ID Your Motor

Unfortunately Mandatory Disclaimer…

Please use common sense when installing and uninstalling electric motors. Turn off the electricity before touching any tools. Use a volt meter or detector immediately after cutting power to verify that there is no current. Electricity can, and will kill you if not properly handled. In addition, belts and pulleys can cause serious harm to loose clothing, long hair, and hands. If you are at all unsure of what you are doing, call a professional. If you can’t read the wiring diagram, call a professional. If you’re saying “Whatever, this guy is just covering his butt. I can figure this out. Nothing bad is going to happen to me.”, call a professional. The bottom line is, you’ve probably already saved some money by sourcing the motor yourself, so please don’t try to save $100 on an electrician or HVAC tech. If you connect the leads incorrectly, you will destroy the motor at the very least. You’ll be starting over, minus whatever you spent on the motor, and you’ll have a smelly, expensive paperweight. If you have any questions about a motor you think will work before you buy it, contact us and we’ll tell you how big of a project you’re getting into.


Before going into IDing your motor, just a quick(ish) note on frame sizes. Most motors in the US are built to NEMA specifications. NEMA is a government organization that standardizes and regulates many specs for electrical equipment, and electric motor frame size is one of those specs. Frame size gives you information about shaft size, and mounting dimensions, and because they are standardized, matching up the frame is a good place to start when looking for a replacement motor. It is important to match up the frame and frame suffix. For example, a 145T frame motor has a 145 frame, and a T frame suffix. All 145T frame motors will have the same shaft dimensions and location, as well as the same mounting dimensions. The motor may be longer or shorter, but the motor will mount the same. The only time this isn’t true is if the frame suffix is a Y or Z. These two frame suffix just denote special mounting and shaft dimensions respectively, but don’t specify what is special. If you have a 48Y frame motor, a different motor with a 48Y frame might not be the same. Always look at the dimensional drawings, if they are available, to ensure a match. With that said…

There are a few ways to find the right motor. The methods listed below are from most reliable to least reliable in identifying the correct motor…

  1. By catalog or model number.
  2. By “crossing” from an OEM number.
  3. By the motors specs.




Many motors in use today are not made for a specific manufacturer and are not proprietary, so any motor manufacturer can make these motors and sell them to fit in a wide range of applications. These motors are called “stock” motors. You can usually identify these motors by catalog number (sometimes called a stock number). There is usually, at least one identifying number on a nameplate, but there could be many, so it can get a little confusing. On the example to the right, there are 2 numbers that are relevant: The catalog number (highlighted in green), and the model number (highlighted in yellow). Either of these numbers identify the same motor. You can enter either into the search bar above, and this motor will come up. Any motors that we carry will have both numbers as searchable terms, so you will go directly to the correct motor. If you enter a number that does not return any results, you will have to try to ID the motor through one of the methods below.




For as many motors that can be replaced by a stock motor, there are just as many or more that are OEM (Original Equipment Manufacturer) motors. These motors are special in some way that makes them “non-stock”. The difference could be something major like an extended shaft, or something as minor as paint color. Either way, many manufacturers make replacement motors for the most commonly used equipment. In this example, the number highlighted in green is the OEM part number. Many times this will be labeled as CPN (customer part number), p/n, or it might not have any identifier.

These replacement motors are usually drop in replacements however, in some instances they may require modifications. These can include cutting shaft the shaft or thru-bolts, or only connecting certain speeds. This is because manufacturers will make one motor to replace many motors in the field to keep stocking easier. Modifying a motor in a way suggested by the manufacturer does not void the warranty for the motor, but it does make it non-returnable to ASAP Electric Motors, so please contact us before modifying any motor you buy from us. You can try typing this number into our search engine above to see if we have a direct replacement. If nothing comes up, you will have to try to cross the motor based on specs alone. Sometimes there is nothing we can do to cross a motor because it is too specialized. If this is the case, we will gladly try to get you the contact information for the OEM.




Many motors can be identified by their specs. While identifying a motor this way is the least reliable method of picking a motor, you can still find a motor to fit your needs in most situations. You will need the following information to begin searching for your replacement motor.

  • Horsepower (HP)
  • RPM
  • Voltage (V)
  • Phase (Ph)
  • Frame (Fr)
  • Enclosure (Encl.)

In addition to these specs, you will also need to know some physical characteristics of the motor. These include, but are not limited to…

  • Mounting– How is the motor mounted? With studs coming out of one end of the motor? With a Belly band around the barrel of the motor? Or maybe a welded foot, or cradle base? Also note that if there is a Y at the end of the frame, it means that there is a non-standard mount. Please confirm before ordering.
  • Physical Dimensions– Most of this info will be provided by the frame size, but if your motor is in a space with little room around it, physical dimensions (not mounting related) may be an issue. Motors with the same frame will have the same mounting an shaft dimensions, unless there is a Y and/or Z in the frame suffix. If one is available, we put dimensional drawings for each motor on the motor’s product page.
  • Shaft Dimensions- This is addressed in the frame size again, but if there is a Z at the end of the frame, it means that there is non-standard shaft and should be confirmed before ordering.
  • Rotation- This one is a little tricky. First of all, any rotational information on this website is based on looking at the motor from the shaft end, unless otherwise specified. With that being said, there is no industry standard as to how a motor is labeled as far as rotation is concerned. Many motors today are reversible, but if yours is not, getting the rotation wrong is just as bad as not having a motor at all. A motor could just be labeled as CW (for Clockwise), but that only tells you half of the information. You also need to know which end of the motor you are determining the rotation from (either the shaft end(SE), or lead end(LE)). You might see a rotation labeled as CCWLE, meaning counter-clockwise, lead end. So, you need a motor that rotates counter-clockwise when you are looking at the motor from the lead end. Furthermore, CCWLE is the same rotation as CWSE. Finally, some motors just have an arrow printed somewhere on the nameplate showing rotation.

If All Else Fails…

We have access to many knowledge bases from our manufacturers, with a lot of information that would take forever to add to a website, along with extensive experience replacing all types of motors for our customers in the NY metro area. If you cannot find your motor, or if you just have questions, please fill out our contact form, and drop us a line HERE.