Installation and Application Guide for 600V Conductors
Installation and Application Guide for 600V Conductors Installation and Application Guide For 600v Conductors
Foreward This guide discusses recommended or “best” practices for installing 600 volt conductors in conduit. The purpose of the guide is to identify those critical areas of design, pre-planning and cable pulling that result in a successful installation. Within these areas are numerous commonly overlooked practices that can result in a failed installation.
Best Practices 1. Pull Evaluation a. Know the expected pull tensions and sidewall pressures prior to the pull. Make sure minimum bend radii will not be exceeded. b. Never assume that an installation is routine. 2. Proofing Conduit a. Conduit must be free of all debris and damage. b. Never assume the conduit is clean. 3. Clean entry and exit from conduit system a. Rollers and sheaves are necessary for difficult pulls to eliminate damage when entering and exiting the conduit system. b.
Table of Contents Section 1. Cable and Conduit Selection Installation Assessment Checklist................................................................................. 7 Conductor Type...................................................................................................................... 7 Copper Conductors........................................................................................................... 7 Aluminum Conductors.........................................................
Installing rollers and sheaves...................................................................................... 18 Placement........................................................................................................................ 19 Pulley Sizes and Count.................................................................................................... 19 Sheave Wheel Sizes and Types.......................................................................................
page 7 Section 1. Cable and Conduit Selection Installation Assessment Checklist The following is a recommended checklist for selecting the appropriate conductor and conduit based on the application and environment. This checklist also provides steps to evaluate your selection. 1) C onductor Type: Select a conductor type based on your application and the conductor ratings and listings. 2) C onduit Size: Determine the conductor size required based on your application and conductor ampacity.
page 8 Aluminum Conductors – Aluminum has certain advantages over copper conductors. Aluminum conductors are 2.5 to 3 times lighter than the ampacity equivalent copper conductor. This means lower installation tensions and less likelihood of damaged cable during installation. Aluminum conductors are typically compact stranded which reduces the overall conductor diameter by 10% over concentric stranding.
page 9 Conduit Sizing and Fill Ratio Conduit fill is the percentage of the area inside the conduit taken up by the conductor(s). Consult applicable codes, industry standards, and manufacturer’s data for further information on fill. Dimensions for the various types of conduits can be found in Chapter 9 of the National Electrical Code.® NEC® conduit fill tables for various conduit types can be found in the annex of this guide.
page 1 0 Pulling Evaluation The small details can make the difference between successful installations and having to remove damaged conductors. In preparing for a conductor pull, it is just as important to cover the small details as it is to assure that the conductor does not exceed maximum sidewall pressure, minimum bending radii or maximum pulling tensions. General field practices are provided to aid in preparing for large and small conductor installations.
page 1 1 Maximum Allowable Tension of Conductors – The metallic core of the conductor is generally the only member that can bear the pulling forces without damage. Do not use metallic shielding wires, tapes, braids or armor not designed for the purpose in pulling tension calculations.
page 1 2 Single Conductors: Tc = S∙A pounds Example: Single Type THHN conductor, 4/0 AWG copper Tc = (0.008)∙(211,600) pounds Tc = 1,693 pounds Multiple Conductors (three or less conductors): Ttotal = N∙Tc pounds Example: Two Type THHN conductors, 4/0 AWG copper Ttotal = (2)∙(1,693) pounds Ttotal = 3,386 pounds Multiple Conductors (more than three conductors): Ttotal = (0.8) N∙Tc pounds Example: Four Type THHN conductors, 6 AWG copper Tc = (0.
page 1 3 Calculating Pulling Tensions The following equations allow the user to calculate the expected pulling tension of a conductor in a conduit pull. These calculations only provide an estimate to assist the user in determining the feasibility of the installation in question. Many factors affect the actual tensions and sidewall pressures one might see in an average pull.
page 1 4 Coefficients of Friction The coefficient of dynamic friction (μ) is a measure of the friction between a moving conductor and the conduit. The coefficient of friction can have a large impact on the tension calculation. It can vary from 0.1 to 1.0 with lubrication and can exceed 1.0 for unlubricated pulls. Typical values for the coefficient of friction are presented in Table 5.
page 1 5 Conductor Jamming Jamming is the wedging of three or more conductors when pulled into a conduit. This usually occurs because of crossovers when the conductors twist or are pulled around bends. The jam ratio is the ratio of the conduit inner diameter (D) and the conductor outside diameter (d).
page 1 6 Horizontal Straight Section: Tout = ω μ W L + Tin Inclined and Vertical Straight Section: Pulling Up: Tout = WL(sinθ + ωcosθ) + Tin pounds Pulling Down: Tout = -WL(sinθ − μcosθ) + Tin pounds Approximation for Bends – The equations for calculating pulling tensions through bends with the varying orientations and gravitational pulling directions are complicated. For this reason, it is common practice to use an approximation for all bends.
