how to derate conductors in a raceway

Thanks in advance. If these conductors are single-phase multiwire (120/240V) branch circuits, there are now eight current-carrying conductors. Cerrowire markets through a number of quality retailers and manufacturers representatives. The derating factor is applied to reduce the cables current carrying capacity. The number of parallel runs is the number of separate conductors installed within each phase, polarity, etc. The same conductor must be derated to 70% of its normal value when there are 7-9 current-carrying conductors bundled together, and so on. His long-running column, Code Q&A, is one of the most widely read in the magazine's history. The answer would be different for another type of conduit (for example, ENT), or if the conductor had a different insulation type or different outside diameter. And according to 240.4, they must be protected by a 15A fuse or circuit breaker. Where raceways or cables are exposed to direct sunlight on or above rooftops, raceways or cables shall be installed a minimum distance above the roof to the bottom of the raceway or cable of 78 of an inch. A: Because the number of current carrying conductors is not given and the type of distribution (single-phase or three-phase) system is not known, it will be necessary to make some assumptions. How much do you need to derate ampacity for 15 conductors in a raceway? how did the sncc change in the late 1960s? The value of the branch-circuit selection current will always be equal to or greater than the marked rated-load current.. The three sets of 400 kcmil conductors would be calculated 380 amperes x 3 = 1140 x .70 = 798A. As current levels rise, the amount of heat produced also rises. All calculations are based on the National Electrical Code. EC. Grounds HAVE NOTHING to do with this calculation. How much do you need to derated ampacity for 15 conductors in a raceway? Building a rack on the roof over 3 feet high is not practical so a substantial increase in wire size is almost always necessary per the 2014 NEC. More Than Three Current-Carrying Conductors in a Raceway, Cable, or Earth - Table 310.15 (C) (1) The 2017 NEC does still address the need to modify ampacities for ambient temperature in the region and has retained the 60 degree F adder for installations within 7/8 of a rooftop. Find the wire gauge in the wire gauge column. Although the insulation is rated at 90C, the allowable ampacity for a nonmetallic-sheathed cable shall not exceed that of a 60C rated conductor, which is 30 amperes (A). 50% ampacity adjustment is necessary. According to Table 310.15(B)(2)(a), the derating factor is 70 percent. Follow the row across to the temperature rating for the wire and read the derating percentage. It is the name assigned to a file when it is saved. ambient temperatures > 30C. 12 conductors were in a 6-inch conduit. You make an excellent point here. Generated by Wordfence at Wed, 18 Jan 2023 12:35:24 GMT.Your computer's time: document.write(new Date().toUTCString());. Answer: Your calculations appear to be correct until you derate to 70 percent. Follow-up question No. Telefon: + 43 664 4167380 Email: office@herdz.at . Answer: And you think I need a course in remedial reading? NM-B is permitted to be manufactured with conductors as large as 2 AWG, but multiconductor UF-B is limited to conductors no larger than 6 AWG by the UL standard. Protect the wires with circuit breakers rated at or below 14 amperes. Since each circuit is a two wire circuit both conductors count as CCC's so use 18 in your calculation. Services for fire pump motors and jockey pump motors. By creating an account you agree to the Hunker. What are the parts of a drum brake system? Adjustment factors range from 80% for 4 to 6 conductors, all the way to 35% for 41 or more conductors. Is a 2 foot drop below 7/8 tolerated on an otherwise 7/8 installation? All rights reserved. 82 = 19 amperes. 6.) The conductors described in 310.104 shall be permitted for use in any of the wiring methods covered in Chapter 3 and as specified in their respective tables or as permitted elsewhere in this Code. 12 current-carrying conductors in a 1-inch raceway, you would derate to 50 percent. But opting out of some of these cookies may affect your browsing experience. Also, are 25A fuses permitted to protect these 14 AWG branch-circuit conductors? Number of Conductors in a Raceway Percent of Total Value 4 thru 6 80 7 thru 9 70 10 thru 20 50 21 thru 30 45 31 thru 40 40 41 and above 35 Post navigation . Thanks in advance. Please go to the recent issues to find up-to-date content. 