NEMA Electric Motor Frame Chart

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NEMA frame guide

 The National Electrical Manufacturers Association (NEMA) has established
industry-standard,  base-mounted motor dimensions, which we have listed below.
What this means, is that all motors manufactured under NEMA specifications,
will have the same dimensions, regardless of who manufactured the motor.
So, if a motor is a 143T frame, then all motors with a 143T frame will have the
dimensions.  NOTE:  any frame designation followed by either a "Z" or "Y" or
"YZ" means that the motor has been changed and no longer follows these rules.
The shaft may be different, ie, longer,  shorter, diameter, threaded, ect. And as a
result is no longer a "standard" motor.



                         All Dimensions in inches                          

NEMA
FRAME

D*

2E

2F

BA

H
(dia.)

N Min. U
shaft

V
Min.&

Key
Width

Key
Thick.

Key
Length

42 2 5/8 3 1/2 1 11/16 2 1/16 9/32 slot 1 1/8 3/8  _ _ 3/64 flat    _
48  3 4 1/4 2 3/4 2 1/2 11/32 slot 1 1/2 1/2  _ _ 3/64 flat _
48H  3 4 1/4 4 3/4 2 1/2 11/32 slot 1 1/2 1/2 _ _ 3/64 flat _
56 3 1/2 4 7/8 3 2 3/4 11/32 slot 1 7/8
@
5/8 @ _ 3/16 @ 3/16 @ 1 3/8 @
56H 3 1/2 4 7/8 3&5@@ 2 3/4 11/32 slot 1 7/8
@
5/8 @ _ 3/16 @ 3/16 @ 1 3/8 @
56HZ 3 1/2 ** ** ** ** 2 1/4 7/8 2 3/16 @ 3/16 @ 1 3/8 @
66 4 1/8 5 7/8 5 3 1/8 13/32 slot 2 1/4 3/4 _ 3/16 3/16 1 7/8
143T 3 1/2 5 1/2 4 2 1/4 11/32 2 1/4 7/8 2 3/16 3/16 1 3/8
145T 3 1/2 5 1/2 5 2 1/4 11/32 2 1/4 7/8 2 3/16 3/16 1 3/8
146AT 3 1/2 5 1/2 5 1/2 2 3/4 11/32 2 1/4 7/8 2 3/16 3/16 1 3/8
148AT 3 1/2 5 1/2 7 2 3/4 11/32 2 1/4 7/8 2 3/16 3/16 1 3/8
149AT 3 1/2 5 1/2 8 2 3/4 11/32 2 1/4 7/8 2 3/16 3/16 1 3/8
1412AT 3 1/2 5 1/2 11 2 3/4 11/32 2 1/4 7/8 2 3/16 3/16 1 3/8
182 4 1/2 7 1/2 4 1/2 2 3/4 13/32 2 1/4 7/8 2 3/16 3/16 1 3/8
184 4 1/2 7 1/2 5 1/2 2 3/4 13/32 2 1/4 7/8 2 3/16 3/16 1 3/8
182T 4 1/2 7 1/2 4 1/2 2 3/4 13/32 2 3/4 1 1/8 2 1/2 1/4 1/4 1 3/4
184T 4 1/2 7 1/2 5 1/2 2 3/4 13/32 2 3/4 1 1/8 2 1/2 1/4 1/4 1 3/4
182AT 4 1/2 7 1/2 4 1/2 2 3/4 13/32 2 1/4 1 1/8 2 1/4 1/4 1 3/8
L182ACY 4 1/2 7 1/2 4 1/2 2 3/4 13/32 2 1/4 7/8 2 3/16 3/16 1 3/8
182AT 4 1/2 7 1/2 4 1/2 2 3/4 13/32 2 1/4 1 1/8 2 1/4 1/4 1 3/8
186ACY 4 1/2 7 1/2 7 2 3/4 13/32 2 1/4 7/8 2 3/16 3/16 1 3/8
186AT 4 1/2 7 1/2 7 2 3/4 13/32 2 1/4 1 1/8 2 1/4 1/4 1 3/8
L186AT 4 1/2 7 1/2 7 2 3/4 13/32 2 1/4 1 1/8 2 1/4 1/4 1 3/8

NEMA
FRAME

D*

2E

2F

BA

H
(dia.)

