En el artículo , Gordon Henderson escribió:
indeed.
Playa del Inglés, Gran Canaria, April 2011:
Never did find out if someone got fried.
En el artículo , Gordon Henderson escribió:
No problemo Señor!
What the problem - they have fuses AND they're CE marked
AWEM
Which is why I'm surprised it makes any difference which way around the mains is connected unless the brick is faulty, which is where we came in.
I can recall their mains ovetr there not only having no earth most of the time but being very unreliable as well. One good thunderstorm and a three hour power cut!
I love the way people just use poke in the socket with bare wires with sticky tape technology as well... Brian
I thought this one had been done a few weeks back...
The usual setup seems to be that the neutral to the laptop is also connected to the earth on the mains input. Hence with no earth this is left floating. The mains input additionally will have suppression filters that capacitively link L to E and N to E. Hence without the E being connected, it will tend to float at half mains, and thus the metal bits of the laptop do as well. Its not dangerous since the current you can draw through the suppression filter is tidy, but its enough to give the irritating tingle.
ITYM chassis
Not only confined to laptops, seen the same with sat receivers, tv's and and freeview boxes.
Indirectly yes - but if there are only two wires to the laptop, and one is the neutral, then that is also what gets connected to chassis.
Yup loads of stuff. I noticed it on a hi-fi amp once where the house earthing was TT - the high Ze left enough voltage on the case that you could feel it when you brushed your fingers over it.
The previous owners of our place had put a fusebox - of likely similar vintage to that one - in one of the bathrooms, on the wall at the far end of the bath/shower (or more likely, the fusebox was there first and the room was converted to a bathroom later, but they didn't see the need to relocate the box). It had a home-made plywood cover, held in place by friction alone...
Electrics here in the US are seriously dodgy!
cheers
Jules
That was what I concluded when I lived there.
Only if you want to die. Figure of 8 two pin cables are non polarised. If the laptop is on a two wire connector then the PSU must be double isolated or you have a 50:50 chance of having a live chassis.
Live chassis was the default for old tube based TV sets internally. They were wooden on the outside and had many other much more deadly voltages lurking about inside with the cover off.
Correct. That is sort of OK provided the filter capacitors never fail.
Bad or no earth and input filters leaves the notionally earthed chassis floating somewhere midway between live and neutral. This is OK until one or other of the filter capacitors fails short circuit (rare but not unknown). There is a very good reason why the ratings plates on things with an external metal chassis says "this appliance must be earthed".
Carrying a neon screwdriver on holiday is not a bad idea. It doesn't hurt as much when you find for example a live anglepoise lamp (I did).
In article , Jules Richardson writes
Especially if it's knob-and-tube (still in widespread use) or aluminium* wiring.
%This can't be right as sin(60) = 0.866 approx i.e. less than 1.0 you prolly meant 115/sin(60).
yes sorry, I did mean that. Robert
40?) volt mains? No, their three phase is Delta rather than Star connected,= hence the lack of a Neutral connection. I found that out when fixing a pro= blem with a three phase powered disk motor... (the disk was the size of a l= arge washing machine) -- John W
You get most pecuilar effects if one of the three main fuses blew, disconne= cting one phase and so leaving the affected rooms connecetd in series with = each other. =20
Robert
Yes, part of my house was knob & tube, so I had at least three types of
110V socket in the place.
What laptop?
I can't remember if the discussion was in here or another group but it turns out that the Apple Mac Powerbook brick is not double insulated but has an earth continuity from a pin on the magnetic connector to the computer through to the earth pin on the mains socket. Not believing this, I ran a test meter over my son's Powerbook power unit and found it was exactly like that. I can easily imagine situations where dodgy wiring could lead to the symptoms you describe.
Nick
Not sure I follow... the two wire connection from the PSU to the laptop will have the correct polarity regardless of the polarisation of the mains input.
Many laptop PSU bricks are on a two pin figure of eight non-polarised AC mains connection with no earth. On a UK 3 pin mains plug cable the handedness is well defined but on a continental two pin plug it is not.
To be safe a two pin unearthed PSU must be double isolated since you cannot be sure which of the mains input lines is neutral.
It is not completely unknown to find some wiring monkey or DIYer has swapped L & N on a UK wall socket either. In foreign parts it is as well to assume that the electricity supply is unsafe until proved otherwise. Ditto for the gas central heating and hot water boiler. A neon screwdriver is a handy thing to have with you at all times...
You don't have to go far afield to find deadly gas water heaters - Belgium has a very bad record in that regard or did when I lived there.
Ah, 'aluminium' with a 'u' in it!
Funny, I haven't seen that Enterprise ad. for a while now. I wonder if somebody finally realised?
That's not what double insulation means or does. You could have a perfectly normal isolating mains transformer to provide the low volts (as of old) which doesn't comply to the double insulation standard. I think you're confusing things with having a live chassis as was common with old valve TVs. In the UK, if the plug was wired correctly, the chassis would be to neutral therefore 'safe', reverse the connections and it was at
240v. But nothing uses that these days.
Yes, but not for that reason. (ITYM double insulated rather than isolated).
The uncertainty of input polarity is not the factor that requires it to be double insulated, its the lack of earth provision on the supply - or to reverse it, it the fact that its double insulated that permits it to be supplied with a two wire non earthed lead.
A non contact volt detector would be a better bet.
All agreed.... still not sure what that has to do with the DC supply to the laptop though (where the neutral may actually be "riding" half mains at a high impedance).
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