Morning Kelly
The NEC addresses the current de-rating of conductors, be they in a power
cord or not, article 310 should be of help to you. This derating is do to
the current handling capacity and heating of the metal conductors at various
temperatures. The temperature marking you refer to on the jacket is for the
insulation system and is separate from the conductor.
I believe you will have to derate it as you would with any other conductor.
Maybe you can do me a quick check. I am trying to trace down the actual
document that describes the actual operating environment as 50C. GR-1089
indirectly refers to it in some of the temperature test requirements but
that doesn't seem to be the root document. I am thinking the NWT-000063 may
be it, but I don't have a title on that or a copy yet. (I got there from
another indirect reference)
Thanks
Gary
-----Original Message-----
From: Kelly Tsudama [mailto:[email protected]]
Sent: Thursday, March 09, 2000 7:33 PM
To: [email protected]
Subject: Correction factor for power supply cords.
Hi Group
I am hoping that I can get your opinions with an issue
regarding the correction factor of power supply cords. For instance, in the
NEC table 310-17, for single conductors in free air, there is a chart at the
bottom of the table that allows you to determine how to factor in the
ambient temperature. However, for a flexible power cord, the table 400-5
does not have any correction factor table.
At first I thought that this is because cords always have a
temperature rating marked on them, but then I recall that most (if not all)
single conductors have this marking too.... Is there a need to "de-rate" a
power cord's current rating based on the expected ambient temperature? If
so, where in the NEC did I miss this fact? If not, why not?
Thanks for your help,
Kelly
****************************************************************
Kelly Tsudama
Cisco Systems
[email protected] <mailto:[email protected]>
408-527-0216
408-525-9150 fax
408-322-9024 pager
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