inspectorreuben Posted March 31, 2011 Report Share Posted March 31, 2011 Does anyone know what might have caused the scorching at so many of the neutral wires in this panel? It wasn't split circuits run off the same phase. Click to Enlarge 51.41 KB Quote Link to comment Share on other sites More sharing options...
Tom Raymond Posted March 31, 2011 Report Share Posted March 31, 2011 Loose connection(s)? There is debris between the top two neutrals and severe corrosion on the bottom two in that pic, does it really matter? You've got more than enough to call in a sparky, and the melted wires reinforce the importance of doing so sooner rather than later. Quote Link to comment Share on other sites More sharing options...
inspectorreuben Posted March 31, 2011 Author Report Share Posted March 31, 2011 There is debris between the top two neutrals and severe corrosion on the bottom two in that pic, does it really matter? Yes. I like knowing how stuff works and why stuff happens. - Reuben Quote Link to comment Share on other sites More sharing options...
Mr. Electric Posted March 31, 2011 Report Share Posted March 31, 2011 Looks like a combination of loose connections and heavy loads. I have seen this in older homes that have been overloading the circuits by using things like hair dryers in the bedroom, or portable heaters to heat the house. For sure want to call for a licensed electrician to check it out. Quote Link to comment Share on other sites More sharing options...
Marc Posted March 31, 2011 Report Share Posted March 31, 2011 Perhaps only one or a few of the scorched connections generated the heat and the conducted heat ended up being sufficient to burn the insulation of other nearby conductors. Heat in small quantities does worsen some types of connections and lead to additional heat being developed. As to which connection began developing heat...look at the screws. There's one that sticks out. Third from the bottom. Look like it severed and left a piece of conductor. Marc Quote Link to comment Share on other sites More sharing options...
inspectorreuben Posted March 31, 2011 Author Report Share Posted March 31, 2011 I have seen this in older homes that have been overloading the circuits by using things like hair dryers in the bedroom, or portable heaters to heat the house. Interesting. Without a loose connection, I would have thought a circuit breaker would trip before this happened. - Reuben Quote Link to comment Share on other sites More sharing options...
inspectorreuben Posted March 31, 2011 Author Report Share Posted March 31, 2011 Perhaps only one or a few of the scorched connections generated the heat and the conducted heat ended up being sufficient to burn the insulation of other nearby conductors. Heat in small quantities does worsen some types of connections and lead to additional heat being developed. As to which connection began developing heat...look at the screws. There's one that sticks out. Third from the bottom. Look like it severed and left a piece of conductor. Marc I see the screw you're talking about. It seems unlikely that one scorched wire could have caused all of those other wires to get scorched like that though, doesn't it? - Reuben Quote Link to comment Share on other sites More sharing options...
randynavarro Posted March 31, 2011 Report Share Posted March 31, 2011 I've only found one scorched conductor at a time. Multiple ones is kinda weird. Quote Link to comment Share on other sites More sharing options...
Tom Raymond Posted March 31, 2011 Report Share Posted March 31, 2011 I had a panel with multiple cooked wires once, but there where so many loose connections that lights all over the house flickered when I removed the dead front. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted March 31, 2011 Report Share Posted March 31, 2011 Does anyone know what might have caused the scorching at so many of the neutral wires in this panel? It wasn't split circuits run off the same phase. Electrician with a limp wrist. - Jim Katen, Oregon Quote Link to comment Share on other sites More sharing options...
Phillip Posted March 31, 2011 Report Share Posted March 31, 2011 It looks like you have more issues than the scorched neutrals. You also have ground wires on the neutral bus bar and two neutrals under one screw. Quote Link to comment Share on other sites More sharing options...
Richard Moore Posted April 1, 2011 Report Share Posted April 1, 2011 You also have ground wires on the neutral bus bar ... I see a bonding strap on that bar so, presumably, it is service equipment and therefore no harm having grounds and neutrals on the same bar. Quote Link to comment Share on other sites More sharing options...
inspectorreuben Posted April 1, 2011 Author Report Share Posted April 1, 2011 I've only found one scorched conductor at a time. Multiple ones is kinda weird. Agreed. I've never seen a bunch like that before either. Electrician with a limp wrist. Maybe I should have tried tightening a few of the screws to see if they were loose? I wanted to pull on a few of the wires, but the panel was just too messy to go sticking my hands in there. You also have ground wires on the neutral bus bar ... I see a bonding strap on that bar so, presumably, it is service equipment and therefore no harm having grounds and neutrals on the same bar. Correct. - Reuben Quote Link to comment Share on other sites More sharing options...
Douglas Hansen Posted April 1, 2011 Report Share Posted April 1, 2011 Could this damage be the result of a lightning strike? Douglas Hansen Quote Link to comment Share on other sites More sharing options...
John Kogel Posted April 1, 2011 Report Share Posted April 1, 2011 The neutral bus grounding strap has also been hot, and it is right next to that burnt neutral. There could have been a massive power surge on a neutral. I wondered about lightning as well, or a high tension lead striking the service drop. Maybe a transformer blew. If a surge hit the neutral service, it could have taken the grounding strap back to ground. I wouldn't have messed with it at all. Best to let the electrician see the panel in it's unaltered state. Good catch, Reuben. Quote Link to comment Share on other sites More sharing options...
