Electric Motors - Explaining Lead-End & Shaft-End In Layman's Terms

You see it all the time when looking at the various rotations of motors – one might be listed as clockwise lead end and another might be listed as clockwise shaft end. Which perspective is lead end and which is shaft end? We’re going to answer this question for you today.

What are electric motor leads and what is lead end? 

First, let’s start by getting the 10,000 lbs. gorilla out of the room. What is a lead? The leads on an electric motor are the attached wires or cables that come off the motor and connect to the power supply to energize the motor. Simply put, they’re the motor’s wires.

Knowing that the motor’s wires are called leads, it’s fair to assume that the lead end of a motor is the end of the motor in which the wires come off of it. The leads are almost always on the end opposite to the shaft in order to avoid cluttering the leads with whatever the motor is driving. Therefore, lead end is also called opposite shaft end. The one exception to this rule is double shafted motors. The leads need to come out of one end or the other and both ends have a shaft coming out, so there’s not much you can do.

To determine rotation from lead end perspective, you need to look at the end of the motor with the wires coming off of it and the shaft pointing away from you. To determine rotation from shaft end perspective, you need to look at the end of the motor with the shaft pointing directly at you.

Here's the lead end perspective:	Here's the shaft end perspective:

With lead end being opposite shaft end and shaft end being opposite lead end, the following are all true: Clockwise lead end is counter clockwise shaft end, clockwise opposite shaft end, and counter clockwise opposite shaft end. Clockwise shaft end is counter clockwise lead end, clockwise opposite lead end, and counter clockwise opposite shaft end.

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Do manufacturers use Lead End or Shaft End? 

It should be noted that most electric motor catalogs give the rotation from a shaft end perspective unless stated otherwise.

What does Lead End and Shaft End have to do with rotation? 

Now that you understand what Lead End and Shaft End mean, you are better equipped to understand motor terminology when it comes to rotation. Motor manufacturers utilize terms such as Clockwise Lead End, Clockwise Shaft End, Counter Clockwise Lead End, and Counter Clockwise Shaft End in their catalogs. To learn more about these terms and how they impact your motor replacement, check out our guide here:  Motor Rotations Explained

Does Lead End and Shaft End impact how I choose a replacement fan blade or blower wheel? 

Lead end and shaft end terminology is commonly used in regards to motor, fan blade, and blower wheel replacement. It is critical that you choose the correct rotation of your fan blade or blower wheel when making replacements in your HVAC system. Choosing the incorrect rotation will impact the airflow of your system and can lead to premature failure of your motors.

To learn more about condenser fan blade replacement, check out our guide here: How to select the correct condenser fan blade.

To understand how manufacturers label a blower wheel's rotation, check out our guide here: How to select the correct rotation for your single inlet blower wheel

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