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Electric shock when unplugged

 
 
Twixer
 
Reply Mon 19 May, 2014 05:19 am
Hello all, a novice here, I recently bought a brand new pressure washer, on using it for the first time, it would not run, on doing all the checks, the last check was on the fuse in the plug (in a cartridge) fuse was ok and on pushing the fuse back in I received an electric shock? (from the live and neutral plug prongs) The manufacturer disputes this but it happened! How is this possible?
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Type: Question • Score: 4 • Views: 3,516 • Replies: 28
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contrex
 
  1  
Reply Mon 19 May, 2014 06:58 am
You could have built up a static charge on your body which was discharged when you touched the prongs. This has happened to me more than once.

timur
 
  2  
Reply Mon 19 May, 2014 07:14 am
@contrex,
Or a static charge on the device itself that was discharged through the user's body.

One or another, that's the number one cause.

Also, equipment that use switch-mode power supplies usually comprise capacitors that hold sufficient charge to provoke an electric shock.
0 Replies
 
dalehileman
 
  0  
Reply Mon 19 May, 2014 11:00 am
@Twixer,
Twix your circumstances aren't entirely clear. Static yields a slight instantaneous shock, as from a spark; whereas contact with 60-hz ac is often more severe, esp if your hand is damp, and of course can be felt to pulsate if contact is held more than a small fraction of a second

Yet you say it's unplugged so like Con and Tim I'd guess the former

Static too usu doesn't persist once discharge has occurred so if you immediately touch it again nothing happens

Quote:
(from the live and neutral plug prongs)
What's also puzzling here is that a fuse holder doesn't usually have a neutral prong so you might clarify. (Tim, what am I missing here)
timur
 
  2  
Reply Mon 19 May, 2014 12:01 pm
@dalehileman,
Dale wrote:
(Tim, what am I missing here)


At least, your conclusion is not as silly as usual.

However, for the last part of your comment, you doesn't seem to envision a socket like this one, where, after pushing the fuse case, you can have an electric shock between the live and neutral prongs (discharge of capacitors):

http://www.futurlec.com/Pictures/IECMALESOCKFUSE.jpg

Or an electric shock due to static:

http://www.affordablepropertysolutions.co.uk/wp-content/uploads/2013/02/electrical-discharge-in-multiple-sparks-from-prongs-pins-of-uk-electric-mains-plug-3-prong-fuse-carrier-in-base-rescan-rescan-rescan-ajhd-701x522.jpg
contrex
 
  1  
Reply Mon 19 May, 2014 12:54 pm
@dalehileman,
dalehileman wrote:
Quote:
(from the live and neutral plug prongs)
What's also puzzling here is that a fuse holder doesn't usually have a neutral prong so you might clarify. (Tim, what am I missing here)


Maybe he is outside the US. Here is a British standard 13 Amp fused plug; brown=live, blue-neutral; green/yellow=earth

The one in the picture is a rewirable type; all new appliances must by law have a moulded-on, non-rewirable type plug with the fuse accessible by a plastic holder without dismantling the plug.

Front

http://ecx.images-amazon.com/images/I/31h849yNelL._SY300_.jpg

Inside

http://blog.sparksdirect.co.uk/wp-content/uploads/2010/12/esc-plug.jpg
dalehileman
 
  0  
Reply Mon 19 May, 2014 01:48 pm
@timur,
Quote:
At least, your conclusion is not as silly as usual.
Tim I'm flattered

Quote:
However, for the last part of your comment, you doesn't seem to envision a socket like this one,
No indeed, you'll have to give an old guy some leeway Tim. So I fetched my Better Half, whom you must know is smarter than I; and, relieved to report, she couldn't ID it either

Quote:
where, after pushing the fuse case,
Again forgive, Tim, but what does it mean to push a fuse case

Quote:
you can have an electric shock between the live and neutral prongs (discharge of capacitors):
Until I understand more fully, and I'd hardly blame you Tim for not responding to this fringe lunatic on the verge of Alz's, I'd hope you might in language suitable to the Average Clod (me) the precise location of the capacitance storing this potential charge

