Adding a new circuit to electrical box

I just recently installed a new microwave/hood combo in my kitchen. Previously only a hood existed in that space. Now it seems that I'm overloading that circuit. It's on a 15A circuit shared by the kitchen lights, garage lights, and 1st bedroom outlets (including the computer). Kitchen outlets are on their own circuit. When the microwave (1000W unit) and the computer (300W) are both on the breaker buzzes and occasionally trips. If I turn off all the lights and computer the breaker still has a very faint buzz when running the microwave.
My plan is to put the microwave on it's own circuit. The breaker box is in the garage just on the other side of the kitchen wall. Running wiring will be pretty easy because I have an attic space above. My question is if I can just plop in another 15A breaker into the box. I've got plenty of space in the box, but I don't know if I'd have to get a permit or not, and if there are any caveats I should be aware of. Should I use a 20A breaker since the 15A breaker still buzzes when only the micowave is on?
I'm not afraid of doing my own wiring. I've done plenty of it in the past. I've just never had to deal with the breaker box before.
Thanks in advance.
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Bill

 

You're right on with the physics. So I too am a little baffled why a 15A circuit is giving me troubles with the microwave. I can't just swap in a 20 or 30A circuit because the wiring is 14awg. I'd have to have 12awg for a 20A circuit. From what I understand I would be presenting a fire hazard by putting in a 20A breaker.
I've considered just replacing the old breaker with a new high quality 15A like you suggest. Theoretically I should be able to handle 1650 watts on that circuit (assuming I'm only getting 110 volts and not 120). With the microwave, computer and 4 lights that are no greater then 80 watts each, that's a total of 1620 watts. Ooo, cutting it close there.
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Bill

 

Hmm...it seems that my microwave/hood is actually requires 1800 watts. It seems the first time I read it there wasn't enough light and I thought that 8 was a 0. That really explains a lot! But it's going to cost me $50-$75 for a permit. It will cost me no more than $15 to make the change. I'm really thinking I can just not get the permit. Would I also have to pay for an inspector, or is that part of the permit cost? What's that $50 permit going to get me?
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Bill

 

I guess I'm going to have to go downtown and talk to somebody there to get the details of everything I need to do then. I really think it's ridiculous that I'd have to pay even $50. That raises the cost of the project over 400%. I think it's the permit costs alone that keep people from getting one when it's just a simple job. In my opinion permits should be priced as a fraction of the overall expected cost. Let's say 20%, not to exceed $100. So my permit would cost me about $3. I like that. Then the insurance company can send out an inspector. After all, the insurance company already has my money, and it's their own butt their looking out for.
I should also clarify, the oven says "Input...1800W; Output...1000W." So whatever that means. That's where I got those numbers from. I need to go get my eyes checked too.
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Bill

 

Thanks for all the replies. You've all been a big help in getting some questions answered.
Well, my wiring is only 20 years old and it does comply with current codes (all copper). But I plan on running new wiring out anyway.
I also plan on rounding up the help of an electrician friend of mine, if I can every get him over here.
One of my other concerns with having an inspector come out is him not signing off because of other projects that are lying around incomplete. I've been rewiring the garage to actually fix previous code violations and have left some wire dangling from the ceiling (properly capped so it's 100% safe) where I'm going to eventually drop it down and install plugs for my workbench (if I ever get that built). The problem is, the inspector will have to come into the garage to inspect the breaker box and surely will see the other things (there won't be a problem once I'm finished with them). Although it may not be an issue because it is safe.
My biggest concern though is still not wanting to spend that money. That permit is going to cost me 2 DVDs! Also, I've been doing a lot of rewiring throughout the house (added 2 ceiling fans, garage outlets, garage lights, an entire wall rewired and switches relocated) all without permits, and all required pulling new wiring. Why should this by any different?
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Bill

 

Well...I'm finished. I talked an electrician friend of mine into coming over and helping me pull wire into my breaker box. He also gave me a few pointers to make sure I do everything to code. I installed a new 20A breaker, a new box by the microwave, and pulled 12/2 Romex (12 gauge, 2 conductor with a ground) into the new box. Everything works great. No more breakers buzzing or tripping. Woohoo!
Thanks again for all your input.
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Bill