[omgdiddy]

My home was built about 20 years ago. I am replacing the dishwasher. I turned off the power and removed the old unit. I found it is hard wired with a black and a white wire connected to the unit. I noticed in the home wiring, there is a third wire that the previous installer just cut back flush with the outer bundle of wire insulation. Does this third wire need to be hooked up somewhere, or is it ok to just leave it as is? Thank you...

 

[rjniles]

The 3rd wire is probably the ground and it needs to be hooked up. Swing the cable into the sink base and install a receptacle. Install an appliance cord on the DW.

 

[Bob Sanders]

The 3rd wire is probably the ground and it needs to be hooked up. Swing the cable into the sink base and install a receptacle. Install an appliance cord on the DW.

That must be an American thing because it's not the way it's done in Canada. It's not a "portable" device and therefore can't have a plug. It's hardwired directly to breaker panel.

 

[IslandGuy]

Since this is a replacement appliance, hardwiring the DW just as it was, (but connect the ground) is perfectly acceptable. Pre existing non conforming.

 

[Arrow3030]

Follow the DW installation instructions. It will most likely have a cord and plug with it or give instructions to buy a UL listed appliance cord. If it does, you'll need a receptacle, possibly a gfci. It will definitely say to ground the DW

 

[rjniles]

That must be an American thing because it's not the way it's done in Canada. It's not a "portable" device and therefore can't have a plug. It's hardwired directly to breaker panel.

The NEC requires a DW to have a disconnect within sight of the appliance. This can be done with a switch or a cord set. Whether a hardwired DW without a disconnect would be grandfathered would be up to the AHJ. But since most would not get a permit, its probably moot.
Do not have familiarity with the CEC to comment on having no disconnect for a DW.