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.
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.
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.
Tests have been conducted on SureSeal® cables, cooled to as low as minus 20 degrees C, that show ample flow to seal insulation breaches.
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).
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.
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
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.
No, only the area located for repair by the underground cable fault locator.
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.
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.
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.
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.
SureSeal® cable is manufactured and tested in accordance with UL 854, and is listed as a type USE-2 cable.
"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.
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.
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.
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.
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.
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®.
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.
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
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.
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.
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.
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.
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.
“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”).
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.
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.
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.
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.
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.
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.
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.
For ACSS (or ACSR), the minimum conductor bending radius, before permanent deformation occurs is 12 times the conductor overall diameter.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Yes. The core for ARMOR-X® must be stripped using a cutting tool while interlocked armor cable can be peeled back to proper length. ARMOR-X is more difficult to train in close quarters than interlocked cable; however, both constructions can be difficult unless the contractor has the proper equipment.
No. Contact Wire and Cable Technology Support for more details.
Yes. If supported properly by a correctly sized messenger.
On sizes 600V AWG #14-10 we can include up to 37 conductors. On sizes 600V AWG #8 stranded through 500 kcmil, we can install 4 conductors with 2 ground wires or 3 conductors with 3 ground wires. Check your catalog sheets for more specific details.
Yes. We can put any of our insulated conductors in the ARMOR-X® core.
The price is 5% to 20% higher for ARMOR-X® depending on quantities and sizes.
The cables must be secured to supports every 6 feet.
This cable construction is a complete wiring system that’s ready for installation with phase-identified conductors. The product meets and exceeds industry standards. Medium voltage constructions include proven EPR compounds for insulation, providing excellent corona-free cable. The 600v XLPE insulations are tough, reliable and proven compounds that have been used for many years by Southwire Company, LLC.
Petroleum and chemical companies use the majority of the product. Pulp and Paper ranks second in usage. A relatively new application involves the use of high speed variable frequency AC drives (VFD) connecting to the motor. (A flyer & IEEE paper written by Dave Cooper and Dave Mercier is available from Southwire Records Management.) However, the product can be installed in any location that Type MC cables are allowed per the NEC. If the end user is concerned about reliability of the electrical conductors, we have an opportunity to up-sell from interlocked armor to ARMOR-X. The basic selling feature is the excellent protection provided by the impervious cable construction.
Okonite (CLX) makes a complete size and voltage range. Rockbestos (Gardex) makes a complete size range but stops at 5kV non-shielded. Nexan (Corflex) manufactures a partial range but offer a complete range. They outsource their sizes of medium voltage. General (Philsheath) manufactures a partial range but also offers a complete range. They outsource their 600v sizes. Nexan’s manufactures their product in Canada. Rockbestos is in Connecticut, Okonite makes the product in Kentucky and California and General in Indiana.
Reference the catalog sheet for a listing of the areas.
All Southwire ARMOR-X cables include a copper-free aluminum armor that holds up to fatigue failure in all types of installations.
Yes. The Armor-X mini brochure has a complete list of connector manufacturers and connector sizes.
Currently, Southwire manufactures:
600V AWG #14 to 750 kcmil multi-conductor cable power (w/grd) and control (wo/grd)
5-15kV MV up to size 3/c 750 kcmil MV-105
Please check catalog sheets for dimensions. For voltages higher than 15kV, please contact power cable department.
Yes. This is added to provide additional safety and to meet or exceed our competitor’s products.
It is the most explosive environment with a designation of Class I, Division I. The cable designation is MC-HL. All conductor required in this environment must have a separate equipment ground. The armor cannot be used for grounding.
Yes. The circular mil area of the aluminum sheath is adequate to serve as a ground wire, according to NEC Table 250-95, but only in Non-HL locations (Class 1, Div. 1)
Yes. However, the cable cannot be marked as such.
Yes. It can be installed without the jacket; however, the coefficient of friction may increase and the chances of damaging the armor are increased. We would not recommend installation without the jacket unless the application warrants this type of construction.
Yes. PVC is the most common. It can be manufactured in various colors. It can also be jacketed with oil-resistant, sunlight-resistant and flame-resistant compounds.
