What is the purpose of Article 430 in the NEC?
Article 430 in the National Electrical Code (NEC) is titled “Motors, Motor Circuits and Controllers.” As the scope of the article states, it covers motors, motor branch-circuit and feeder conductors, motor branch-circuit and feeder protection, motor overload protection, motor control circuits, motor controllers, and …
What does NEC Article 430 Part IX require?
Part IX. You need a disconnect for each motor controller. You must locate it within sight of the controller (see Figure 430-20). “Within sight” means visible and not more than 50 ft from each other [Article 100].
In which part of Article 430 would you expect to find requirements for sizing branch circuit conductors?
While the MCC itself must be installed in accordance with Article 430, Part VIII, the motor branch circuit conductors and motor circuit components must be sized and installed in accordance with provisions located in other parts of Article 430. Requirements for motor branch circuit conductors are in Part II.
What is the information in the NEC motor tables used for?
The table value ensures that no matter what motor is installed, the conductor and branch-circuit, short-circuit, and ground-fault protective devices are sized to safely operate the motor.
What is the main function of overload relay?
Overload relays cut off current to the motor when a high-current situation develops due to a ground fault, short circuit, phase failure, or mechanical jamming. They are an inexpensive way of avoiding downtime for repair or replacement of failed motors from excessive current.
What size motor requires a disconnect?
Code Change Summary: Disconnection requirements have been simplified for permanently connected, motor operated appliances over 1∕8 horsepower (HP). Section 422.30 requires a means to simultaneously disconnect each appliance from all ungrounded conductors in accordance with Part III of Article 422.
Do all motors need overload protection?
EVERY motor needs overload protection of some type. Some small motors are impedance protected by design. Some motors can be overload protected by breakers or fuses. Some motor have internal temp probes that shut down the motor starter.
Is a motor a continuous load?
When sizing a motor branch circuit for a single motor, the motor load is determined using the appropriate table and then multiplying that number by 1.25. A continuous duty motor is treated as a continuous load, a load where the maximum current is expected to continue for three hours or more.
What are the two most common types of overload devices?
There are two major types of overload relays: thermal and magnetic. Thermal overloads operate by connecting a heater in series with the motor.
What are the two major types of thermal overload relays?
What are the two major types of thermal overload relays? Bi-metal strip and solder metaling/pot overloads.
How high can I mount a disconnect?
Generally, disconnect switches have a height limit of not greater than 2.0 m (6 ft 7 in.) above the floor or working platform as indicated in 404.8(A). Exception 2 to 404.8(A) relaxes this requirement and allows greater heights to meet the provisions of 440.14 for these types of equipment.
Can a breaker be used as a disconnect?
For permanently connected appliances rated over _____ the branch-circuit circuit breaker can serve as the disconnecting means where the circuit breaker is within sight from the appliance, or is capable of being locked in the open position with a permanently installed locking provision that remains in place with or …
What is Article 430 in the National Electrical Code?
Article 430 in the National Electrical Code (NEC) is titled “Motors, Motor Circuits and Controllers.”. As the scope of the article states, it covers motors, motor branch-circuit and feeder conductors, motor branch-circuit and feeder protection, motor overload protection, motor control circuits, motor controllers, and motor control centers.
How many parts are there in Article 430?
The section numbers in Part III are 430.31 through 430.44 (see Figure 1). The bottom half of Figure 430.1 only shows eight of the 14 parts in Article 430. This does not mean the parts not shown are not important and do not pertain to motors; all of the parts in Article 430 pertain to motors either directly or indirectly.
What does the provision in 430.22 pertain to?
The provision in 430.22 pertains to a single motor used in a continuous duty application. Many, but not all motors are used in a continuous duty application.
What kind of motor is in section 430.22?
Other motors covered here include: a DC motor operating from a rectified power supply; a multispeed motor; and a wye-start, delta-run connected motor. Section 430.22 also has a subsection for other than continuous duty motors. Section 430.22 (E) pertains to motors used in a short-time, intermittent, periodic and varying duty application.