Kelly,
UL 1950 has a D1 (more restrictive) deviation in clause 3.2.1 than IEC 950:
"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."
We got into a tussle with UL over this about four years ago on one of my power
supplies. After two weeks of discussions with them we wound up accepting their
interpretation of "attachment plug" as including the wall plug itself, the AC
cordage, and any IEC-320 plugs/sockets/appliance inlets between the wall outlet
and the common-mode choke of the power supply. Power Dynamics and other
companies make IEC-320 plugs/sockets/appliance inlets that are rated 15A by UL
and CSA, and 10A by the Europeans. But the specific approvals (wall plug to
cordage, IEC-320 plug/socket to cordage) at that time only went up to 16AWG wire
which is rated for 13A by UL and CSA. We wound up limiting the auxiliary-output
current to 9.8A, for a maximum total input current of 10A to keep UL happy.
John Barnes Advisory Engineer
Lexmark International
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