Microwave

[Zeke]

I've seen several microwave/convection combos. The heating elements are causing the trippage. New high end micro/convection can use both processes at once cooking the food from the inside while also cooking from the outside.

These things might be the wave of the future. They ain't cheap.

[Charles (in GA)]

Micro/convection combos used to be common. I have a real nice, about 25 year old Quasar combination unit. I really liked it. Great for baking a small batch of biscuits or a small pizza, or broiling a steak. It worked great till part of the touch pad ceased to function and its too old to get parts for, so a perfectly good microwave is junk. I've noticed a resurgence popularity for the convection/microwave combinations.

Charles

[Highbeam]

Regular non-countertop microwaves take lots of juice. I installed a seperate 20 amp dedicated circuit for my microwave I installed to replace an old vent hood. Fairly certain the instructions required the 20 amp dedicated circuit.

Even if that bugger only uses 15 amps aren't you supposed to oversize the circuit? The microwaves do plug in but they are essentially hardwired.

[Speedy Petey]

Originally Posted by nehog

Nope, directly from a sampling of microwave oven specifications... The rating on a microwave is the magnetron's output power, not the oven's input power.

I guess I can't see how an appliance (ANY appliance) is rated for a certain wattage, yet draw more current that what is on the rating plate.

[Speedy Petey]

Originally Posted by Highbeam

Even if that bugger only uses 15 amps aren't you supposed to oversize the circuit?

No, you are not "supposed" to oversize anything. Circuits are sized according to the load served and the condition of the appliance. Fixed in place, shared circuits, etc.

Originally Posted by Highbeam

The microwaves do plug in but they are essentially hardwired.

Plug-in is plug-in. Hard wired is hardwired.
Fixed in place or not is a similar thing.
It either is or isn't.

[pop pop]

OP should check the instructions as stated. My unit is also a convection/microwave and is on a 20 amp dedicated circuit as it required. Great appliance too!

[rburke65]

What does the mfg. tag on the back of the unit say? For how many watts is it rated ?

[Fred43]

Sirsloop,
I have fifty years as an electrician and 37 years as an Electrical Contractor - shop owner.
Your reasoning may be correct in that the microwave might not draw enough to overload a 20 amp circuit. There are three other factors to consider beside common sense. It is in the NEC that any outlet added to a Kitchen, Dining area or Dining room be wired to 20 amp capacity. Secondly if you are doing this work without an inspection it is best to play it safer than just meeting code so that there is less chance of problems. Thirdly, if there was a problem resulting in an insurance case, at least they cannot blame this work if installed correctly. Liability is a big thing with Wire inspectors, insurance adjusters and fire marshals. For $5 extra dollars of materials -Please BE SAFE!!!
Fred

[nehog]

Originally Posted by Speedy Petey

I guess I can't see how an appliance (ANY appliance) is rated for a certain wattage, yet draw more current that what is on the rating plate.

So you buy a 35" television... The width of the television itself is not 35 inches. The 700 watt, 1100 watt, etc., rating of a microwave is the output power and the label (should) say that clearly. Or you buy a stereo amplifier with 200 watts output, it will draw much more than 200 watts when you are driving it to full output, as it is not 100% efficient. Same for the microwave...


As to power consumption ratings, there is always a label/plate on the back near the cord that lists exactly how much power it draws from the outlet.

[Speedy Petey]

Originally Posted by nehog

As to power consumption ratings, there is always a label/plate on the back near the cord that lists exactly how much power it draws from the outlet.

THAT'S my point. It CANNOT draw more than the rating plate states. Not unless there is a problem with the unit.

[nehog]

Originally Posted by Speedy Petey

THAT'S my point. It CANNOT draw more than the rating plate states. Not unless there is a problem with the unit.

You leave me (and I think others) confused. No one is saying it is drawing more than the name plate states. What I say is that a nominally rated 1100 watt microwave oven (which is what you will see on that sticker when you buy it...) draws much more than 1100 watts input from the line. There are many inefficiencies in the system (transformer, magnetron, etc.) that waste input power. IOW, the thing is never, ever going to be 100% efficient.

[Speedy Petey]

Originally Posted by nehog

You leave me (and I think others) confused. No one is saying it is drawing more than the name plate states.

Well it seemed to me that is exactly what you were saying here:

Originally Posted by nehog

Just for the record, most microwave ovens (non-convection, just the typical microwave oven) are between 60 and 70% efficient. So a 1100 watt rated microwave would draw about 1800 watts of current from the line, or with a nominal 120 volt circuit, 15 amps (assuming 65% efficiency.)

No worries. I get the impression we both know what we're talking about, but are expressing it differently.

[sirsloop]

might as well put a GFCI receptacle on there... dont want little Jimmy to spray the receptacle down with the dish hose sprayer thing and get zapped ya know while we are in the mood to spend some cash and all! HAHAH

[sberry]

I have seen good micros trip a 15, if its built in I would certainly want a circuit, an extra wire and breaker doesn't mean squat in most cases. When I moved to older home only made a couple wire changes but one was running a piece of 12/3 for 2 new circuits on the counter tops. Most heavy draws I use these circuits, straight from the panel, not hooked in the existing building wiring with who knows how many junctions, etc.

I also do not have an issue with the cheap recepts, have hundreds of them in service, even some with fairly high duty cycle and cant recall the last time I had a problem with one.

[Fudog]

I thank everyone for the input and I will be putting a dedicated circuit in with a 20 amp breaker. Thanks!