I am planning on installing a dish washer in our kitchen. There was never one there before, so I will have to run all new electric. I know most manufactures recommend putting a dishwasher on it’s own circuit, however last fall I installed a microwave on it’s own 20A circuit which took up the last available space in my box. I was discussing with an electrician friend of mine and he suggested getting a 20A tandem breaker, replace the 20A microwave breaker with this, and then put both the microwave and the dishwasher on the tandem. Looking at the layout and specs that were included in my electric box, it appears I can use a tandem breaker in any slot. The microwave and the dishwasher would be the only items on the tandem circuit. From what I have been able to research, this seems like this would be up to code. I wanted to see if I could get some opinions on this and see if this approach really is in fact code. Any input is appreciated, thanks!

As long as the breaker is the same make or listed as compatible with your panel, you can do what you want. Very common.

Yep, I made sure it is, thanks!

In your research, you did come across the fact that you must use GFCI receptacles in you kitchen.

Donf, hope all is well, He won't need GFI for Micro or DW. They will both need to have own neutral, if on a Tandem. You can use a 2 pole 20 amp(if #12), then Tandem something else. May be easier to get 1 wire there than 2? To location. Can Elaborate more if Multicircuit is considered. Micro should have single, not duplex recpticle.
Good luck.

Strat,

How have you been? My purpose was to remind him that if he puts a receptacle in the kitchen for either of these circuits (counter use) it has to be GFCI.

As written, my original response was extremely unclear. So much for rushing!