I'm not sure the NEC would regulate this stuff unless it was part of a new
construction occupancy inspection, even then they may quit looking as soon
as they see a NRTL mark, assuming they already did that part.
But that is somewhat outside the point. UL and the NEC work pretty much
hand-in-hand and when one changes the other changes as well. The NEC has
hired UL on occasion to perform long term tests as part of their process.
Bazillions of years ago I can remember seeing a years long aging test of
aluminum wire for home construction test, that was a partnership between the
two.
So I wouldn't expect there to be many differences in the issues we are
talking about regardless of who is doing the interpretation. But among other
things you need to point out to whomever that you intend it to be in a
higher than average ambient, or it will be investigate as if it were a 30C
ambient, and you will probably get a different answer.
Gary
-----Original Message-----
From: Dick Grobner [mailto:[email protected]]
Sent: Friday, March 10, 2000 10:12 AM
To: '[email protected]'
Cc: '[email protected]'
Subject: FW: Correction factor for power supply
cords.
-I agree with Ed's comment. Were mfg. of medical equipment,
thus within our
"global" standard EN60601-1 Table XV provides a cross
reference between the
conductors cross sectional area (mm sq. for copper)and the
rated current of
the equipment. Also referring to UL 2601 (our US std) in the
"UL Deviations"
too IEC 601-1 it doesn't reference the NEC. I'm not an
electrician (or an
expert on the NEC)but would tend to say that the NEC would
not "regulate"
this area but rather the appropriate product standard would.
Hope this helps
-----Original Message-----
From: [email protected]
[mailto:[email protected]]
Sent: Friday, March 10, 2000 9:12 AM
To: Kelly Tsudama
Cc: [email protected]
Subject: Re: Correction factor for power supply cords.
Kelly:
The NEC is written to keep structures safe. Flexible cords
used in
structures
are normally used in free air.
If you are using a flexible cord in equipment, you need to
rate its ampacity
in
accordance with whatever standard you are using. The NEC
relies on the NRTL
label and testing for the safety of equipment.
If you are using a flexible cord in a high ambient I would
contact the mfg
for
the appropriate derating.
Kelly Tsudama <[email protected]> on 03/09/2000 09:33:14 PM
Please respond to Kelly Tsudama <[email protected]>
To: [email protected]
cc: (bcc: Ed Rauch/MAIN/MC1)
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]
408-527-0216
408-525-9150 fax
408-322-9024 pager
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