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Fried dishwasher wiring!

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[#1] Posted: 02/20/2008 - 12:58:32 AM
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Fried dishwasher wiring!

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Joe Tedesco, NEC Consultant
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Fried dishwasher wiring!
[#2] Posted: 02/20/2008 - 01:05:01 AM
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Hi Joe,

Which brand and model of dishwasher? Was this one of those that's been recalled for defects that are fire hazards?

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M.

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Fried dishwasher wiring!
[#3] Posted: 02/20/2008 - 02:07:53 AM
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If this dishwasher is on a Multi WWire Circuit, and both hot legs were incorrectly hooked up to the same bus, creating an "additive" effect on the neutral, could it have an effect like this?
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Fried dishwasher wiring!
[#4] Posted: 02/20/2008 - 03:31:07 AM
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This picture was sent to me by a homeowner, he said: "As you can see, the white wires have fused together and the wire cap is completely melted. The other two wire caps (one black wire and the other neutral) did not melt, but had visible burn marks on them. The fuse was not tripped when I checked it, so I have no idea what could have caused this fire hazard. Should I just cut back the white wires and recap or give it a go or should I call in somebody? The dishwasher is four years old and has never experienced anything like this before."

I sent him a message just now asking about the repair or replacement status and brand of the product.

Joe Tedesco, NEC Consultant
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Fried dishwasher wiring!
[#5] Posted: 02/20/2008 - 06:53:38 AM
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Hi Joe,

Got my 80 winks, now I'm up again. There are a lot of dishwasher recalls but over the past 4 years only GE, Whirlpool, and Hotpoint have issued any. The Whirlpool ones were sold under the Whirlpool and Kenmore names; the GE ones under the GE Profile, GE Monogram, Hotpoint, Sears-Kenmore names; and the Maytags under the Maytag and Jenn-Air names.

The Whirlpool recall involved a defect that can allow the motor to catch fire; the GE and Maytag recalls involved leaky rinse aid dispensers that cause a short and a fire in the wiring.

Go to http://www.recalls.gov for particulars.

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Fried dishwasher wiring!
[#6] Posted: 02/20/2008 - 09:39:34 AM
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It's got nothing to do with the dishwasher. This is simply a bad wire nut connection. I could have happened anywhere in the house. This is why we put our electrical connections in boxes.

- Jim Katen, Oregon

Jim Katen, Oregon
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Fried dishwasher wiring!
[#7] Posted: 02/20/2008 - 12:46:45 PM
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Quote: Originally posted by Jim Katen

It's got nothing to do with the dishwasher. This is simply a bad wire nut connection. I could have happened anywhere in the house. This is why we put our electrical connections in boxes.

- Jim Katen, Oregon



Thanks Jim, agreed, here's his reply to my question:

"Hi Joe,

Thanks for the follow-up. I took my pictures to an the electrician that sponsors my son's baseball team (his office is right across the street from mine) and showed him the pictures. He said that it was a pretty common problem, and that he sees this problem all the time. He said it's not caused by a power surge, but the wiring loosened up and crossed each other (I don't know the technical term). He said to just cut back the damaged wire and rewire it, making sure it was wired tired. He said that's what he would do if we was to come to my house. I've been using it since then without any problems.

Hopefully, problem solved.

Thanks again for your concern,

Joe Tedesco, NEC Consultant
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Fried dishwasher wiring!
[#8] Posted: 03/21/2008 - 9:58:38 PM
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Quote: Originally posted by Joe Tedesco

Fried dishwasher wiring!

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This probably wouldn't have happened if the ground wire had not ben cut. Therin lies your problem.

KY Master Electrician
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Fried dishwasher wiring!
[#9] Posted: 03/22/2008 - 05:21:06 AM
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Quote: This probably wouldn't have happened if the ground wire had not ben cut. Therin lies your problem.


Stewart, I'm not sure I'm following your train of thought here. Would you please elaborate your cut ground theory?

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Fried dishwasher wiring!
[#10] Posted: 03/22/2008 - 06:45:33 AM
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Quote: Originally posted by Chad Fabry

Quote: This probably wouldn't have happened if the ground wire had not ben cut. Therin lies your problem.


Stewart, I'm not sure I'm following your train of thought here. Would you please elaborate your cut ground theory?



The ground wire having been cut, with the neutral wires being burnt the fault had no were to go. The fault used the the only means available to it. The ground is intended as a safety measure. What would have happened if the grounded conductor had come loose and the ground not attached? By the way, where is the wirenut for the black wires?

The romex connector may be too tight and might be pinching the neutral, causing an inabilty of the wire to carry the proper amount current. It looks like the dishwaher is hardwired. Common practice in my area is a switched receptacle under the sink. The DW is then connected with a 6' appliance cord if within reach. This serves as a disconnecting means as well. I am not a fan of hardwired DW's. If there is enough slack in the romex, I would cut back the wires and install it properly.

