On Thu, Nov 02, 2006 at 01:00:50PM +0100, Erik Mouw wrote: > Europe has unearthed plugs only for double insulated equipment (which > can be recognised by a symbol resembling two squares in each other). > Double insulated equipment comes with the flat unearthed "europlug" > that is supposed to fit in all sockets, earthed or not (except of > course in the UK which uses a different socket). > > Note that the europlug is a lot safer than US plugs: with the europlug > it is impossible to touch the life wire through the metal because the > poles are made from plastic with only a small metal tip. The tip is > already well in the socket before it actually connects to the life > wire, the still visible plastic part of the pole can be touched without > hazard. In the US the poles are made from metal so it's quite easy to > hurt yourself (but hey, 110V is a lot "safer").
The north american plugs also bend much easier and are often bent when you pull them out unless you are very nice to them. > Most if not all desktop computers aren't officially double insulated so > they need to be earthed and come with an earthed plug. Unfortunately > lots of older houses still have unearthed sockets and the earthed plugs > fit quite easily. Current regulations require earthed sockets in all > new houses (or rather: for all new electrical installations). If you > really don't have a grounded socket for your computers, make at least > sure that the ground wires from all computer equipment is connected to > each other (easy to do with an earthed extension socket). Better is of > course to have the socket replaced by an earthed one. I think all houses I have seen built in the last 35 years have all earthed outlets. Older than that very well might not have earthed outlets. Old buildings have a tendancy not to be kept in north america. We apparently always want new. Historic value has little meaning here. > Yeah, I agree the UK system is silly and has ugly bulky plugs. I guess > the idea is to protect the cable from the plug to whatever is connected > to the other end of the cable. That would only make sense if you don't > have fuses in the electrical panel. I wonder if it is a leftover from when people didn't have fuses in the electrical panel, or proper lightning rods or anything else. I know my dad has told me when he was a child in the 50s lightning storms could cause interesting sparks and such coming out of outlets, which of course you don't see anymore. > Europe doesn't need such plugs because over here earth and ground are > two different and unconnected things, whereas in the US and Canada they > are usually connected together at the electrical panel (at least it was > like that in the houses I've seen in New York state). The ground wire > is the ground for the electrical system. It can and is allowed to have > a different potential from the earth (within limits, of course). The > earth wire is connected to the earth by a metal wire burried a couple > of meters deep into the earth. Certainly true as far as I can tell. It does seem that ground and neatral are considered one and the same for many things here. > There are still some places in Europe where you actually have two life > wires operating at 115V wrt to the ground instead of a 230V life wire > and a ground. The reason for this is that if you balance a 3 phase > triangle system properly you don't need the ground wire and hence you > can save 25% on copper wiring. Right now this is seen as dangerous > cause equipment with a single switch can still be life, so houses are > converted to connect to a 3 phase star configuration with ground wire. > (It was however nice cause without a residual current detector you > could run US 110V equipment without a transformer by connecting it to > one of the life wires and earth.) I thought it was usually that you had 230V between neatral and a live wire, and about 400V between a pair of live wires (out of the 3 available). That is what I remember being the standard setup in denmark at least. Here we have 2 phase to residential with 230V between them and 115V between one and neatral/ground. What countries ran the other way? > That's possible in Europe because earth and ground are not the same > thing. It ought to be possible here since earth and neatral should only become the same thing at the electrical panel. > Another great card is the Western Digital/SMC WD8013 (or even the 8 > bit ISA WD8003). It uses the same 8390 chipset as the NE2k, but its > packet buffer is memory mapped where the NE1k and NE2k have their > packet buffers only reachable through slower IO space. Back in the old > days I could easily flood a thin ethernet using a 8003 in a 386DX40 :) I never used the WD cards. I remember SMC made some awful chips that I didn't get along with. -- Len Sorensen -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]