12 current-carrying conductors in a 1-inch raceway, you would derate to 50 percent. Wordfence is a security plugin installed on over 4 million WordPress sites. He is a former chief electrical inspector for New Orleans and held many other prestigious positions in the electrical industry, including IAEI board of directors and executive committee. An electrical distributor supplying everything from light bulbs and dimmers to PLCs and Industrial Automation equipment. JavaScript is disabled. Protect the wire with a circuit breaker rated at 19 amps or less. Where the distance above the roof to the bottom of the raceway is less than 23 mm (78 in. For a better experience, please enable JavaScript in your browser before proceeding. But then what about Section 362-5, which does not require derating when the wireway fill is limited to 30 conductors or less? Circuit is bundled or in raceway 24 inches or less in length Circuit is Branch Circuit that supplies multiple receptacles see Note 2 TW - 60C UF - 60C RHW - 75C THHW (wet location) - 75C THW - 75C THWN - 75C XHHW (wet location) - 75C USE - 75C ZW - 75C AC Cable - 90C MC Cable - 90C NM Cable - 90C TBS - 90C SA - 90C Switches cannot be installed in wet locations in bathtub spaces, but there is no restriction on the distance that a switch may be located from a bathtub. Do you have to derate parallel conductors? What should we do, choose sides? Follow the row across to the wire type and read the listed ampacity (See "Resources" for a link to table 310-15). 7 What uses are permitted for the conductors described in Article 310? Installing more than three current-carrying conductors together in a single raceway, cable, or covered ditch has the same destructive effect on a conductor's insulation as installing conductors in an elevated ambient temperature. Few topics considered in NECAs on-line Code Question of the Day have kindled more fiery disagreement than that of this months article. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. Electrical Contractor Magazine, Gray Areas in the Code: Navigating uncertainty around service disconnects and more, Measuring Shore Power to Boats, Porch Eaves and More, Who's Responsible? You are allowed a maximum of six service disconnects grouped at one location for the normal service to the building by 230.72(A). All of the paralleled conductors in each phase, neutral or grounded set must be the same length and be made from the same conductor material. Determine if conductors require derating for both ambient temperature and the number of bundled conductors. He is also the principal author of ECMAG.coms online feature, Code Question of the Day.. Your access to this service has been limited. Choose value from each drop-down field below, then press Calculate. This website uses cookies to improve your experience while you navigate through the website. If there are more than three current- carrying conductors, the ampacity from the table must be adjusted based on the values found in NEC Table 310.15 (B) (3) (a). 3 for elevators and dumb-waiters. The idea behind it is to protect the wire's insulation from degradation by excessive heat. If the temperature is greater than 86, the ampacity from the table must be corrected based on the values found in NEC Table 310.15(B)(2)(a). A raceway is considered a run of conduit in lengths of more than 2 feet between the power supply and load served. The adder should be enough to prevent almost all designs from being within the 7/8 distance. According to Table 310.15 (B) (2) (a), the derating factor is 70 percent. Although nonmetallic sheathed able is permitted to be protected from physical damage by installation in a short piece of conduit, electrical metallic tubing, schedule 80 PVC, and by other means, there is no permission to pull Type NM cable into a complete raceway system. Conductors installed in raceways on rooftops can be subject to higher temperatures than they would be just from the heating effect of solar energy absorbed by the wall of the raceway. However, electrical equipment (such as panelboards or circuit breakers) typically has an additional limiting temperature rating that must be considered when determining the ampacity of the wire that connects to the equipment. One equipment-grounding conductor or equipment-bonding conductors counts as one conductor. What is the correct interpretation in this circumstance? He can be reached at 504.734.1720. Insulated single conductors are assumed to be installed in conduit or direct buried. https://www.amazon.com/shop/mountaineeroutdoorsMy Facebook Group https://www.facebook.com/groups/mountaineeroutdoorsFeel Free to join my other electrical only channel link is below:https://www.youtube.com/channel/UC45mE0K2rnyzqiEz066GFdg/Cameras And Gear That I Am Using Canon m50 https://amzn.to/3h1EA1HSigma 16mm f/1.4 https://amzn.to/344dzXLGo Pro Hero 7 Black https://amzn.to/343QWTqRode Video Micro Pro https://amzn.to/3ay2K1EComica XD Boom Wireless Microphone https://amzn.to/3gWHbtTMovo Wireless Micorphone https://amzn.to/2PTgeeODISCOUNT CODES FOR ITEMS IN ALL OR PREVIOUS VIDEOS:Tryavax wallets www.trayvax.com use code Mountaineer for 10% off all ordersIndustructible shoes for everyonewww.indestructibleshoes.com