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Energy FAQs

How is SureSeal® constructed?

SureSeal® is constructed by applying two layers of tough cross-linked polyethylene around six streams of sealant. Conductor strand is fed into an extrusion head where the insulation and sealant are applied at the same point to the conductor. A vacuum pulls the insulation and sealant down onto the wire strand to insure a good grip, eliminating potential shrink back issues. The result is a totally bonded construction that provides equal protection around the entire cable. Since the insulation totally encapsulates the sealant, you get cleaner stripping. As well, there is no chance that sealant can migrate, or "leak down", into the strand where it could reduce sealing capability from external damage.

What is the sealant utilized in SureSeal® cable?

SureSeal's® sealant is a non-toxic, non-corrosive, proprietary visco-elastic formulation that exhibits the properties of both a liquid and a solid. Similar compounds have been used in the construction industry for decades. It is important to understand that the sealant will remain in the visco-elastic form, even after it exits the sealant channels to seal cable damage. The visco-elastic sealant will not solidify over time.

How does stripping work?

Below are photos that demonstrate the visco-elastic properties of the sealant contained in our SureSeal® cable.

A similar test was done on a SureSeal® cable heated to 90 degrees C for 24 hours, then allowed to cool to room temperature, then reheated to 90 degrees C for another 24 hours, and so on, through a total of eight cycles. No dripping occurred throughout the testing.

Will SureSeal® sealant flow at cold temperatures?

Tests have been conducted on SureSeal® cables, cooled to as low as minus 20 degrees C, that show ample flow to seal insulation breaches.

I've tried washing the sealant off my hands and tools with soap and water and several solvents, but nothing seems to work. What will clean the sticky residue?

The best cleaner for the sealant material is a good quality citrus based cleaner. Pre-wetted wipes are available, as well as liquids. See below for additional information related to SureSeal® sealant contact with rubber gloves or other personal protective equipment (PPE).

If a sample of SureSeal® was purchased to trial, is it reasonable for the customer to make a typical cut in the SureSeal® and then energize it to accelerate the testing and demonstrate the value of the cable?

Field testing of SureSeal®, with a deliberate cut in the insulation, is a feasible way to evaluate performance. It is typically done with a conventional control cable with identical damage. However, it may take quite a while to see corrosion in the field, due to the wide variability in soil chemistry and water content. For this reason, our trials have been most successful in a controlled "dirt box" test, where the soil is formulated to be extremely corrosive, and the water content can be monitored. In this way we can assure that a conventional cable will only last a few weeks, while in the field the same test may take a year to see results.

An installed SureSeal® cable has a nick in the insulation that is repaired by the sealant in the cable. Then some time later experiences extensive damage to same conductor in different location & fails. Do both cables have to be located & fixed?

No, It is quite likely that an underground cable fault locator would never see the initial sealed area. Testing has shown that SureSeal® recovers a large portion of the initial breakdown strength from the sealing process. The longer it is allowed to fill in the cut, the higher the breakdown strength. AC breakdown testing showed recovery to 4000 volts after 30 minutes and 8000 VAC after 1 week, while soaking in a water bath. This is not an impulse, but a sustained voltage applied for 5-minute steps

Will the utility need to locate and fix both faults or will only the second, permanent failure, be located?

If the initial failure point is not located, and the cable is effectively repaired to these levels, there is no need to repair the initial area.

Will the utility need to dig multiple holes in the yard?

No, only the area located for repair by the underground cable fault locator.

Will SureSeal® still "work" if a sharp object is stuck in the insulation to the conductor? Will the sealant block the area around the object to halt moisture ingress?

A: The sealant in SureSeal is designed to fill cuts in the insulation. It is formulated to have a tackiness that binds it to the insulation and also to any foreign object that may be in the cut. However, if the object is conductive and it has contacted the conductor, there will still be leakage current from the penetrating object into the surrounding soil.

What type of aluminum conductor is utilized to produce SureSeal® cable?

SureSeal® cables use the same aluminum conductor types as conventional 600V-UD cables. The stranding for aluminum SureSeal® cable will be SIW compressed per ASTM B 901 or compressed per ASTM B 231.

What sizes do we currently make with SureSeal®?

SureSeal® cable was initially developed to target service entrance and street lighting cables. These cables are usally sold in #6 AWG to 500. SureSeal® cable is currently available in the full range of sizes from #6 AWG to 500.
Southwire continues to monitor demand for larger sizes of SureSeal cable. If you have an application for a larger size SureSeal® product, please contact your Southwire representative.