page 1 7 Figure 3 Sidewall Pressure Factors Table 6 - Maximum Allowable Sidewall Pressure Cable Type SP lbs/ft 600V Nonshielded Control Cable (Type TC Cable) 300 600V & 1kV Nonshielded Power Cable (Types THHN, THWN, USE, RHH, and RHW) 1000 Bend Radius The minimum allowable bend radii of non-shielded conductors are typically expressed as a multiplier of the conductor outside diameter. The general guidelines for conductor training bend radii are given in Table 7.
page 1 8 Section 2.
page 1 9 Placement – First, determine the number and location of rollers, sheave wheels or radius roller assemblies that are required based on the conductor minimum bend radius and support needed. Be sure that sheaves and rollers are mounted securely to withstand the required pulling forces. Sheave wheels, pulleys and rollers must be maintained and lubricated to reduce friction. Many times the conductor(s) are pulled across a pulley or sheave as it exits the conduit run.
page 2 0 Preparing Conductors for Installation Package Inspection – Preplanning is an important part of every pull. The conductor package should be checked for the following prior to beginning the pull. 1) Check the conductor(s) for: a. Correct size and type b. Shipping damage c. Special instructions 2) Check the reel(s) for: a. Damage b.
page 2 1 Cable Lubrication Reducing the coefficient of friction is the primary factor in the selection of a lubricant. Compatibility of the lubricant with cable and conduit is extremely important. The lubricant should not have any deleterious effects on the conduit or on the physical or electrical properties of the cable insulation, or jacket materials. An estimate of the quantity of required lubricant can be determined: Q = 0.
page 2 2 Handling and Storage of Reels – It is important to properly store and handle conductors on the reel. Below is a list of general guidelines to follow when moving and storing reels. 1) Unloading equipment should not come in contact with the conductor or its protective covering. 2) If a crane is used to unload cable, a shaft through the arbor hole or a cradle supporting both reel flanges should be used. Proper Reel Handling Techniques 3) Forklifts must lift the reel by contacting both flanges.
page 2 3 6) Reels should be stored out of harm’s way. Consider both physical and environmental hazards. 7) Conductor ends must always be sealed to prevent the entrance of moisture, etc. 8) Remove temporary lashing. 9) While pulling, in order to eliminate sharp bends and crossovers, always have a person feed the cable(s) straight into the conduit by hand or, for larger conductors, over a large diameter sheave. Proper Improper 10) Do not pull conductors directly across short, sharp angles.
page 2 4 Permanent Support – After the conductors are installed, they must be supported per NEC® 300.19 Supporting Conductors in Vertical Raceways. The installation must meet the maximum spacing intervals and support methods in NEC® 300.19. Properly applied electrical or friction tape under the device is important to ensure long-term support. Terminating Conductors Proper termination of the conductors is directly related to system reliability. It is imperative that properly rated devices are used.
page 2 5 Section 3. Design and Application Guidelines 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.
page 2 6 Ampacity Considerations Copper is assigned a conductivity of 100%. The conductivity of all other metals is compared to copper. The conductivity of aluminum is approximately 62% of that of copper. It is commonly accepted that comparable current-carrying copper and aluminum conductors are separated by two AWG sizes. For example, an 8 AWG copper and 6 AWG aluminum conductor can carry the same amount of current.
page 2 7 Section 4. Annexes Annex A. Type THHN Conductor Specification 26 05 19 WIRE AND CABLE TYPE THHN PART 1 GENERAL 1.1 SPECIFICATION INCLUDES 1.1.1 Cable Type: Type THHN/THWN for use as services, feeders and branch circuits. 1.1.2 General Applications: Type THHN/THWN cable may be used in the following general applications per the National Electrical Code.® 1.1.2.1 In Conduit 1.1.2.2 In Cable Tray 1.1.2.3 For Services 1.1.2.4 For Feeders 1.1.2.5 For Branch Circuits 1.1.2.6 Wet or Dry Locations 1.
page 2 8 PART 3 INSTALLATION 3.1 INSTALLATION 3.1.1 Manufacturer’s Instructions: Type THHN cable shall be installed per the manufacturer’s published installation instructions. Industry guides may supplement the manufacturer’s instructions. 3.1.2 Field Support: Manufacturer shall provide, when requested, field engineering support for Type THHN cable installation. 3.1.3 Manufacturer: Type THHN cable for circuits, feeders and services shall be supplied from a single manufacturer. 3.1.
page 2 9 Annex B. Type XHHW Conductor Specification 26 05 19 WIRE AND CABLE TYPE XHHW-2 PART 1 GENERAL 1.4 SPECIFICATION INCLUDES 1.4.1 Cable Type: Type XHHW for use as services, feeders and branch circuits. 1.4.2 General Applications: Type XHHW cable may be used in the following general applications per the National Electrical Code.® 1.4.2.1 In Conduit 1.4.2.2 In Cable Tray 1.4.2.3 For Services 1.4.2.4 For Feeders 1.4.2.5 For Branch Circuits 1.4.2.6 Wet or Dry Locations 1.5 SUBMITTALS 1.5.