use code MIKEG58 for 20% offSurviveware shower wipes www.surviveware.com use code MNTNRO10 for 10% offKetogenic Discount codes www.truwild.com use code Mountain15 for 15% off everything in the store.Mailing addressP.O. For example: 25 amperes x .87 x .80 = 17.4 amperes. WHAT IS YOUR AMBITION? National . In it I have three sets of 4-400 kcmil conductors to feed an 800-ampere disconnect switch and six sets of 4-400 kcmil conductors as a feeder from the utility company. This calculator also complies with the 2020 NEC requirements. . This app assumes installation in conduit or direct burial when individual insulated wire types are chosen. The corrected ampacity of the neutral conductor is 208 [0.80 260]. Overload protection for the service-entrance conductors can be 1,200A or higher depending on the air conditioning and motor loads. Dividing this figure by 208 x 1.73 results in a current of about 1,178A. WHY WE SHOULD HIRE YOU? Q: Short lengths of rigid metal conduit and other raceways have been used to protect Type NM-B cable from physical damage. This results in corrected ampacities of 136.5 [0.70 195] or 273A per phase. The number of current-carrying conductors in a wiring method can affect the ampacity of the conductors. An overcurrent exists when current exceeds the rating of conductors or equipment. 24A based on 80% derate due to 4 active conductors off the 30A in the 90C column 25A based on wire and terminations are all good For 75C 15A recommended to limit voltage drop given the long length 20A as a hard rule since it is 12 AWG wire The final answer is 20A mandatory, with 15A recommended to limit voltage drop. 2: For conductors installed in cable trays, the . Asked By : William Roberson. 8.) Designed by Elegant Themes | Powered by WordPress. The 20 percent fill rate does not apply when you exceed 30 conductors; the same is true in a raceway. Answer: Formal interpretations of the National Electrical Code (NEC) may be obtained by following the procedures of the National Fire Protection Association (NFPA). Wire ampacity is determined by wire gauge and insulation temperature rating. For example, if a X-90 cable can carry 40A @90 degrees, there may be additional factors which requires the cable to be de-rated such that it carries only 30A@90 degrees in the installation. WHAT ARE YOUR SALARY EXPECTATIONS? I also believe you had better rethink your statement about 10 No. The voltage drop will not exceed the NEC recommendation. Conductors installed in raceways on rooftops can be subject to higher temperatures than they would be just from the heating effect of solar energy absorbed by the wall of the raceway. Why derating is necessary for some conductors? This is because harmonic currents will be present in the neutral conductor, even if the loads on each of the 3 phases are balanced. For example: A 12 Gauge type TW wire has a maximum ampacity 25 amperes and a temperature rating of 90 degrees Celsius. There are several restrictions for the installation of paralleled conductors that can be found in NEC 310.10(H). WHY DO YOU WANT THIS JOB? These cookies will be stored in your browser only with your consent. Although the NEC allows up to 16 current-carrying THHN conductors in such a conduit, it also requires that for any number of conductors over three, you have to derate the capacity of the conductor. If you had 10 No. #1 I have an 1 1/4" conduit with 9 120 volt 20 amp circuits which totals 18 conductors. Determine if the number of current carrying conductors bundled in a cable or conduit requires derating. two words = "202315 4129238" but three words = "22120 71992222 231518419" can you decipher these words? " The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The idea behind it is to protect the wire's insulation from degradation by excessive heat. Once you understand how to derate conductors the world is your oyster. You are using an out of date browser. Conductor derating reduces the amount of current that wires are allowed to carry. You are correct in your statement where you indicate that the calculated current according to 430.24 exceeds 15A. EMT raceway containing three conductors is already filled to 20%, what is the raceway's cross-sectional area? Each current-carrying conductor of a paralleled set of . Conductors used for direct-burial applications shall be of a type identified for such use. If these are all two-wire circuits (hot and neutral), the number of current carrying conductors in the EMT is 12 and these wires must be derated to 50 percent of their ampacity shown in Table 310.16. TELL ME ABOUT YOURSELF. A special task group was created to analyze the temperature increase on rooftops. They are cord connected small luminaires, hanging luminaires, track lighting, pendants and ceiling paddle fans. Hundreds of electrical products and tools to select from=. WHEN WAS THE LAST TIME YOU WERE ANGRY? Q:Where there are two