What should I do if SureSeal® sealant comes in contact with my rubber gloves, or other personal protective equipment (PPE)?

Like any hydrocarbon material, long-term exposure to SureSeal® sealant has the potential to degrade rubber-based insulating materials. However, the risk of degradation from incidental, short-term exposure of such insulating materials to the SureSeal® sealant is minimal. It is recommended that exposure of rubber gloves and other insulating personal protective equipment (PPE) to the sealant material be avoided. The SureSeal® sealant, by design, is very sticky. If it contacts equipment it will leave a tacky residue. Studies in Southwire's laboratories indicate that one-time use of a terpene- or limonene-based cleaner, such as cable cleaner or citrus cleaner, to remove the tacky sealant material should not cause significant harm to rubber gloves and other PPE, provided such use is followed by cleaning in accordance with the manufacturer's recommended procedures in a timely manner. However, repeated use of such cleaners will eventually degrade rubber, and should be avoided. Regular testing of the integrity of such PPE in accordance with manufacturer's recommendations is also advised.

Is SureSeal® cable rated to a UL standard?

SureSeal® cable is manufactured and tested in accordance with UL 854, and is listed as a type USE-2 cable.

What happens to a damaged area, and subsequent self-healing properties, if SureSeal® conductor is run at or above rated amps?

"Rated amps" would push the conductor to 90C. Southwire has performed drip tests at these temperatures, and above. The sealant material will flow easier at the higher temperatures, but will not soften to the point where it would run out. In fact, the higher temperature will probably help the speed of sealing.

Is SureSeal® available with a copper conductor?

SureSeal® cable is available with a copper conductor. The current production range for copper conductor SureSeal® is #6 AWG through 2/0.
SureSeal® cable with a copper conductor is a special run product. Should you have interest or an inquiry for this product, please contact your Southwire sales representative for pricing, minimum runs and current lead times.

Is SureSeal® more flexible than standard Hi-Score? What about in cold weather? If yes, why?

Testing has shown that SureSeal® cable is slightly more flexible than Hi-Score cable at room temperature, when comparing like size conductors. This is even the case when comparing SureSeal® street light size gauges with an 80 mil insulation thickness and standard Hi-Score cable with a 60 mil insulation thickness.
Additional testing conducted at -20 degrees C showed that SureSeal® cable was substantially more flexible than standard Hi-Score cable, when comparing like size conductors. The reason for equal to improved flexibility being that a portion of the Hi-Score insulation has been replaced with the viscoelastic sealant material. In some cases, even with improved flexibility, it is yet to be determined if a noticeable difference can be detected in the field.

Does Southwire think SureSeal® sealant will accumulate on the 4x4 stripper we commonly use during installations?

One benefit of the manufacturing process of SureSeal® cable is that the visco-elastic sealant is contained within the layers of the cable insulation. Therefore, it should strip cleaner than other self healing cable designs where insulation is extruded over a sealant layer. However, due to the sticky nature of the visco-elastic sealant in SureSeal® cable, Southwire would expect minimal sealant residue build-up over time. This build-up on the tool can be easily removed with a good quality citrus based cleaner. Other tool cleaners may be tried, and may also work effectively to clean the tool. Some have even found that WD-40 makes and effective tool cleaner.

If SureSeal® cable is in a cable tray or the insulation touches a metal grounded surface such as a transformer cabinet, and abroasion occurs at that point would the cable seal fast enough to avoid flash to ground?

SureSeal® cable is designed to prevent failures resulting from inadvertent nicks and cuts in the insulation, resulting in leakage current through the soil and eventual corrosion of the conductor. However, pushing a conductive object, like a transformer cabinet, through the insulation would result in a direct short circuit between the conductive cabinet and the cable conductor. While SureSeal® passes all requirements for "Ruggedized Cable" as defined by the ICEA, if the abuse is great enough, even Sure-Seal® can't prevent such a failure.

Is it possible to produce SureSeal® cable with reduced insulation thicknesses on products that are normally produced with 80 mil insulation thicknesses?

This is not possible. SureSeal® product needs a full 80 mils of wall thickness in order to have the inner layer, sealant layer, and outer layer. This is why the smaller sizes, normally produced with 60 mil insulation walls, have an 80 mil wall with SureSeal®.

