What does E1 mean on a air-conditioner?

What are the application of chemistry in civil engineering? Why is air gap is necessary in particle magnetic circuits? What are the parts of audio frequency generator? Why are street lights connected in parallel? What is the load for the doorbell circuit? How operating point of transistor shifting? Which starting system component uses a small amount of current to control a large amount of current? What is the application of 3-heat switch control in electrical? Can you use zener diode for rectification purpose? What farad capacitor would you put on a 3 volt DC motor for fastest rpm? What causes a capacitor to blow? What was Thomas Edison's most talked about inventions? Why high CMRR is preferred? What is the frequency of ripple components in the output of capacitor filter? What would happen if electric cords did not have plastic around them? How are electromagnets used in toasters? How do you drop voltage coming into a building just a few volts....It is just a bit too high and the power company says there is not much more they can do..............I am maxing out at 256 volts? Which logic gate have output high if and only if all inputs are low? You have just replaced your ceiling light and when you turned the power back on the light stays on even when you turn off the switch? Minimum number of nand gates required to form full and half adder?