{"id":6989,"date":"2023-01-12T07:25:33","date_gmt":"2023-01-12T07:25:33","guid":{"rendered":"https:\/\/www.clooms.com\/?p=6989"},"modified":"2023-01-16T04:18:17","modified_gmt":"2023-01-16T04:18:17","slug":"cable-ampacity","status":"publish","type":"post","link":"https:\/\/www.clooms.com\/cable-ampacity\/","title":{"rendered":"Cable Ampacity: What is it all about?"},"content":{"rendered":"\n
Cable selection comes with a lot of factors to consider. The key factor is the ampacity rating of the wire. Establishing the highest current power cables can take up without destroying their electrical properties. If you want to select a wire and are unsure of its ampacity, the NEC<\/a> (National Electrical Code) has you sorted. It has the recommended ampacity tables that share the allowable ampacity of insulated conductors. That said, we will go further and find out what the cable ampacity<\/strong> is all about.<\/p>\n\n\n Cable ampacity is the capacity of current that a conductor safely carries without exceeding its temperature rating. In other words, it’s the current-carrying capacity. The calculation of ampacity<\/a> is quite simple, and measurement is in Amperes or Amps.<\/p>\n\n\n\n There are two primary components of wires:<\/p>\n\n\n\n As currents maneuver through the conductor, they cause a voltage drop<\/a> and generate heat. If the heat overpowers the cable rating, it could fail. Therefore, it’s best to dissipate the heat outside the cable. <\/p>\n\n\n\n If you don\u2019t dissipate the heat outside the cable, the cable’s temperature will continue to increase, exceeding its temperature rating. In the end, the cable would deteriorate. <\/p>\n\n\n\n The National Electrical Code(NEC) published cable ampacity tables to keep electrical cables safe from failures to show the maximum currents allowed for different wire sizes and applications. The Institute of Electricals and Electronics Engineers (IEEE) also provides the same. <\/p>\n\n\n\n Tip: IEEE 399, ICEA P-54-440, NEC NFPA 70 current derating ensures cables have the maximum operation and are secure<\/a>. <\/p>\n\n\n\n cable tray with electrical wiring arranged<\/p>\n\n\n There are three most common temperature ratings. They are 60\u00baC, 75\u00baC, and 90\u00baC. However, 90\u00baC is the most common conductor rating temperature. Surprisingly, the conductors can rate up to higher temperatures of 1200\u00baC for special wires and larger power cables. <\/p>\n\n\n\n The material used for insulation and the jacket of the cable will affect the temperature rating. A material with high heat resistance will survive in higher temperatures.<\/p>\n\n\n\n According to the NEC 2014 Article 310 ampacity tables, electrical engineers use a 75\u00baC temperature rating because many connectors rate 75\u00baC. <\/p>\n\n\n Electrical engineers perform derating to reduce the cable’s current carrying capacity. They do this by accounting for all factors that could increase temperatures during power cable installation. The idea is to prevent cable damage and system loss. <\/p>\n\n\n\n There are two major requirements for derating ampacity in line with NEC. First is the ambient temperatures<\/a>, and second is the number of current-carrying conductors. <\/p>\n\n\n\n If more than three current-carrying conductors are in a raceway, the ampacity rating needs derating to control heat flow. When these cable types are closer, they cannot dissipate heat. As a result, there will be an increase in ambient temperature.