If SureSeal® cable is damaged, or cut completely through on one end, resulting in a failure, will it seal itself causing the fault locating device difficulty in determining where the fault is located?

A: In the case of a partial cut in the SureSeal insulation, there is a high chance that the visco-elastic sealant will cover over the cut area, and the user will never know the cut occurred. However, in the case of a cut that severs the conductor, such as a dig-in, the sealant
quantity is not sufficient to totally seal the ends. While some sealant will partially close the cut, the exposed conductor will, most likely,
still be in contact with the earth, making fault locating easier. However, if difficulty is experienced in locating the fault, the sealant is designed with a lower dielectric strength than the polyethylene insulation, so thumping or other high voltage location techniques will breakdown the sealant at the damaged site and not cause damage to the intact cable.

Where would I find more information related to SureSeal® Cable?

A: The SureSeal® web page is now available to you via the web at www.southwire.com/sureseal. From the SureSeal® web page you have access to the following:
• SureSeal® Cut Sheets (Single, Duplex, Triplex and Quadruplex cables)
• SureSeal® Sales Sheets (Economical, Technical, Operational)
• SureSeal® Price Sheet
• SureSeal® Business Case Spreadsheet
Please log on to http://www.southwire.com/ for the latest information related to SureSeal® and other products offered by Southwire Company

What is ACSS and how is it different from ACSR?

ACSS (Aluminum Conductor Steel Supported) is very similar to ACSR (Aluminum Conductor Steel Reinforced).  But, as their names imply, ACSS depends primarily on the steel core for support, whereas the ACSR is supported by both the aluminum and steel components.

ACSR is constructed with 1350-H19 aluminum strands and typically a zinc galvanized steel core, aluminum clad steel is also popular in corrosive environments.  ACSR has a continuous operating temperature rating of 75°C, with a limited time emergency rating of 100°C.   Because ACSR depends heavily on its aluminum strands for strength, operation at temperatures above the annealing point of aluminum (approximately 94°C) can result in loss of strength.

Southwire ACSS is designed such that it can be continuously operated up to 250°C, whereas others rate their standard ACSS products at 200°C.  To accomplish this, Southwire constructs its ACSS with fully annealed 1350-O aluminum strands (see “What does “fully annealed” or “soft” aluminum mean and will it damage easily?” below) and a thermally resistant steel core, usually either a zinc-5% aluminum-mischmetal alloy-coated (Galfan) or aluminum coated (AW) steel core wire.  Since ACSS is designed to be primarily supported by its steel core, its thermal coefficient of expansion is much lower than that of ACSR, meaning it sags less at higher operating temperatures.  And, since it uses fully annealed aluminum, ACSS does not loose strength due to exposure to elevated temperatures, as ACSR would.

What does “fully annealed” or “soft” aluminum mean and will it damage easily?

To produce the strand sizes used in conductors, larger diameter aluminum rod is “drawn”, basically stretched, through a series of progressively smaller dies until it reaches the desired diameter.  In doing this, the aluminum is “work hardened”, meaning its temper and electrical resistance are increased.  Aluminum hardened in this manner can then be annealed – softened and its electrical resistance decreased.  Annealing is accomplished using a specific heating and cooling regimen.  It is important to note that the amount of annealing imparted is a function of both time and temperature – the longer aluminum is exposed to the temperature the more annealing that takes place – and that annealing is cumulative.   Fully annealed aluminum, as used in overhead conductors, is designated as 1350-O aluminum.  This is the lowest strength, most ductile temper rating.  While the 1350-O aluminum is softer than the 1350-H19 aluminum used in ACSR, and is slightly more susceptible to damage, it is not so soft as to require special handling.

Is there any difference between Southwire ACSS and its competitor’s product?

