NEC Section 230.71. Six Switches or Circuit Breakers in One Enclosure
Since the 1937 edition of the NEC, the service disconnecting means used to isolate a building’s premises wiring from the utility provider’s conductors has been allowed to consist of as few as one, but as many as six switches or sets of circuit breakers.
A veteran electrician would tell you that requirement (or permission, depending on your perspective) means six throws of the hand can be used to control all power on the property. Our veteran electrician is correct – if there is one electrical service on the property.
JADE Learning is offering an 11-Hour Renewal Package for Florida Electrical Contractors. The courses are online and meet the requirements for the August 31st, 2020 renewal deadline. All licensed electrical contractors in Florida are required to complete 11 hours of continuing education to renew a Florida electrical contractor license.
Section 408.6: A Brand-New Addition to the 2020 NEC
NEC section 408.6 states: Switchboards, Switchgear, and Panelboards shall have a short-circuit current rating (SCCR) not less than the available fault current. In other than one- and two-family dwelling units, the available fault current and the date the calculation was performed shall be field marked on the enclosure at the point of supply. The marking shall comply with 110.21(B)(3).
Making NEC 408.6 Simple
This new Code Section simply means that electrical panels including main-breaker and main-lug type panels and switchboards & switchgear equipment must be rated (in amps) to withstand the high levels of current that will flow should a short-to-ground or other fault occur at the equipment. In ALL locations other than dwelling units, that anticipated fault current must be marked on the equipment enclosure near where the supply conductors enter in, along with the date that the calculation producing that number was performed. The new Code Section also says the markings on the equipment must comply with 110.21(B)(3). Section 110.21(B)(3) tells us that markings must be sufficiently durable to withstand the environment.
Electric vehicle (EV) charging is not new, as Article 625 was introduced to the National Electrical Code with the 1996 edition. The following year, the Toyota Prius became the first mass-produced (hybrid) electric vehicle. More followed, including Tesla, Nissan, and Chevrolet. Until recently, however, the only viable method for charging an electric or hybrid vehicle was via a direct connection to a power supply, either from premises wiring or at a charging station.
For the 2017 Code cycle, both definitions and requirements have been added to Article 625 for the purpose of regulating another type of EV charging: wireless power transfer, or wireless charging. Before we examine the Code requirements, let’s answer a couple of important questions. First, how does wireless charging work? Second, how efficient is this technology?
How Do I Sign-Up for the California Electrical Certification Exam?
Once you’ve completed all requirements as an apprentice or through and electrical trainee program you can submit your application to have your experience reviewed by the California DIR. After submitting the application and all the required attachments you will be notified of your eligibility. You will have one year to schedule and take your exam. If you do not complete your exam within that time frame you will have to re-submit your application. It is important that you properly prep for the exam to ensure you pass on the first try.
Derating conductors for the environment where they are installed is an important consideration for selecting the type and size of conductor for a particular installation. When installing a system on a rooftop, special consideration must be given to the ambient temperature inside the wire way or conduit that contain the conductors to prevent heating beyond the rating of the insulation of the conductors.
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. This effect becomes more evident when the proximity is very close to the roof or the raceway is in contact with the roof surface.
Transformers are used when power voltages need to be changed, or transformed, to other levels. Sometimes voltages need to be increased when sending power long distances. Other times, voltages need to be decreased for equipment that uses the power. Regardless of whether the voltages are being stepped up or stepped down, the same process of changing windings is used to transform voltages to different levels.
The primary intent of this discussion is to explain how overcurrent protection devices are determined for single motor branch-circuits. References will be taken from the 2020 National Electrical Code (NEC). These references will apply to general single motor applications for a continuous duty NEMA Design B energy efficient motor, unless otherwise noted.
Can you do a box fill calculation at the jobsite? This is an important skill for installers and inspectors alike, since a box that is overfilled can cause a fault, arcing, or even a fire. But how do we determine if a box is overfilled in a real-world situation?
Prior to 2017, only two items were prohibited for use as grounding electrodes, underground gas piping and aluminum. For 2017, another item has been added to the list of prohibited items. For the 2017 NEC Code cycle, the structures as well as steel reinforcement materials that pertain to swimming pools have been added to the list found in 250.52(B)(3) of components that are prohibited from being used as grounding electrodes for an electrical system.