Help with nameplate markings

Anyone know what the following nameplate markings stand for and where in
the NEC codebook they are discussed:
T1, T2, T3, T4
Any help is appreciated
Reply to
Sports One
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The markings in question are specific lead markings for a utilization device such as a motor, heater, or transformer etc. You wont find specific information in the NEC about them that will provide information meaningful to you.
There are quite a number of very knowledgeable people frequenting this news group. If you would post additional specifics on the device you have, and exactly what information you are looking for it would be much easier to help you.
Louis
Reply to
Louis Bybee
For hazardous location motors these are T codes that give the maximum operating temperature of the motor per Table 500.8(B). The temperature marking specified in 500.8(B) shall not exceed the ignition temperature of the specific gas or vapor to be encountered.
Table 500.8(B) Classification of Maximum Surface Temperature
Maximum Temperature Temperature Class (T Code) C° F° 450 842 T1 300 572 T2 280 536 T2A 260 500 T2B 230 446 T2C 215 419 T2D 200 392 T3 180 356 T3A 165 329 T3B 160 320 T3C 135 275 T4 120 248 T4A 100 212 T5 85 185 T6
Reply to
Gerald Newton
Here is one for you. The Trans Alaska Pipeline has thousands of motors installed at pump stations and at the terminal in what was originally Class 1, div 1 locations. At the time the motors were installed the ignition temperature of crude was thought to be around 750 degrees F. based on assays. Many years later they started injecting gas liquids into the crude before it came down the line. This changed the ignition temperature to a lower value. So how do you solve this problem. Do you change all the motors? Simple: You reclassify the Class 1 Div 1 areas as Class 1 Div 2.
For Class 1, div 1 locations: Totally enclosed motors of the types specified in 501.8(A)(2) or (A)(3) shall have no external surface with an operating temperature in degrees Celsius in excess of 80 percent of the ignition temperature of the gas or vapor involved.
But for Class 1, div 2 locations: In Class I, Division 2 locations, the installation of open or nonexplosionproof enclosed motors, such as squirrel-cage induction motors without brushes, switching mechanisms, or similar arc-producing devices that are not identified for use in a Class I, Division 2 location, shall be permitted.
Reply to
Gerald Newton

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