To produce the strand sizes used in conductors, larger diameter aluminum rod is “drawn”, basically stretched, through a series of progressively smaller dies until it reaches the desired diameter.  In doing this, the aluminum is “work hardened”, meaning its temper and electrical resistance are increased.  Aluminum hardened in this manner can then be annealed – softened and its electrical resistance decreased.  Annealing is accomplished using a specific heating and cooling regimen.  It is important to note that the amount of annealing imparted is a function of both time and temperature – the longer aluminum is exposed to the temperature the more annealing that takes place – and that annealing is cumulative.   Fully annealed aluminum, as used in overhead conductors, is designated as 1350-O aluminum.  This is the lowest strength, most ductile temper rating.  While the 1350-O aluminum is softer than the 1350-H19 aluminum used in ACSR, and is slightly more susceptible to damage, it is not so soft as to require special handling.Southwire believes, and comments from customers tend to verify, that its manufacturing process produces a superior product, which is easier to install.  As described above, ACSS uses fully annealed aluminum.  To make ACSS, all wire and cable companies start by using a large diameter rod, which is then drawn down to the appropriate size, being hardened in the process.  To make the final ACSS product requires two final steps: annealing and stranding the aluminum onto the core.

What differentiates Southwire is its approach to annealing and stranding.  The competition generally will anneal the aluminum first, then strand this softened aluminum onto the core.  Since they are working with softened aluminum, the tensions at the strander must be kept low to prevent stretching and work hardening of the aluminum.  Southwire, however, strands the aluminum onto the core prior  to annealing, and then anneals the assembled conductor in ovens.  This allows Southwire to strand at higher tensions, thus making a tighter construction, which results in a product that is easier to install.

Another significant difference can be the thermal rating of the conductor and the core material used.  The core material used can limit the operating temperature of the conductor (see What is “Galfan” coated steel wire and why do I need it?).  Southwire offers the highest thermally rated standard ACSS conductor in the industry, 250°C continuous operating temperature.  To do this, Southwire only uses Galfan coated or Aluminum Clad steel core wires.  Other ACSS, and some HTLS conductors, are limited to 200°C or below, due to the susceptibility to loss of strength or core coating damage at higher temperatures.

Why should I want “Galfan” coated steel wire in my ACSS if I am not planning to operate it at 250°C?

Think about this, would you buy a car that can only go the speed limit?  What would you do if the speed limit is increased, or you had an emergency?  So, would you want to buy an ACSS whose thermal rating is limited to the operating temperature you think the line will need rather than what the conductor should be able to deliver?

Most utilities operate lines in a wide variety of applications.  While the operation of any HTLS conductor at high temperature is not particularly desirable, it is sometimes necessary (see Why should I use ACSS instead of ACSR? and I hear that ACSS is a “lossy” conductor.  Why should I use a conductor that increases my line losses?  Won’t that cost me money in the long run?).  In many cases the utility may have one conductor, which operates in a multitude of conditions and ratings.  These can range from traditional operating temperatures to temperatures close to or in excess of 200°C (usually for relatively short durations).  Sometimes the competition will try and sell a galvanized steel core product, which should be restricted to temperatures below 200°C, at a lower price.  While this may meet one application, it might not meet all the applications that conductor type is required to operate in across your system.

Southwire believes in providing conductor that you can depend on to perform as expected over the full temperature range of the product.  Therefore Southwire only uses Galfan coated and Aluminum Clad steel core wire to ensure reliable operation at its industry leading standard product rating of 250°C.

What is “Galfan” coated steel wire?

Galfan is a trade name for zinc-5% aluminum-mischmetal alloy-coated steel core wire.  The Galfan coating contains 95% zinc, and a 5% mixture of aluminum and rare earth mischmetal (a mixture primarily of cerium and lanthanum).  Galfan is used because it is thermally stable up to and beyond Southwire’s 250°C rated operating temperature for ACSS. 

Standard zinc galvanized steel core wire has traditionally been rated for a continuous operating temperature of 200°C.  However, this rating is questionable as testing at 200°C has shown deterioration, full flaking, of the galvanized protective coating occurred at 49 days in one test and 120 days in another.  Since the amount of deterioration is dependent on the applied temperature and the time of exposure, it is reasonable to assume that damage to the core begins to occur at temperatures below 200°C.

An additional benefit is that Galfan coated steel core wire has excellent corrosion resistance, better than Class C galvanized steel.  What this means for you is that ACSS made with Galfan coated steel core wire will perform reliably, at continuous maximum operating temperatures, for the life of the conductor.

What does “TW” or “Trap Wire” mean?

“TW” or “Trap Wire” refers to a bare overhead conductor made with trapezoidal shaped aluminum strands instead of round.  The purpose for using trapezoidal shaped wires is to reduce the gaps, or interstices, that occur between round strands.  This makes for a more compact conductor, and, for a given kcmil size, a smaller overall diameter.  TW conductors are available in “Area Equivalent” and “Diameter Equivalent” sizes.  For example, the Area equivalent to a 795 kcmil “Drake/ACSS”  (OD = 1.108”) is a 795 kcmil “Drake/ACSS/TW” (OD = 1.010”) and the Diameter equivalent is a 959.6 kcmil “Suwannee/ACSS/TW” (OD = 1.108”).