page 3 0 PART 3 INSTALLATION 3.5 INSTALLATION 3.5.1 Manufacturer’s Instructions: Type XHHW cable shall be installed per the manufacturer’s published installation instructions. Industry guides may supplement the manufacturer’s instructions. 3.5.2 Field Support: Manufacturer shall provide, when requested, field engineering support for Type XHHW cable installation. 3.5.3 Manufacturer: Type XHHW cable for circuits, feeders and services shall be supplied from a single manufacturer. 3.5.
page 3 1 Annex C. Product Data sheets SIMpull THHN® • 600 Volts. Copper Conductor.
page 3 2 WEIGHTS , ME A SUREMENTS A ND P A C K A GING ALLOWABLE INSULATION JACKET NOMINAL O.D. APPROX. NET WEIGHT (mils) PER 1000 FT. (lbs) AMPACITIES* THICKNESS THICKNESS SIZE Number of (mils) (mils) SOL. STR. 60°C 75°C 90°C SOL. STR.
page 3 3 XHHW • 600 Volt. Copper Conductor • Cross-Linked Polyethylene (XLP) Insulation • High-Heat and Moisture Resistant • Sizes 14 Through 8 AWG Also Rated SIS • Black Sizes 2 AWG and Larger Sunlight Resistant Applications Suitable for use as follows: Southwire Type XHHW-2 conductors are primarily used in conduit or other recognized raceways for services, feeders and branch circuit wiring, as specified in the National Electrical Code.
page 3 4 WEIGHTS , ME A SUREMENTS CONDUCTOR A ND P A C K A GING ALLOWABLE AMPACITIES* NOMINAL O.D. (mils) 60°C 75°C 90°C APPROX. NET WEIGHT PER STANDARD 1000 FT. (lbs) PACKAGE SIZE/CONST. (AWG or kcmil) no.
page 3 5 Annex D. Field Testing Safety – Even low potential testing has inherent hazards to personnel and equipment. Thus safety rules are applicable for both high voltage and low voltage testing. Before conducting tests on any cable system, verify the cable system is properly de-energized. If the cable system has been previously energized, you must follow the prescribed rules for conducting the switching necessary to de-energize, lock-out, tag, and ground the cable system.
page 3 6 Table 10 – Temperature Correction Factors for Insulation Resistance Calculations ºF TYPES XHHW/RHH/RHW/USE TYPE THHN 50º 55º 60º 65º 70º 75º 80º 85º 0.73 0.86 1.00 1.17 1.36 1.59 1.86 — 0.56 0.75 1.00 1.34 1.79 2.40 3.21 4.
page 3 7 Annex E. Reference Materials NEC® Table 250.122 - Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of Equipment, Conduit, etc.
page 3 8 A r t i c l e 3 5 8 – E l e c t r i ca l M e t a l l i c T u b i n g ( EMT ) Nominal Internal Diameter Total Area 100% 60% 1 Wire 53% 2 Wires 31% Over 2 Wires 40% Trade Size mm. in. mm.2 in.2 mm.2 in.2 mm.2 in.2 mm.2 in.2 mm.2 in.2 1/2 15.8 0.622 196 0.304 118 0.182 104 0.161 61 0.094 78 0.122 3/4 20.9 0.824 343 0.533 206 0.320 182 0.283 106 0.165 137 0.213 1 26.6 1.049 556 0.864 333 0.519 295 0.458 172 0.268 222 0.346 1 1/4 35.1 1.
page 3 9 Artic l e s 3 5 2 a n d 3 5 3 ( RN C ) , Sc h e d u l e 4 0 , Nominal Internal Diameter Total Area 100% 60% – R i g i d PV C C o n d u it a n d HD P E C o n d u i t 1 Wire 53% 2 Wires 31% Over 2 Wires 40% Trade Size mm. in. mm.2 in.2 mm.2 in.2 mm.2 in.2 mm.2 in.2 mm.2 in.2 3/8 - - - - - - - - - - - - 1/2 15.3 0.602 184 0.285 110 0.171 97 0.151 57 0.088 74 0.114 3/4 20.4 0.804 327 0.508 196 0.305 173 0.269 101 0.157 131 0.203 1 26.1 1.
page 4 0 Table 310-16 Allowable Ampacities of Insulated Conductors Rated 0 Through 2000 Volts, 60°C Through 90°C (140°F Through 194°F), Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F) T e m p e r a t u r e Ra t i n g o f C o n d u c t o r ( S e e Ta b l e 3 1 0 .
page 4 1 NOTES: ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ _____________________
page 4 2 Installation and Application Guide For 600v Conductors
Printed in the USA 2007 Armorlite is a trademark of Alflex Corporation. EZ-MC, SIMpull THHN and Southwire are registered trademarks of Southwire Company. MEGA MC XXL Connectors and AlumaFlex are trademarks of Southwire Company. Southwire Company, One Southwire Drive, Carrollton, GA 30119 National Electrical Code and NEC are registered trademarks of the National Fire Protection Association, Inc., Quincy, MA 02169. © 2007 Southwire Company.