N Min.

U

V
Min.&

Key
Width

Key
Thick.

Key
Length

189AT 4 1/2 7 1/2 10 2 3/4 13/32 2 1/4 1 1/8 2 1/4 1/4 1 3/8
203# 5 8 5 1/2 3 1/8 13/32 2 1/4 3/4 2 3/16 3/16 1 3/8
204# 5 8 6 1/2 3 1/8 13/32 2 1/4 3/4 2 3/16 3/16 1 3/8
213 5 1/4 8 1/2 5 1/2 3 1/2 13/32 3 1 1/8 2 3/4 1/4 1/4 2
215 5 1/4 8 1/2 7 3 1/2 13/32 3 1 1/8 2 3/4 1/4 1/4 2
213T 5 1/4 8 1/2 5 1/2 3 1/2 13/32 3 1 3/8 3 1/8 5/16 5/16 2 3/8
215T 5 1/4 8 1/2 7 3 1/2 13/32 3 3/8 1 3/8 3 1/8 5/16 5/16 2 3/8
219AT 5 1/4 8 1/2 11 3 1/2 13/32 2 3/4 1 3/8 2 1/2 5/16 5/16 1 3/4
2110AT 5 1/4 8 1/2 12 1/2 3 1/2 13/32 2 3/4 1 3/8 2 1/2 5/16 5/16 1 3/4
224 # 5 1/2 9 6 3/4 3 1/2 13/32 3 1 2 3/4 1/4 1/4 2
225 # 5 1/2 9 7 1/2 3 1/2 13/32 3 1 2 3/4 1/4 1/4 2
254# 6 1/4 10 8 1/4 4 1/4 21/32 3 3/8 1 1/8 3 1/8 1/4 1/4 2 3/8
254U 6 1/4 10 8 1/4 4 1/4 17/32 3 3/4 1 3/8 3 1/2 5/16 5/16 2 3/4
256U 6 1/4 10 10 4 1/4 17/32 3 3/4 1 3/8 3 1/2 5/16 5/16 2 3/4
254T 6 1/4 10 8 1/4 4 1/4 17/32 4 1 5/8 3 3/4 3/8 3/8 2 7/8
256T 6 1/4 10 10 4 1/4 17/32 4 1 5/8 3 3/4 3/8 3/8 2 7/8
284 # 7 11 9 1/2 4 3/4 21/32 3 3/4 1 1/4 3 1/2 1/4 1/4 2 3/4
284U 7 11 9 1/2 4 3/4 17/32 4 7/8 1 5/8 4 5/8 3/8 3/8 3 3/4
286U 7 11 11 4 3/4 17/32 4 7/8 1 5/8 4 5/8 3/8 3/8 3 3/4
284T 7 11 9 1/2 4 3/4 17/32 4 5/8 1 7/8 4 3/8 1/2 1/2 3 1/4
286T 7 11 11 4 3/4 17/32 4 5/8 1 7/8 4 3/8 1/2 1/2 3 1/4
284TS 7 11 9 1/2 4 3/4 17/32 3 1/4 1 5/8 3 3/8 3/8 1 7/8
286TS 7 11 11 4 3/4 17/32 3 1/4 1 5/8 3 3/8 3/8 1 7/8
324 # 8 12 1/2 10 1/2 5 1/4 21/32 4 7/8 1 5/8 4 5/8 3/8 3/8 3 3/4
326 # 8 12 1/2 10 1/2 5 1/4 21/32 4 7/8 1 5/8 4 5/8 3/8 3/8 3 3/4
324U 8 12 1/2 10 1/2 5 1/4 21/32 5 5/8 1 7/8 5 3/8 1/2 1/2 4 1/4
326U 8 12 1/2 12 5 1/4 21/32 5 5/8 1 7/8 5 3/8 1/2 1/2 4 1/4
324T 8 12 1/2 10 1/2 5 1/4 21/32 5 1/4 2 1/8 5 1/2 1/2 3 7/8
326T 8 12 1/2 12 5 1/4 21/32 5 1/4 2 1/8 5 1/2 1/2 3 7/8
324TS 8 12 1/2 10 1/2 5 1/4 21/32 3 3/4$ 1 7/8$ 3 1/2$ 1/2 1/2 2 $
326TS 8 12 1/2 12 5 1/4 21/32 3 3/4$ 1 7/8$ 3 1/2$ 1/2 1/2 2 $
