--- title: "Anatomy of a Conductor Part 3: Voltage Levels and Base Current Value" description: Series on NEC requirements for electrical conductors in the power distribution system with this issue addressing voltage levels and base current value. image: https://blog.powercalc.co/hubfs/Blog_Images/Anatomy%20of%20a%20Conductor%20Part%203.jpg --- [![Powercalc_Logo.png](https://blog.powercalc.co/hs-fs/hubfs/Images/Powercalc_Logo.png?width=592&height=91&name=Powercalc_Logo.png "Powercalc_Logo.png")](https://www.powercalc.co) # PowerCalc Blog # Anatomy of a Conductor Part 3: Voltage Levels and Base Current Value By James Khalil, P.E. | Oct 12, 2017 11:00:00 AM | [electrical engineering](https://blog.powercalc.co/posts/topic/electrical-engineering), [NEC](https://blog.powercalc.co/posts/topic/nec) [![Share on Facebook](https://static.hubspot.com/final/img/common/icons/social/facebook-24x24.png)](http://www.facebook.com/share.php?u=https%3A%2F%2Fblog.powercalc.co%2Fposts%2Fvoltage-levels-and-base-current-value%3Futm_medium%3Dsocial%26utm_source%3Dfacebook) [![Share on LinkedIn](https://static.hubspot.com/final/img/common/icons/social/linkedin-24x24.png)](http://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fblog.powercalc.co%2Fposts%2Fvoltage-levels-and-base-current-value%3Futm_medium%3Dsocial%26utm_source%3Dlinkedin) [![Share on Twitter](https://static.hubspot.com/final/img/common/icons/social/twitter-24x24.png)](https://twitter.com/intent/tweet?original_referer=https%3A%2F%2Fblog.powercalc.co%2Fposts%2Fvoltage-levels-and-base-current-value%3Futm_medium%3Dsocial%26utm_source%3Dtwitter&url=https%3A%2F%2Fblog.powercalc.co%2Fposts%2Fvoltage-levels-and-base-current-value%3Futm_medium%3Dsocial%26utm_source%3Dtwitter&source=tweetbutton&text=Anatomy%20of%20a%20Conductor%20Part%203%3A%20Voltage%20Levels%20and%20Base%20Current%20Value) [![Share on Pinterest](https://static.hubspot.com/final/img/common/icons/social/pinterest-24x24.png)](http://pinterest.com/pin/create/button/?url=https%3A%2F%2Fblog.powercalc.co%2Fposts%2Fvoltage-levels-and-base-current-value%3Futm_medium%3Dsocial%26utm_source%3Dpinterest&media=) [![Share on Email](https://static.hubspot.com/final/img/common/icons/social/email-24x24.png)](mailto:?subject=Check%20out%20https%3A%2F%2Fblog.powercalc.co%2Fposts%2Fvoltage-levels-and-base-current-value%3Futm_medium%3Dsocial%26utm_source%3Demail%20&body=Check%20out%20https%3A%2F%2Fblog.powercalc.co%2Fposts%2Fvoltage-levels-and-base-current-value%3Futm_medium%3Dsocial%26utm_source%3Demail) ![Anatomy of a Conductor Part 3.jpg](https://blog.powercalc.co/hs-fs/hubfs/Blog_Images/Anatomy%20of%20a%20Conductor%20Part%203.jpg?width=640&name=Anatomy%20of%20a%20Conductor%20Part%203.jpg "Anatomy of a Conductor Part 3.jpg") Let's continue discussion of the anatomy of the conductor focusing on voltage levels and base current value.   Base Current Value  In Part 1, we discussed the different types of conductors in relation to their location in the building's power distribution system and the service provided. [Anatomy of a Conductor, Part 1](https://www.powercalc.co/anatomy-of-a-conductor-pt1?utm_campaign=Anatomy%20of%20a%20Conductor%20Newsletter&utm_source=hs_email&utm_medium=email&_hsenc=p2ANqtz--FcnPTd92IleTYw_iJ5tWYHzo8Fki1hs7shjQeoiVxY80dbxqfTV_OzdGRvn5QnxNfqKxp) The types are service conductors, service entrance conductors, feeder conductors, branch circuit conductors, ground electrode conductor and neutral conductor. The factors to consider in meeting the NEC's detailed but confusing requirements were also listed. Then in Part 2, we discussed sizing the conductor. [Anatomy of a Conductor Part 2](https://blog.powercalc.co/posts?utm_campaign=Anatomy%20of%20a%20Conductor%20Newsletter&utm_source=hs_email&utm_medium=email&_hsenc=p2ANqtz-87WcE-Ss6pn9sQqgK0cXYxxS_utCR0bwIg5b0qVWkO3qpyEA4kjF2mRizQn5SemjakHQJH) Back to factors, those for consideration by the electrical professional can be organized into three categories: (1) *Primary Factors*, (2) *Secondary Factors* and (3) *Ancillary Factors*. *Primary Factors* are those used to determine load as "seen" by