Hey, I need some clarification help on a Low Voltage issue. This is the background of what I am doing. I am making a residential stair lighting system for my home. I have a class II power supply which feeds a PCB within an enclosure. Coming out of the enclosure I am feeding each step with a separate cable for the lights on each step; which are LED strips. Each cable will have 4 wires. Specifications for Maximum rating of system: (Using RGB “colored” LED strips; it will be using 4 wires per step) One wire “power lead” going to the each step will be supplying +12V DC (Max 900mA or (1.08A with 20% added) The other three wires will be the Neutral side from the step to the enclosure, each wire using Max. 300mA or (360mA with 20% added). NOTE: The LED strips are made of LED’s which have three internal LED’s making the RGB colors. Each return wire "Neutral", are independent using Max 300mA. The max distance one way would be less than 30 feet. The max number of steps or cables are 21 steps or 21 cables. I am using conduit from the enclosure to the bottom step, then hanging the cables open air (in an enclosed stairway, not Plenum) with one hanger at every step. My question after all that is this: In the NEC2011 book, it does not specify any Ampacity for anything lower than 18 AWG that I could find. Also in other charts on the internet, I have found for smaller AWG; but they do not specify any voltage, only Ampacity. Is the Ampacity the deciding rule for what AWG to use or is the actual Wattage should be considered. Since the NEC book charts (600 Volts & lower) is based on 115V (at least it's my understand that it is); wouldn’t the AWG for Low Voltage be based on wattage and not just Ampacity? Second, could one clarify what would be the proper AWG for a four pair cable for the above scenario? While I'm here since I am using 30VDC or less and it's enclosed space, do I really need a raceway under the steps? Thanks for any help one can give me.

Hi Yesterday I plugged an office fan to an inverter with built-in UPS and battery charger, this inverter is plugged to 2 batteries,the fan works but the motor sound is a little higher and after turning it off, the temperature of the motor raise up gradually until it's very very hot, Although it's not hot while working, just after turning off. I tested more than a once. The inverter is NOT pure sine wave. When I plug the fan to the normal electric (government electric) it doesn't be hot after turning off. If I will turn it on via the inverter when power outages, is there any danger ?