box, cabinet, or fitting. Flat cables shall not be
stapled on edge.

Sections of cable protected from physical damage by raceway
shall not be required to be secured within the raceway.
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don_resqcapt19 said:
I continue to disagree with you on this issue. In my opinion triplex and quadplex are very clearly "identified" for the purpose and permitted by sixth list item in Table 396.10(A). Note that is the only list item in that table that does not have an NEC article reference.
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You may be on something with this, first time I am aware of that bit of information anyway.

I still not sure what to think of that last part " where described in a particular Code requirement".

Where is this type of aerial cable described in pretty much any code section? Why does all other conductors need to be a type mentioned in art 310, or cable assemblies need be a type covered in one of the chapter 3 sections - but this type not mentioned at all yet is possibly qualified by "identified for the purpose"? Not like this stuff just came out last year:?
 
kwired said:
That AL bare conductor has a steel strand in the center for support - which is what ACSR is Aerial Cable Steel Reinforced.

Aluminum would not survive long without reinforcement - some short runs maybe are the exception. Otherwise the aluminum doesn't have the strength to support the load, and withstand additional load added by wind, snow and ice, etc.
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http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet34

Not all Triplex has ACSR. At lot of it doesn't. The spans for most service drops are not that long and AL is more than sufficient. See the attached from Southwire. Aluminum neutral/messenger is easier to handle and easier to cut. Go find a scrap of it and cut it to see. All AL also corrodes much less than ACSR.

6201 AL is designed to be strong. http://www.nehringwire.com/aluminum/bare-aluminum-and-acsr/aaac-all-aluminum-alloy-6201-conductor

Remember AL alloys cover a great range of properties; from aluminum foil to the armor on APCs.
 
kwired said:
Multiple conductors spaced evenly in free air, should probably have more impedance then if same conductors were multiplexed, or installed in close proximity in a raceway, but spacing them evenly does give you same impedance on each conductor because each one is subjected to same characteristics.
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You only get the same impedance if you arrange the conductors in the same relative positions as their voltage? [current??] vectors. In this case the hot wires positioned on the corners of an equilateral triangle and the neutral in the center of the triangle equidistant from each of the corners. I know that works for capacitance, given the conductors spacing is greatly smaller than the distance to other electrically charged objects (other conductors, earth, metal structure).

That is hard to do on a single linear cross arm.

Granted the wave fronts of many short circuits are steep and move the apparent frequency way up, which causes impedance effects that are small at 60Hz.
 
don_resqcapt19 said:
I continue to disagree with you on this issue. In my opinion triplex and quadplex are very clearly "identified" for the purpose and permitted by sixth list item in Table 396.10(A). Note that is the only list item in that table that does not have an NEC article reference.
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In addition:

396.2 Definition.
Messenger-Supported Wiring. An exposed wiring support system using a messenger wire to support insulated conductors by any one of the following:

....

(4) Multiplex cables utilizing a bare conductor, factory assembled and twisted with one or more insulated conductors, such as duplex, triplex, or quadruplex type of construction

Which not only describes service drop type cable but also indicates that the messenger is a conductor.

Further:

396.30 Messenger.

....

(B) Neutral Conductor. Where the messenger is used as a neutral conductor, it shall comply with the requirements of 225.4, 250.184(A), 250.184(B)(7), and 250.187(B).

(C) Equipment Grounding Conductor. Where the messenger is used as an equipment grounding conductor, it shall comply with the requirements of 250.32(B), 250.118, 250.184(B)(8), and 250.187(D).

250.184 Solidly Grounded Neutral Systems. Solidly grounded neutral systems shall be permitted to be either single point grounded or multigrounded neutral.

(A) Neutral Conductor.

(1) Insulation Level. The minimum insulation level for neutral conductors of solidly grounded systems shall be 600 volts.

....

Exception No. 2: Bare conductors shall be permitted for the
neutral conductor of overhead portions installed outdoors.

Exception No. 3: The grounded neutral conductor shall be
permitted to be a bare conductor if isolated from phase
conductors and protected from physical damage.
 
