Dryer Plug

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I have a dryer plug that melted a couple of months ago. I replaced it and the cord to the dryer. the customer called me again and said he could smell the something and when he touched the Plug it was very hot. I suspected a loose connection the first time but don't see how this one could have worked loose in a couple of months. is there something else i should check. could it something simple like an overloaded dryer.
 

LEO2854

Esteemed Member
Location
Ma
I have a dryer plug that melted a couple of months ago. I replaced it and the cord to the dryer. the customer called me again and said he could smell the something and when he touched the Plug it was very hot. I suspected a loose connection the first time but don't see how this one could have worked loose in a couple of months. is there something else i should check. could it something simple like an overloaded dryer.

It sounds like the dryer is the problem, have you amp it out?
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
It sounds like the dryer is the problem, have you amp it out?

Leo,
what could cause an overload internal to the dryer that will cause an over current?

On a second note,
Also, she may have done continuous loads and the plug got warm to touch. What may be hot to one person may be warm to another.
 

kwired

Electron manager
Location
NE Nebraska
Were conductors of sufficient size?

Were conductors overheated from the first failure? If they have "lost their temper" so to speak they can cause more trouble if used again and should be cut back to a point that had not been overheated - if possible, otherwise they need replaced.
 

kwired

Electron manager
Location
NE Nebraska
I agree.

Edward, an element shorted to ground could cause higher current.

True, but unless you have a "no trip" FPE or Zinsco breaker, shouldn't you be tripping the overcurrent protection at some point? Assuming you have properly sized protection of course.
 
I've found that the pigtails at most big box stores are Chinese-made and of very poor quality. Same goes for Lowe's house brand of receptacles and cords (Utilitech). Could this be the case?
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I have a dryer plug that melted a couple of months ago. I replaced it and the cord to the dryer. the customer called me again and said he could smell the something and when he touched the Plug it was very hot. I suspected a loose connection the first time but don't see how this one could have worked loose in a couple of months. is there something else i should check. could it something simple like an overloaded dryer.

Did you inspect the connections to the receptacle? Also, if a receptacle got hot enough to melt plastic, there is a good chance the receptacle is damaged. It probably has lost its tension and has oxide on the mating surfaces of the socket.
 

growler

Senior Member
Location
Atlanta,GA
I have a dryer plug that melted a couple of months ago. I replaced it and the cord to the dryer. the customer called me again and said he could smell the something and when he touched the Plug it was very hot. I suspected a loose connection the first time but don't see how this one could have worked loose in a couple of months. is there something else i should check. could it something simple like an overloaded dryer.


When you have heat at a receptacle the most common problem is a poor connection. A bad connection will cause heat and yet not allow enough current flow to trip a breaker.

It only takes a few minutes to remove the panel cover and use the ammeter to measure current draw. I think on a second trip I would do this just to be on the safe side even if you do notice a bad connection.

I find that lots of material are not really of high quality even those not made in China. I think that quality control is a thing of the past.

I have seen dryer plugs go bad in a very short time. I don't know why, I assumed they were not installed corectly but who knows. May have been poor quality materials.
 

electricman2

Senior Member
Location
North Carolina
Occupation
Retired Electrical Contractor
Did you inspect the connections to the receptacle? Also, if a receptacle got hot enough to melt plastic, there is a good chance the receptacle is damaged. It probably has lost its tension and has oxide on the mating surfaces of the socket.

I agree, if the plug was melted, most likely the receptacle was damaged as well.
 

iwire

Moderator
Staff member
Location
Massachusetts
It sounds like the dryer is the problem, have you amp it out?

I agree.

Edward, an element shorted to ground could cause higher current.

True, but unless you have a "no trip" FPE or Zinsco breaker, shouldn't you be tripping the overcurrent protection at some point? Assuming you have properly sized protection of course.

Well isn't a dryer cord and plug supposed to be able to carry the load?

Isn't one of the first steps in troubleshooting something like this taking a current reading?

Lets not forget a properly operating 30 amp breaker can likely pass 35 or more amps forever.:)


I do not know what is causing the problem, but I do know that I agree with Leo about taking a current reading.

Basically I was just trying to answer Edwards question.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
I agree.

