Southwire C7 - Conductor Grips

Page 13 of 23 Guide for Installation and use of Southwire C
7
Overhead Conductor
to more exposed spans during times of high wind. Temperature changes can also cause slack to
travel across the blocks from the long spans to the short spans and vice-versa. Southwire
recommends that any conductor be pulled up to sag and clipped in as soon as possible. IEEE
524 recommends the conductor remain in the stringing block no longer than 72 hours. The
attachment points can be marked immediately after sagging if the conductor must be left in the
blocks for an extended period of time. If a conductor must be left in the sheaves for an
extended period of time, it should be left at a tension less than 50% of sagging tension, close to
pulling tension, to prevent creep from affecting the sag values. Upon request, Southwire will
recommend creep correction factors if a line was held above 50% of sagging tension for longer
than several hours required for clipping in.
Conductor Grips
All grips used for C
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must be of the transmission grade. The jaws of transmission grade grips are
longer to ensure more gripping area on the conductor. Grip jaws may be round or oval but not
V-shaped. Grips must be properly sized for the conductor type, conductor diameter, and
tensions to be installed. Range taking grips that accept a range of conductor sizes, e.g. 25 mm
to 28 mm, should not be used. Any grip with an off-set in the jaw area should not be used as it
could damage the core.
Prior to use, grips must be inspected to ensure they are in good operating condition and tested
for holding strength on the conductor to be installed. Southwire recommends taking a section
of the conductor to be installed and, using two line trucks as temporary anchors, testing the
holding strength of the grips using a chain hoist and dynamometer to verify grip holding
strength. During testing, grips should not slip when subjected to a minimum tension of 110% of
the working tension during installation. The following grips may be used for C7 conductor:
For pulling:
• Basket Grips: Also referred to as a Kellems grip, a basket grip is the only acceptable grip
for pulling C
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conductor. Basket grips must be double-banded on the ends to prevent
slipping.