364 # 9 14 11 1/4 5 7/8 21/32 5 5/8 1 7/8 5 3/8 1/2 1/2 4 1/4
364S # 9 14 11 1/4 5 7/8 21/32 3 1/4 1 5/8 3 3/8 3/8 1 7/8
365 # 9 14 12 1/4 5 7/8 21/32 5 5/8 1 7/8 5 3/8 1/2 1/2 4 1/4
364U 9 14 11 1/4 5 7/8 21/32 6 3/8 2 1/8 6 1/8 1/2 1/2 5
365U 9 14 12 1/4 5 7/8 21/32 6 3/8 2 1/8 6 1/8 1/2 1/2 5
364T 9 14 11 1/4 5 7/8 21/32 5 7/8 2 3/8 5 7/8 5/8 5/8 4 1/4
365T 9 14 12 1/4 5 7/8 21/32 5 7/8 2 3/8 5 7/8 5/8 5/8 4 1/4
364TS 9 14 11 1/4 5 7/8 21/32 3 3/4$ 1 7/8 3 1/2$ 1/2 1/2 2 $
365TS 9 14 12 1/4 5 5/8 21/32 3 3/4$ 1 7/8 3 1/2$ 1/2 1/2 2 $
404T 10 16 12 1/4 6 5/8 13/16 7 1/4 2 7/8 7 3/4 3/4 5 5/8
405T 10 16 13 3/4 6 5/8 13/16 7 1/4 2 7/8 7 3/4 3/4 5 5/8
404TS 10 16 12 1/4 6 5/8 13/16 4 1/4$ 2 1/8$ 4 $ 1/2 1/2 2 3/4$
405TS 10 16 13 3/4 6 5/8 13/16 4 1/4$ 2 1/8$ 4 $ 1/2 1/2 2 3/4$
404U 10 16 12 1/4 6 5/8 13/16 7 1/8 2 3/8 6 7/8 5/8 5/8 5 1/2
405U 10 16 13 3/4 6 5/8 13/16 7 1/8 2 3/8 6 7/8 5/8 5/8 5 1/2
444T 11 18 14 1/2 7 1/2 13/16 8 1/2 3 3/8 8 1/4 7/8 7/8 6 7/8
445T,
447T &&
11 18 16 1/2 7 1/2 13/16 8 1/2 3 3/8 8 1/4 7/8 7/8 6 7/8
444TS,
447TS&&
11 18 14 1/2 7 1/2 13/16 4 3/4$ 2 3/8$ 4 1/2$ 5/8 5/8 3 $
445TS 11 18 16 1/2 7 1/2 13/16 4 3/4$ 2 3/8$ 4 1/2$ 5/8 5/8 3 $
444U 11 18 14 1/2 7 1/2 13/16 8 5/8 2 7/8 8 3/8 3/4 3/4 7
445U 11 18 16 1/2 7 1/2 13/16 8 5/8 2 7/8 8 3/8 3/4 3/4 7
449T 11 18 25 7 1/2 13/16 8 1/2 3 3/8 8 1/4 7/8 7/8 6 7/8
449TS 11 18 25 7 1/2 13/16 4 3/4$ 2 3/8$ 4 1/2$ 5/8 5/8 3 $
        
* Dimension D Will never be greater than the above values on rigid mount motors, but it may be less so that shims up to 1/32" thick (1/16" on 364U and 365U frames) may be required for certain machines.
@@Motors designated 56H have two sets of 2F mounting holes--3" and 5".
$ Standard short shaft for direct drive applications.
# Discontinued "pre-NEMA" frame.
**Base of 56HZ frame motors has holes and slots to match NEMA 56,56H,143T & 145T mounting dimensions.
& Dimension "V" is shaft length available for coupling, pinion or pulley hub--this is a minimum value.