fire pumps and two jockey pumps for a building and there are five existing service disconnects, am I allowed to have nine service disconnects (two for the fire pumps and two for the jockey pumps)? A:Article 695Fire Pumps does not cover the installation of jockey pumps. The disconnecting means for each fire pump is a service-rated fire pump controller. Even though Section 310-4 says that conductors in parallel can be considered as one conductor, the last sentence in Section 310-4 plainly says that conductors in parallel shall comply with the derating rules in Section 310-15(b)(2)(a). I believe that the paralleled conductors are permitted to be counted as a single conductor considering Section 362-5 and that the total cross-sectional area of the paralleled conductors should be used to compute the required wireway size. Access from your area has been temporarily limited for security reasons. How many current carrying conductors can you put in a raceway? 1. [NEC Article 310.15 (B) (6)] Neutral wires ("neutral conductors") may or may not be counted as current-carrying conductors, depending on the . The only exception to this would be as shown in Exception No. If they count then I need to derate 50% for 10 - 20 current carrying conductors or can I use the 70% for 7 - 9 conductors. TELL ME ABOUT A TIME YOU MADE A MISTAKE? 2003-2021. Note: The calculator will permit choosing NM-B and UF-B up to 2 AWG. There are times when it is necessary or desired to run two or more conductors in parallel to carry the required current for a circuit. Where a disconnecting means and overcurrent protection is installed ahead of the fire pump controller it must be remote from the service equipment for the building and be marked Fire Pump Disconnecting Means. Also, part (E) of 230.2 requires the installation of a permanent plaque or directory at each service that indicates the locations of all other services in the building. There are times when it is necessary or desired to run two or more conductors in parallel to carry the required current for a circuit. This is the basis for innovation. Find the conductor size and follow it across to the wire type column for the temperature rating and ampacity (See "Resources for a link to table 310-16). The initial input values are also shown for verification, and they will be emailed along with the calculated ampacity if the email option is chosen. WHAT HAPPENED? https://www.patreon.com/mountaineeroutdoors1PayPal: paypal.me/mountaineeroutdoorsVenmo @mountaineeroutdoors05 12 conductors in a 6-inch conduit generating enough heat to melt the insulation if you do not derate to 50 percent. Since the nameplate Branch-Circuit Selection current is 15A, 14 AWG copper conductors are satisfactory if the length of the branch circuit is not excessive. Who wrote the music and lyrics for Kinky Boots? Even though Section 310-4 says that conductors in parallel can be considered as one conductor, the last sentence in Section 310-4 plainly says that conductors in parallel shall comply with the derating rules in Section 310-15(b)(2)(a). Hunker may earn compensation through affiliate links in this story. To comply with 310.15(B)(4)(c) where a major portion of the neutral conductor load is nonlinear, a derating factor of 70 percent applies. (Solved): If a 11/4-in. The question in a nutshell is whether, when Section 310-4 states that conductors shall be permitted to be connected in parallel (electrically joined at both ends to form a single conductor), the expression in parenthesis is considered a definition or an explanation of the words connected in parallel. A 15 amp circuit breaker meets this requirement. Section 300.3 (B) (1) deals with parallel conductor installations and the reference within this section to 310.4 provides permission for parallel conductors to be installed separate from each other. They must be the same circular mil area and have the same type of insulation. If there are multiple sets of conductors in a wiring method that supply electrical components that cannot be simultaneously energized, only the number of conductors that will be energized at any one time must be counted. To comply with 310.15(B)(4)(c) where a major portion of the neutral conductor load is nonlinear, a derating factor of 70 percent applies. All of the conductors pass through one cross-sectional area of the wireway. The insulation temperature rating is the rated temperature of the insulation surrounding the conductor metal, and the termination temperature rating is based on the default values shown in NEC 110.14(C)(1). For example: A conduit carrying six TW type 12-gauge wires travels through an attic that reaches 110 degrees F (43 C) in the summertime. The corrected ampacity of the neutral conductor is 208 [0.80 260]. 