Both my DW and disposal were set up that way when house built in 1980. While doing kitchen update I installed an old work box for each and then added a properly sized ac cable to DW and disposal. Where I live I need to meet 2005 electrical code. If you want GFCI outlets to meet newer codes I suggest putting a 2 outlet old work box in the sink cabinet and route DW power cable through the cabinet. Use 2 GFCI outlets.

You just make a hole in the wall. You only need a box if you intend to make a connection right there. In that case, there's nothing magic about the box, you just put a type NM fitting on the back.

The 2005 NEC doesn't require GFCI for the receptacles under the sink. This changed in the 2014 code. 2014 and after requires GFCI for all outlets within 6' (including under) the sink. Prior to that it either said "other than kitchens" (2011, ) or specifically "Laundry, utility, and wet bar sinks" (2008 and earlier)

I like to install a plug box and when I work on the device I just unplug it for safety.

Yes, you need a disconnect for the unit and the easiest (and most common around here) is to just use a cord and plug. If you hardwire it, you're going to need to add some other sort of disconnect ( a switch under the sink is another common one).

The electrical code says nothing about holes in drywall. Of course, your local fire code might have something to say about that.

Thanks , Ron. I should have included the fact that it is a different “department”.

I’d guess that a plug and outlet is more popular because no talented electrical work is needed for the next replacement DW.

Most dishwashers come with plugs these days. That probably all the main reason. Garbage disposals on the other hand tend to come without and still I see a short piece of romex with a plug on it installed (technically illegal).

With disposals either a cord and plug or a pigtail is acceptable as long as manufacturer instruction is followed?

Either is fine. My only comment is using type NM as a "cord" isn't legitimate.

If there is a window in the same wall as the DW, then there would be no fire code for holes in drywall. Interior walls of dwelling units are rarely fire rated by gypsum board. Energy efficiency codes would only require caulking. In other words, it would be highly unlikely to find a code in other departments that would not allow Romex through drywall in a structure that Romex is allowed in.

Not universally true. The code here will NOT allow certain holes even in non-exterior walls but all you have to do is seal around the romex and the inspectors will be happy. There's a lot of 3m fireblock foam shot around wires here.

Good to know. My initial thought was that the burn resistance of interior walls is more important than exterior walls in preventing spread of fire within the structure. On the other hand, fire getting at more flammable materials behind the drywall is a disaster of pretty equal magnitude whether interior or exterior walls are involved given the speed of spread.

Broan says my kitchen stove fan unit has to be hard wired. My old 28 year old unit was

hardwired. have 14/2 romex coming through a hole in the drywall. Am going to hardwire

the fan and put fire block material around the romex coming through the sheetrock.

YouTube has people putting cords where they should not. Had the dishwasher installed

by the Appliance store where I bought it. They put an outlet in the wall and plugged in the

dishwasher, about 3 years ago. No GFCI ????