Seating a HID bulb into a socket?

[Stevareno]

Edit: I guess I mean HID lamp? :ashamed:

I've seen instructions that come with HID lamps that (basically) recommend you screw in the lamp as far as it will go without extra effort, then reverse a couple of turns and re-tighten.
Is there a purpose for this?

Of course I follow the installation directions, but for regular (household) lamps there is no such instruction. I install my incandescents by screwing them in to where they light up plus 1/4 turn. I've run across many a situation where people screw their lamps too tight and end up breaking the socket or breaking the lamps with the base stuck in the socket.

 

[the blur]

for a while, I used no-ox on the threads, to prevent seizing. just a dab.

 

[Little Bill]

Edit: I guess I mean HID lamp? :ashamed:

I've seen instructions that come with HID lamps that (basically) recommend you screw in the lamp as far as it will go without extra effort, then reverse a couple of turns and re-tighten.
Is there a purpose for this?

Of course I follow the installation directions, but for regular (household) lamps there is no such instruction. I install my incandescents by screwing them in to where they light up plus 1/4 turn. I've run across many a situation where people screw their lamps too tight and end up breaking the socket or breaking the lamps with the base stuck in the socket.

More often than not, what happens in a regular socket is people screw them in too tight and bend the contact tab in the socket. You might not see any problem until you change the bulb and the new bulb won't make good connection. There are sometimes differences in the base of bulbs and some are shorter and won't make contact if the tab is bent in. Also, there is a small amount of solder on the end of the bulb, and that differs greatly between bulbs. If I run into a situation where a bulb won't burn or flickers, I usually check the tab and bend it back out if needed. Also helps to clean it too.