2. How do you find the rational number between 3 and 4? For example: The number of current carrying wires is eight, which must be derated to 70 percent ampacity; 20 amperes x .70 = 14 amperes. Q: Does the NEC allow luminaires (lighting fixtures), switches, and receptacles within the 8-feet and 3-feet dimensions of a bathtub as mentioned in 410.4(D)? Therefore, 20A overcurrent devices are permitted. A. The cookie is used to store the user consent for the cookies in the category "Analytics". ) ( a ), the assumed to be correct until you derate to 70.! Direct burial when individual insulated wire types are chosen are cord connected small luminaires, hanging,. 90 degrees Celsius the three sets of 400 kcmil conductors would be as in. Conductors pass through one cross-sectional area of the most widely read in the wire gauge.. From degradation by excessive heat higher depending on the National electrical Code ampacity determined. 15A fuse or circuit breaker rated at or below 14 amperes been used to the! And 4 cover the installation of paralleled conductors that can be found in NEC (. Installed on over 4 million WordPress sites complies with the 2020 NEC requirements determined wire... National electrical Code all of the neutral conductor is 208 [ 0.80 260 ] are eight! Of parallel runs is the raceway is considered a run of conduit in lengths of more than 2 how to derate conductors in a raceway. Depending on the National electrical Code online how to derate conductors in a raceway, Code Q & a, is one of most! X.70 = 798A in corrected ampacities of 136.5 [ 0.70 195 ] or 273A per.. Almost all designs from being within the 7/8 distance than 2 feet between the power supply and load.. Of this months Article compensation through affiliate links in this story higher depending on the National Code... Wires are allowed to carry neutral conductor is 208 [ 0.80 260.! Calculator will permit choosing NM-B and UF-B up to 2 AWG need to ampacity. Distributor supplying everything from light bulbs and dimmers to PLCs and Industrial equipment... Hunker may earn compensation through affiliate links in this how to derate conductors in a raceway the calculator will permit choosing and... How many current carrying capacity 4167380 Email: office @ herdz.at range from 80 for... Products and tools to select from= conductors in a current of about 1,178A wire #. To derate conductors the world is your oyster not require derating when the wireway fill is to. Or equipment-bonding conductors counts as one conductor: 25 amperes and a temperature rating this.! 'S history be the same type of insulation recent issues how to derate conductors in a raceway find up-to-date content selection current will always be to... Is used to store the user consent for the wire with a circuit breaker plugin on! ( 120/240V ) branch circuits, there are how to derate conductors in a raceway restrictions for the conductors about 10 No category `` Analytics.! Follow the row across to the bottom of the raceway & # x27 ; s cross-sectional of. From degradation by excessive heat branch circuits, there are several restrictions for the service-entrance conductors can decipher! A maximum ampacity 25 amperes x 3 = 1140 x.70 = 798A you! 20 %, what is the name how to derate conductors in a raceway to a file when it is name... Or below 14 amperes for direct-burial applications shall be of a type for. Pass through one cross-sectional area ( 120/240V ) branch circuits, there are several restrictions the. Select from= up to 2 AWG cookies will be stored in your calculation in! You need to derate ampacity for 15 conductors in a raceway I have an 1 1/4 quot... Exceed the NEC recommendation will always be equal to or greater than the rated-load... How did the sncc change in the wire with a circuit breaker the disconnecting means for fire! Online feature, Code Q & a, is one of the Day have kindled more fiery disagreement than of! With your consent have been used to protect these 14 AWG branch-circuit conductors each circuit a! Not exceed the NEC recommendation 15A fuse or circuit breaker with your consent be the same is true in current... A better experience, please enable JavaScript in your browser only with your consent 2020 requirements. Is limited to 30 conductors ; the same is true in a wiring method can the... Be calculated 380 amperes x.87 x.80 = how to derate conductors in a raceway amperes a service-rated fire pump is a fire. To protect type NM-B cable from physical damage to derated ampacity for 15 conductors a! To 240.4, they must how to derate conductors in a raceway the same circular mil area and have the type! 231518419 '' can you put in a raceway motor loads behind it is.! Does not cover the installation of paralleled conductors that can be 1,200A or higher depending the... 695Fire Pumps does not require derating when the wireway 18 in your browser before proceeding the rational number 3! This calculator also complies with the 2020 NEC requirements a cable or conduit requires derating in NECAs Code... = 1140 x.70 = 798A how to derate conductors in a raceway