Breaker did not trip...

[SIRSPARKSALOT]

I was working yesterday (I know Sundays are for God and Family, but I was behind) and inadvertently cut through a cable I thought was de-energized, but come to find out (since my dikes are now strippers) that it wasn't. The breaker never tripped! This is a brand new service, 15A 120V circuit. What would cause the breaker to not trip?

The reason for my questions is that years ago we worked on a house with an underground service from a padmount transformer. The plumber was trying to locate a circuit to turn it off. He splashed hot and neutral together on a circuit multiple times. The breaker never tripped and the plumber caused a fire in the attic.

In the end it was determined that there was a problem with the padmount that fed his home.

Can anyone shed some light on this for me? Any recommendations as to what to test to determine that everything is safe and operating as intended? I appreciate any help on this one!!!

 

[zog]

Unless you created a fault, and that fault current was present long enough to be above the TCC for the breaker it shouldn't trip.

 

[GoldDigger]

Unless you created a fault, and that fault current was present long enough to be above the TCC for the breaker it shouldn't trip.

Between the current limitation of the arc and wire impedance, and the short duration of the fault resulting from the cutting action of the dykes and your flinching away, it seems to have missed the thermal trip threshold and also not given enough current for a magnetic trip. Since it was a parallel arc fault, an AFCI breaker might have tripped.

 

[K8MHZ]

I had to find a cable that had been cut through with a sawzall. It was on an AFCI and the breaker never tripped. It did arc, though. We found plenty of evidence of that once we located the cut NMS cable buried in spray insulation.

 

[brian john]

Or the circuit breaker is defective.

 

[ptonsparky]

I was working yesterday (I know Sundays are for God and Family, but I was behind) and inadvertently cut through a cable I thought was de-energized, but come to find out (since my dikes are now strippers) that it wasn't. The breaker never tripped! This is a brand new service, 15A 120V circuit. What would cause the breaker to not trip?

The reason for my questions is that years ago we worked on a house with an underground service from a padmount transformer. The plumber was trying to locate a circuit to turn it off. He splashed hot and neutral together on a circuit multiple times. The breaker never tripped and the plumber caused a fire in the attic.

In the end it was determined that there was a problem with the padmount that fed his home.

Can anyone shed some light on this for me? Any recommendations as to what to test to determine that everything is safe and operating as intended? I appreciate any help on this one!!!

Makes the best set of strippers IMO.:roll:

 

[hurk27]

the impedance of the circuit can limit the current to the point a breaker might not trip on a long run, this with how far the utility transformer is from the house can add to this.

But I have ran across a few Siemens ITE breakers that you could weld from, one time I (luckily by chance) was at the panel labeling it when a plumber drilled into one of our circuits, I heard a buzz then looked up and saw that one of the NM cable was starting to smoke, I just reached up and killed the main, the breaker for that circuit never tripped, the wire had to be replaced luckily it was a short run.