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Hendrix Molded FAQs


How does the mechanical strength of HDPE insulators compare to porcelain with regards to turning angles (transverse loading)?

Our HDPE insulators exceed ANSI cantilever requirements of 3,000 lbs.  Porcelain versions have not always met this criteria as confirmed by independent lab testing.

What protection is recommended in both equipment and overhead distribution lines in lightning prone areas?

Do you see any increase in rates of failure as conductor size increases?

In over 50 years of experience, there is no correlation to conductor size and failure rates. Most failures occur as a result of an over-voltage event, such as lightning, or a fault-current event, such as prolonged line-to-line or line-to-ground contact.

How do you define "high" lightning areas?

We use the NASA data, which identifies areas with historic frequency of lightning strikes.

Is there a difference in performance between post insulators and pin insulators?

Inherent in the design, the resultant performance of line post insulators provide greater flashover, impulse and puncture performance.

What is your standard warranty on insulators?

Hendrix polymer pin insulators are Guaranteed for Life.

What is the maximum conductor angle that can be applied to a polymer pin insulator?

While Hendrix does not stipulate maximum allowable angles, the tested cantilever ratings of all our insulators exceed the ratings of most mounting hardware (cross arm pins, ridge pins, etc).

What is the material compound used in the polymer insulators?

95% of the material in a Hendrix insulator is 100% virgin high density polyethylene, with the balance a proprietary blend for UV resistance, track resistance, manufacturability, and color.

Do you have a comparative analysis between porcelain and polyethylene insulators?

Yes, please reference page 4 & 11 in the Hendrix Molded Catalog

For coastal environments, would you recommend a higher Class insulator than for inland applications?

With porcelain insulators it is common practice to use higher-class insulators than used inland for the same distribution system voltage levels.  The porcelain surface is hydrophilic and small amounts of contamination, coupled with fog, mist or light rain can lead to frequent tracking, discharge and flashover at relatively low voltage levels.  So application of porcelain insulators with higher leakage and flashover ratings made practical sense to reduce flashover incidence and related damage.
Polyethylene insulators are hydrophobic and non-polar, naturally repelling water and surface contaminants, making them less prone to flashover in coastal applications than their porcelain counterparts.  Higher class HPI insulators may be used to further increase flashover withstand capability, but may lead to a higher rate of puncture in areas with high lightning densities.

Why should porcelain insulators not be used with tree wire or covered conductor?

There is a dielectric incompatibility between the materials which creates high electrical stress at the interface.  Porcelain has a dielectric constant in the range of 6 to 8, while Polyethylene is 2.2 to 2.4.  Over time, the electrical stress at the interface can lead to destructive discharge and tracking, causing conductor covering erosion and puncture. 
Porcelain insulators with a Radio-Free semi-conducting coating create even higher electrical stress at the covered conductor interface and should be avoided.

Will cyclic changes in temperature loosen the hand tight insulators?

No. In actuality, the conductor and tie (or Vise jaw) will hold the insulator in place to prevent any rotation. Hendrix polymer pin insulators are installed in all 7 continents and all 50 states in the U.S.

Do you have statistics on the failure rate of porcelain vs. polyethylene type insulators?

The failure rate of polyethylene insulators is less than one-tenth of one percent (0.1%). We do not have data on porcelain.

Does Hendrix recycle insulators and how is this different from porcelain?

HDPE is 100% recyclable. It is the same as a #2 rated plastic (i.e. milk cartons, water bottles). Porcelain has no redeemable after life except as landfill. When broken, it is a sharp and dangerous by-product.

How easy are poly insulators cleaned vs. porcelain?

Polyethylene is a naturally hydrophobic, non-porous material lending to easy natural cleaning via normal rainfall. Porcelain relies on the glazing to seal and protect from the elements. Any breakdown in this protection can lead to contamination buildup and ultimate failure.The hydrophobicity of polyethylene is much greater than that of porcelain.

How do Vise Tops compare with tie tops in the event of a large limb falling on wire. i.e. breaking arms or causing wire to break?

Vise Tops will provide adequate grip the on conductor to varying degrees depending on wire size and type. Many users prefer the Vise Top for the benefit of being able to easily re-sag the line in the event of unintended loading rather than complete damage to the cross arm and pole. We can supply grip strength information on the Vise Tops.

Does the Vise-Top insulator damage the covering of covered conductor?

No.The first generation Vise Top and new Universal Vise Top insulators with plastic and composite inserts, respectively are specifically designed to maximize performance without damage to covered conductors.

Has there been independent lab testing on porcelain insulators to ANSI standards?

Yes, an independent group study performed a comprehensive test, in 2010, comparing porcelain pin insulators to polymer pin insulators. The polymer pin insulators outperformed the porcelain by far.

Do you make a post insulator in this technology?

Yes, we offer line post insulators for a range of distribution systems.  You can find them in our catalog and website, www.HendrixHPI.com.

How easy is it to remove/replace eyebolts on Vise Top insulators. Why is there a shearing eyebolt on the Vise Top insulators?

After a Vise Top insulator is installed, there remains a hex bolt head that allows bolt removal/replacement with a standard socket or wrench. The shear bolts allows for the proper and consistent amount of tightening while allowing indication of completed installation.