This type of construction is completely impervious to moisture, gas, and fluids. It keeps out contaminants that could cause premature failure of the conductors if the contaminants were allowed to penetrate the armor. With interlocked armor cable, moisture and contaminant penetration is possible. Continuous armor provides greater reliability over the long term when compared to interlocked cables - assuming all other factors are equal.
No. It is not necessary, but normally is done so that termination fittings will securely fit over the armor and lock in place. Close fitting terminations are needed to make a good ground connection. Corrugation also makes the armor more flexible and less likely to crack during bending.
The armor is made by forming an aluminum strip around a cable core. Where the edges of the strip butt together, they are welded electrically to form a solid smooth core. The core is then pushed/pulled through a machine tool that causes indentations or corrugations. The addition of the corrugations gives the cable flexibility.
ARMOR-X® is Southwire’s product name for a continuous welded aluminum armor that is corrugated. When jacketed, it has the appearance of an interlocked armor cable.
The use of pin connectors, also referred to as pin adapters, is acceptable for use with aluminum conductors. A pin connector used with aluminum conductors may be used if the existing equipment terminations are rated for use with only copper conductors. Pin connectors may also be used when existing terminations are not sized correctly for the aluminum conductor. In this case, a pin connector can be used to transition from the aluminum conductor to the incompatible termination. Adapters are intended to be assembled using the tool specified by the manufacturer in the instructions which are provided by the pin connector manufacturer. Incorrectly installed connectors can lead to overheating and failed connections. The most common point of failure in electrical circuits is at the termination. Using pin connectors actually increases the number of connections and can increase the risk of failure. Pin connectors typically require proprietary tools and a specific number of crimps, resulting in the chance for installation errors to be greater than with set-screw connections. The specification and installation of pin connectors should be avoided unless conditions deem them to be necessary.
UL Listed compression connectors are available for aluminum, copper, or dual-rated for both copper and aluminum. Compression connectors may be pre-filled with anti-oxidant. Based on field experience with installations, set-screw connections are equally reliable for use with copper and aluminum conductors. UL Listed mechanical set-screw lugs have proven to be highly reliable with AA-8000 or copper conductors. Set-screw lugs provided with equipment are made with a tin plated AA-6000 series aluminum alloy body. Connectors manufactured without this plating are rated for aluminum conductors only. Because standard lugs are dual-rated, they are plated with tin to avoid galvanic corrosion between the copper conductor and the aluminum connector. When terminating a conductor with a compression connector, the bare conductor should be inserted into the connector barrel and crimped with the tool and die recommended by the connector manufacturer. The compression connector is typically marked with the required die size. Excess oxide inhibitor should be removed after the crimping process is complete.
When terminating a conductor with a set-screw connector, the bare conductor should be wire brushed and an oxide inhibitor applied to the bare conductor. Unless included in the connector manufacturer’s instructions this is considered a best practice and is not a requirement. The screw should be tightened using a calibrated torque wrench to the appropriate torque value as recommended by the connector manufacturer. An over tightened screw’s performance can be as detrimental as an under-tightened screw. Over tightening can lead to damaged conductors and connection points. Proper tightening or torqueing is necessary to attain a reliable connection. Once the correct torque is achieved, there is no need to go back and re-torque the lug with an AA-8000 series aluminum alloy conductor.
A thin layer of oxide naturally occurs on aluminum and copper conductors and will be broken by the physical act of tightening the setscrew connection or crimping the compression connection. Wire brushing aluminum or copper conductors should be performed if the connector manufacturer recommends this in their installation instructions. If required, brush the exposed conductor before applying the oxide inhibitor and terminating the conductor. This will remove the oxide on the exposed conductor and remove any contaminants that may interfere with the connection. Oxide inhibitor use is considered good workmanship for all aluminum or copper terminations. The oxide inhibitor provides a barrier at the connection point that prevents moisture and other potentially damaging environmental substances. The oxide inhibitor must be listed for the application. Oxide inhibitors are made for use with copper, aluminum, or both copper and aluminum. Compression connectors typically come filled with an oxide inhibitor. When tested per UL 486B, mechanical set-screw terminations are tested without wire brushing and oxide inhibitor is not added if the connector is pre-filled with an oxide inhibitor.