What are “type numbers” and why are they used instead of strandings for Trap Wire conductors?

A “type number” is simply the percent area ratio of steel to aluminum in a conductor.  Type numbers are used to indicate the relative strengths of conducts, just as strandings do for round-wire constructions. 

Which offers more corrosion resistance, Galfan or Aluminum Clad steel core wire?

Class A Galfan, designated MA, has been shown to have corrosion resistance exceeding that of Class C zinc galvanized steel.  However, Aluminum Clad steel wire core gives the highest level of corrosion protection.

What is “HS285™ ”?

HS285™ is the trade name for Southwire’s ultra high strength Galfan coated steel core wire.  The chemistry of HS285™ steel is very similar to that found in high strength steel used in core wires today. However, the strength of steel wires is a complex function of not only the chemistry, but also the strain hardening and annealing that takes place throughout the rod and wire manufacturing steps. HS285™ steel arrives at its strength through a variety of process improvements.  What is important to the user is that HS285™ provides a combination of superior strength and corrosion resistance without sacrificing ductility or performance.

When I measure the overall diameter of an ACSS/TW conductor in the field, I get a larger diameter than is shown in your tables. Is this a problem?

Conductor diameter measurements are taken in accordance with ASTM, which stipulates that the measurements should be taken “between the closing die(s) and the capstan of the strander”.  This means that the conductor is under tension.  Product delivered to the customer has likely “loosened” during transport, thus it may have a diameter slightly larger than that published by Southwire, per ASTM.  Experienced ACSS hardware manufacturers are aware of this and size the aluminum sleeves accordingly.

Why is ACSS said to be self-damping and what does this mean?

ACSS is designed to operate with practically all of the conductor tension carried by the steel core.  The aluminum strands relax around the core both temporarily when experiencing high operating temperatures and permanently when the conductor is subjected to mechanical loading (ice or wind) or after exposure to low temperatures.  Once the aluminum strands are thus decoupled from the steel core, any wind-induced vibration in the aluminum occurs at a different frequency from that induced in the steel core.  The physical interaction of the aluminum strands and steel then tends to dampen the vibrations and to prevent the vibration from reaching a resonant, destructive level.  This gives utilities, which in the past have not been able to install ACSR lines to the tension limits provided in the NESC due to vibration concerns, the option of utilizing the full allowable NESC tension limits when installing ACSS.

How does ACSS install compared to ACSR?

ACSS installs in the same manner as ACSR.  However, ACSS is less forgiving of improperly sized or damaged equipment and “shortcuts” than ACSR.  Southwire recommends that any conductor installation be done in accordance with IEEE 524 Guide to the Installation of Overhead Transmission Line Conductors.  For ACSS conductors, Southwire recommends that all stringing blocks be properly sized, lined and in proper working order.  Many times stringing blocks are roughly handled and do not perform well, i.e. rotate freely, etc.  Bullwheels should also be properly sized and lined, v-groove tensioners are not recommended.  As with any conductor, minimal braking tension should be applied to the payoff to prevent damage to the reel or conductor.

If there are questions, or you need assistance or training regarding the installation of ACSS conductor, Southwire offers the resources to support you.  These resources include access to some of the industries top application engineers, installation instructions, and on-site field training.  Southwire also partners with top hardware manufactures to provide complete training for the installation.

What size bullwheel and stringing blocks are recommended for use with ACSS?

Southwire recommends a minimum bullwheel bottom groove diameter of 35 times the conductor overall diameter.  Southwire recommends never using a v-groove tensioner with ACSS.   Southwire recommends a stringing sheave bottom groove diameter of 20 times the conductor overall diameter.  For severe angle pulls, this diameter may need to be increased.  For severe pulls or questions regarding the sizing of installation equipment, contact Southwire technical support.

What is the minimum bending radius for ACSS conductor?

For ACSS (or ACSR), the minimum conductor bending radius, before permanent deformation occurs is 12 times the conductor overall diameter.

Is ACSS hardware (dead-ends, splices, etc) the same as ACSR hardware?