<\/p>\n\n\n\n In hot climatic regions, the soil has high ambient heat. Installing a cable in these soils reduces heat dissipation. As a result, the cables will become hotter. As such, the cables will require derating to minimize current-carrying capacity. In simpler terms, current rating.<\/p>\n\n\n\n Not all conductors carry current. Therefore, carry out derating depending on the number of current-carrying conductors. <\/p>\n\n\n The table below shows the allowable ampacities of insulated conductors at rates between 0 to 2000 volts, 60 degrees celsius to 90 degrees Celsius, and not more than three carrying conductors in raceway, cable, or earth. <\/p>\n\n\n According to NEC, no overcurrent protection<\/a> device shall exceed 15A for 14 AWG copper, 20A for 12 AWG copper, and 30A for 10 AWG copper.<\/p>\n\n\n Multiply the allowable ampacity as shown in the above table with the correction factors below. <\/p>\n\n\n\n These ampacity charts guide electrical professionals toward the right cable gauge and length. These charts are a plus for professionals in the welding sector. They must use proper cable gauge size<\/a> for their safety and deliver high-quality welding.<\/p>\n\n\n\n So, cable experts advise choosing the required welding cable to achieve this. Failure to do so will cause excessive heat absorption, further damaging the welding equipment. <\/p>\n\n\n\nTable of Contents<\/h2>\n
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What is Cable Ampacity?<\/h2>\n\n\n
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Temperature Ratings of Cables<\/h2>\n\n\n
Derating Factors of Cables<\/h2>\n\n\n
Maximum Ampacities for Wire <\/h2>\n\n\n
Based on ambient temperatures of 30 degrees Celsius<\/h3>\n\n\n
Wire Size (AWG or Kcmil)<\/td> Copper Conductor temp rating <\/td> Aluminum Conductor Temp rating<\/td><\/tr> <\/td> Types TW, UF<\/strong><\/td> Types RHW, THHW, THW, THWN, XHHW, USE, ZW<\/strong><\/td> Types TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2<\/strong><\/td> Types TW, UF<\/strong><\/td> Types RHW, THHW, THW, THWN, XHHW, USE, ZW<\/strong><\/td> Types TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2<\/strong><\/td><\/tr> <\/td> 60\u00baC (140\u00baF)<\/td> 75\u00baC (167\u00baF)<\/td> 90\u00baC (194\u00baF)<\/td> 60\u00baC-(140\u00baF)<\/td> 75\u00baC (167\u00baF)<\/td> 90\u00baC (194\u00baF)<\/td><\/tr> 14*<\/td> 20<\/td> 20<\/td> 25<\/td> –<\/td> –<\/td> –<\/td><\/tr> 12*<\/td> 25<\/td> 25<\/td> 30<\/td> 20<\/td> 20<\/td> 25<\/td><\/tr> 10*<\/td> 30<\/td> 35<\/td> 40<\/td> 25<\/td> 30<\/td> 35<\/td><\/tr> 8<\/td> 40<\/td> 50<\/td> 55<\/td> 30<\/td> 40<\/td> 45<\/td><\/tr> 6<\/td> 55<\/td> 65<\/td> 75<\/td> 40<\/td> 50<\/td> 60<\/td><\/tr> 4<\/td> 70<\/td> 85<\/td> 95<\/td> 55<\/td> 65<\/td> 75<\/td><\/tr> 3<\/td> 85<\/td> 100<\/td> 110<\/td> 65<\/td> 75<\/td> 