Pun unintended
timur
 
  1  
Reply Mon 19 May, 2014 01:56 pm
@dalehileman,
Does this talk to you?

http://www.geocities.ws/dushang2000/images/Mains%20socket%20with%20fuse%2001.jpg

timur
 
  1  
Reply Mon 19 May, 2014 01:59 pm
@dalehileman,
Location of capacitors:

Timur wrote:
Also, equipment that use switch-mode power supplies usually comprise capacitors that hold sufficient charge to provoke an electric shock.
0 Replies
 
dalehileman
 
  0  
Reply Mon 19 May, 2014 02:08 pm
@timur,
Quote:
Does this talk to you?
No Tim it doesn't but thanks anyhow

I understand how hard for you youngsters to believe anyone so ancient could still be alive

Quote:
Timur wrote:
Also, equipment that use switch-mode power supplies usually comprise capacitors that hold sufficient charge to provoke an electric shock.
Well Tim I'm familiar with switching supplies of this sort but believe it or not I wasn't aware they could hold such a risky charge at a location so exposed to the user

So I briefly looked into it

https://www.google.ca/#q=switch+mode+power+supply+holds+charge

...and sure enough some do. However meantime the condition has apparently been recognized so that many such devices are now provided with a bleeder that discharges it after a short time. I suppose then the rule is, wait for a while
0 Replies
 
dalehileman
 
  0  
Reply Mon 19 May, 2014 02:35 pm
@contrex,
Thank you for those illustrations. Incidentally Con, in another thread,

http://able2know.org/topic/245206-1

...Tim also took me to task for providing links in an attempt to identify transistors other than the junction type which might have high input impedance/resistance so if you're at all interested and have a spare moment, if you'd review that posting as I'm still puzzled about how I apparently went wrong
dalehileman
 
  0  
Reply Mon 19 May, 2014 02:57 pm
@Twixer,
So Twix, evidently three sorts of jolt. The third, a dc charge, would feel similar to that of 60 hz, but if you were able to hold your fingers upon it, without the accompanying pulsation
0 Replies
 
contrex
 
  1  
Reply Mon 19 May, 2014 03:43 pm
@dalehileman,
dalehileman wrote:
I'm still puzzled about how I apparently went wrong


I am not sure what Tim was complaining about; maybe it's because you keep posting links like this to google.ca (Google Canada) which don't work for many people me included (I just get a blank search page). You have been doing this for a long time.

https://www.google.ca/#q=transistor+high+input+impedance



dalehileman
 
  0  
Reply Mon 19 May, 2014 04:11 pm
@contrex,
Quote:
….maybe it's because you keep posting links like this to google.ca (Google Canada) …..You have been doing this for a long time.
Good gosh Con I wasn't aware it was still in effect. Not having had the accusation for several years now I supposed this software problem had been rectified. I have no idea why or how it happened but now I will sure do something about it

..though don't know exactly what. I will contact my sons who understand all that kind of stuff so much better than I
0 Replies
 
Twixer
 
  2  
Reply Mon 19 May, 2014 10:03 pm
Yes people, it's a UK moulded plug with a little fuse holder between the plug prongs,, i'm tending to agree with Timer's conclusion about capacitors, but to all who expressed an opinion, thanks.
0 Replies
 
dalehileman
 
  1  
Reply Tue 20 May, 2014 10:44 am
@contrex,
Thanks again Con for calling that nutty software glitch to my attention. Pursuing the obvious, below I have deleted the "ca" and so if it's no trouble I wonder if you'd try 'em out and let me know if they now work as supposed

Thanks again


https://www.google/#q=transistor+high+input+impedance

https://www.google/#q=different+types+of+transistors
0 Replies
 
Romeo Fabulini
 
  1  
Reply Tue 20 May, 2014 10:47 am
Prepper/survivalists are always tinkering with gadgets and stuff and blowing themselves up or electrocuting themselves so you could try asking here-

http://www.prepperforums.net/forum/general-talk/
0 Replies
 
contrex
 
  1  
Reply Tue 20 May, 2014 11:04 am
Even worse. At least before we got the google.ca search page; now I just get the message "Cannot find the server at google. " That's because when you took the ca off the end, you needed to replace it with something else, but you didn't. Try com

dalehileman
 
  1  
Reply Tue 20 May, 2014 11:08 am
@contrex,
Con I was afraid of some such technicality
So here goes


https://www.google.com/#q=transistor+high+input+impedance

https://www.google.com/#q=different+types+of+transistors
0 Replies
 
contrex
 
  1  
Reply Tue 20 May, 2014 11:24 am
Both work fine.
 

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