Electric Motor NEMA Frame Sizes Table
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The following are dimensional size charts for standard electric motor NEMA standard frames and configuration.

Standardized motor dimensions are established by the National Electrical Manufacturers Association (NEMA) - are tabulated below and apply to all base-mounted motors listed herein that carry a NEMA frame designation

Note: All units are in inches. See bottom of webpage for more information on specifications.

NEMA
Frame

D*
2E
2F
BA
H (dia.)
N Min.
U
V Min.
Key Width
Key Thickness
Key Long
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
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 3/8 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 12 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$
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 7/8 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 NEMA frame.
  • ** Base of 56HZ frame motors has holes and slots to match NEMA 56, 56H, 143T and 145T mounting dimensions.
  • @ Certain NEMA 56Z frame motors have 1/2" x 1 1/2" long shaft with 3/64" flat. These exceptions are noted in the General Catalog.
  • & Dimension "V" is shaft length available for coupling, pinion or pulley hub - this is a minimum value.

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