Fire Hazard

[mcquillerpvamu]

I am a new graduate so I have very little industry experience. For the most part I just started work 2 weeks ago. Anyway, downstairs to the control room, a fire started a couple months ago in an electrical cabinet. With an engr background, everyone thinks I can provide the answers. The electrician thinks a coil shorted and caught the panduit on fire which trickled to other wiring and along left side of cabinet. How valid is this guess? Also, there is a circuit branch attached to a 50A breaker. There are about 6 tie-ins and All the wiring there is 12 gauge? Now I don't believe that is the right gauge to handle that amperage. How much of a problem could this be in the future? We do no have any updated drawings so a toner had to be used make reconnections. There are also another 11 MOVs tied to a 50 A breaker. This also seems to be a problem. The electrical wiring dates back to the 1940's. There are even fuses I have never seen before. Since there is too much on 1 branch, is that providing an overrating on the wires & circuits? If anyone has some guidance it would be much appreciated.

 

[itsmoked]

mcquillerpvamu; Any chance of a picture of this..this.. thing? It would help a lot.

Certainly the 50A circuit has to be larger then 12AWG or there will be a bigger fire.. Soon.

When there are over-heats they can lead to fires that lead to short circuits. The short circuits can result in arcs which are extremely hot, like surface-of-the-sun hot. The resulting damage can be spectacular.

I would forget what happened, or speculation on what happened, and instead go for making everything correct and right! After all, this is what they will really complain about when you've been brought in to look at things and they fizzle again.


Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[mcquillerpvamu]

No there is no picture. They through the coil away. What exactly will happen the 12AWG is overamped? This should produce a short also right? From what I can tell, many people use the word "short" but not by its exact definition. Why would the coil short also?

 

[RalphChristie]

Anything that produces heat can start a fire.
Thermal energy = I²t

Thus, if there was a short on a coil (breakdown of insulation, two wires at different potentials touching each other, etc) and the protection (fuse, overload, etc) didn't operate, it could have resulted in a very high current flowing and thus ending in a fire.

For overloading wires: Wires are specified to carry a certain current continuously, and higher currents for certain times. (I²t - the higher the current, the shorter the time) The longer an overload condition exists, the hotter the wires will become, resulting in a breakdown of insulation and even sometimes fires.

Regards
Ralph

[red]Failure seldom stops us, it is the fear for failure that stops us - Jack Lemmon[/red]

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