the conductor: (1) system voltage, (2) system phase, (3) equipment # of poles, (4) equipment utilization voltage and (5) total electrical loads. *Secondary Factors* are those that impact the size and type of conductor as referenced in the NEC. These include: (1) temperature limitations, (2) temperature correction factor, (3) adjustment factor, (4) equipment grounding conductor, (5) load type (receptacle, lighting, motor and welding equipment), (6) conductor insulation (TW, THW, THHN and others), (7) ground electrode conductor and (8) material (CU or AL). Last, there are the *Ancillary Factor*s that support the *Secondary Factors*. These are design driven and considered in relation to installation. They include: (1) voltage drop, (2) conductors in parallel, (3) tap rule, (4) current carrying conductor, (5) demand load calculation and (6) amperage interrupting capacity (AIC). The outcome of applying the *Primary Factors* is the base current value in AMPS. The designer based on design requirements and location, then applies the *Secondary Factors* to obtain conductor size and the associated overcurrent protection device (OCPD).  Once these 2 basic values are determined, then the designer finally applies the* Ancillary Factors* to complete the design and specify the correct wire size and insulation rating. Voltage Levels The *Primary Factors* are applied as part of the following basic engineering equation for power to determine the base current value (l). P = l x V x √3       for a 3 Φ distribution system P + l x V     for a single Φ - 1 pole and single Φ - 2 pole distribution system Where P stands for Power (VA); V stands for Volt (V); l stands for Current (A) Any electrical circuit, in its simplest form, consists of two wires which carry  electrical current at a voltage level (electrical potential). The motion of the free electrons (charges) in a given electrical potential in a solid conductor constitutes an electric current (l). Said electric current (l) travels at the speed of light (186,000 miles/second). The unit of electric current is Ampere (Amps). One Ampere of current = 6.251 x 10 to the power of 18 electrons pass given cross section in 1 sec.  The higher the voltage, the higher the current flow for a given resistance. The flow of current (l) in an electric circuit is impeded by the resistance (R) [R = V / l] and produces heat (wasted energy). This wasted energy can be calculated by the following equation: P = l² R. It is because of this equation, one should properly size the conductor to minimize wasted energy. [![Request a Free Trial Today!](https://no-cache.hubspot.com/cta/default/1002713/db8fc271-b9a5-4a04-9cc3-41b94ff1b8bd.png)](https://cta-redirect.hubspot.com/cta/redirect/1002713/db8fc271-b9a5-4a04-9cc3-41b94ff1b8bd) Distribution systems in a building are classified according to the voltage level used to transfer the power needed to operate its equipment. The most common distribution system voltage levels that are widely used in the United States are: 480Y / 277 V 3 Φ;  208Y / 120 V - 3 Φ; 230 V closed Δ, 3 Φ; 230 V open Δ; 230 V - 2 poles, 1 Φ; 120 V - 1 pole In summary, the voltage, the phase, equipment # of poles, equipment utilization voltage and total electrical loads determine the base current value. This discussion about the complex requirements of the conductor will continue in future blogs. Visit [www.powercalc.co](https://www.powercalc.co).   ![](https://blog.powercalc.co/hubfs/James%20at%20desk.jpg) **About The Author** James Khalil, P.E. is President, Co-founder and Inventor of PowerCalc. He has 30+ years of experience at his MEP firm in Delray Beach, FL and with Carter Burgess (now Jacobs) in Fort Worth, TX; Mason & Hanger (now Zimmerman) in Lexington, KY; and Gee & Jenson (now CH2M) in West Palm Beach, FL. He received his B.S. in Electrical Engineering from the University of Texas. His experience includes projects for Saudi Arabia and Qatar; the US Departments of Energy, State, and Defense; and universities, schools, health facilities, and arts centers. 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