Drudge through this you will get it before the end.
You need to know all the watts of the appliances. You know the 1300 watts, but you don't know the watts of the microwave. Look in your papers for that specification or research it on the internet, most manufacturers publish the specifications on the net.
For the purposes of this reply, I will use 1500 watts for the microwave.
Volts X Amps = Watts soooo Watts / Volts = Amps, lets use your appliance 1 as 1300 watts and the appliance 2 the microwave guess at 1500 watts for a total of 2800 watts (1300 watts + 1500 watts = 2800 watts) then 2800 watts / 120volts = 23.3 amps to run both appliances.
If the breaker is not a 30 amp breaker you are out of luck in this scenario because a 20 amp breaker will not do the job. I do not recommend installing a larger breaker unless a qualified electrician does it. Because if the wire is not large enough to carry 30 amps, the wire becomes a fuse. The breaker will not trip but the wire will fry the insulation off and WILL cause a fire in your fiver.
So look at that dedicated microwave breaker to see what amperage it is, 30 amp? go for it. 20 amp? install the plug but know that if you run both appliances or it will trip the breaker. You don't have to worry about installing a switch to prevent using both at the same time, the breaker will trip if you accidently run both at the same time.
But do not install bigger breaker unless an certified electrician does it and even then I would be careful.
good luck, put hubby on the project and look over his shoulder to make sure he does it right. LOL.
BTW do the math but realize that each of those appliances vary in the number of watts they use, so you could have a 1500 watt microwave that has a startup of 1750 watts and the other appliance could have a start up of 1500 instead of 1300, if they surge at the same time you would be looking at a 3250 watts instead of 2800 watts. Im not saying this is the case, but you have to look at the max amps or watts that an appliance can draw. So look at those specifications closely.
Amps X Volts = Watts
*120v is the voltage of your system it is the constant in the formulas below
If watts are known then total watts / 120volts = Amps
If amps are known then total amps X 120volts = watts
Tell your hubby you can figure it out with Ohms Law! Ohms is not just a law it a good idea too.
Sorry if this is in the wrong area but not sure where it would go. We own a 2012 Sundance and the microwave has a dedicated outlet beside it. The outlet only has the one plug in for the microwave and we would like to make it a two if possible. We know this, as there is a breaker in the fuse box marked microwave. Question is can we add to it to make it a double outlet so we can plug a induction cook top into the same outlet? The unit we would like to use is 1300 watts and it would sit under the microwave on the stove top. This would be the best place to use the induction cooktop because of the vent and lack of space otherwise.
I thought I would ask before asking hubby to do a mod that could or shouldn't be done.
Dawn