Beware of loose connections!

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Stevareno

Senior Member
Location
Dallas, TX
I took a service call a while back. Main complaint was breakers tripping, but also the main breaker was getting unusually hot.
The panel was mostly lighting circuits, so I turned on all the lights, took the cover off the panel and started checking the amperage of the individual circuits.
After a couple of minutes, something caught my eye.

jrtnbs.jpg


No, that's not a reflection. It's a glowing red spot. :eek:
I checked that bus bar with digital thermometer and it was reading over 700 degrees F! :eek:

Here's a wider shot:
fddr94.jpg


Both the A and B phase bus bars are charred black. All three bolts connecting the bus bars together were loose.

And look at this:
mvktio.jpg




Something else I found. I know you can't tell from the picture, but the highlighted screw is not factory. My guess, someone stripped out the factory screw and replaced it with this one.
Also note how the middle screw turned black from the heat.
Needless to say, I replaced that panel two days later.

So, just a reminder to you fellow electricians out there, double check for loose connections on your installations.
 
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George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
I have heard many tales of loose factory connections as well - it's tough to catch them all, but it's never hurts to second guess the factory as well. :eek:hmy:
 

hurk27

Senior Member
Why does this not suprise me with a GE panel, I can't count how many I have found from the factory with loose buss bars, but they are not even close to the failures I found when T&B was "trying" to make service gear, their meter packs had the worst problem of loosing neutrals and phases because of the way they used self taping screws to hold the buss bars together, yes steel screws right in to soft aluminum buss bars no spring washers or anything.

Square D both Home Line and QO can have loose nuts between the top mounted main and the buss bars but not too common.
 
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the blur

Senior Member
Location
cyberspace
I just seen a 60 amp breaker melt with just a 15 amp load on it. The breaker melted to the buss bars. Loose breaker over 20 years or so. I needed a rubber mallet to whack it out, and only then I saw the buss bars.

turned into a $2000 panel job,.
 

Stevareno

Senior Member
Location
Dallas, TX
Found another one.

Found another one.

3504d92.jpg


From the looks of it, that neutral wire had been loose for a long time. It heated up that bus enough to cause the other neutrals around it to show signs of heat stress.
 
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