The hardware is very similar, but there are some differences.  The major hardware suppliers have specific lines of hardware available for use with ACSS conductors.   ACSS hardware has more aluminum than its ACSR counterparts to carry the higher currents.  ACSS dead-ends all have NEMA four hole pads, whereas some ACSR dead-ends will have two hole pads.  Because of the higher operating temperature of ACSS, rubber inserts and corrosion inhibitors are usually different.   Southwire recommends the use of two-piece compression hardware with all of its ACSS products.  Check with your hardware manufacturer for their recommendations for ACSS products.

Can ACSS hardware (dead-ends, splices, etc) be used with ACSR conductors?

Usually you can, but the converse is never true – most ACSR hardware cannot be used on ACSS due to the higher operating temperature and current load carried by ACSS  (see Is ACSS hardware the same as ACSR?).  In fact, some companies that use both types of conductor have standardized on ACSS hardware to reduce cost and prevent confusion.   Check with your hardware manufacturer for their recommendation.

Can I use automatic splices with ACSS conductor?

Automatic splices are not recommended for use with ACSS conductors.  Southwire only recommends the use of two-piece compression splices, which ensure proper gripping of the steel core.

What grips can I use on ACSS?

For sagging, the three most common types of grips – pocketbook, Chicago, and wedge – can all be used with ACSS conductors (see “Is there a difference in grip rating?” below).  Southwire recommends the use of transmission type grips with ACSS.  Transmission type grips have longer jaws, thus more gripping area, than the smaller distribution type grips.

Regardless of the type of conductor (AAC, ACSR, ACSS, etc), Southwire recommends that all grips must be properly sized for the conductor, and that they should be tested in the field (using a dynamometer, pulled up to sagging tension) prior to use.  Always check with the grip manufacturer for their recommendations for use with any conductor.

Is there a difference in the grip rating when used on ACSS verses ACSR?

Some manufacturers publish their grip ratings based on use with ACSR conductors and then derate them for use with ACSS conductors.  This is because they must grip the fully annealed aluminum on the ACSS verses the hardened aluminum on the ACSR.  Deratings of 30% are not uncommon.  Check with your grip manufacturer for their recommendation before using any grip with ACSS conductors.

I have heard ACSS birdcages when being terminated, is this true?

Not if properly installed.  The fully annealed aluminum in an ACSS conductor does tend to extrude more than the hardened aluminum in ACSR.  Using the following technique, this will not be a problem:

An important consideration should be grip placement.  Whether dead-ending or splicing conductor, the grip should be placed as far as practical from the crimping point.  This will allow the extra, extruded strand length to be easily worked into the conductor.

First, the conductor is pulled up to sagging tension and the steel sleeve, with the eye, is compressed onto the conductor’s steel core.  Next, the aluminum sleeve is crimped on the eye side of the steel sleeve crimp, stopping at the point where the steel sleeve crimp begins.  Never crimp the portion of the aluminum sleeve that goes over the steel sleeve crimp.  Next, make one crimp in the aluminum sleeve past the point where the steel sleeve crimp ends (this is usually marked on the aluminum sleeve).  Release tension and remove the grip (only leave the grip attached where necessary for additional safety reasons – for example, road crossings – and then moving it as far from the termination point as practical).

Continue making the crimps, always progressing from the eye end towards the open end, while watching for strand elongation.  If the elongation causes the strands to separate, work the excess strand length back into place with a gloved hand, then resume crimping.  Tapping the conductor with a piece of wood, or application of an approved lubricant spray may assist in the strands settling into place.  Making all of the crimps and then trying to work the excess strand length into the conductor will make the process much more difficult.

I have damaged several strands in the outer layer of the ACSS conductor, what should I do?

In ACSR (Aluminum Conductor Steel Reinforced), the aluminum strands serve two purposes: they carry the current and they contribute significantly, 30% – 50% sometimes, to the overall strength of the conductor.  When the aluminum strands are severely damaged in an ACSR, the overall strength of the conductor is reduced.  Any aluminum strand repair method must reestablish both the lost strength and current carrying area.  Consult your repair rod manufacturer for their recommendation.
 
