RECEPTACLE FAILURE

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ep27pe's picture
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Joined: 2014-03-13

Attached are images of an outlet failure. I would appreciate if anyone knows who manufactured the device and an opinion of what caused the failure. The device was located in a commercial kitchen.

 

 

 

 

 

 

 

mdshunk's picture
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Joined: 2014-03-14

I don't see the attached image, but I can speculate based on the stated location and my own years of experience. In a commercial kitchen, typically it would either be a loose receptacle based on years of wear from frequent interface of attachment plugs or water/grease infiltration. It doesn't really matter who makes the receptacle... none are immune to the effects of time and the environment of a commercial kitchen.

ep27pe's picture
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Joined: 2014-03-13

Pics are uploaded now.

mdshunk's picture
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Joined: 2014-03-14

The manufacturer appears to be Songny Electrical Appliance Co., Ltd. Double-check that for yourself, please. Oddly, I can't seem to find them in the UL or ETL manufactuter directory.

The failure, however, looks fairly typical for a high resistance contact. This is generally due to low insertion/extraction force that occurs due to normal wear and tear.

Mike b's picture
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Joined: 2013-10-28

I agree. It looks like there may have been a loose connection. GFCI receptacles do not see arcs, only shorts.

electrogasman's picture
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Joined: 2014-03-16

Looks like maybe the wires were "stabbed in" not wrapped around the terminal screws. This is a terrible connection. It is hard to tell from what is left of the device.

darrin's picture
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Joined: 2013-12-02

A 20 amp device may have helped, some.

howelec8's picture
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Joined: 2014-03-17

I a in agreement with the other posts. I have replaced many 'identical' failures of this nature and most were caused by contact with water and/or grease. Degreasers were also a culprit, as I was often called for a repair the morning after a night chemical cleanup and wall wash. When a liquid enters the receptacle it will cause it to arc/short internally momentarily, but often for a much longer time before it clears or worse possible fire. Before the Code changed (re: GFI use in commercial kitchens) the problem was limited to standard receptacles - more forgiving than a GFI.

mdshunk's picture
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Joined: 2014-03-14

[quote=darrin] A 20 amp device may have helped, some. [/quote]

Not so sure, myself. I worked for a good many years for AMP (now Tyco), and we made the internal contacts for many of the major brand receptacles. The 15 and 20 amp internals were identical. The only difference was the molding of the plastic parts. Insertion/extraction force specs, the material of the contacts, and the thickness of the contact materials were identical.

With regard to this potentially being "back stabbed", that idea can go out the window. This receptacle is "back wired", which is different. The wire goes in a hole, and as the screw is tightened, it's clamped between two metal plates. Electricians will know, however, that if you have a "kink" in the stripped section of the conductor the clamp will feel tight but the connection will not be good.

Additionally, it's reasonably well-known that "overseas" receptacles often feature screws that will strip the threads off if the screw is over-tightened, making the connection feel proper but will loosen a thread or two over time as the installation ages.

I still feel pretty confident that this receptacle failed due to water/grease contamination or normal internal contact wear/loosening due to frequent attachment plug interchange. This receptacle is obviously a budget brand, and possibly (possibly, don't quote me - I'm just an electrician) not listed by a nationally recognized testing laboratory, but I don't really pin the failure on either of those reasons. The failure pictured is very typical.

cowboycaly's picture
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Joined: 2014-03-18

I would have used a 20 amp receptacle and turned the screw terminals tightly. Looks like loose connections to me.

IrishElectrician's picture
Joined: 2014-03-03

[quote=ep27pe] Attached are images of an outlet failure. I would appreciate if anyone knows who manufactured the device and an opinion of what caused the failure. The device was located in a commercial kitchen. [/quote]

What was plugged into it?

David Sewell's picture
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Joined: 2014-02-05

I have seen this and what caused it in my case was the constant insertion and extraction of devices. The hot wire receives small wear holes from the plug moving in and out ever so slightly, but in time because the folding of the conductors is not done in a manner that keeps them from being in direct contact with the GFI as it moves.

jsaporito's picture
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Joined: 2012-08-09

Two things are wrong. One is that a 20A circuit was used to power it up because it's a 15A GFCI and when the conductors were installed it wasn't torqued properly. This created arcing when it was in use, which caused it to heat up. Since it was on a 20A circuit the CB never opened up.

mdshunk's picture
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Joined: 2014-03-14

There's actually no requirement to use a 20 amp rated receptacle on a 20 amp circuit when anything more than a single (simplex) device is used. I say again, the internal parts are absolutely identical.

sparky377's picture
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Joined: 2013-10-07

Just my observations:

1. Based on the device being tamper resistant (TR on front) it is only a few years old. Therefore, I would not expect to see failure due to insertion/extraction of plugs this soon.

