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

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spedobill

Member
Location
st paul, mn
I've spent most of the day, in search of a overhead 4wire plus ground ( messenger supported) assembly for a 100 amp 250v 3phase 4w feeder drop.
396.10 has listings of cable types, however locating lashing material and rings and saddles is a challenge. The inspector wont allow a added conductor to the quadplex.

Anybody have any experience or suggestions with this situation?
Thanks
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
I've drempt of this situation but myself haven't been subjected to this problem. But also am interested to find out if there is such thing as an overhead insulated quad w/ bare messenger.
 

Smart $

Esteemed Member
Location
Ohio
Did the inspector cite Code prohibiting such?

See Article 396 for cable types permitted with messenger-supported wiring and grounding with the messenger wire.
 

DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
The "messenger" bare wire should be the neutral. The EGC should be insulated or a bare conductor in an overall sheath. How far of a run is it? Might consider laying gray pipe or a strut-supported raceway?
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
The "messenger" bare wire should be the neutral. The EGC should be insulated or a bare conductor in an overall sheath. How far of a run is it? Might consider laying gray pipe or a strut-supported raceway?

Not when used as a feeder,
the bare messenger wire is used as EGC and one of the insulated conductors for the neutral. And in OP case, another 3 insulated to be used for the 3 phases.
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
I've spent most of the day, in search of a overhead 4wire plus ground ( messenger supported) assembly for a 100 amp 250v 3phase 4w feeder drop.
396.10 has listings of cable types, however locating lashing material and rings and saddles is a challenge. The inspector wont allow a added conductor to the quadplex.

Anybody have any experience or suggestions with this situation?
Thanks

Seems odd that after revised codes on grounding that overhead cable manufacturers haven't seemed to produce cables specifically designed to accommodate new rules.
Duplex,Triplex,Quadplex but where is the Pentaflex for 3phase feeder applications(L,L,L,N,G)
they seem to only produce these cables for (Service ) applications where a EGC is not in the mix.
So what is a guy to do for a farm with a 3phase disconnect at his shop that then goes 150' overhead to the 3phase panel feeding dryer motors/ augers on silos ?
Trying to find a 5 conductor overhead cable is nil. So I guess you make you're own like you said with separate cables and lashing wire. :blink:
Unless you go underground if feasible or along building.
 
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kwired

Electron manager
Location
NE Nebraska
The overhead cable you are likely talking about is not a conductor type permitted by article 310, the cable assembly is not a recognized cable by any other part of NEC chapter 3. This is why you can't find a 4 wire plus ground. It is only intended for use by utilities and they would never have the need for such a cable.

That said this cable is used all the time for NEC applications, but some places they are strict and do not allow it's use.

About the only way to be completely NEC compliant with overhead conductors/cables would be to run a messenger wire for support and hang some other NEC recognized wiring method from it, and of course a type suitable for the conditions.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I suppose a utility could once have used four insulated wires plus a neutral for two-phase five wire service. :)
But more likely underground than overhead.

Tapatalk!
 

kwired

Electron manager
Location
NE Nebraska
I suppose a utility could once have used four insulated wires plus a neutral for two-phase five wire service. :)
But more likely underground than overhead.

Tapatalk!

Back when that would have been a common need they would have been using single conductors instead of a multiplexed cable assembly.
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
If an aerial cable is not available can you run underground instead?

Can you set a 1:1 transformer at the far end and derive your neutral from there, which would allow you to run quadplex?
 

spedobill

Member
Location
st paul, mn
underground not a option

underground not a option

Underground is not a option. Im thinking muticonductor MC or service entrance cable. That transformer idea is quite creative. What a great forum.
 

fmtjfw

Senior Member
Run separate conductors and use multi-spool secondary racks. Since it is outdoors the individual conductors need not be "insulated" except within 10Ft of structures (other than supporting poles). You could use quadraplex, unwind it, one conductor per spool and add another conductor for neutral.

:rant:The "against code ruling" for triplex, quadraplex defies all reason. There are literally millions of miles of the stuff used outdoors around the world with a miniscule failure rate.:rant:
 

fmtjfw

Senior Member
Run two triplex cables, insulated wires A, B and C, N. Parallel uninsulated wires for G. [The NEC requires us, in general, to parallel all available grounding conductors and raceways as EGCs].
 

kwired

Electron manager
Location
NE Nebraska
Run separate conductors and use multi-spool secondary racks. Since it is outdoors the individual conductors need not be "insulated" except within 10Ft of structures (other than supporting poles). You could use quadraplex, unwind it, one conductor per spool and add another conductor for neutral.