ACSS (Aluminum Conductor Steel Supported), however, is primarily supported by the steel.  Therefore, severe damage to, or the loss of, an aluminum strand does not significantly impact the strength on the conductor, but rather only reduces the current carrying area.  Any aluminum strand repair method must reestablish this lost current carrying area.  Repair methods include the application of a repair sleeve or armor rods over the damaged area.  Overhead hardware manufactures have these repair sleeves, or kits, available for ACSS conductor.  Consult your hardware manufacturer for their recommendation.

ACSS, being made with fully annealed 1350-O aluminum (see What does “fully annealed” or “soft” aluminum mean and will it damage easily?) is slightly more susceptible to surface abrasion than ACSR.  Minor abrasion, which may occur during shipping, handling or installation, does not normally affect the performance of the conductor and is no cause for concern.  However, if the conductor is being used in an EHV application, any abrasion should be evaluated for possible corona issues. 

If you have any questions regarding the severity of any abrasion or damage to your conductor, contact your Southwire representative.

How much braking tension can I apply to the payoff reel?

Whether ACSR, AAC, or ACSS, reels are only designed to transport the conductor.  Reels are not designed for use as tensioning devises for conductor installation.  That is what tensioners are made for.  The amount of braking tension applied to the payoff reel should be kept to a minimum – only enough to keep the reel from over-rotating when the pulling operation stops.

How long can I leave my ACSS conductor in the stringing blocks and at what tension?

Any conductor (ACSR, ACSS, AAC, etc) that must be pulled in and then left in the blocks for an extended period of time can be easily damaged.  S since it is not secured, inclement weather and other factors are of concern.  Southwire recommends that any conductor be pulled up to sag and secured as soon as possible.  The IEEE 524 installation guide recommends that conductor be clipped in within 24 hours of sagging to prevent excessive conductor elongation, and within 72 hours to prevent damage to the conductor.

If an ACSS conductor must be left in the stringing blocks, it should either be left at a relatively low tension (compared to sagging tension), close to pulling tension if possible, to prevent excessive conductor elongation.  In some cases, especially where safety is an issue, the conductor cannot be left at low tension.  In these cases, Southwire recommends pulling the conductor up to and leaving it in the blocks at sagging tension.  The conductor should then be clipped in as soon as possible.

Be aware - once an ACSS conductor has been pulled up to sagging tension, the tension should never be significantly reduced.  Doing so may cause excessive birdcaging in the conductor.

How does ACSS compare to other High Temperature Low Sag (HTLS) conductors?

Very favorably, in fact, superior in most cases.  Southwire has found very few applications that cannot be solved using ACSS verses other HTLS conductors.

ACSS conductors were introduced in the early 1970’s, so have a proven, established operating history.  It is estimated that over 150 million pounds of ACSS has been installed in the U.S., and that 10 to 20 million pounds are currently being installed annually.

ACSS conductor installs similar to ACSR, which, as most companies have extensive experience installing ACSR, means little training or retooling is required.  ACSS two-piece compression dead-ends and splices are very similar to those used for ACSR, and can be installed with similar equipment (see How does ACSS install compared to ACSR?).

ACSS is not significantly higher than traditional ACSR.  ACSS generally ranges from 1.1 to 1.5 times the cost of a comparably sized ACSR, depending on strength and core requirements.  The cost of the new composite core conductors ranges widely, but is significantly higher than ACSR – from 4 times to 25 times the cost.  And this does not take into consideration any increased hardware or labor cost.

Southwire uses only Galfan coated or Aluminum Clad steel core wire in its products, which gives them the highest, continuous, standard thermal rating, 250°C, in the industry.  Other ACSS products may be supplied with galvanized steel core.  These products have thermal ratings less than 200°C.

Why should I use ACSS instead of ACSR?

ACSS provides more VALUE than ACSR.  Let’s use an example to illustrate.  Assume a new line is designed to use 795 kcmil ACSR “Drake”, 1000 ft ruling span, NESC Heavy loading with NESC tension limits, 26 ft sag limit.  Using assumed, typical rating parameters, this line would be rated 730 amperes at 75°C, I2R loss of 74125 w/mi and have a maximum tower tension of 15250 lb under the initial loaded condition.

One ACSS option would be to use the diameter equivalent 959.6 kcmil “Suwannee/ACSS/MA/TW” conductor.  There could be several advantages to using this conductor:

- Carrying the same 730 ampere load, this conductor would operate at 70°C, with a significantly lower I2R loss of 58670 w/mi and sag of 23 ft, and similar maximum tower loading of 15300 lb under the initial loaded condition. 

