- 1 What is the purpose of Article 430 in the NEC?
- 2 What NEC article would contain requirements on motors?
- 3 What does NEC Article 430 Part IX require?
- 4 In which part of Article 430 would you expect to find requirements for sizing branch circuit conductors?
- 5 Do all motors need overload protection?
- 6 What article in the NEC covers motor overloads?
- 7 What is the most common method used for motor control?
- 8 Is ground-fault protection required for motors?
- 9 What is locked rotor current?
- 10 What size breaker do I need for a 3 phase motor?
- 11 How do you protect an overcurrent motor?
- 12 What size motor requires a disconnect?
- 13 Are motors considered continuous load?
- 14 What size branch circuit conductors are required for a 2 horsepower 230 volt single phase motor?
- 15 Where in the NEC would you find the requirements for most motor controls?
What is the purpose of Article 430 in the NEC?
430 Part IV explains the requirements for branch short circuit and ground fault protection. The idea here is to protect the branch circuit conductors, the motor control apparatus, and the motor against overcurrent due to short circuits.
What NEC article would contain requirements on motors?
Figure 4 – NEC Article 430 Contents Section 430.6 references table values that must be used in motor full load current (FLC) calculations, rather than the motor nameplate data. The motor nameplate contains useful application information and is a required element on the motor.
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.
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.
What article in the NEC covers motor overloads?
This article is based upon the 2017 edition of NEC. Part III of Article 430 covers overload protection for the motor and its circuit. It is important to protect motors, motor control equipment and motor branch circuit conductors from motor overloads and excessive heat.
What is the most common method used for motor control?
By far the most commonly-used AC motor control method is the use adjustable-speed drives. In most commercial and industrial environments these have supplanted virtually every other motor speed control method. An adjustable-speed drive works on the principle of varying the frequency to vary the speed of the motor.
Is ground-fault protection required for motors?
Code Change Summary: Changes in 680.21(C) make it clear that all single-phase, 120-volt through 240-volt branch circuits serving pool motors require ground-fault circuit-interrupter (GFCI) protection for personnel. GFCI requirements are expanding and are expected to keep doing so in the years to come.
What is locked rotor current?
locked-rotor amperage (LRA) The very high current or amperage a motor draws when power is first applied, due to low counter emf. It is usually five to six times the running load amperage.
What size breaker do I need for a 3 phase motor?
The breaker must be sized for 7.6 * 1.25 = 10 Amps. Therefore, it is good practice to size the breaker at 15 Amps.
How do you protect an overcurrent motor?
Overcurrent protection is generally accomplished by separating the overload protection from the short-circuit and ground-fault protection device. If you use fuses, you must provide one for each ungrounded conductor (430.36 and 430.55). Thus, a 3-phase motor requires three fuses.
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.
Are motors considered 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 size branch circuit conductors are required for a 2 horsepower 230 volt single phase motor?
The minimum rating in amperes for conductors supplying a 2 hp, 230-volt, single-phase motor is 15 amperes (see Figure 2).
Where in the NEC would you find the requirements for most motor controls?
NFPA 70’s National Electric Code (NEC) is an enforceable standard by Authorities Having Jurisdiction (AHJ) that defines the specific requirements for motors in Article 430. This section defines the general requirements for motors, conductor sizes, ampacities, protection requirements, and several other considerations.