85<\/td><\/tr> 2<\/td> 95<\/td> 115<\/td> 130<\/td> 75<\/td> 90<\/td> 100<\/td><\/tr> 1<\/td> 110<\/td> 130<\/td> 150<\/td> 85<\/td> 100<\/td> 115<\/td><\/tr> 1\/0<\/td> 125<\/td> 150<\/td> 170<\/td> 100<\/td> 120<\/td> 135<\/td><\/tr> 2\/0<\/td> 145<\/td> 175<\/td> 195<\/td> 115<\/td> 135<\/td> 150<\/td><\/tr> 3\/0<\/td> 165<\/td> 200<\/td> 225<\/td> 130<\/td> 155<\/td> 175<\/td><\/tr> 4\/0<\/td> 195<\/td> 230<\/td> 260<\/td> 150<\/td> 180<\/td> 205<\/td><\/tr> 250<\/td> 215<\/td> 255<\/td> 290<\/td> 170<\/td> 205<\/td> 230<\/td><\/tr> 300<\/td> 240<\/td> 285<\/td> 320<\/td> 190<\/td> 230<\/td> 255<\/td><\/tr> 350<\/td> 260<\/td> 310<\/td> 350<\/td> 210<\/td> 250<\/td> 280<\/td><\/tr> 400<\/td> 280<\/td> 335<\/td> 380<\/td> 225<\/td> 270<\/td> 305<\/td><\/tr> 500<\/td> 320<\/td> 380<\/td> 430<\/td> 260<\/td> 310<\/td> 350<\/td><\/tr> 600<\/td> 355<\/td> 420<\/td> 475<\/td> 285<\/td> 340<\/td> 385<\/td><\/tr> 700<\/td> 385<\/td> 460<\/td> 520<\/td> 310<\/td> 375<\/td> 420<\/td><\/tr> 750<\/td> 400<\/td> 475<\/td> 535<\/td> 320<\/td> 385<\/td> 435<\/td><\/tr> 800<\/td> 410<\/td> 490<\/td> 555<\/td> 330<\/td> 395<\/td> 450<\/td><\/tr> 900<\/td> 435<\/td> 520<\/td> 585<\/td> 355<\/td> 425<\/td> 480<\/td><\/tr> 1000 <\/td> 455<\/td> 545<\/td> 615<\/td> 375<\/td> 445<\/td> 500<\/td><\/tr> 1250<\/td> 495<\/td> 590<\/td> 665<\/td> 405<\/td> 485<\/td> 545<\/td><\/tr> 1500<\/td> 520<\/td> 625<\/td> 705<\/td> 435<\/td> 520<\/td> 625<\/td><\/tr> 1750<\/td> 545<\/td> 650<\/td> 735<\/td> 455<\/td> 545<\/td> 615<\/td><\/tr> 2000<\/td> 560<\/td> 665<\/td> 750<\/td> 470<\/td> 560<\/td> 630<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Ambient temperatures exceeding 30 degrees celsius<\/h3>\n\n\n
Ambient Temperatures <\/strong><\/td> Copper Conductors <\/strong><\/td> Aluminium Conductors <\/strong><\/td><\/tr> 21-25\u00baC
69-77\u00baF<\/td>1.08<\/td> 1.05<\/td> 1.04<\/td> 1.08<\/td> 1.05<\/td> 1.04<\/td><\/tr> 26-30\u00baC
78-86\u00baF<\/td>1<\/td> 1<\/td> 1<\/td> 1<\/td> 1<\/td> 1<\/td><\/tr> 31-35\u00baC87-95\u00baF<\/td> 0.91<\/td> 0.94<\/td> 0.96<\/td> 0.91<\/td> 0.94<\/td> 0.96<\/td><\/tr> 36-40\u00baC96-104\u00baF<\/td> 0.86<\/td> 0.88<\/td> 0.91<\/td> 0.86<\/td> 0.88<\/td> 0.91<\/td><\/tr> 41-45\u00baC
105-113\u00baF<\/td>0.71<\/td> 0.82<\/td> 0.87<\/td> 0.71<\/td> 0.82<\/td> 0.87<\/td><\/tr> 46-50\u00baC114-122\u00baF<\/td> 0.58<\/td> 0.75<\/td> 0.82<\/td> 0.58<\/td> 0.75<\/td> 0.82<\/td><\/tr> 51-55\u00baC
123-131\u00baF<\/td>0.41<\/td> 0.67<\/td> 0.76<\/td> 0.41<\/td> 0.67<\/td> 0.76<\/td><\/tr> 56-60\u00baC
132-140\u00baF<\/td>–<\/td> 0.58<\/td> 0.71 <\/td> –<\/td> 0.58<\/td> 0.71 <\/td><\/tr> 61-65\u00baC
141-149\u00baF<\/td>–<\/td> 0.47<\/td> 0.65<\/td> –<\/td> 0.47<\/td> 0.65<\/td><\/tr> 66-70\u00baC
150-158\u00baF<\/td>–<\/td> 0.33<\/td> 0.58<\/td> –<\/td> 0.33<\/td> 0.58<\/td><\/tr> 71-75\u00baC
159-167\u00baF<\/td>–<\/td> –<\/td> 0.50<\/td> –<\/td> –<\/td> 0.50<\/td><\/tr> 76-80\u00baC
168-176\u00baF<\/td>–<\/td> –<\/td> 0.41<\/td> –<\/td> –<\/td> 0.41<\/td><\/tr> 81-85\u00baC177-185\u00baF<\/td> –<\/td> –<\/td> 0.29<\/td> –<\/td> –<\/td> 0.29<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n