- Operating this conductor up to the sag limit of 26 ft, this conductor would be rated for 1300 amperes at 125°C, with similar maximum tower loading of 15300 lb under the initial loaded condition.

This is only one of several options, but it shows that, when properly utilized, an ACSS conductor will have lower line losses and provide more operational flexibility than ACSR.  Reducing line losses results in reduced operating cost and reduced generating capacity requirements (thus reduced carbon emissions).  Operational flexibility means the line can be operated at almost twice the original line rating without violating sag clearances and with no loss of strength issue.  This allows the utility to extend the life of the line by avoiding or delaying future upgrades, allows for overloading to schedule lines for maintenance or to re-route power in the event of a line or equipment failure, or to maximize potential revenues if selling power.  All of this, for only a relatively small increase in conductor cost with ACSS.

If you have questions regarding what is the best type and size of conductor for your application, Southwire is here to help.  Southwire can provide conductor evaluations including thermal rating and sag-tension calculations to determine a range of conductor options to meet your need.

I hear that ACSS is a “lossy” conductor. Why should I use a conductor that increases my line losses? Won’t that cost me money in the long run?

As shown earlier (see Why should I use ACSS instead of ACSR?) ACSS actually has lower line losses than a comparable sized ACSR conductor under similar operating conditions.  This is due to the use of fully annealed aluminum (see What does “fully annealed” or “soft” aluminum mean and will it damage easily?), which has higher conductivity (lower resistance) as compared to the hardened 1350-H19 aluminum used in ACSR and AAC, and the ability to use larger kcmil conductors due to its low sag characteristic.

The misnomer that ACSS is “lossy” comes from the ways it is sometimes used.  When any HTLS conductor is operated at high ampacities, the I2R loss is high.  However, when applied properly, (see Why should I use ACSS instead of ACSR?) this only occurs in situations where operational considerations outweigh the cost of higher losses, such as when temporary overloading occurs to prevent outages, facilitate maintenance, or generate revenue through power sales.  The majority of the time a line conductored with ACSS is operating with lower losses than if the line were conductored with a comparable sized ACSR conductor under similar operating conditions.

Another situation that contributes to this misnomer is that ACSS is a very effective option for uprating existing lines.  In this case existing structures are usually to be retained, so in many cases the replacement conductor must be approximately the same size as the existing conductor.  Therefore, to get more power throughput, the line must operate hotter.  In these cases, the ACSS conductor may have high I2R losses, but these are still much lower than those of a comparably sized ACSR under similar operating conditions.  The costs of these losses is offset by the savings from reusing the exiting structures, delaying a major line replacement, reduced permitting, reduced need for approvals and greatly reducing the environmental impact from new construction.

If ACSS is so good, and has been around so long, why hasn’t it been used more?

ACSS conductor has been widely used since its introduction, in fact, some utilities have standardized on ACSS.  However, many utility engineers are not familiar with ACSS.  There are two main reasons why:

First, as its name implies, ACSS is supported by its steel core, receiving very little support from its aluminum component.  Thus, for a given construction, the ACSS conductor has typically had lower strength than its ACSR equivalent.  With the advent of the higher strength HS285™ steel core by Southwire, this is no longer the case and ACSS has equivalent strength to ACSR conductors and superior thermal properties.

The second reason is partly human nature, partly the conditions utilities have operated in for years.  Human nature says why change unless we have to.  The utility industry has traditionally been slow to accept change, preferring to take little risk.  Power consumption per household was relatively small and ROW’s were easy to obtain.  Today, power usage per household, and in businesses, has increased dramatically and new ROW’s are extremely hard to obtain, so the old ways of doing this are not able to keep up with the growing demand.  ACSS conductor offers a proven solution to both uprating existing lines at reasonable cost and maximizing the capability of new lines being installed.
 

Is there any history or concerns about lightning striking the ACSS and damaging it because the aluminum is so soft?

Lightning strikes will cause a short term temperature rise in the outer surface of a cable. If the temperature is high enough, and it exceeds the melt point of the outer material, there could be melting of the wires. Since soft aluminum and hard aluminum have the same melt temperature, we would not expect there to be any difference in the degree of damage from a direct lightning strike.

Is there any history or concern about hail damaging the soft aluminum?

This has never come up to our knowledge. We would not be concerned since the aluminum is relatively thick and would not easily be damaged by such an impact.