Is my 12 amp microwave damaging the wiring to my 15 amp breaker?

Status
Not open for further replies.
M

mazersandmizers

Member
Is my 12 amp microwave damaging the wiring to my 15 amp breaker?

i live in an appartment "cooperative" complex. The complex was built in the 1940's - 50's to supply simple housing to our returning soldiers and thier families.

I have a 15amp breaker and a 2004 model microwave:
120 VAC, 12 amp 60 Hz
Input 1350 Watts, output 900 Watts.

Using the microwave will eventually trip the breaker; maybe every other day, give or take. The panel lists a 20 amp GFCI outlet which will also trip. while this is a bother it has not been unbearable. And why replace the microwave without knowing that this will solve the problem.

But am i putting my family at risk from overheated wires? Am I operating the microwave below performance standards creating some other risk?

Because of the two breakers -- 15amp and 20amp -- tripping on my microwave, is it a good bet that the microwave is the problem?
 
Does the microwave have a 15 amp attachment plug? If so it's safe to operate it on a 15 amp circuit. The OCPD will protect the conductors from damage. If the unit constantly trips the CB it may be faulty.
 
infinity said:
Does the microwave have a 15 amp attachment plug? If so it's safe to operate it on a 15 amp circuit. The OCPD will protect the conductors from damage. If the unit constantly trips the CB it may be faulty.
Click to expand...

Or, there may be other loads on that circuit that when combined with the microwave draw enough to trip the 15A breaker. I would recommend you enlist a qualified electrician to trace that circuit (identify all loads) and also check the actual (true RMS) current being drawn when the breaker trips. There are many things that can cause a breaker to trip. MOST of them are a hazard of some magnitude.

Mark
 
Bad Microwave.

Bad Microwave.

I repair microwaves. Most are under warranty because it is cheaper to buy a new one than have it repaired. The best way to check your microwave is to plug it in to a GFI protected receptacle. If you can heat up a large cup of cold water without the GFI tripping the microwave is good. Don't use an extension cord on the microwave. If the GFI trips the microwave is bad, and it isn't worth fixing. The parts involved are expensive not to mention the labor cost. The microwave has to run for a while. I would even try to cook some frozen vegetables. Usually it is the high voltage diode or the high voltage capacitor breaking down that causes this problem, possibly the magnetron is going bad also.. If the microwave works good on a GFI protected receptacle I would suspect a wiring problem.
 
Funny I didn't know a microwave was like a motor load with input & output (12 amp & 1350 watts input, & 900 watts output)?

The 12A load is not too much for even a 15A circuit. NEC would allow this appliance to plug into a multi outlet branch circuit as long as the rating of the appliance does "not exceed 80% of the branch-circuit ampere rating" - 210-23(A)(1) - & 15A x .80 = 12A works in this light.

Either the appliance is failing, or there are other items on (this could be inconsistent and sporadic) check amperes with appliance off then on, or the breaker is failing load it up to 15A and hold it, or simply change the breaker
 
Mr original poster with only one post . Please call an electrician. Do not try to replace any breakers yourself, you could get hurt. If you feel your wiring may be of questionable quality the best way to find out is to have an expert check it for you.
 
busman said:
I would recommend you enlist a qualified electrician to . . . .
Click to expand...
macmikeman said:
Mr original poster with only one post . Please call an electrician.
Click to expand...
Did either of you notice that the OP?s profile says, ?electrician?? Is there a reason for you to suspect that this is a DIY question?
 
peter52 said:
Usually it is the high voltage diode or the high voltage capacitor breaking down that causes this problem, possibly the magnetron is going bad also.. If the microwave works good on a GFI protected receptacle I would suspect a wiring problem.
Click to expand...

within the kitchen itself there are three outlets, each on its own breaker:
a 15amp GFCI with a load going to the porch light.
*a 15amp with load to kitchen light (standard 60w bulb :)
a 20amp (which i haven't tried) for the fridge.

the 15amp GFCI outlet trips the breaker without tripping the GFCI.
the one i use most (*) trips whether the kitchen light is on or off.

the fridge recommends a 15amp outlet and i would need an extension cord to use this with the microwave. i would rather not.....

i'm leaning towards your diode diagnosis. I shall start shopping for a new (and smaller) microwave.

if the prob persists, i will get an electrician in here to check the loads.

thank u everyone for ur input.
 
A smaller microwave will probably prevent the problem from happening again. However, that doesn't mean there is a problem with the microwave. Like others said, it could just be too much current on one circuit with the microwave and some other unknown load.

However, try this: Open the microwave door, and look inside it where you put the food. Look for a ceramic cover over an opening into the oven. (Just look, don't take anything apart). What does it look like?? Is it missing? Is it black? Does it have a hole burnt into it?

