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#213917 09/06/14 11:35 PM
Joined: Jan 2004
Posts: 1,507
G
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Here's the deal (Ernie pay attention) can a contractor install a 4800v. feeder using directional boring run 1000 feet and not install a "Warning ribbon" 12" above the conductors? See (NEC 300.50).

Second question, if he needs the "warning ribbon" how does he install it?

Note- this is a feeder not Service conductors.


George Little
2017 / 2014 NEC & Related Books and Study Guides
Joined: Apr 2002
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George:
The only reference to 'directional boring' that I can find within the '11 NEC is 300.5 (k).

Neither relates directly toyour question.

Boring is something I have not come upon here.

There is no reference within 'over 600 volts' regarding boring that I find.

All the high voltage I come upon is in duct banks & concrete encased.


John
Joined: Jan 2004
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G
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Maybe the question should be: Can you directional bore customer owned conductors over 600v.


George Little
Joined: Jul 2004
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I don't know about customer owed but the utilities do it all the time around here and I am sure they are not boring another hole for a warning ribbon.
They bored a HV line behind my house that I am betting was over 100kv. The existing on the poles is (2)48kv and 250kv.


Greg Fretwell
Joined: Feb 2003
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M
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Would boring in the orange HPDE pipe and then pulling the cable in be more acceptable?

Joined: Apr 2002
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George:
Talking to two HV guys today, neither has done any directional boring installs.

I'm curious to see if Scott35 has any comments from the 'shaky side'!!

Last two, and one upcoming (13.2KV) at the college are duct banks (4x5" PVC) and concrete encasement. (Red concrete), per specs.


John
Joined: Mar 2003
Posts: 849
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George
Done all the time. Why DB if your gonna dig up the street or sidewalk to put ribbon.
Yoopersup

If we install HDPE in a open trench (which we do sometimes),
Ribbon is installed then.

Last edited by Yoopersup; 09/10/14 10:44 AM. Reason: Add
Joined: Mar 2003
Posts: 849
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George
Conductors marked with a rated temperature higher than that of the raceway can be used when the conductors are operated within the raceway temperature rating.

One application of 353.10(6) is the use of 105C-rated medium voltage cables, Type MV, where the cable ampacity at
the 105C rating is reduced to the cable ampacity at 75C or 90C to match the listed operating temperature rating of HDPE (75C or 90C).
Direct bury power cable systems are designed for long life, use of HDPE conduit to encase and protect the power cable from rock impingement is gaining favor as it allows for quick and easy repairs without excavation of the cable. HDPE conduit and innerduct is used to carry low 600V-transformer to end user) and medium (<69kV-substation to transformer) voltage power lines.

Yoopersup

Joined: Jan 2004
Posts: 1,507
G
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Thanks Ernie, I knew you dealt with this type of installation on a regular basis and would have a good answer.

See ya in Frankenmuth.


George Little

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