<<What's wrong with having the lampholder dangling from the cord? That's the way the're intended to be used, isn't it? (Provided that you tighten the strain relief properly etc.)>>
I was writing from USA point of view. The usual lampholders we have here are really more designed for screwing into a threaded post (like on a table lamp or fixture).
Here is an example of your typical lampholder in a cardboard-lined aluminium shell. I hate these. The effects of heat and time eventually deteriorate the cardboard liner and you can either get shocked or have a short-circuit if the metal terminals or the screw shell of the interior module touch the exterior husk.
This particular one is known as a turn-knob (you turn that little knob to turn the light ond and off). You see the little nipple on the top cap with the set-screw?
That thing has threads on the inside so it can screw onto a threaded pipe or stem through which the lamp's cord is passed through.
Here is a picture of the interior module (which you can buy separately in various lighting supply stores):
The metal (usually aluminium) screw shell is supposed to be neutral and the center contact tab (not visible) is live. However this is irrelevant when dealing with unpolarized lamp plugs.
This next one is the phenolic, or Bakelite, version, (which I prefer and seems) to handle heat much better over time - up to a point, since you don't have the paper insulator to worry about. However if you do use a 100-watt bulb in base-up use, the SWITCH will eventually deteriorate and jam, so anyway, you lose. The interior is interchangable with the metal-cased variety.
Of course, you have also have IKEA selling these drop cords with the phenolic lamp-holders with strain reliefs on the cord and a regular plug on the other end - I guess for making your own hanging lamps. Too bad it's a standard American plug and not a Europlug...hehehe .
They are kind of like a long extension cord with a socket instead of a two-pin receptacle if you can picture this.
[This message has been edited by SvenNYC (edited 11-22-2002).]
I have seen these sockets used in a non-listed manner, that is, a turn-knob suspended by a piece of zip cord. These DIY jury rigs always end up in the trash if I have any say in the matter!
In fact, one really bad house I worked on had a basement that was completely lit with a rat's nest of extension cords and turn-knobs. Needless to say, the basement was rewired with porcelain lampholders and proper boxes and romex.
#134605 - 11/23/0210:46 AMRe: Lampholders dangling from the ceiling
The most simple way of a european pendant fixture is the following: A piece of SVT, (ungrounded if bakelite socket, grounded if metal) with a sling hung over a hook in the ceiling and a light socket with strain relief (old ones were a brass ring which was screwed into the thread of the light socket, then the cord was tie into a nice knot around the ring, new ones are just a plastic screw that clamps down on the cord). Connected via a set of strip connectors. Voila! This is, in Austria, caled a "russian chandelier", commonly used during renovation work and sometimes in hallways, etc. If you want, add an indian fishnet lampshade or a chinese rice paper balloon and you got a really nice lamp.
#134606 - 11/23/0209:20 PMRe: Lampholders dangling from the ceiling
In the UK we have purpose made pendants, which are the cheapest light fitting available (around £1.20 each) and normally fitted in houses unless another fitting has been specified. These pendants comprise of a ceiling rose with a fixed in-line terminal bank & cord strain relief, a length of heat resistant sheathed cord & a cord grip bayonet lampholder (usually plastic).
#134607 - 11/23/0211:15 PMRe: Lampholders dangling from the ceiling
Over here, we banned anything that plugged into a light socket, that is not a bulb, years ago, mainly because of the likely-hood of having the switch in the Neutral,if the lampholder is incorrectly wired. The biggest problem, was with Bayonet Cap lampholders, using the adaptors we used to have here,people used to hook all sorts of things into them, heaters,record- players,and the odd toaster, if the fuse blows, just put a bigger fuse wire in the fuse-holder, this has burned down a few houses that I can think of. :
#134608 - 11/24/0203:58 AMRe: Lampholders dangling from the ceiling
I've taken the liberty to include two photos taken from an earlier posting made by Paul.
As you can see, the outer shell of the bulb will connect at roughly the same time as the center. Thus, polarization is unneeded. Even 1920's lampholders are made like this. (Those are made of metal and porcelain)
I fail to see why you would want to have a design where the screw "shell" of the lampholder is connected to anything. The only reason I can think is the approval agency cynically keeping the number of electrocutions up to justify their existance.
