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Energy Independence and Security Act of 2007 (EISA)

Phihong Power Supplies that are Compliant


Class A External Power Supply – A devices that is (I) designed to convert line voltage AC input into a lower voltage AC or DC output; (II) is able to convert to only 1 AC or DC voltage at a time; (III) is sold with, or intended to be used with a separate end-use product that constitutes the primary load; (IV) is contained in a separate physical enclosure from the end-use product; (V) is connected to the end-use product via a removable or hard-wired male/female electrical connection, cable, cord, or other wiring; and (VI) has nameplate output power that is less than or equal to 250 watts.


A class A external power supply manufactured on or after the later of July 1, 2008, or that date of enactment of this paragraph, shall meet the following standards:

Standards for Class A External Power Supplies
Effective July 1, 2008

Nameplate Output

Minimum Efficiency in Active Mode

<1 Watt

 0.5 * Nameplate Output

Greater than or = to 1 and Less than or = to 51 Watts

 0.09 * Ln(Nameplate Output) + 0.5

> 51 Watts



Maximum Energy Consumption in No-Load Mode

Any output

0.5 Watts

Where Ln (Nameplate Output) = Natural Logarithm of the nameplate output expressed in Watts.

Marking Requirements

The nameplate of class A external power supplies shall be clearly and permanently marked (e.g ., imprint, label, etc.) with the appropriate Roman numeral (I – VI) that corresponds to specific minimum Active and No-Load efficiency levels. The appropriate Roman numeral shall be determined by: 1) comparing the unit’s Active and No-Load test data with the performance requirements at each level of the Roman numeral scale; and 2) choosing the highest Roman numeral where the power supply meets the Active and No-Load requirements.

The mark shall comply with the following:

      a. Format. Roman numeral: IV
      b. Font. Preferred Times Roman (or other plain serif fonts)
      c. Size. Legible and indelible
      d. Color. Text to contrast with the nameplate background

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