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Wire temp rating

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donvol

Electrical
Dec 10, 2004
1
The NEC table 310-16 shows minimum wire sizes required for distribution feeders based on amperes, wire insulation temp rating and ambient temp. etc.
What wire temperature rating is required for feeding 3-phase elevator drive equipment, via conduit? Can it be 75C rated wire? Are there any more restrictive local codes that require using 60C rated wire? (Chicago?, LA?)
60C wire is obviously larger, requiring more $$ and larger connection terminals for the same (hundreds of) amp rating.

 
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In general, the limitation is the temperature ratings of the terminals or lugs on each end of the cable. At 125A and above, UL requires new equipment to have 75 deg C terminals, so you can safely use 75 deg rated wire.

Below 125A most new breakers, switches, etc are rated for 75 deg terminations, but it is not required. So for smaller wire sizes you are safer to size based on 60 deg C ampacity.

Of course, the actual insulation used can have temp rating exceeding the minimum required as long as you don't apply it above the ampacity for the appropriate temp rating.

There may be some special requirements for life safety wiring that I have forgotten, so don't quote me.
 
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