The alloying and annealing processes used with AA-8000 aluminum conductors results in an AA-8000 conductor that is more flexible than the equivalently sized copper conductor based on ampacity. It should be noted that NEC® Table 312.6(B), requires the same bending space at terminals for equal ampacity AA-8000 conductors. A 500 kcmil copper conductor requires the same bending space as 750 kcmil AA-8000 aluminum conductor. Pulling aluminum conductors requires less tension resulting in less damage during installation. It should be noted AA-8000 series aluminum alloy conductors have a higher strength to weight ratio than copper conductors resulting in a higher safety margin when pulling in aluminum conductors. Also, copper is about twice as heavy as aluminum to achieve the same conductivity. This results in AA-8000 aluminum having a clear advantage over copper when pulled through conduit, especially in vertical installation. When installing conductors in vertical conduit runs NEC® Table 300.19(A)provides the distances required between supports for the conductors. Pulling tension calculations should always be made before installation.
Southwire has always recommended the same basic process for installing aluminum building wire as copper building wire. The conductor’s insulation should be stripped from individual conductors using tools manufactured for the conductor type and insulation type, or by standard methods such as penciling or whittling the insulation from the conductor. The installer should never “ring cut” the insulation due to the risk of nicking the conductors inside. One perception with aluminum building wire is that it is more susceptible to breaking than copper building wire if nicked during installation. This is based on the older AA-1350 aluminum wire used prior to 1972. The EC-1350 aluminum was 99.5% pure aluminum, hard-temper and was more sensitive than copper building wire to nicks during installation. This is no longer true with AA-8000 aluminum alloy building wire. AA-8000 aluminum is a fully annealed aluminum alloy conductor that is very strong and flexible.
NECA/AA 104-2000 “Recommended Practice for Installing Aluminum Building Wire and Cable” defines a minimum baseline of quality and workmanship for installing electrical products and systems and was referenced in the 2008 NEC.® This standard was jointly developed by the Aluminum Association and NECA. It should be noted that NECA is also developing a standard for installing copper building wire.
The NEC® requires that these MC fittings must be “Listed and Identified” for use with MC Cables, (NEC Section 330.40). No red heads are required on any type of MC Cable. However, please contact you Local Inspector to verify. The NEC does require that “red heads” be used on AC Cables. Reference NEC 320.40.
Arlington MC Cable Fitting: 8412 – 8417
The NEC® requires that MC Cables be “supported” and “secured” every six feet. Reference NEC® Section 330.30(C).
Per NEC 330.30(C) Supporting – unless otherwise provided, cable shall be supported a interval not exceeding 1.8M (6FT)
No – Neither “interlocked jacket armor” or “PVC Jacketed MC Cables” can be installed in a plenum. Interlocked Type MC Cable without an overall nonmetallic jacket can be installed in air-handling areas. Please reference NEC® 300.22(C).
No – The NEC has no restrictions on the number of bends for MC Feeders or Branch Circuits.
On average, Cable Design Evaluator shows a 50% savings.
None, same procedures as copper, per the NECA aluminum association guide.
Per UL 1569 gauges 6&8 is 1000 lbs per inch and 4 and larger is 2000 lbs per inch.
No, attached the pulling rope to the conductors in the cable. See podcast installing MEGA MC for further details.
Per NEC 330.24(B) Interlocked – Type Armor or Corrugated Sheath. Seven times the external diameter of the metallic sheath.
MEGA MC™ is available in low voltage and high voltage colors.
MC can be used in wet location per NEC 330.10(A) (11) which states – MC Cable can be used in wet locations when the insulated conductors under the metallic covering are listed for use in wet location
When installing SIMpull THHN®, Southwire recommends the same COF used to evaluate standard lubricated THHN installations.
The specially designed pre-lubricated SIMpull THHN® product has a COF as low as 0.17 when following best installation practices. This has proved to be true through miles of cable pulling tests.
Recommended practice for calculation pulling tensions is to begin with a conservative coefficient of friction such as 0.35. This will provide some safety factor for any debris in the conduit or other unexpected field conditions. Southwire’s application engineers utilize a 0.35 COF when evaluating cable pulls. This conservative approach is a result of not having the ability to evaluate the condition of the conduit in the field.
The tape should be applied in half–lapped layers with sufficient tension to produce a uniform wind (for most applications this tension will reduce the tape’s width to approximately 5/8 of its original width). Apply the tape with no tension on the last wrap to prevent flagging. Locate the phase tape near the end so it will be under the pull head and protected during the pull.
