Kelly,
UL 1950 has a D1 (more restrictive) deviation in clause 3.2.1:
"Where equipment is intended to be connected to a source of supply by a power
supply cord, the attachment plug shall be rated no less than 125 percent of the
rated current of the equipment."
UL's interpretation of "attachment plug" includes not only the plug that goes
into the wall outlet, but the entire path between the wall outlet and your power
supply, including:
* Wall plug.
* Cordage.
* IEC-320 plug.
* IEC-320 appliance inlet.
John Barnes Advisory Engineer
Lexmark International
---------------------- Forwarded by John Barnes/Lex/Lexmark on 03/10/2000 10:50
AM ---------------------------
wolfgang_josenhans%[email protected] on 03/10/2000 10:09:58 AM
Please respond to wolfgang_josenhans%[email protected]
To: ktsudama%[email protected]
cc: emc-pstc%[email protected] (bcc: John
Barnes/Lex/Lexmark)
Subject: Re: Correction factor for power supply cords.
Kelly,
You derate the cord with respect to the ampacity allowed by the receptacle it
connects to. Art. 210-23 of the NEC indicates that cord connected equipment can
draw no more than 80 % of the maximum receptacle rating.
Regards,
Wolf Josenhans
Kelly Tsudama <[email protected]> on 03/09/2000 09:33:14 PM
Please respond to Kelly Tsudama <[email protected]>
Sent by: Kelly Tsudama <[email protected]>
To: [email protected]
cc: (Wolfgang Josenhans/MW/US/3Com)
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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