This article describes the installation of a dishwasher in a newly-built house. This procedure also applies to a newly remodeled kitchen. Replacing a dishwasher is quite similar, except that the old appliance needs to be removed first. That may require turning off a circuit breaker and shutting off the hot water supply.

There are 3 basic connections for a dishwasher:

• Hot water supply line.
• Drain hose.
• Electrical supply, which is usually 20 Amps and 120 Volts.

Before I started drilling holes, I wanted to be sure the dishwasher actually fit in the cabinet opening. The standard dishwasher opening is exactly 24" wide and the height of a standard base cabinet, which is usually close to 34½".

This opening is nothing special... it's just a gap between cabinets. Installing a new dishwasher in an existing run of cabinets is possible, if there is a 24" base cabinet adjacent to (or close to) the kitchen sink.

The only connection that normally comes with dishwashers is the drain hose. I bought a 6 foot dishwasher supply kit, which came with a braided steel hose and a brass elbow/adapter fitting.

 

All the connection points were under the kitchen sink: 1. Hot water shut-off valve. 2. Drain connection. 3. Electrical outlet.

First: Electrical Connections:

Because the supply and drain connections were to the left of the center of the sink, those hoses will dictate how far the dishwasher will be able to extend out of the cabinet. I could make the electrical lead as long as I wanted, so I did that first.

For whatever reasons, the electrician just wired up a receptacle below the sink. One of the plugs is switched (for a future disposal) and the other is hot-at-all-times.

Every time I've installed a dishwasher on my own houses, I've just ran a 12-2G cable from the breaker box to the floor area behind the dishwasher.

One seemingly easy option is to fabricate an extension cord from 12-2G cable or 12 gauge flexible cord. Installing a male plug on one end is simple... but there's a drawback to that approach. A plug in the wall does not make as secure a connection as a permanent wire-nutted installation. I have seen too many appliance plugs lose their firm contact and begin to overheat. A permanent connection reduces the risk, however slight, of a fire caused by a poor-fitting plug.

But in this case I went ahead and made up an extension cord

I drilled 3 holes, using a 1¼" hole saw that was just big enough for the drain hose.

 

I connected a heavy-duty male plug to one end of an 8-foot piece of 12-2G cable.

 

This little metal box is for the electrical supply connection. The front panel needed to be removed to reach this box.

 

Every dishwasher I've ever seen has a removable front panel. This GE unit had a deluxe 2-piece panel, which allows for the lower section to be adjusted up and down to cover any gaps at the bottom.

 

I attached a cable clamp to the other end of the cable (after I threaded it through the hole in the cabinet).

 

I connected the respective hot, neutral, and ground wires with wire nuts.

 

I replaced the cover to the connection box. These boxes are quite small, so there is not much room for excess wire length.

 

Plumbing Connections:

This blue device is the supply valve. The hot water enters here.

 

That's a 3/8" NPT (National Pipe Thread, also called Iron Pipe thread) female fitting on the bottom of the valve. Every dishwasher I've ever seen needs an elbow fitting to turn the corner. I don't know why the appliance manufacturers can't just make the valve point to the back.

 

I dabbed some pipe thread compound on the fitting and tightened it. This was tricky because there were no wrench flats on the valve. Holding the plastic valve body could easily break it. I used a pair of channel-locks to hold the steel bracket. Iron pipe fittings need to be pretty tight, end the elbow needs to point towards the back.

 

I connected the braided stainless steel supply hose to the elbow/adapter. This is a 3/8" compression fitting, which requires less torque than a pipe thread fitting. Some compression fittings, like this hose, use rubber seals under the hex nut, and excessive tightening can damage the seal, causing a leak that only gets worse with further tightening.

Unfortunately it takes a little experience to become familiar with just how tight to make these fittings. I've learned my lessons by: 
1. Having leaks at fittings that were not tight enough, and 
2. Having to run out and buy new parts after I've damaged them from overtightening.

I threaded all the hoses through the holes in the cabinet.

 

I connected the supply hose.

 

The end of the drain hose was too big for the barbed fitting the plumber installed.

 

But the hose end was labeled for different sizes of pipe, so I just cut at the designated line.

 

I secured the drain hose with an automotive-type hose clamp, which the plumber had left behind with his temporary plug.

 

I set the dishwasher in place and turned the leveling screws to raise it up. I didn't want to leave a big gaping hole at the top, and the bottom cover panel can be adjusted.

 

I positioned the appliance so the door was about 1/16" away from the cabinet. If the door was too close it might hit the wood before making a tight seal.

 

I installed the two tiny screws that hold the dishwasher in place. Every dishwasher I've seen just sits in the floor and uses 2 small wood screws to hold a pair of metal straps to the bottom of the countertop.

Then I plugged in the power cord, turned on the water, and ran the machine. I waited for a full cycle and checked for leaks before replacing the front cover panels.

Notes On Maintenance And Repairs:

When I worked in hotel/condo maintenance, we routinely replaced leaky dishwasher drain hoses with 7/8" automotive heater hose, which is actually a hose used on large trucks. This hose is very durable and resists high temperatures. We would just use automotive hose clamps to fasten the hose ends to the fittings. Those condos all had garbage disposals, which have a larger dishwasher drain fitting than is often found in installations such as the house in this article. In some cases I suspect that 5/8" heater hose might work.

Since any water-using appliance can leak or overfill, I have formed a habit of only using the dishwasher (and clothes washer) while I am at home. I have heard of new appliances malfunctioning while people were away and causing thousands of dollars in flood damage.

Handy Tip: HammerZone reader Brent Huhta shared this idea: "I've found that it is good to apply some varnish or polyurethane to the front underside edge of the typical Formica-clad particle board countertop directly above the dishwasher.  When the dishwasher is done and you open it up, you usually get a big cloud of steam coming out of it.  This moisture, over time, makes the particle board swell if it isn't sealed.  Not a major problem, but it's helped me."

Tools Used: Cordless Drill/Driver Adjustable Wrenches Channel-Lock Pliers Nut Drivers Miscellaneous Hand Tools Small Level

Materials Used: Braided Stainless Steel Supply Hose Adapter Elbow, 3/8 IP to 3/8 Compression 12-2G Cable Cable Clamp Male Plug, Heavy-Duty