Conventional Fixtures HPL exploding when being installed

[rphilip]

I was showing a friend how to install a lamp in a S4 Par fixutre today and it wasn't going in well so I was pushing hard to seat the lamp and it then exploded on me when the lamp finally seated.

The lamp was used but still looked clear.

Is this unusual? What might have caused it to happen.

Thanks

Philip

 

[derekleffew]

It's rare, even rarer than http://www.controlbooth.com/forums/lighting-electrics/12040-catastrophic-lamp-failures.html , but still happens enough that the manufacturer suggests holding the lamp cap with the socket facing away from you when seating the lamp.

For seating lamps, I just put the lamp in the socket, then turn the socket so it's facing away from me, and use three fingers from each hand to push the lamp towards me and into the socket. I believe that is the same way the ETC manuals instruct users how to install lamps.

It sounds more awkward than it really is. (Mike, have you seen this method endorsed? I could have sworn I'd seen it on their site, but can't find it now.)

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PNTA: Maintaining a Source Four Lamp & Socket (00:04:08) - YouTube


You might also see http://www.controlbooth.com/forums/lighting-electrics/10475-best-seat-lamp-insertion-tool.html .

 

[MNicolai]

Page 4 of this manual recommends those steps for installing lamps: http://www.etcconnect.com/docs/docs_downloads/manuals/S4_User_Manual_UL_revB.pdf

Can't say I've ever seen the globe break upon installation except where someone's hand has slipped and knocked the globe accidentally.

 

[derekleffew]

Thanks for the citation. I knew I had seen it illustrated.

 

[ship]

Certain brands and ages of lot numbers of fixtures or lamps are a little less friendly with each other in standards. Modern days, all should be fine but in the past - Sch.40 pipe and rubber mallet to install lamps at times on a weekend extra hours at times years back.

Great fixture, quality control has gone up both for standard in lamp and fixture since introduction. Suspect these are earlier fixtures with later lamps.

Beyond installing, "lamp looked clear" how did the pins to that lamp look? That which connects to the socket of the fixture? Very often from moving light lamp to conventional fixture, a virus of bad lamp into good socket or bad socket onto good lamp gets done in two other options for the situation all also bad.

Lamp looks clear, pins crap, transferrs bad conductivity to a new socket in what was bad in one fixture, the same lamp in now both just made both fixtures bad by way of we now have bad conductivity and by way of resistance destroyed another lamp socket. This in changing lamps between sockets as opposed to just plain putting putting perfectly good lamps into bad sockets and seeing them again in a few weeks - thus complaining "bad lamps"?

Ought to get our money back on the lamps or tech people installing them as presented often the latter and my thoughts the after.

I digress, possible with lot number, a certain brand of lamp and lot of fixture will be harder to pund home than others in fitting well. Clean that lamp after installing with a lint free denatured alcohol whipe - this no matter if you think you touched or now. Someone else touch it even if new? Exploded after that to work on.

Anyway what I suspect in happening.

Also and even more suspect globe damaged while installing or sweat/dirt left on the globe "quartz glass" that should not be exposed to it. Guy in photo not wearing gloves and no mention of cleaning the glass after install without gloves. Finger .... touched, the lamp while installing??? Possible?

 

[65535]

I make it a point to only handle the base incase the envelope does fail. The quartz fractures with sharp edges like most glass rather not cut my hands on it.

 

[gafftapegreenia]

Best Seat Lamp Tool

Maybe I'd use mine more if I hadn't left it 700 miles away in Michigan.

 

[DELO72]

I had this happen to me the other day on a lamp with a G22 (mogul bi-pin) base. I was having a hard time getting it into the socket I had in my office and knew it was going to happen as I tried to force it in.

The cause of this (in the times I've had it happen to me firsthand) is that sometimes the pins in the socket are too tight (either from a buildup of corrosion, or the backer springs may be a little too firm. When you put that much pressue on the pins you are pushing them up into the quartz and basically the quartz starts to fracture from the pressure and it shatters above the press-- and since HPLs are under 3-4 atmospheres of pressure (nitrogen, HBr, Xenon or Argon, etc.) with their fill gasses, they go "pop" and the whole envelope goes.

The Best Seat tool is a great item to help guard against this. 90% of the time it's the fit of the lamp into the socket, and the pressure being put onto the lamp pins-- not the lamp-- that causes the rupture. That said, if the lamp has any micro-fractures from pressure put on the quartz in the past (which is why ETC shows in that image to push only on the base, and never by holding the envelope), it could shatter with minimal additional force.

So- my advice is if you are trying to seat a lamp and you meet more resistance that usual: 1) check the pins on the lamp. Are they aligned? Are they corroded? 2) Check the socket by trying another lamp. If that has resistance too, change the socket.


Cheers,

Mark

 

[LightTamer]

When you point the socket away from you, i've found that it actually makes it EASIER to get the lamp into the socket, as you're basically just bracing the socket against your palms, and then you can put as much pressure as required (or possible with your hands) onto the base of the lamp until it seats. Much better than trying to get a lamp in the other way without touching the glass.

 

[derekleffew]

/pedantic

... on a lamp with a G22 (mogul bi-pin) base.

It is my understanding that the G22 is a medium bipost base, such as on the EGT. Closest to "mogul bi-pin" would be the G20, as found on T17 fluorescent lamps.

Lamp Base Examples

 

[JD]

The very nature of quartz guarantees there are micro-cracks.
It is, after all, a crystal. I am surprised they are as well behaved as they are

In any case, I used to have a flat head screwdriver with a notch cut out of it. When I ran into a lamp that would not seat, I would use it to push on the porcelain base, alternating between sides until it was seated.

Tight contact springs are a blessing and a curse. If they are fresh and tight, they are far less likely to arc and burn. The flip side is it makes installing a lamp a lot harder. Over the years I had one or two break during removal when they were dead. Learned real fast that if the dead lamp resisted it was best to slip a piece of tubing over it, break the lamp, and then remove the base with pliers.

 

[rphilip]

Thanks for the reassurance that I'm not crazy.

I was quite something to have the lamp pop and be left holding the lamp base in the fixture cap. It was interesting that most of the glass seemed to go out perpendicular to the line of the pins. The pressure wave was quite something to feel.

The pins and socket both look fine. It felt like something was missaligned but I'm not sure what. It will be interesting to see how well another lamp goes in the cap.

I've got a best seat, I just didn't have it with me. I've also noticed that people can't seem but to want to put their fingers in side.

Thanks,

Philip

 

[DELO72]

I stand corrected! Well noted, Derek! medium bi-POST it is!