An Idiot hahn? you're lack of professionalism is enough proof that you are a subject of your surroundings.
we are not discussing switchgear !
If you want to trade insults, toss another one my way and you'll find out how serious and knowledgable i am.
Mr. Perry the rest of the Physical World continues to function outside of your environment metal boxes & panels.
A Cat-Ion can do wonders for you., or not.
You sound like the type of P.E. that likes to make The Electric Field more impre$$ive than it already i$.
In this Field; we learn together or die apart.
I am, what I am, nevertheless, I Am
Here are some references that explain that it is not just "a flash of energy".
This should get you started to understanding that an arc flash or arc fault is not just a flash. There is a great deal of energy that sends out pressure waves. The vaporizing of conductors creates a huge amount of expansion. I have seen switchgear after an arc flash, it can be quite ugly.
Charles Perry P.E.
A manhole, switchgear...very similar in this case. Both confined spaces with electrical conductors inside. An arc flash in a confined space has to go somewhere. In the case of a manhole, it will blow the cover off. You refuse to accept the FACT that an arc flash can blow a manhole cover off. You should at least read the references.
Charles Perry P.E.
I never said it didn't take a sp ARC k, how else would their be a blast ...
you are the one trying to make everyone sound like they don't know jack of what they are talking about., and you want everyone to hail you like the irrefutable authority in the group.The Truth is sometimes you make as much sense as phil@
seems the one denying anything else is at play there is you.
You are saying that an arc alone cannot blow a manhole cover. That is wrong. An arc flash can, all by itself, with no combustible gas present, blow a manhole cover into the air.
Pay attention.
Charles Perry P.E.
back off a minute! stop putting words in my posts. I said nothing to the contrary about arc flashes involvement in these blasts.
The fact is that you are thinking an arc would cause the explosion "always", when in fact an arc can occur and disseminate itself (lose potential) to the atmosphere inside the manhole without any further manifestation., the full potential in the transmission line doesn't always discharge itself (a Balance may occur) unless a Heavy Grounding Presence is added (as when & if the Cables Collapse or Expand touching Metal parts inside the cavity or equipment)., the presence of Gas changes that dramatically and when it ignites the whole Manhole chamber & Conduit Flashes Launching the Manhole into the air.
An Arc Flash & it's Magnitude is subject to the environments surrounding having a path for it., seldom will the High Tension Cable Arc towards a Manhole Cover, but to other conductors and nomenclature with Ground Potential, if that occurs an Arc Alone Explosion is plausible.
again, an Ionic Displacement such as that possible through a Charged Gases would enhance the Flash Potential & Cause The Explosion with out any Ground Potential Contact. it happens.
Realize: Your Arc alone theory for a Manhole Explosion is not a stand alone concept., if you want to believe so, that is totally up to you.,
I am sure they May Occur under Several Conditions and/or a combination of several Long Term (charge/discharge) Flash Occurences leading to an Explosion when the chamber and conduit is full of Gases produced in the fault & reaction of cable/insulation fuming into the air inside the chamber.
so if the Cables/Hardware Shortout, whether through Water, Contact or Ionization Boom ! i agree, but, also,
If a milder potential or leak charge is present due to damaged insulation overheating, chemical reactons & displacement occurs over time you'll have a gas filed chamber and eventually, Boom !
I think that discussion on Motor Models is going to far };-)
What ever you're arguing Charles Perry P.E.
Gregs' Delinquency
as a youth is a Living Testament of the presence of Gases in that environment, not to mention the natural gas pipes and steam running adjacent to the underground electrical systems as well., leakage and accumulation occurs.
Admit it and stop throwing in The Arc Flash as an excuse to Lord yourself "Omniscient" about this };-{)
a spark is needed, I agreed, isn't that enough for you?
It's enough for me......
No, what you seem to think of as arc flashes is actually just sparks. An arc flash is much more violent.
No grounding at all is required for an arc flash.
??? You really don't understand arc flashes. The arc doesn't flash to the manhole cover. It can happen with one energized conductor arcing to ground, or two energized conductors arcing between each other (and/or ground), same with three conductors. The flash causes temperatures high enough to vaporize the conductor. Read the references. You are still thinking of sparks, not arc flash. Copper expands something linke 60,000 to 1 when vaporized. That creates a tremendous pressure wave.
Charles Perry P.E.
I said that already,
I was in the hospital once with a Lineman that got caught in a Flash and the power blew out through his arm with massive burns to his arm & lower neck too, (he never touched the power cable, it was a rainy humid day & it just drew him in, he fought the arc and got knocked off) He was unconscious for three months in a coma, when he came too, he spent several weeks recovering to get his memory back., luckily he fully recovered
don't tell me any more about what you think i don't know.
Do you think Con-Ed runs Power cabe threw the storm drains? I hope you don't. Can Sewer gasses explode? yes. but there should not be any in the electrical vaults. Manhole explosions are typicaly a winter/spring fenominum when the salts and water from snowstorms leak into the vaults. When you have a nearly closed chamber it takes very little preasure to move a heavy load. As I remember a typical manhole is about 2 feet in diameter and waighs 80lbs.
that means the preasure is acting on 452 square inches. at less than 0.2 PSI diference the manhole will lift. that is not much preasure at all.
as you wrote in another post
with that amount of energy being reliesed into the vault, things will heat up fast. that means preasure increases fast and things blow. Basic physics.
A manhole must have a drain system built into it so that water can drain out of it, sometimes it's just rocks under them to let it drain into the soil beneath, sometimes it's elaborate & could include the sewer or storm drain system....
Gases do find there way around, but we've already established that gases are not the only or predominant factor in Manhole flying 5-25ft into the air.
It'd be nice if you spelled checked before you answer, i'm no English Major but i spotted at least 3 errors & had trouble understanding your response.
ps:I asked & ConEd workers confirmed my suspicions that gases & steam do find there way into their manholes., and they have exploded in the summertime as well. thanks for your interest though, if that is what it was.
An old Usenet rule. If you are going to slam someone for poor spelling or grammer you had better be darn sure your post does not contain such errors. What is "spelled checked"?
Charles Perry P.E.
ah, somehow i feel it's all a setup };-)
a typo is a different story Charles,
I wasn't slammin anybody
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