How many micro wave ovens will a 20 amp circuit support?
Please stick with me to the end ... some examples are for example only. There is no 1000 watt circuit per'ci.
This will not be possible overload, this is an accident waiting to jump on you, my friend
Install dedicated circuits for these ovens, my friend. It will cost you a little but will be better than having dissatisfied guests or talking to the zoning board or boarding house authority or (gasp) the fire inspector after the fire.
If you don't do this, when the breakers start flipping off, tenants will run extension cords to outlets that have power. A whole different and worse, problem!
Rule of thumb, lighting circuits should be designed to operate at 80%, for example, if you have 800 watts of lights on a 1000 watt circuit, you are at the max.
So, there is a possibility that your circuit for lights is already near max. Adding ovens is trouble. Don't forget the iPOds and cell phone chargers as well as lap top chargers, walkman chargers (older students), little TV's, DVD players, clock radio's, electric shavers, curling irons, steamers, popcorn makers, lava lamps and occasional electric heaters that will be snuck into the room.
What is a 1000 watt circuit ... good question. Ohms law comes into play here.
Volts X Amps = Watts
120 volts X 8.333 amps = 500 watts (a smoothie blender) 300 watts (slow cooker) 200 watts (hand mixer) = 1000 watts.
A 15 amp circuit will protect #14 wire and can carry about 1800 watts (a toaster (1500 watts), for example).
A 20 amp circuit will protect #12 wire and can carry about 2400 watts (i am using a big paint brush here. these numbers are pretty close but not exact and I am not a licensed electrician.)
When I wire, I aim lots lower, preferring to OVER build than to under build.
10 amp circuits are rare in modern homes. In general practice, if the need was to be protected at 10 amps, the wire used in the circuit would be #14 and it would be protected by the breaker at 10 amps. In this case, it is the device plugged into this 10 amp circuit that needs protection rather than the #14 wire (which would be technically oversized)
Another consideration for you is where is the water? If you have an outlet that is 5 feet from a water source (bath - kitchen - etc) it must be protected by a GFIC
A 30 amp circut will protect #10 wire --- but this is not a normal household circuit.
Maybe the best option is for you to have your electrician install a sub panel in the vicinity of use and run several 20 amp circuits from that location to the various rooms.
The answer to your question "How many (1150 watt)micro wave ovens will a 20 (amp circuit handle)" is TWO with nothing else on the line. The National Code requires dedicated circuits for micro wave ovens, BTW. A commercial application may have a different (more stringent) standard in your town.
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This is an unacceptable method of powering the warming plate. We can not have all the lights in our house flickering -- as though an arc welder was being turned on and off every 1/10 second. Need solution to elliminate the problem.
New GE coffee maker #169209 (1300 watt) 12 cup digital. All house lights flicker when in hot plate warming mode. Tried on both 15 amp GFI circuit and dedicated 30 amp #10 wired circuit.
Oscilloscope (measuring voltage across series shunt) reveals a super high INSTANTANEOUS current draw massively exceeding the breaker rating for only 1 to 3 60 Hz cycles (depending on hot plate setting of 1, 2,or 3) before going completely off for another number of cycles. This high draw/off cycle continues for a minute (warming) and then ceases entirely for several additional minutes (rest) before the whole high draw/off cycling repeats.
Called GE and they said it was defective, got another and it does the same thing.
Why does GE want to operate the warm cycle in this fashion? Perhaps to prevent the hot plate from burning up when there is either no coffee in the pot or the pot is removed? Is this normal? It is interesting to note that the AVERAGE POWER during these short/off cycles is either 200, 400, 600 watts as the book says.
New GE coffee maker #169209 (1300 watt) 12 cup digital. All house lights flicker when in hot plate warming mode. Tried on both 15 amp GFI circuit and dedicated 30 amp #10 wired circuit.
Oscilloscope (measuring voltage across series shunt) reveals a super high INSTANTANEOUS current draw massively exceeding the breaker rating for only 1 to 3 60 Hz cycles (depending on hot plate setting of 1, 2,or 3) before going completely off for another number of cycles. This high draw/off cycle continues for a minute (warming) and then ceases entirely for several additional minutes (rest) before the whole high draw/off cycling repeats.
Called GE and they said it was defective, got another and it does the same thing.
Why does GE want to operate the warm cycle in this fashion? Perhaps to prevent the hot plate from burning up when there is either no coffee in the pot or the pot is removed? Is this normal? It is interesting to note that the AVERAGE POWER during these short/off cycles is either 200, 400, 600 watts as the book says.
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