I was waiting for someone to be that silly.. what if the TV melts and you get mains on the TV aerial/sat dish? Do firemen refuse to enter a house with a TV aerial in case its been made live from the mains and is wet?
Rain is not clean once its landed on a roof, it is full of stuff that was on the roof before it rained.
The same place as the supposed water from the hose.. nowhere.
They are built to better standards than TVs are so if a live TV aerial isn't a significant problem, mains getting through an inverter isn't.
As I read the original article, they didn't fail to fight the fire. They simply didn't do so from inside the building. The result of that seems to have been that they had to content themselves with containing it, rather than extinguishing it as quickly as they would have liked. So, Harry's house will probably be destroyed if his roof catches fire, but any neighbours might be OK.
I've never quite understood why they were not more dangerous.
Although there was a break in the third rail for foot crossings on the South East Region suburban lines when I was a schoolkid, they were not very far from the crossing point and some people (not me) would go up to the third rail and kick it. Presumably, when you are standing on well drained ballast with rubber shoes there is more than enough resistance to earth to keep you safe.
People don't seem to get electrocuted when they fall on tube/underground tracks either.
I don't recall hearing of anyone trying to lob a piece of metal to bridge from the third rail to the adjacent rail. On wet winter evenings, the arcing when a train passed would light up the low cloud and be clearly visible from at least half a mile away, so I guess we treated them with some respect.
We would regularly place pennies on the main rails to get them flattened. The crossing was several hundred yards from the nearest station, so there was no effective surveillance and maybe 100 junior and secondary school kids used my local crossing every day.
The dcan and sio, but te thing is desingned to maoke it likely for people to fall into a trebnch built for the purpose. I recall one or toe poeple every yeasr got electrocuted on Southern Region when I was a kid.
NO, I heard one kid did it..but it was maybe apocryphal.
yes. I had too much respect to do that, but other kids did.
Also nicked detonators from railway huts and stuck them on the rails. God that boy was a dick. I beleive he became a british rail porter. Too thick to even pull a signal up and down.
You could get away with that, there're normally at 750 volts DC relative to the other running rails so yep, could be done seeing that most shoes these days are plastic composition as long as there're not that wet or contaminated..
They do but not AFAIR that often. IIRC its -210 volts and appx 420 V on the outer rail with the running rails being "tied" by resistors so you'd have to have a decent grip or connection with a 400 rail and a running rail.
Yes impressive that, good ole Arc. Overhead lines are quite impressive especially Ice coated ones;)..
Yep best done with Steam Loco's and that did teach us not to get anywhere near them when they were running;!!>..
Which normally there might well not be but under fault conditions?..
Doesn't really matter if the panels are live then their live and a few leakage paths aren't going to make that much difference..
Yes they really ought to thump an earthing rod into the ground before deploying them and perhaps an earthed braid in the hose like they do with high voltage supply lies in TV transmitters where they used to use a co-ax cable:)..
What about it when all is wet and damp?.
Yes what current needs to flow thru the human fame before serious damage arises?, its not that much, its in the low milliamp region..
I can. If they had done it, there woud be a video of it happening somewhere.
There's no guarantee that the DC source will remain floating in a fire situation. If, say, the fire burns through the insulation on a couple of cables in the installation, there will be anything up to 700 volts relative to earth on the loose, according to your figures.
Low enough to give enough voltage at the hose end for a lethal, or at least disabling, current to flow. I urge you to try the experiment. If you haven't yet bred, there would probbaly be a Darwin Award in it for you.
Instructions are given, and reinforced by training to never knowingly use water on any fire where electicity may be flowing.
It works fine if it's perfectly dry. Unfortunately, when you're holding the business end of a fire hose you *do* get wet. And if you're not wet from the water being sprayed around in great quantities, you're probably sweating copiously inside the clothing, too, although with sweat being a good conductor, that may channel some of the current away from the core of your body and along your skin.
The going rate is one life lost to ten houses saved without any damage at all, roughly, if all you're counting is the money.... If you're not totally mercenary, any life lost in attempting to fight a fire only involving property is one too many, as buildings can be replaced, but a life lost affects many others, with no possibility of replacement ot
It isn't. So that is where the danger lies. One end of the solar panel string is connected to the line/phase conductor. (via electronic components) The older systems ran at very low voltages and had a transformer. One side of the panels was earthed back then.
The newer ones have no transformer and are much more efficient. (Around 95%) However when the output from the panel falls below the peak voltage of the mains (around 340 volts) they shut down. There is a bank of capacitors in the inverter too, that just makes them more dangerous again.
You got the wrong end of the stick. In the old systems there was a transformer which meant the systems on the primary and secondary sides were not electrically connected. They were "isolated" from each other by the insulation on the transformer windings.
Like your electric train set was not connected to the mains.
There's a bit here on the technology. There's a few people here need to read up before shooting their mouth s off.
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