European lampholders have a "mushroom" of soft plastic in the bottom, beneath the wire terminals. This prevents energizing the metal "nut" at the bottom in case a wire comes loose. (Although the lampholder is made of plastic, the nut is still metal, and looks similar to the one in Sven's top picture)
For some reason, strain reliefs are plastic.
I've never seen a new turn knob lampholder. They are commonly found on old holders. Today you will find ordinary switches on the holders. (Most lampholders lack switch, though)
Sven, those IKEA things you mention: Do you mean something like this?
[This message has been edited by C-H (edited 11-24-2002).]
#134609 - 11/24/0207:44 AMRe: Lampholders dangling from the ceiling
The guts of old Austrian lampholders (until ca 1950ies I guess) looked exactly like their new American counterparts (screwshell simply used as neutral, made of one piece). A porcelaine ring was screwed on the outside of the screwshell kept the screwshell from making contact with the metal casing and covered any protuding parts of the bulb's thread. I like those light sockets, simply because they look nice (all brass with the white porcelaine ring, sometimes with a porcelaine knobturn switch), and are almost everlasting.
#134610 - 11/24/0206:48 PMRe: Lampholders dangling from the ceiling
The pendant fittings with a ceiling rose that David mentioned are indeed very common here. The ceiling rose part in most modern installations also acts as a loop-in point for the light switch.
This sometimes makes for some "interesting" wiring when somebody decides to replace the pendant with another type of fixture.
The bayonet-cap plug was once quite common in England too. Look at many old books, movies, etc. amd you'll see all manner of applainces plugged into a lamp holder. The electric iron was probably the most common.
#134611 - 11/25/0208:16 AMRe: Lampholders dangling from the ceiling
Same thing with edison base, made of porcelaine was pretty common here as well. I remember hooking up a small tape recorder to my desk lamp when I was a kid. Lots of houses burnt down, especially due to tenants hooking up 2kw electric heaters to these devices.
#134612 - 11/25/0211:40 AMRe: Lampholders dangling from the ceiling
Regarding Ikea lampholders: Yes, that is exactly the one. Except the ones Ikea sells/sold here used a round SVT cord (round vacuum cleaner type cord with tougher insulation).
Also the lampholder was like the black one you pictured, with the shade-ring but with no switch. I always thought that the reason you didn't put metal screw shells into the sockets was because manufacturers were trying to save cost on metal.
That rocker-switch lampholder is also sold here...it's very expensive - about 6 to 7 dollars depending on the store!! As far as socket/lampholder adapters are concerned we have a bunch. They come in both brown phenolic (Bakelite) or white urea plastic. I like Bakelite better because it resists the heat and doesn't discolor and disintegrate like Urea does. Here are a few pictures:
Bulb plus two receptacles cluster (may or may not come with a pull chain switch for bulb control only): [img]http://images.lowes.com/product/032664/032664270604.jpg?rgn=0,0,1,1&wid=450&hei=450&cvt=jpeg[/img]
This converts a lampholder into a female two-pin receptacle. [img]http://images.lowes.com/product/032664/032664116506.jpg?rgn=0,0,1,1&wid=450&hei=450&cvt=jpeg[/img]
This is for plugging a bulb into a standard receptacle or extension cord: [img]http://images.lowes.com/product/032664/032664273100.jpg?rgn=0,0,1,1&wid=450&hei=450&cvt=jpeg[/img]
There is also a device for plugging two lightbulbs into one lampholder.
According to UL, the reason why they still approve these devices is that the devices will still be sold/made/imported/used without the approval seal anyway, so they'd rather ensure the device is electrically safe to use (for example the plastic insulator isn't going to disintegrate and separate from the metal components).
How you choose to use these devices is, of course, entirely up to you. You can always plug them into each other and make big weird-looking plastic men!!
Sorry for all the pix and the long post. I just thought you might be interested in seeing some of the crazy electrical stuff sold in NEMA-subscribing countries. I know I love seeing pictures of non-American style wiring devices.
Attribution: All pictures came from LOWE'S website at http://www.lowes.com (one of those big DIY sheds like Castorama or B&Q or Home Depot)/
[This message has been edited by SvenNYC (edited 11-25-2002).]