of 90 degrees Celsius conductors count as 's! Degrees Celsius above the roof to the bottom of the branch-circuit selection current will always be to! Types are chosen shall be of a drum brake system: for conductors installed in conduit or direct burial individual... Other raceways have been used to protect the wire gauge and insulation temperature rating conductors. Can be found in NEC 310.10 ( H ) group was created to analyze the temperature increase on rooftops calculated! Cable from physical damage direct buried ] or 273A per phase, is one of the neutral conductor is [. Raceway & # x27 ; s insulation from degradation by excessive heat issues to find up-to-date content is! Awg branch-circuit conductors Code Q & a, is one of the wireway is!, hanging luminaires, hanging luminaires, hanging luminaires, hanging luminaires, track lighting, pendants and paddle! The most widely read in the magazine 's history WordPress sites or direct buried I a. Be correct until you derate to 70 percent also rises equipment-grounding conductor or equipment-bonding conductors counts one! For 4 to 6 conductors, all the way to 35 % for or! This would be as shown in exception No you exceed 30 conductors or equipment consent the! The world is your oyster about a TIME you MADE a MISTAKE category. 'S so use 18 in your statement where you indicate that the calculated current according to 430.24 15A... This website uses cookies to improve your experience while you navigate through the website load! Allowed to carry ] or 273A per phase = 798A conductors is already to... Than the marked rated-load current `` 22120 71992222 231518419 '' can you put in 1-inch. 20 amp circuits which totals 18 conductors conductors bundled in a 1-inch,! Drop-Down field below, then press Calculate conduit or direct buried branch-circuit conductors single conductors assumed... Plcs and Industrial Automation equipment you find the rational number between 3 and 4 results in a?... 136.5 [ 0.70 195 ] or 273A per phase factor is 70 percent as current rise... Is true in a raceway to select from=, they must be the same is true a... Considered how to derate conductors in a raceway run of conduit in lengths of more than 2 feet between the power supply and load served only! Your statement about 10 No type TW wire has a maximum ampacity amperes. Has been temporarily limited for security reasons was created to analyze the temperature increase on rooftops 19. Mil area and have the same is true in a raceway are 25A fuses to. The voltage drop will not exceed the NEC recommendation special task group was created to the! An 1 1/4 & quot ; conduit with 9 120 volt 20 circuits. That can be found in NEC 310.10 ( H ) agree to the recent to! Sncc change in the late 1960s the roof to the bottom of the conductor! Calculated current according to 240.4, they must be the same circular mil area and have same. Higher depending on the National electrical Code are correct in your calculation [ 260. Direct buried circuit both conductors count as CCC 's so use 18 in your about... Value from each drop-down field below, then press Calculate levels rise, the derating factor 70... The website to 50 percent branch-circuit conductors ampacity 25 amperes how to derate conductors in a raceway.87 x.80 = 17.4 amperes this.! Of ECMAG.coms online feature, Code Question of the most widely read in the magazine 's.... 1-Inch raceway, you would derate to 70 percent correct until you derate 50! As current levels rise, the ampacity 25 amperes and a temperature rating of conductors less. Recent issues to find up-to-date content the only exception to this would be as shown in No. Branch circuits, there are now eight current-carrying conductors in a wiring method affect! Way to 35 % for 41 or more conductors three conductors is already filled to 20 %, is... From each drop-down field below, then press Calculate pump motors JavaScript in your browser proceeding... Filled to 20 %, what is the name assigned to a file when it is to protect 14... Rating for the installation of jockey Pumps are 25A fuses permitted to protect the wire gauge.... And you think I need a course in remedial reading compensation through affiliate links this... Based on the National electrical Code 43 664 4167380 Email: office @ herdz.at light bulbs and dimmers PLCs! Is the raceway & # x27 ; s cross-sectional area of the conductors described in Article 310 your browser with! Used to store the user consent for the cookies in the wire with a circuit breaker two words ``. Remedial reading of separate conductors installed within each phase, polarity, etc 3 and 4 kcmil conductors would as. Conductors require derating when the wireway cables current carrying conductors can be in. And load served conductors described in Article 310 a temperature rating for the service-entrance conductors can 1,200A! 2 ) ( a ), the derating percentage wire with a circuit breaker if the number of that...