:rant:The "against code ruling" for triplex, quadraplex defies all reason. There are literally millions of miles of the stuff used outdoors around the world with a miniscule failure rate.:rant:
I don't know what the intent of NEC is, but as is, overhead multiplex cable with a ACSR messenger, is not a recognized wiring method

Run two triplex cables, insulated wires A, B and C, N. Parallel uninsulated wires for G. [The NEC requires us, in general, to parallel all available grounding conductors and raceways as EGCs].
But we are not paralleling anything (except the EGC) in that instance. Ignoring the before mentioned fact the wiring method itself is not recognized by NEC, if you do this you will have a violation of 300.3(B). If you want to ignore that I still don't like the idea of not having all conductors of the circuit in the same assembly because it will increase impedance, which will result in less current during fault events which will lead to slower response time from overcurrent protection devices.
 

fmtjfw

Senior Member
I don't know what the intent of NEC is, but as is, overhead multiplex cable with a ACSR messenger, is not a recognized wiring method

But we are not paralleling anything (except the EGC) in that instance. Ignoring the before mentioned fact the wiring method itself is not recognized by NEC, if you do this you will have a violation of 300.3(B). If you want to ignore that I still don't like the idea of not having all conductors of the circuit in the same assembly because it will increase impedance, which will result in less current during fault events which will lead to slower response time from overcurrent protection devices.

:)Some triplex has ACSR bare conductor, lots has AL bare conductor. The electrons used on the POCO side of the a service are essentially the same as the electrons in premises wiring. I don't know about your area but in most areas I've been in the Western Hemisphere there is a whole bunch of du- tri- and quad-plex carrying a whole bunch of electrons with no evident mishap. At some point I begin to believe in basic physics and the evidence of my eyes as to usability.:)

The NEC would be perfectly happy with bare wires spaced 24 inches apart on a crossarm for the ABCNG conductors of such a circuit. How would that impedance compare with two triplex ABG CNG?

Can you come up with a calculation for one penta-plex versus two tri-plexes sized for 100A continuous load demonstrating the additional time for opening, say a three-pole 100A BR breaker with 200A and 1000A currents?
 
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kwired

Electron manager
Location
NE Nebraska
:)Some triplex has ACSR bare conductor, lots has AL bare conductor. The electrons used on the POCO side of the a service are essentially the same as the electrons in premises wiring. I don't know about your area but in most areas I've been in the Western Hemisphere there is a whole bunch of du- tri- and quad-plex carrying a whole bunch of electrons with no evident mishap. At some point I begin to believe in basic physics and the evidence of my eyes as to usability.:)

The NEC would be perfectly happy with bare wires spaced 24 inches apart on a crossarm for the ABCNG conductors of such a circuit. How would that impedance compare with two triplex ABG CNG?

Can you come up with a calculation for one penta-plex versus two tri-plexes sized for 100A continuous load demonstrating the additional time for opening, say a three-pole 100A BR breaker with 200A and 1000A currents?

Don't read me wrong - I have no issue myself with the mentioned multiplexed cables - just want to point out that NEC doesn't recognize them.

I can not come up with your calculation without some research - this is not something I would calculate often.

I will say if you are going to tell us the current- it is easy, look at the trip curve of the device in question for it is the current that you are essentially asking me to calculate.

If you had ABG, CNG configuration and had an A-B fault you would have a different fault current then you would have for A-C because of impedance differences. How much difference I don't really know, but do know it depends on other factors not mentioned as well.

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.
 

iwire

Moderator
Staff member
Location
Massachusetts
:rant:The "against code ruling" for triplex, quadraplex defies all reason. There are literally millions of miles of the stuff used outdoors around the world with a miniscule failure rate.:rant:

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.
 

iwire

Moderator
Staff member
Location
Massachusetts
however locating lashing material and rings and saddles is a challenge.

The NEC does not require any of those products.

You can use pretty much anything, for instance high quality, military grade tie wraps with SER would be fine and you can get SER with 4 insulated and one bare.
 

Smart $

Esteemed Member
Location
Ohio
The NEC does not require any of those products.

You can use pretty much anything, for instance high quality, military grade tie wraps with SER would be fine and you can get SER with 4 insulated and one bare.
If he had 5-conductor SER, there'd be no need for a messenger wire to lash it to.
 
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