John Dirks Jr Posted April 1, 2011 Report Share Posted April 1, 2011 The uniform discoloration of the neutral bar might suggest that the neutral bar was the source of the heat. If so, my vote would be for lightning. It may have heated through energy traveling through the ground conductors. The corrosion on the connections could have happened after the affects of lightning. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted April 1, 2011 Report Share Posted April 1, 2011 The last time I saw one like that, each of the screws was loose. The installer (I hesitate to call him an electrician) had simply neglected to tighten them. Click to Enlarge 83.66 KB Quote Link to comment Share on other sites More sharing options...
Douglas Hansen Posted April 1, 2011 Report Share Posted April 1, 2011 I wondered about the "all screws loose" scenario too. In Reuben's photo, it looks like the screw heads are recessed to the level they would be if they were tightened. The ones in your photo don't look the same. Douglas Hansen Quote Link to comment Share on other sites More sharing options...
hausdok Posted April 1, 2011 Report Share Posted April 1, 2011 Could that happen if the service grounding conductor was disconnected from the electrode and the house took a lightning hit? ONE TEAM - ONE FIGHT!!! Mike Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted April 1, 2011 Report Share Posted April 1, 2011 I wondered about the "all screws loose" scenario too. In Reuben's photo, it looks like the screw heads are recessed to the level they would be if they were tightened. The ones in your photo don't look the same. Douglas Hansen Though I rarely use a flashlight when taking pictures, I used one here just to highlight the height of the screws. Reuben used the flash on his camera, which tends to flatten the image. Still, I see what you mean. If those screws are loose, they're not loose by much. If it was from a lightning strike, it would had to have been just right - enough to burn the higher-resistance connections, but not high enough to burn the wires themselves. I'd also expect to find similar burning at other connections elsewhere in the system. - Jim Katen, Oregon Quote Link to comment Share on other sites More sharing options...
Douglas Hansen Posted April 2, 2011 Report Share Posted April 2, 2011 I wondered about the "all screws loose" scenario too. In Reuben's photo, it looks like the screw heads are recessed to the level they would be if they were tightened. The ones in your photo don't look the same. Douglas Hansen Though I rarely use a flashlight when taking pictures, I used one here just to highlight the height of the screws. Reuben used the flash on his camera, which tends to flatten the image. Still, I see what you mean. If those screws are loose, they're not loose by much. If it was from a lightning strike, it would had to have been just right - enough to burn the higher-resistance connections, but not high enough to burn the wires themselves. I'd also expect to find similar burning at other connections elsewhere in the system. - Jim Katen, Oregon In Reuben's photo, there are indications of overheating on the equipment grounds and the bonding jumper, perhaps a point for the lightning scenario. There is also a lot of corroded copper, something I wouldn't anticipate from a one-time event, and that would more likely be associated with some long term overheating. Take back that point from the lightning side of the scorecard. It would be interesting to know the history. Douglas Hansen Quote Link to comment Share on other sites More sharing options...
Richard Saunders Posted April 2, 2011 Report Share Posted April 2, 2011 Whats with the bottom two where the conductors are completely gone, only the ends visible? Nice picture, BTW. Quote Link to comment Share on other sites More sharing options...
gregzoll Posted April 2, 2011 Report Share Posted April 2, 2011 The key is shortest path to ground. Unless it is a Sub[panel (ie Lighting, Receptacles, more circuits) a loose connection, or lighting strike will cause the over-voltage to seek Shortest path to ground, thus causing also the effect you saw. Quote Link to comment Share on other sites More sharing options...
gregzoll Posted April 2, 2011 Report Share Posted April 2, 2011 Perhaps only one or a few of the scorched connections generated the heat and the conducted heat ended up being sufficient to burn the insulation of other nearby conductors. Heat in small quantities does worsen some types of connections and lead to additional heat being developed. As to which connection began developing heat...look at the screws. There's one that sticks out. Third from the bottom. Look like it severed and left a piece of conductor. Marc I see the screw you're talking about. It seems unlikely that one scorched wire could have caused all of those other wires to get scorched like that though, doesn't it? - Reuben The breaker will never trip, as long as volts & amps are within its limits. If volts are low, and amps are high, the breaker will only trip if if overheats to the point that it exceeds the setpoint that it was engineered for. Quote Link to comment Share on other sites More sharing options...
Marc Posted April 2, 2011 Report Share Posted April 2, 2011 Perhaps only one or a few of the scorched connections generated the heat and the conducted heat ended up being sufficient to burn the insulation of other nearby conductors. Heat in small quantities does worsen some types of connections and lead to additional heat being developed. As to which connection began developing heat...look at the screws. There's one that sticks out. Third from the bottom. Look like it severed and left a piece of conductor. Marc I see the screw you're talking about. It seems unlikely that one scorched wire could have caused all of those other wires to get scorched like that though, doesn't it? - Reuben The breaker will never trip, as long as volts & amps are within its limits. If volts are low, and amps are high, the breaker will only trip if if overheats to the point that it exceeds the setpoint that it was engineered for. A thermal/magnetic breaker will trip much sooner than normal if it receives additional heat from an external source such as a bad connection at the terminal or bus bar. Marc Quote Link to comment Share on other sites More sharing options...
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