Melted AC breaker

Status
Not open for further replies.
C

Curtiszeph

Member
Location
Murray Ky
20190712_195830.jpg20190712_200409.jpg20190712_202224.jpg20190712_203032.jpgGot called out for a panel that was making a "buzzing" sound, opened it up to find the AC breaker had caught fire without tripping any breakers. the neutral bar was melted in places with weld marks all over the inside of the can and grounds melted in half. Siemens I.T.E panel was installed in 1985, no ground was ran from the meter base. Is this just a loose connection/breaker malfunction or am i looking for bigger issues with the AC unit itself? Of course I am replacing the panel but just curious what you guys thought
 
That's classic "loose connection" causing high resistance and heat, resulting in the melted breaker.
No ground wire should be run from the meter. The grounding (EGC) begins at the service panel or first means of disconnect w/OCPD.
 
Little Bill said:
That's classic "loose connection" causing high resistance and heat, resulting in the melted breaker.
No ground wire should be run from the meter. The grounding (EGC) begins at the service panel or first means of disconnect w/OCPD.
Click to expand...

thats what i was thinking too. not sure what you mean about it not needing a EGC, this is the only service panel and disconnect. the EGC should have been ran with the feeders from the meter socket but there is only the 240 and neutral
 
Curtiszeph said:
the EGC should have been ran with the feeders from the meter socket but there is only the 240 and neutral
Click to expand...
Incorrect. The EGC system should not start until the enclosure that contains the main disconnect, and should also be where the GECs terminate. Before that, there should only be the neutral, and everything that should be grounded, like the meter base, is grounded via the neutral.
 
LarryFine said:
Incorrect. The EGC system should not start until the enclosure that contains the main disconnect, and should also be where the GECs terminate. Before that, there should only be the neutral, and everything that should be grounded, like the meter base, is grounded via the neutral.
Click to expand...

yes, i understand that. what i am saying is that the EGC connected to the ground rod is terminated at the meter socket, the 100A breaker in the photo of the panel is the disconnect for this panel, the EGC from the ground rod should have been brought to this panel but was not. there is no disconnect between this panel and the meter socket. the nipple you see in the lower left corner is connected directly to the meter on the other side of the wall, but they knocked out the opening too big so the nipple isnt even touching the panel can.
 
Curtiszeph said:
yes, i understand that. what i am saying is that the EGC connected to the ground rod is terminated at the meter socket, the 100A breaker in the photo of the panel is the disconnect for this panel, the EGC from the ground rod should have been brought to this panel but was not. there is no disconnect between this panel and the meter socket. the nipple you see in the lower left corner is connected directly to the meter on the other side of the wall, but they knocked out the opening too big so the nipple isnt even touching the panel can.
Click to expand...

First, let's get some terminology straight.
The wire/conductor from the ground rod is called a GEC (grounding electrode conductor) and connects/bonds to the neutral conductor
The wire/conductor from the grounding bar in the panel to the load is called EGC (equipment grounding conductor). It is used to provide a clear path for fault current back to the panel, should there be a fault, to clear the fault by tripping the breaker

The GEC is allowed by the NEC to be connected anywhere from the weatherhead, down to the meter, or to the panel.
Since yours is connected to the meter socket, you don't need one in the panel. So you would only have two hots and a neutral ran from the meter to the panel.
The EGC starts in the panel on the grounding bus/bar. The EGC ran with the circuits lands on this bar. No EGC runs to a meter with the exception of a meter-main combo.
 
Okay, Curtis, I see the issue: EGC = Equipment Grounding Conductor; GEC = Grounding Electrode Conductor.

The GEC from the rod may terminate anywhere on the neutral at or before the main disconnect enclosure. Unless it's prohibited where you are, like it is here, the meter is the ideal place for a ground rod conductor.

I'm going to go out on the proverbial limb here and guess that the neutral bus was never bonded to the enclosure; that the green screw was not installed. Without it, because of the nipple not connected to the enclosure, it is not grounded/bonded to the neutral.
 
This was at my rental doublewide, earlier this week

AC breaker not from factory, evidently furnished by AC installer

HO panel, my partner took breaker with him so I didn't see it, but he said was not HO breaker
 

Attachments

  • 174 M'ton meltdown.jpg
    174 M'ton meltdown.jpg
    86.9 KB · Views: 2
electrofelon said:
Is it just me or do I see some burn marks in a few places at the bottom of the cabinet?
Click to expand...

I noticed that right off too. I don't think that can is bonded to anything. And whoever installed that panel didn't just break out the whole concentric KO, they didn't know what they were doing else they would have used a shorter nipple. Smacks of DIY or handyman.:rant:

-Hal
 
Picture #3 you can see upper right grounds burned, time for a service change and cutting back on the HR wires to get to non damaged insulation as the outer rx thermoplastic is discolored from heat. I would also check everything in the electrical circuits for damage before I put my name on it; lawyers.
How this passed inspection?
 
Status
Not open for further replies.
Top