What went on in this GFCI receptacle?

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ELA, it is my understanding that the internal parts of the same grade and brand of 15 and 20 amp receptacles are identical. Only the face is different.
 
090502-1250 EST

ELA:

The Leviton brass or other alloy leaf spring that supports the silver contact is 0.012" x 0.130" or 0.00156 sq-in. This is between the cross sectional area of #17 and #18 and it is not copper so the resistivity is somewhat greater. However, it is sort of in free air. The other conductors are larger in area. And there are the four heavily soldered joints in the high current path. Copper fusing current is about 82 A for #18 copper.

The Leviton I have is labeled as 20 A.

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I've more than once picked up a brand new GFI put it in and it doesn't act like it should. They can be finnicky sometimes.
 
480sparky said:
If you're concerned about your wiring, install a 20a bath circuit and use a GFI breaker and a commercial-grade receptacle.
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No I am not concerned with my wiring. I have a GFCI breaker feeding the bath circuits.


My comments were along the line of the original poster and possible failure modes of GFCIs.

Personally I feel more comfortable with the construction of a GFCI breaker than I do the GFCI receptical. I think there is a lot of pressure to produce inexpensive GFCI recepticals that could lead to lessor quality devices.


Gar,
I was looking for your orginal pictures on the GFCI you took apart and did not locate them. I thought maybe one of your pictures detailed the contact assembly?

I think my main concern with the construction of the receptical was the reliance on a mechanical alignment of the contact assembly halves. The terminal mounted contacts to the other half of the contacts. That construction was a little contrary to my concept of reliable.

It appeared that enough torque used when tightening the terminations could aggravate the contact alignment?
 
I am guessing that your wife/daughters hair dryers cooked it. every device has its given service life.
 
090503-2100 EST

ELA:

I ran a voltage drop test on a Leviton 7899-W at 12 A load plugged into the socket. No load on the output terminals.

The voltage drops from the input terminals to the output terminals were 0.019 and 0.022. This is for the path from the input terminal thru the current transformer, all the heavy solder stuff, and to the separation point of leaf spring pairs. Thus, it does not include the spring portion of the leaf spring and the silver contacts. These resistances are 0.0016 and 0.0018 ohms.

When the leaf springs and silver contacts are included the drops are 0.055 and 0.058. The corresponding resistances are 0.0045 and 0.0048 ohms, and the power dissipations were about 0.7 W, or a total of 1.4 W. At 20 A this would be almost 4 W.

The drop in a QO20 A breaker is considerably higher.


For the person that commented on quality.

Mass production does not mean low quality. Management policy is what determines quality.

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Thanks Gar,
Your picture # 2592A details the contacts. I was speaking of the part labeled "Hot Load Terminal" in your picture. This part is only held in place by the plastic molded housing.
The alignment of this part to the other half of the contact is what I had some concerns with.

I would have liked to have seen this area on the original posters device.


I thought I remembered you mentioning that you examined a 20A device.
Did you compare both a 15 and 20A device and can you confirm what iwire mentioned about the only difference being the face?
 
090504-1125 EST

ELA:

I only looked at 20 A devices. Contacts have a radius so there is only a small contact area. I do not think there should be an alignment problem unless there is a failure of quality control.

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gar said:
The Leviton brass or other alloy leaf spring that supports the silver contact is 0.012" x 0.130" or 0.00156 sq-in. This is between the cross sectional area of #17 and #18 and it is not copper so the resistivity is somewhat greater. However, it is sort of in free air.
Click to expand...
It's also only an inch or so in length.
 
I'm with nakulak on this one. When my daughter is home from college I have to make special arrangements with the POCO for more power (We're on a 1st name basis:grin:). I walk in the house and just about everything is on - lights, hairdryers, curling irons, etc.

Anyway, I see the general consensus is that either a loose connection at the terminal (clamp or wrap around) cause the burn and I tend to agree with that.
 
090504-1657 EST

Larry:

From the contact center to the split on the leaf spring is about 0.5". From my above measurement of the resistance of the leaf plus contact I have about 0.0048-0.0018 = 0.003 ohms. 20 A thru this portion is a power of about 1.2 W. A fair amount of heat for a small area.

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