With all the flooding down south of late what would be the situation if you came down in the morning and you have say a foot of water covering the ground floor.
Would the electricity have blown as water is likely to be covering plug sockets on the wall, or would it still be live?
I suppose in a similar way if there is a gale and the roof is blown off and water dripping down through the floors what would one do regarding electrical safety?
with any luck your RCD (trip) will have operated.
Depends on if you have RCDs or not. Without them, the presence of water alone in unlikely to pass enough current to trip a circuit breaker or fuse.
Walking in water or even wet floors inside your house is a bad idea until you are sure the electricity is turned off.
It will likely trip out the RCD (if there is one) but it might not. The installation will need to be tested out before you switch back on if water gets in anywhere. If you think the house is about to flood you should turn it off beforehand.
ss wrote on 28/12/2012 :
With the electrics completely submerged there is actually less risk of anything blowing. The risk of issues starts as things start to dry out. Voltage gradients through the water mean that the risk to you becomes greater, the nearer you get to live parts of the installation.
An RCD would trip the supply and likely avoid any risks.
A few years ago I attended a site where all of the electrics were in a basement at a commercial premises. The basement had been flooded by water ingress due to burst pipes in the pavement and the main panel was some 6 feet below water. It took three days to pump out and I nursed the site along for another two weeks, until a contractor could replace everything. Several MCB's exploded in that time, whilst they were drying out.
Why would anybody care about flooding in the south?
So take very short steps on your wet floor... :-)
SWMBOs grandparents came down (3 story "town house") and found a fridge floating in 3ft of water bit still operating perfectly.
MBQ
Because if the south becomes ocean then the bottom half of the north will become the new south? :-)
And we cant have THAT.
Well the issue really is difficult as the main feed would be underwater so any amount of tripping devices would be rather pointless.
If you were far enough away from the feed though it would probably be OK. Brian
my feed comes out of the cable 4ft above ground level, so the flooding would need to be of Noah's Ark proportions to get that under water. But then it was installed in the 1920s when they probably worried about such things.
Pure H2O is not a particularly good conductor, but most flood water will contain salts. Complete immersion will rapidly cool any localised heating due to conduction, but as the water level falls, the current will begin to track along the insulation causing localised burning. Once that process begins, the insulation would be rapidly carbonised providing a highly conductive path, sufficient to pop fuse and MCB's.
the reason I posted this was I find it quite surprising that with all the flooding of late there has been no electrocutions.
Sit in a full bath, put a line and neutral live cable into the bath with you. You are most unlikely to be electrocuted, or even shocked. However, the water will heat up. There are industrial water heaters that still use ths principle.
If, however, you go and grab hold of the line cable, then the current will flow through you, and you will get a shock, but probably not electrocuted, as the fault current will take out the circuit protection.
So, in the real world, water will enter the socket outlet, the current will flow between line and neutral, and possibly take out the CB/fuse, or it could be gently heating up the water, or, if the path is easier between line and earth, it will take out the RCD, or, if no RCD, will take out the fuse/cb, or possibly go on heating the water.
The only danger to a person is if they touch the line terminal and a good earth point at the same time.
RCDS work.
Have you a reference for that last bit? Intuitively it sounds doubtful to me. I would be surprised if you got enough current flow tracking damp insulation etc to cause any significant heating. More to the point, should something wet (but not immersed) get hot, it will tend to dry out.
John Rumm formulated the question :
No reference, I have just witnessed it numerous times.
A.Lee formulated the question :
I agree - all due to voltage gradient. Apart that is of the liklehood of the fuse or MCB blowing - water just does not have the conductivity needed to pass the current.
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