The key points in creating a secure coil are the type of tape used, taping the cable ends, and placing secure wraps on the cable after it is removed from the coiling head.
Using a vinyl electrical tape will provide some compression as the tape is stretched and will move and give as the coil moves. The most important point is back-wrapping the cable end with tape to provide and area for the tape wraps to stick to the ends and secure them. Finally, the coil will likely relax once it is removed from the coiling head. At this point tight and secure wraps should be applied around the coil at the loose cable ends and in at least a couple of evenly spaced areas around the coil. Taping in three to four locations on the coil will usually be secure.
The tape should be applied in half–lapped layers with sufficient tension to produce a uniform wind (for most applications this tension will reduce the tape’s width to approximately 5/8 of its original width). Apply the tape with no tension on the last wrap to prevent flagging. A two to three inch band of tape is adequate for most coils. This is best practice for all THHN.
Staples are typically used to secure the conductor to the reel. If using rope, use friction tape to secure the rope to conductor. Tying the conductor in two locations with rope may be sufficient to eliminate slipping.
From our experience, Older and poorly maintained equipment may suffer from numerous issues. The counter wheels will become polished with use, and may result in accuracy issues. The wheels can stiffen on the shaft and not spin as freely as they should, and finally, the springs are subject to fatigue and need to be replaced regularly.
The machines also need to be cleaned and lubricated regularly to keep parts moving freely with as little friction as possible. Counter manufacturers recommend replacing the springs every 6 months to a year depending on the amount of use. The springs cost $37.80 for a set. Older machines should be re-furbished to alleviate the wear problems.
The following offers solutions that are common to conductors slipping in cable feeders.
Too little pinching force.
Engage ratchets another notch.
Too little tire pressure.
Inflate tires to 22 psi.
Upper drive unit unplugged.
Plug in upper drive unit.
Reel(s) hanging up or dragging.
Inspect cable reels for free unobstructed operation.
Yes. Southwire's new SIMpull THHN® results in less stress on the nylon during installation resulting in less splitting. It should be noted that the major contributor to nylon splitting is installing THHN in cold weather.
If installing in cold weather, the cable should be stored in a heated environment overnight prior to installation. Cold temperatures approaching freezing can cause the insulation to become stiff and possibly brittle. Care should be taken to mitigate the effects of cold weather when installing in these situations. The cables should be kept in heated storage for at least 24 hours prior to installation and only removed from heated storage just prior to installation. Cables installed in cold weather should be handled more carefully and pulled more slowly. Even given these mitigating methods Southwire does not recommend installing thermoplastic insulated cables at temperatures below –10C (14F).
Nylon damage in underground conduit seems to occur more frequently than in conduit systems indoors. We have observed that nylon tearing rarely occurs in clean conduit. Underground conduit, despite efforts to keep debris out, will collect dirt, rocks, and other debris. It is recommended that all conduit is cleaned out prior to conductor installation, especially if it is underground conduit. Care should be taken to ensure the cable is centered in the conduit when paying off the reel. A conduit bushing should be used to reduce the possibility of the conduit lip damaging the cable.
Specifying Conduit Proofing Cable is commonly damaged due to debris left in the conduit during installation. Prior to pulling the conductors it is considered good practice to proof the conduit system. The purpose of proofing the conduit system is to ensure the conduit is intact, not crushed or disjointed, and the conduit is clear from debris that could damage the conductor jacket or insulation. This is accomplished with the use of wire brush mandrels, duct swabs and mandrels.
Pulling conductors with vehicles is never recommended. This method results in the tension surging and spiking during the pull. These spikes in tension can damage the conductors and exceed the rated tension of the rope or other pulling devices. It is nearly impossible to perform a smooth pull using a vehicle. That's why recommended practice is a tugger. It never hurts to check rope for wear. Ropes must also have tensile strength greater than the calculated pulling tension-- assumes pulling tension is calculated beforehand. Ropes also lose tensile capacity after significant use/abuse. Southwire has worn out more than one rope in our testing of the installation of conductors in conduit. When using a tugger with monitored tension, a rope should have tensile strength greater than maximum possible pulling tension of the tugger.
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