Edward, an element shorted to ground could cause higher current.

I have not tried this and am not sure, but if the element is rated at 240V and one end shorts to frame doesn't it mean that it will only see 120V across it. And will you have current flow across a 240V rated element that has 120V to it?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I have not tried this and am not sure, but if the element is rated at 240V and one end shorts to frame doesn't it mean that it will only see 120V across it. And will you have current flow across a 240V rated element that has 120V to it?
If the short to the frame doesn't cause the OCPD to clear the fault, the element will still have 240 across it.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
If the short to the frame doesn't cause the OCPD to clear the fault, the element will still have 240 across it.

And for increased current, the fault could also be somewhere between the element ends but not right at the middle. The result of that would be increased current in one leg and decreased current in the other. Total current would go up as well, but the critical thing is that one pole of the two pole breaker will trip if the increase is great enough.
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
And for increased current, the fault could also be somewhere between the element ends but not right at the middle. The result of that would be increased current in one leg and decreased current in the other. Total current would go up as well, but the critical thing is that one pole of the two pole breaker will trip if the increase is great enough.

I agree, check to make sure that the element isn't shorting to case.
I've seen burnt receptacle/cord ends plenty of times.
Personally I think that even though a cable may be properly sized it seems to be the attachment of the wire to terminal within the molded plug that is the culprit, I think cords should be upsized 1 just to cover the possibility that a strand(s) may be broken or cut durring the stripping/manufacturing of the cord end and this goes for more than just dryer cords.
 

kwired

Electron manager
Location
NE Nebraska
Well isn't a dryer cord and plug supposed to be able to carry the load?

Isn't one of the first steps in troubleshooting something like this taking a current reading?

Lets not forget a properly operating 30 amp breaker can likely pass 35 or more amps forever.:)


I do not know what is causing the problem, but I do know that I agree with Leo about taking a current reading.

Basically I was just trying to answer Edwards question.
wasn't intention to point a finger at any particular reply here, sust saying if you have a typical application of a household electric dryer you have a 30 amp receptacle, a 30 amp cord, 30 amp conductors and a 30 amp overcurrent device - unless something fails what is there to overload without tripping the overcurrent device? Yes the breaker may hold 35 amps indefinitely, but that 30 amp cord, plug, branch circuit conductors should also not have significant heating.

I have not tried this and am not sure, but if the element is rated at 240V and one end shorts to frame doesn't it mean that it will only see 120V across it. And will you have current flow across a 240V rated element that has 120V to it?
It will have 120 volts from nearest ungrounded end to the fault, but as mentioned unless the fault is exactly at mid point of the element, you will not have balanced current. If a solid fault were at the 25% point of element length you would be applying 120 volts to a section of element that under normal operation only has 60 volts drop across it.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
wasn't intention to point a finger at any particular reply here, sust saying if you have a typical application of a household electric dryer you have a 30 amp receptacle, a 30 amp cord, 30 amp conductors and a 30 amp overcurrent device - unless something fails what is there to overload without tripping the overcurrent device? Yes the breaker may hold 35 amps indefinitely, but that 30 amp cord, plug, branch circuit conductors should also not have significant heating.

It will have 120 volts from nearest ungrounded end to the fault, but as mentioned unless the fault is exactly at mid point of the element, you will not have balanced current. If a solid fault were at the 25% point of element length you would be applying 120 volts to a section of element that under normal operation only has 60 volts drop across it.

How can the element short half way or 1/4 of the way of the lenght . Isn't the "heating element" encased in a tubular piece?
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
How can the element short half way or 1/4 of the way of the lenght . Isn't the "heating element" encased in a tubular piece?
It is, but the tube is metal, probably with mineral insulation similar to MI cable.
But I suppose it is possible for a failed element to short to the tube. A high resistance can lead to a hot spot that melts the wire.
 

iwire

Moderator
Staff member
Location
Massachusetts
How can the element short half way or 1/4 of the way of the lenght . Isn't the "heating element" encased in a tubular piece?

Being a thrifty yankee I have repaired electric dryers and none of the ones I have worked on had that kind of element. They used open 'spring like' elements held on stand offs inside a metal duct.

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