I agree also that it more than likely would be a loose wirenut. More than likely the wires weren't twisted together. The installer simply used the wirenut. If the wires were just connected by the wirenut, the neutral wires could come loose and arc causing the burnt condition.

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Fried dishwasher wiring!
[#11] Posted: 03/22/2008 - 08:53:51 AM
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Quote: I agree also that it more than likely would be a loose wirenut. More than likely the wires weren't twisted together. The installer simply used the wirenut. If the wires were just connected by the wirenut, the neutral wires could come loose and arc causing the burnt condition.


I agree that the condition is caused by a bad connection. How would the ground wire be an alternative current path in that case? I'm not getting your point. The bad connection created high resistance, the high resistance created heat and the nut and insulation melted as a result. Having a ground wire wouldn't prevent that?

Chad Fabry
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Fried dishwasher wiring!
[#12] Posted: 03/22/2008 - 09:00:26 AM
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Quote: Originally posted by Sodapop

The ground wire having been cut,


There's nothing in the picture or the explanation of the problem to indicate that the ground wire had been cut.

Quote: with the neutral wires being burnt the fault had no were to go. The fault used the the only means available to it.


No. This wasn't a ground fault. It was a loose connection. What you see in the picture is the result of a series arc, not a ground fault. A series arc might or might not trip a breaker.

Quote: The ground is intended as a safety measure. What would have happened if the grounded conductor had come loose and the ground not attached? By the way, where is the wirenut for the black wires?


I think that the homeowner took it off while trying to figure out what was going on.

Quote: The romex connector may be too tight and might be pinching the neutral, causing an inabilty of the wire to carry the proper amount current.

If that had been the case, we'd be seeing the overheating taking place at the pinched neutral, not at the wirenut.

Quote: It looks like the dishwaher is hardwired. Common practice in my area is a switched receptacle under the sink. The DW is then connected with a 6' appliance cord if within reach. This serves as a disconnecting means as well. I am not a fan of hardwired DW's. If there is enough slack in the romex, I would cut back the wires and install it properly.

Using an appliance cord is a fine way to wire a dishwasher. But hardwiring it is also perfectly acceptable. Please don't make the mistake of labeling your way as the "proper" way.

Quote: I agree also that it more than likely would be a loose wirenut. More than likely the wires weren't twisted together. The installer simply used the wirenut. If the wires were just connected by the wirenut, the neutral wires could come loose and arc causing the burnt condition.

For at least the last 30 years, the instructions that come with wire nuts say NOT to pretwist them. The last time I saw instructions that told you to pretwist them was around 1974.

- Jim Katen, Oregon

Jim Katen, Oregon
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Fried dishwasher wiring!
[#13] Posted: 03/22/2008 - 1:12:18 PM
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In viewing the picture in close up it appeared that the ground wire had been cut. After another viewing, it does appear that the wirenuts have been removed. My error.

My using the word "fault" was also incorrect.

Regarding the romex romex connector, I have seen both as in your quote.

Regarding the dishwasher cord, I wasn't saying that my way was the proper way. I simply stated that is normally how it's done around here. That is my preferred method.

And lastly:

Regarding the wirenut: I was mainly refering to solid copper. In my experience, if you don't twist the wires together you can't get a solid connection and the wires work loose, arc. I have seen this too many times in the field and IMHO is due to poor workmanship.

No harm done. Thanks for dissecting my post. I'll never be too old to learn.

KY Master Electrician
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Fried dishwasher wiring!
[#14] Posted: 12/12/2008 - 3:50:04 PM
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Quote: Originally posted by Joe Tedesco

This picture was sent to me by a homeowner, he said: "As you can see, the white wires have fused together and the wire cap is completely melted. The other two wire caps (one black wire and the other neutral) did not melt, but had visible burn marks on them. The fuse was not tripped when I checked it, so I have no idea what could have caused this fire hazard. Should I just cut back the white wires and recap or give it a go or should I call in somebody? The dishwasher is four years old and has never experienced anything like this before."

I sent him a message just now asking about the repair or replacement status and brand of the product.

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Fried dishwasher wiring!
[#15] Posted: 12/12/2008 - 7:34:51 PM
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Hi Russel,

If you want to reply to a post with quotes, you need to post your own comments after the section of code that displayed in your composition box and looks like this - [/quote]. Once you've done that, submit your response and it will display.

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Fried dishwasher wiring!
[#16] Posted: 05/17/2009 - 5:11:32 PM
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This is a loose connection in the wirenut area. Both wires and the entire length of both wires had the same amount of current flowing through them but only the wirenut area experience extreme heat. This could have been through a very small (high resistance) connection or a totally open connection where arcing took place. Arcing gets very hot (like welding). As the voltage swing peaks at 120 and then again at -120 (actually +198 volts and -198 volts) it looks like it was high enough to jump the gap in this case. The higher the voltage, the further it will jump.
   
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