I was talking to someone from this area and he said that the household light bulbs in the UK (and most of Europe) are the bayonet type (similar to some automotive bulbs) where they have pins on opposite sides and are inserted in to the socket and given 1/4 turn (I think). The bulbs never have the problem of becoming loose due to vibration or whatever. It seems to me that this is a great idea. It would be much faster to insert, and more secure to have this type of light bulb/socket set up. Any ideas why this wasn't adopted in the US? Are there any disadvantages to this type of setup?
The Wobulator
*Please REMOVE the obvious for my correct email address*
I don't know why the US uses screw-in bulbs, but one advantage of the UK ones is that they have both contacts on the end: the brass cap itself is not live, so there is less chance of somebody contacting a live conductor while removing or inserting a bulb without turning off the power (and with a two-way- or multi-way-switched circuit, who can tell whether the lamp socket is live or not?).
-=- Alan
On 11/04/03 07:32 pm The Wobulator put fingers to keyboard and launched the following message into cyberspace:
I've never known a lightbulb to get "loose" for any reason. Never.
By the time Europe stole er... borrowed our invention, the Edison base lamp was already the standard. They changed the base due to (reason below.)
Nothing insecure at all about a simple corkscrew thread and socket combination. I've never felt it took too long to screw in a bulb, or unscrew it for that matter. Nor have I ever witnessed or heard of one falling out due to vibration.
Because we didn't "adopt" the initial invention at all, Europe did - and changed the design to meet their particular needs, outlined below.
Europe went with the bayonet base because they went with a 240 volts to ground residential distribution system. Practically all household appliances, and lights, run on 240v.
If one tried to change a bulb with the outer screw shell hot (remember, no polorization there either for light sockets) you would be killed if you were grounded. In the USA you'd get a nice jolt from the 120, but probably not likely to cause permanent injury.
So Europe sunk BOTH lamp contacts to the bottom of the socket. They also added small fuses to every lamp and appliance cord, because they don't call their room outlets "mains" for nothin - they're at 240v and typically 30-40a can be had at any receptacle. At 240v any shock can be deadly.
when I was young I lived in Europe. I spent about 30 seconds with the neutral in my right hand and the hot in my left, at 220, until someone unplugged me.
I'm still trying to figure out how come I'm still alive.
I've lived with both. Apart from any differences in the quality of the sockets both have some disadvantages IMHO. UK style bayonet. Contact pressure on the two contacts on the base usually depends on two small springs inside the small piston style electrodes of the socket. The bayonet style bulb is inserted, pressed down, turned a few degrees; two pins, one each side of the bulb engaging with hooked slots in the socket (as somebody said, as some automobile lamps) and then released with the small springs maintaining the contact pressure and holding the bulb in place. I found that a very small screwdriver was required to attach wires within the base of many UK bulb sockets and if one of the small screws went astray they were hard to find/replace. Also that any damage to the hooked slots could cause, occasionally, bulb to be loose or wobbly in the socket. many sockets were brass and of good quality. North American (Edison Screw). While NA polarized plugs are now more common it is possible for the outside of the bulb socket to be 'live' if improperly wired. However one's fingers are not usually down at the base of the bulb and if one is prudent the lamp/circuit is switched 'off'! Because of the lower voltage (115-120) compared to 230, the current at each bulb is higher i.e. twice. However with the relatively large contact area of the screw in base and the metal contact on the bottom, unless there has been corrosion, doesn't seem to be a problem. It does require several 'turns' to screw them in, but this sets the contact pressure required. I think the screw in type does allow cheaper materials to be used for construction but this is only a personal opinion and UK experience now out of date. Both work. Bulbs are an inefficient source of light. Many lamps are now made in China or somewhere. Current price for a package of four 40s, 60s or 100 watters is here (eastern Canada at Can. Tire/Wal Mart etc.) around 88 Can. cents, plus sales tax; or approximately UK 44 pence (11 pence each). So they are cheap enough even compared to the price of the electricity they waste. (Well if one is heating with electricity anyway, during the winter, that heat is part of ones heating bill!). Cheers.
This is hilariously ignorant. In fact, Edison is widely believed to have read about the light bulb invented by Sir Joseph Swan, which was written up in Scientific American some 10 months prior to Edison's patent application for the incandescent bulb.
In truth, as with aviation, there were lots of people around the world all working on this cutting-edge "electricity" thing at the same time. Edison made some key innovations but was far from the only person to invent the light bulb. There had been less viable versions invented much earlier. What Edison achieved was a durable, manufacturable, and relatively inexpensive light bulb.
In fact, Edison lost patent fights both in the UK (to Swan, whom he was forced to take on as a partner in "Edison-Swan") and the US. He was a better businessman (founder of GE) and self-promoter, even if this didn't help him win the DC vs. AC fight.
"Nyet, Kepten, light bulb is *Russian* inwention!"
Because it is a fix looking for a problem. In over 50 years I have never seen a problem related to screw in lamps. I have seen problems with both systems, but not related to design as they both share the problems, generally do to poor materials and or design.
you don't get it. you have no guarantee that the socket is connected to the ground, and that the switch cuts the phase. if the hot is conencted to the socket and the switch is incorrectly wired to cut the ground instead of the hot, you can get electrocuted.
Many also run on the 600v DC track voltage, which is fed in series through 5 sockets.
Temporary lights on construction projects are also left hand thread. To cut down on theft, and to prevent the use of receptacle adaptors in the non-gfci protected 2-circuit stringers.
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