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Posted by Doug Miller on December 11, 2006, 10:42 pm
Klipstein) wrote:
> Klipstein) wrote:
>>>>
>>>>> I'm just curious how the code views that?
>>>>
>>>>As a violation.
>>>>
>>>>>For example, if I but a common house type ceiling
>>>>>fixture, they generally have 8 inches or up to several feet (on a
>>>>>chandlier) of #14 standed wire as part of the fixture. So, if I am
>>>>>running a 20A circuit I am already using #14 in the circuit.
>>>>
>>>>Fixture wires generally have a much higher temperature rating than supply
>>>>wires, which enables them to carry higher current on smaller wires.
>>>
>>> Since resistance increases with temperature, actual ampacity does not
>>>increase much with an increase in temperature rating.
>>
>>The temperature rating of a conductor depends on its *insulation*, not the
>>conductor itself. Ampacity *does* increase substantially with an increase in
>>temperature rating, due to the ability of the insulation to withstand a higher
>
>>conductor temperature.
>>
>>Example: for copper wire, #8 TW has an ampacity of 40 amps; #8 THHN has an
>>ampacity of 55 amps.
>>
>>Another example: #18 copper wire is permitted to carry 14 amps, IF it has 90
>>deg C insulation (e.g. THHN or THHW).
>>
>>>And ampacity
>>>according to the code does not increase at all.
>>
>>This simply is not true. See NEC Table 310.16 for abundant proof that the Code
>>absolutely does recognize increased ampacity for increased temperature
>>ratings.
>
> This sounds to me specific to appliance cords, as opposed to romex.
Nope, wrong again. It applies to *all* premises wiring covered by the NEC.
There's a lot more than just "romex" involved.
Like I said... See NEC Table 310.16
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
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