N1755L
Computer
- Dec 27, 2002
- 17
Hello everyone,
Attached is a photo of a disconnect switch that was installed to disconnect a 600V, 3-phase, 30A water heater tank. The switch is indeed rated for 600V, 30Amps.
As you can see from the photo, the two outer screws have suffered a considerable amount of meltdown on the downward side facing the plate, and though the plate has spatter on it, it doesn't appear to have any arc burn damage (for as much as I can visually ascertain). Yes, that is a bit of insulation lifted off the left-side wire, but I can't really tell if it was blown off because of arcing, or if it was handling damage (whoever did this installation was not easy on the wire). The next thread, "What happened here? Your best guess welcome... Photo2" shows another angle of that left-side wire. The strange part is that the exposed copper is immaculate where that insulation is nicked, all the strands from the copper there has absolutely no damage at all (see photo2.jpg, on next thread, sorry, can't get the bloody camera to focus exactly on the wire, but let me assure you, there is no damage to the copper).
Another electrical company had been there earlier this morning and changed the elements in the hot water tank 'cause they'd made the assumption that there must be a problem with the elements 'cause it appears from what we've been told that the main fuses for the restaurant had previously blown before the breaker for this circuit had a chance to disengage. The manager says that after the elements had been changed, the circuit had been ok for approx. 15 mins. this morning, then the main fuse had popped again. Apparently, the previous times this "main fuse popping" had happened, the hot water tank would run for a period of time and eventually one of the main fuses would go, like this morning. I'm guessing that a second or third element in the hot water tank kicks in when this happens... will take a closer look at the tank tomorrow when I go install the replacement for that switch (a fused disconnect).
Is it possible for arcing to cause burning like what is seen on the switch screws in this photo, without similar burning at the other end of the arc (the nicked wire)? I can't imagine, I'm fairly certain it could not, but then where else would the arc have been going to on the end opposite the screws on the switch?
The burnt side is the line side, yes.
How did these switch screws sustain so much damage without any further damage being seen/found on either the wires, nor the cover of the box?
What's your best guess? Thanks.
Attached is a photo of a disconnect switch that was installed to disconnect a 600V, 3-phase, 30A water heater tank. The switch is indeed rated for 600V, 30Amps.
As you can see from the photo, the two outer screws have suffered a considerable amount of meltdown on the downward side facing the plate, and though the plate has spatter on it, it doesn't appear to have any arc burn damage (for as much as I can visually ascertain). Yes, that is a bit of insulation lifted off the left-side wire, but I can't really tell if it was blown off because of arcing, or if it was handling damage (whoever did this installation was not easy on the wire). The next thread, "What happened here? Your best guess welcome... Photo2" shows another angle of that left-side wire. The strange part is that the exposed copper is immaculate where that insulation is nicked, all the strands from the copper there has absolutely no damage at all (see photo2.jpg, on next thread, sorry, can't get the bloody camera to focus exactly on the wire, but let me assure you, there is no damage to the copper).
Another electrical company had been there earlier this morning and changed the elements in the hot water tank 'cause they'd made the assumption that there must be a problem with the elements 'cause it appears from what we've been told that the main fuses for the restaurant had previously blown before the breaker for this circuit had a chance to disengage. The manager says that after the elements had been changed, the circuit had been ok for approx. 15 mins. this morning, then the main fuse had popped again. Apparently, the previous times this "main fuse popping" had happened, the hot water tank would run for a period of time and eventually one of the main fuses would go, like this morning. I'm guessing that a second or third element in the hot water tank kicks in when this happens... will take a closer look at the tank tomorrow when I go install the replacement for that switch (a fused disconnect).
Is it possible for arcing to cause burning like what is seen on the switch screws in this photo, without similar burning at the other end of the arc (the nicked wire)? I can't imagine, I'm fairly certain it could not, but then where else would the arc have been going to on the end opposite the screws on the switch?
The burnt side is the line side, yes.
How did these switch screws sustain so much damage without any further damage being seen/found on either the wires, nor the cover of the box?
What's your best guess? Thanks.