Technical Tips

Motor Controllers & Self-protected Combination starters


May 2022

Method of Marking/Tagging the KT_9 Motor Controllers

Are there any snap-in marker cards or adhesive label options to tag the KT_9 products?


May 2022

KT_9 Handle Stops At Or Below Trip Position When Breaker Is Turned Off

Why does my motor controller handle not turn completely to the off position?


November 2018

Using KT_7-25S/25H/45H Controllers on Non-Motor/Resistive Loads

Can a KT_7-25S/25H/45H controller be used a branch circuit protection on non-motor or resistive loads like a heater?

KT7 Auxiliaries

November 2015

KT7 Front Mount Vs. Side Mount Auxiliaries

What is the maximum voltage rating of KT7 front mounted auxiliary contacts verses side mounted auxiliaries. How do these differences effect KT7 assembled devices, such as E-Combo starters?


May 2015

Use of KT7 Motor Controllers with variable frequency drives

A motor branch circuit including a variable frequency drive and one or more KT7 Motor Controllers is a complex system. Successful performance depends on all components, devices and their interconnections. Several key points must be considered when using KT7 devices with VFDs.


KTA3 vs KTA7

May 2015

What is the replacement for KTA3-100 Motor Controllers?

I have a KTA3 in my multi-motor control panel. What is the replacement? What are the alternatives to KTA3 Motor Controllers? KTA3-25 controllers transitioned to KT4 or KT7 controllers. KTA3-100 controllers were replaced with KT7 controllers, but only up to 45 amps.

KF7 Fuse Holders

April 2015

What are KF7 Fuse Holders used for?

KF7 fuse holders can be applied on the line side of KTA7 or KTC7 motor circuit controllers and matching CA7 contactors. KF7 can also be connected on the line side of a CA7 contactor and/or starter as you would a standard fuse holder. This can increase a panels KAIC rating.

KTU7 Busbars

March 2015

KTU7 Molded Case Circuit Breaker Busbar Alternatives

KTU7 busbar can be used on both KTU7 and KT7 motor controllers, but KT7 busbars cannot be used on KTU7 MCCBs. What are some alternatives when assembling multi-motor starter panels?


November 2014

How to specify a disconnect, short-circuit & overload device in one unit

Proper selection of motor controllers for self-protection relies on the motor FLA, and the motor HP. Choosing based solely on motor FLA can cause problems.


June 2014

Short Circuit Current Ratings (SCCR) and Control Circuits

Do the components in a control circuit have a short circuit current rating? UL and NEC rulses define which components in a control panel require a short circuit current rating.


December 2013

Converting KTA3-25 to KT4 Motor Controllers

My panel uses a KTA3-25 motor controller. What is the replacement for this device? KT4 Manual Motor Controllers are a direct replacement for KTA3-25 controllers with only a few exceptions.

KT7 Busbar

November 2013

How to choose the right KT7 busbar power wiring system

There are several different types of bus bar systems available. How do I know which system to choose for my assembly? If I have an old bus bar system, what is the current replacement recommendation? What if I need to add a unit to an existing system?


August 2013

Installing KT7 Handles in an Extra Deep Enclosure

When I mount KT7 in a deep enclosure the shaft seems to droop and miss the handle mechanism. What do I do?

Short Circuit

March 2013

Can components be reused after a short-circuit?

Unlike the fuse box in most residential power centers, industrial circuit protection can rarely be reused after a short-circuit. Some products are specifically tested by UL to withstand a short circuit.


May 2012

The big motor and a little motor rule

A little known rule of UL inspectors outlines what protection should be used in multi-motor starter panel applications.

Circuit Breakers

August 2012

How to specify motor circuit breakers

A variety of products can be used to perform as a circuit breaker for motor and non-motor loads, but some perform better than others.


December 2012

Door Interlock Mechanisms on CX7 KWIKstarters

CX7 KWIKstarters are UL508 approved because they have a removable cover instead of a hinged door. Rules specifically outline the difference between a cover and a door.

KT7 Busbar

September 2012

Using bus bars in multi-motor starter panels

When mounting multiple motor controls in a multi-motor panel, using bus bars is an efficient use of space. Installing the right bus bar for the job can make a big job simple.

Wye vs. Delta

September 2012

Wye power vs. Delta power systems

What is the meaning of a delta connected system versus wye connected power systems when applied to motor controllers and circuit breakers?

Primary Fuses

May 2008

The importance of Primary Fuses in enclosed circuit controllers

Most panels without control transformers are ordered without any “optional” control circuit fuse, which can leave the control circuit wiring unprotected.



March 2012

Methods of Applying KT7 Motor Controllers

Proper design and compliance with UL/CSA and NEC standards for motor controllers and circuit breaker devices.