Steve
 
charlie b said:
Did either of you notice that the OP?s profile says, ?electrician?? Is there a reason for you to suspect that this is a DIY question?
Click to expand...
Click to expand...

How are you related to the electrical industry?:
um, ...electrician.

Charlie, I think that says it all:roll:
 
ceb said:
How are you related to the electrical industry?:
Click to expand...
ceb said:
um, ...electrician.

Charlie, I think that says it all
Click to expand...

I think not. I think the sequence of questions person must answer, while attempting to register on this site, could use some updating. It?s not terribly important, but it does result in some interesting responses. Keep in mind that the first few times a new member attempts to post a comment on this forum, the post is held back (kept hidden) until a moderator reviews the post. It is our way of reducing spam, and it has worked very well. When I see a new post by a new member, before I ?approve? the post I will always look at the person?s profile page. When you have already answered the question of ?Occupation? with ?electrician,? what do you answer to the question ?How are you related to the electrical industry?? You have already said you were an electrician, so what else do you say? I have seen any number of interesting replies, and ?um . . . electrician? is relatively normal.
 
infinity said:
Does the microwave have a 15 amp attachment plug? If so it's safe to operate it on a 15 amp circuit. The OCPD will protect the conductors from damage. If the unit constantly trips the CB it may be faulty.
Click to expand...

Not with absolute certainty.

I was called to see why a 15 amp breaker kept tripping. After looking about and not finding anything, I asked if there was a pattern to the problem. Indeed, wife using hair dryer (which was not in view when I came to look at the circuit). It had a 15 amp attachment plug and the sticker on it showed it to draw 1950 watts (16.25 amps @ 120 volts).

I believe it was made in China.
 
mazersandmizers said:
. . . if the prob persists, i will get an electrician in here to check the loads.
Click to expand...
Please clarify this. Your profile says you are an electrician. Is that an error, or perhaps are you an electrian with a different area of specialization? Please note that our forum rules prohibit us from giving "how-to" assistance to a person who is not an electrician.
 
charlie b said:
When you have already answered the question of ?Occupation? with ?electrician,? what do you answer to the question ?How are you related to the electrical industry??
Click to expand...


I think that answers such as " by blood" or " by marriage" would be appropriate.

For some reason I have never seen either answer. Don't these people have a sense of humor. They should be advised right up front that they are going to need it.
 
mazersandmizers said:
Is my 12 amp microwave damaging the wiring to my 15 amp breaker?

i live in an appartment "cooperative" complex. The complex was built in the 1940's - 50's to supply simple housing to our returning soldiers and thier families.

I have a 15amp breaker and a 2004 model microwave:
120 VAC, 12 amp 60 Hz
Input 1350 Watts, output 900 Watts.

Using the microwave will eventually trip the breaker; maybe every other day, give or take. The panel lists a 20 amp GFCI outlet which will also trip. while this is a bother it has not been unbearable. And why replace the microwave without knowing that this will solve the problem.

But am i putting my family at risk from overheated wires? Am I operating the microwave below performance standards creating some other risk?

Because of the two breakers -- 15amp and 20amp -- tripping on my microwave, is it a good bet that the microwave is the problem?
Click to expand...

I am going to try to be as honest and candid as I can. Without knowing the condition of the wiring in the structure one cannot be certain that a 12 amp additional load is damaging anything or not. My concern would not be with the wiring being damaged, but rather the insulation or connections. You also did not specify how the GFCI trips. Did it trip the overload or the fault section of the breaker?

Are you putting your family at risk? To be on the safe side, I would have to say that *anything* connected to your system that repeatedly trips a breaker is putting people at risk. The reason is that breakers that have been tripped repeatedly have the possibility of becoming ineffective. I also don't know the brand of breaker you are tripping. GE's are referred to as 'arc welders' and CH's are referred to as 'widow makers' by the local peanut gallery in my area. I personally have seen a 15 amp CH in an older home carry 115.7 amps without tripping. *AMPS*, not volts!

Even though the nameplate lists 12 amps, without actually measuring the draw there exists some uncertainty. I use a break out cable to measure current draw of a single cord connected device.

My suggestion is to stop using the device on *any* circuit that is not capable of handling the load, for whatever reason.

Besides, food tastes much better when cooked on a stove in either a cast iron skillet or a stainless steel pot.

If I lived within a half hour drive from you I would come over and measure the draw for free, just to keep you and your family safe. I have found that such service always pays off in the long run.

I live in Muskegon, Michigan....Norton Shores, to be precise.
 
mazersandmizers said:
Is my 12 amp microwave damaging the wiring to my 15 amp breaker?
Click to expand...

No, if your circuitry is installed correctly! This is why we love to do our job right. :) You can always choose to install a dedicated circuit, maybe even get a micro/hood combo to replace the range exhaust hood, then you'll get some counter space back.
 
Status
Not open for further replies.
Top