Installation Guide

Motor Control Solutions Structure of a Motor Starter in Accordance with UL 508A

Required Functions of Combination Starters

Combination starters are the most common type of packaged motor controllers.

They are called combination because of their construction and combined functions.

NEC Article 430 defines the required functions of combination starters.

Underwriters Laboratories, Inc.

(UL) specifies the tests and verifications that the

components must pass before they can be listed as suitable for use for those

functions.

See Figure 3 for the four component functions that compose a complete motor

branch circuit as defined by the NEC.

Figure 3 – Required Functions of Combination Starters

Motor Disconnect

Motor Branch

Circuit Protection

Motor Controller

Motor Overload

Protection