On 03/19/2014 02:05 PM, William Herrin wrote:
50 watts DC. It won't electrocute you (that's AC) but it's the same
power that makes a 40 watt bulb burning hot.
802.3af is limited to 15.4W, and 802.3at to 25.5W. The limits for Class
2 and 3 circuits are found in Chapter 9, Table 11 (A and B), of the NEC
(Table 11(B) for DC circuits, and for a power source of 30 to 60 volts a
Class 2 circuit can have, for a 44VDC supply power, up to 3.4A available
(a max nameplate rating of 100VA). For AC, Table 11(A) tells me that a
120VAC circuit, to meet Class 2, must be current-limited to 5mA.
BICSI has a good set of slides on the NEC at
http://www.bicsi.org/uploadedfiles/Conference_Websites/Winter_Conference/2012/presentations/Interpreting%20the%20National%20Electrical%20Code.pdf
