My Bosch micro/oven need 120 volt 20 Amp receptacle. I do not have a 20 Amp circuit breaker for this purpose. Can I couple two separate 15 Amp breakers as a dedicated source to provide higher Amperage limit (20 Amp)? Theoretically this will increase wire cross-section area for a higher Amp. limit. Is it permissible by code?
Paralleling is NOT Allowed
You can't do this (except under very limited circumstances that don't apply to your situation). The problem (ignoring the code violation) is that if one of those wires breaks (disconnected at any point between device and breaker) then all of the current will flow on one wire, which is not safe as it would put all 20A on one wire. If the wire that breaks is a neutral wire then things are even worse because then the breaker will never trip because it is protecting the hot wire with the assumption that the neutral will carry the same current as the hot wires. (In a 240V-only circuit, the neutral carries the difference between the hot wires - as little as "0", but in a 120V circuit it carries the same as the hot.)
You also must NOT simply replace the 15A breaker with a 20A breaker. Almost definitely the existing wire is 14 AWG, rated for 15A, and not 12 AWG (or larger) rated for 20A. So upsizing the breaker without upsizing the wire will also be a real fire hazard (and code violation).
The only real solution is to replace the wire and the breaker (i.e., a new circuit) or to find an oven that is rated to run on a 15A circuit.
Circuit breakers don’t work like that. Did your microwave come with a plug that has 1 straight blade and 1 blade at 90 degrees? If so you will probably need a dedicated 20 amp circuit with #12 wire. 2 breakers depending on how located in the panel could provide 240v and if connected together “boom” If they could be paralleled they would not work correctly as breakers are inverse time devices. And as mentioned above if you have 15 amp breakers your wiring is probably only 14 gauge and 15 amp is the max breaker size. Large micro waves are one of the few devices that I have seen that require a 20 amp circuit so if the blades are not parallel 15 amp you will need a new circuit. To parallel wires they have to be 1/0 or larger, we do not parallel breakers.
The short answer is NO. Of course it might help to explain why.
"In theory" this would work as you expect (the part about increasing the wire cross section), but it's forbidden by code because there are a lot of dangerous issues related to this as well as practical ones.
You can't use two 15 amp breakers because that would still trip at 15 amps. You might be tempted to take two existing 15A circuits and connect them both to a 20A breaker, and that would "double" your wire size and work, but it's not safe. If there is just one bad connection somewhere (or a connection goes bad over time), the circuit would appear to work fine, but you would be pulling all that current over one wire instead of two which would overheat and potentially cause a fire. Even with all of that there's still the problem of trying to connect those two wires to devices that only expect one larger wire.
No, for reasons the other answers already address well. Moreover, rather than adding a circuit, it would be a lot less expensive and more useful just to replace the microwave with a normal 15A one. There's no need for high-wattage microwaves; to do anything other than heating water (cooking/reheating/thawing/etc.) you have to run them at lower power levels, which are usually just short duty cycle. A 50% duty cycle at 1000W is going to heat your food more evenly than a 25% duty cycle at 2000W.
Sounds workable in theory, but...
As already stated in other answers, it would be a code violation because it would be unsafe; electrical codes exist for good reason.
Going beyond safety issues, there are all sorts of reasons why this just isn't a workable idea.
Most kitchen outlet boxes are wired with two "hot" lines so that top and bottom outlets can each serve up to a 15A load, for 30A total at 120V right? WRONG! The two hot lines are on opposite phases; between them you actually have 15A capacity at 240V. Yes you normally use them as if it was 30A worth of 120V, but that's not what is actually going on, so you can't simply join them in the outlet box. If you attempted to join them in the breaker panel (VERY BAD IDEA) you'd theoretically have 30A capacity on the hot lines, but only 15A capacity on the one neutral feeding the box (all sorts of unsafe/bad/fire hazard). If you tried to gang up power from other outlets, you might as well just run a new 20A circuit.
As already stated, your only two options are:
- Exchange the appliance for one which can operate on a 15A circuit, or
- Run a proper 20A circuit to feed your microwave.