Is there an electrician in the house? Weird home electrical issue
 

We have a Bosch dishwasher. A couple weeks ago it would on occasion not start up. When you push the on/off button, the panel would not light up. But then a couple hours later, if you tried, it would light up and run.

Yesterday it wouldn't light up or run at all.

It is plugged in under the sink, in a standard 2 outlet socket (was plugged in the lower socket). Also plugged in there is the garbage disposal (in the upper socket).

Naturally, I tried the garbage disposal, to confirm that socket gets power. It worked.

So I plugged the dishwasher in, didn't work.

Then I tried plugging in the garbage disposal into the socket where the dishwasher was, to see if it is powered.

This is the weird part. When I plug the garbage disposal in the lower socket, it runs, but even if the garbage disposal is not turned on! In other words, when plugged into that socket, the disposal will constantly run, whether the switch is turned on or off. When I plug it into the upper socket, the disposal runs normally.

Conceptually, I don't see how that is possible, how is the switch being bypassed?

One other clue is I noticed that one of the blade prongs on the dishwasher plug is burned.

This morning, I used an extension cord and plugged the dishwasher into one of the other sockets in the kitchen (one that has the "reset" button on it, like used in kitchens and bathrooms), and the washer runs fine.

Any idea what's going on with the socket? Is this likely a problem with the socket, or the dishwasher?

Thanks and happy new year!

Receptacles an be wired independently (split outlet) by breaking off a 'tab' that connects the upper and lower socket. http://electrical.about.com/od/diyprojectsmadeeasy/ss/wiresplitoutlet_6.htm We do it in bedrooms so that light by bed can be switched and outlet for alarm clock is always powered.

I'd change the plug and receptacle.

Found the answer on the switch issue, it's the way the switch is wired and normal.

Electrical Wiring in the Home: outlet wiring for garbage disposal, diagonal cutters, garbage disposal

My guess now is there is some internal, intermittent issue in the dishwasher.

(I didn't know you can't delete threads in this forum, even after only 5 minutes of posting! Never tried to until now).

That outlet is called a "half-hot". The lower is controlled by the switch on the wall and the top is wire normally, and has power at all times.

If you ran an extension cord from any other outlet and plug in the disposal, it would run constantly.

Re dishwasher, what kind of on/off button? Membrane style or push button?

We were both posting at the same time.

Is it common to change plugs? How is that done, just cut it off and use twist on caps to splice a new one in?

I think I will use an extension cord and plug the dishwasher into on of of the "resettable" plugs in the kitchen, to test it for a few weeks.

Push button.

One time when it would not fire up, I did a standard diagostic that I do with these kinds of appliances (opened and slammed the door shut) and it got it working.

I've changed course, I think I'm going to open it up and take a look at the wiring to see if there is anything loose, burned, etc.

I'll also change out the socket, as suggested by dad911, to eliminate that as a problem.

Start with the on/off button. Google the model number with "on off button" and see what pops up. If slamming worked, I'd bet the mechanical part of the button is flaky.

I would check for a flaky interlock switch on the door latch.

DW will not work or turn on unless the door is fullly closed. Check that switch or sensor there.

That is the only clue you need.

I am not sure of the electrical code but a plug on a permanently installed dishwasher sounds suspect.

Dishwashers are NOT required to be hard wired into the box.

McLovin, if you do this yourself, please examine the gold screw side of the existing recpt and put the wires on just like they are now. If that means a white to a gold screw, do it. AND look at the tab between the screws. On the old recpt will not be there; snapped off. Do this too.

Remember that there may be 2 hot circuits in this box controlled by 2 breakers.

Years ago (almost) all were hard-wired. Quite common to have plugs now.

On this dishwasher, there is a "clean" wood front (matches the other cabinets) on it. There are no buttons on the outside, you have to open it to get to the buttons.

So, it is designed to "light up" the control panel with the door open.

Of course, it won't run until the door is closed. So there is a switch for that.

But, it wouldn't even light up. So I think that rules out the door sensor.

Milt - will do, thanks for the info. Like just about everything I do these days, I'll take a bunch of close up pictures before disassembly.

Thanks all for the comments. The depth of knowledge here is really remarkable.

I have a Bosch SHX dishwasher. The tag says 12 amps.

I am curious what kind of cord he has run from the junction box in the dishwasher to the plug.

Seems something is amiss if the plug caught on fire.

Usually the garborator and the dishwasher should have been on independent circuits.
Code may be different there, but having two pretty big motor loads (and heaters for the water) doesn't make too much sense.

I don't think there is any cord run like that.

From what I can see, the dishwasher came from the factory with the cord on it. Designed to be plugged in, not hardwired.

The plug didn't catch fire, but looks a little "burnt" on one of the prongs. I'll see if I can snap a pic.

I agree, though, that the burnt-ness seems to indicate something is amiss. Don't know if it is the receptable, or the appliance?

Mine is a Bosch SHV. It also says 12 amps.

My vote is that the receptacle needs to be replaced. As others have stated, be careful of the wires. Replacing a receptacle is really easy, but electricity demands respect.

Also, if it would make you feel better, you could probably pick up another pigtail from the hardware store for $10-15.

Do you just cut off the end of the plug, and splice in a new one? I guess I could solder in a new one and tape it up to look ok.

I've replaced a lot of receptacles over the years. They are inexpensive, the one in there is 30 years old, and certainly couldn't hurt to replace it.