With all this talk of NRTLs we have to remember that we are OUTSIDE.

I an amazed that some inspectors tag triplex or quadraplex.

I've never seen an inspector require NRTL listed poles, cross arms, insulators, or conductors on customer owned 12.7kV lines.
So why do we suddenly drop back to these arguments when the voltage is less than 601 volts?

I can understand the argument about separated neutral and grounding on branch circuit and feeders, again for low voltage.
 
fmtjfw said:
Not all Triplex has ACSR. At lot of it doesn't. The spans for most service drops are not that long and AL is more than sufficient.
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Did not look at your links, I do trust there is such a beast. You will not find it around here that I am aware of though. Lots of stuff with steel reinforcement does come down in both winter and summer storms we have here quite often. No steel would be even worse.

Though service drops designed to break away before pulling the service mast with them could have some benefits, just need to make sure the neutral is last conductor to break somehow and then you really have something people would be interested in.
 
What about tray cable, lashed to a messenger? If it's sunlight resistant is there a problem, or are we back to the listsings issue (type TC is only listed for use in tray cables)?

http://www.wireandcabletogo.com/1-0-4C-THHN-PVC-Tray-Cable-with-Ground.html

The messenger can be 3/16" or 1/4" aircraft cable, with Nicopress swaged ends. Use tin-plated copper swages for increased corrosion resistance. Talk with your local rigging company about making up the lengths you need if you don't want to buy the swaging tool. It should be very cost-effective.

Is the inspector being difficult? What does he suggest, since you can't go underground?



SceneryDriver
 
kwired said:
Did not look at your links, I do trust there is such a beast. You will not find it around here that I am aware of though. Lots of stuff with steel reinforcement does come down in both winter and summer storms we have here quite often. No steel would be even worse.

Though service drops designed to break away before pulling the service mast with them could have some benefits, just need to make sure the neutral is last conductor to break somehow and then you really have something people would be interested in.
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I actually have not seen tripex with ACSR here. It probably depends on the POCO and the original engineer who wrote the first spec.:D

We have very few, if any, accidents that actually break the triplex, normally tree falls do rip the wiring / mast off the building.
 
fmtjfw said:
I actually have not seen tripex with ACSR here. It probably depends on the POCO and the original engineer who wrote the first spec.:D

We have very few, if any, accidents that actually break the triplex, normally tree falls do rip the wiring / mast off the building.
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Well a falling tree is taking most anything you put up down, but how often do you have major ice build up happen?

We had an ice storm a few years ago where there we had 4 inches of ice build up on lines in some instances, that is a lot of extra weight for even a short span. Yet the weight alone wasn't too much of a problem, but it didn't take much wind at all to get those enlarged lines to sway and that caused lots of problems.
 
fmtjfw said:
I actually have not seen tripex with ACSR here. It probably depends on the POCO and the original engineer who wrote the first spec.:D

We have very few, if any, accidents that actually break the triplex, normally tree falls do rip the wiring / mast off the building.
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I bet they are ASCR and you are mistaken.
 
iwire said:
I bet they are ASCR and you are mistaken.
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One easy way to tell, cut it with your cable cutter that is for copper or aluminum only. If it leaves a scar in the cutting edge it is because there was a steel strand in it.:happyyes:

You will possibly get away with little damage to your cutter if cutting 6AWG or 4AWG but much larger and that steel strand will definitely leave you with an obviously damaged cutter.
 
I am just having a hard time imaging a single aluminum conductor supporting 2-4 other larger conductors over a 100'-150' span. Seems to me it would stretch and sag.

Of course in my area snow and ice loading is a yearly issue.
 
iwire said:
I am just having a hard time imaging a single aluminum conductor supporting 2-4 other larger conductors over a 100'-150' span. Seems to me it would stretch and sag.

Of course in my area snow and ice loading is a yearly issue.
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Have you ever seen single conductors approximately 2AWG or so grow to 4 inches diameter in ice covering? Even ACSR will sag pretty dramatically.
 
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