2. The "LGL" in an oval looks like a trademark, but is one I don't recognize. Thinking cheap knock-off, as alluded to by mdshunk.

3. The major damage is to the rear of the device. I would expect to see more damage on the front is there was an overload or short caused by the load. The only evidence on the front is the scorching at the neutral conductor. The entire hot terminal has been completely blown away on the back. There was a fault condition between the phase conductor and the neutral, equipment grounding conductor, or the box. Based on the damage at the edge between back and top of the housing, but not to the EGC (appears to have been cut - not melted). I am leaning toward hot-to-box, possibly caused by the introduction of water or chemicals during cleaning.

A couple of pictures prior to removal of the receptacle and of the box interior after removal would have been nice and may have provided more information. A nice exercise in forensic engineering.

lojicstash's picture
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Joined: 2013-11-19

I completly agree with sparky377. TR receptacles are new/er, the fault was mostly at the rear or termination point, and without a UL listing, should have never been installed in the first place.

tmegger's picture
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Joined: 2014-04-09

If you look at the load side of this device you will see that the "hump" taped over is the screw used to tighten the conductor when it is stabbed in the back. The line side is the same. I believe that this was a sloppy installation and the screw was never tightened down thus causing the heating up of this termination point when a load was applied. The grounded conductor termination was collateral damage.

ahunter's picture
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Joined: 2013-10-30

Interesting. Did not think I would see this happening to a GFCI.

davepierson's picture
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Joined: 2013-07-31

You will never know for sure what happened. Just replace it with a quality device.

gneault's picture
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Joined: 2013-10-09

It looks to me like water damage, shorting the hot to neutral and/or ground.

Bearfoot's picture
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Joined: 2014-03-03

Would voltage be present on the service entrance ground conductor? Yes or No?

grimmy's picture
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Joined: 2014-05-06

Looks like a unit purchased from an on-line supplier. You have to look closely at the yoke to find the listing agencies.

MEatECM's picture
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Joined: 2013-02-13

I agree with sparky377. The wire was cut. This seems to tell me the wire got so hot the insulation melted and shorted to box. If original wiring was correct, meaning it wasn't connected "reverse polarity" the neutral wire originally had a poor connection to the receptacle, causing the neutral to get hotter than the energized (hot) conductor, causing the neutral wire insulation to melt, then wire to weld to the box. If there was a good connection, then the breaker would have tripped from an overload due to short or load overload.Seems the breaker didn't trip, so the load was able to carry through the little bit of connection it did have. This would have caused the overheating.

MEatECM's picture
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Joined: 2013-02-13

Actually, now that I think of it, seems it was originally wired with reverse polarity and that the hot wire that was connected to the neutral of the receptacle had a bad connection. This would explain why the wire was cut from where the hot wire eventually shorted to the box and then tripped breaker. The bad or poor connection caused the melt down of the receptacle and the insulation of the hot wire. Seems the neutral wire would not have welded to the box.

Brigid Lenfest Gallop's picture
Joined: 2013-10-30

[quote=darrin]A 20 amp device may have helped, some.[/quote]

Definitely! The first thing I noticed: a 15A receptacle in a commercial application?

sparky377's picture
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Joined: 2013-10-07

Brigid:
Most smaller appliances have 5-15P caps making them acceptable on a 5-15R receptacle, even in a commercial kitchen. If the appliance had a 5-20P cap a smart designer would have called for a dedicated individual branch circuit rated 20A with a SINGLE 5-20R, aka "simplex," receptacle.
I don't believe the device was wired with reverse polarity. All new GFCI receptacles, and I am hoping even cheap knock-offs, come from the factory pre-tripped and cannot be reset until wired correctly and receiving power. Therefore, this device could never have experienced an overload because the RESET button would not hold if the receptacle was connected with reverse polarity.
By the way, is it safe to assume a replacement device has been installed and is working without problems?

tmegger's picture
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Joined: 2014-04-09

Brigid, GFI devices are not rated commercial or residential, they rated by amperage and voltage, and per Table 210.21(B)(3), NEC 2011. A 15A or 20A device can be used on a 20A rated circuit. But how do we know it's a 20A circuit? There can be a 15A circuit in a commercial kitchen depending on the load.

jsaporito's picture
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Joined: 2012-08-09

A loose ungrounded conductor, it's always the culprit. I have replaced many of the same conditions.

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