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what caused this?

Discussion in 'Question of the Day' started by ship, Dec 4, 2007.

  1. ship

    ship Senior Team Emeritus Premium Member

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    Photo 1: the wire that melted thru is a neutral wire.
     

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  2. ship

    ship Senior Team Emeritus Premium Member

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    Photo #2 & 3: what caused this?
     

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  3. ship

    ship Senior Team Emeritus Premium Member

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    Photo #4: see a problem here... believe I see a problem Sir..

    What was the cause?
     

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  4. ship

    ship Senior Team Emeritus Premium Member

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    Photo #5: This is what happens when one over-tensions a strain relief on a cable. Given the depressions of the strain relief on the cable, what happens to the insulation surrounding the conductors?

    If flexed near the plug, what most likely is going to happen given this?
     

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  5. ship

    ship Senior Team Emeritus Premium Member

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    Photos 6-9: Safe or not - this especially given most safety cables are around the yoke?
     

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  6. ship

    ship Senior Team Emeritus Premium Member

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    Photo #10: This was in a home I almost bought. Granted the Electric was the minimum problems I would solve. How does this electrical box not comply with the NEC?
     

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  7. avkid

    avkid Not a New User Fight Leukemia

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    That has very little structural integrity with all those "bridges".

    It should be either all one piece or welded at the least.
    From the insurance/liability perspective it's rubbish.

    Personally, I don't want that on the truss above me.

    If it was completely fine I doubt you would be keeping it on your bench, it would be in rental stock making money.
     
  8. ship

    ship Senior Team Emeritus Premium Member

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    Photos 11-14: What caused this on a portable dimmer rack?
     

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  9. avkid

    avkid Not a New User Fight Leukemia

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    Let's see:
    It's open
    200 amp service fed from a 100 amp fuse box?
    That cable coming in the bottom looks like multi-wire 18awg

    There's more, but I don't want to ruin the fun for everyone else.
     
  10. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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    Ship, how many of these do you have, I'm typing as your posting.
     
  11. ship

    ship Senior Team Emeritus Premium Member

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    Photos 15 & 16: Each of these outer globe failures are different. What caused each?
     

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  12. ship

    ship Senior Team Emeritus Premium Member

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    Photo 17: You are the weakest link. Choose which component of this is weakest.
     

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  13. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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    Ok so so far;
    Is that ship's imfamous "wall of shame"?

    1) Not sure at this moment

    2) I know this one because I just delt with one very similar. First, the base is held together with a zip tie. I heard those withstand heat REALLY well. Second, it is wired directly to stage cable. Stage cable is not meant to be used inside of a fixture as would happen here. Along with that, wire nuts are a bad idea, just look at they way the red one melted!

    3) Some sort of over-heating or shorting out. Maybe improperly stripped wire?

    4) The overtightening of the strain relief can cause it to cut through the jacket, and/or insulation on the wires. This can cause a short.

    5) I've seen that yoke before from you ship. Not safe at all. Possibly so, in theory, and if welded, but not in the way it was constructed.

    6) Well that is just a mess! No door on encloser on the box, wires tangled up, the overhead wiring looks poor, and is that cable TV in the same box? Can't cite every violation, don't know all the code, but it all looks very exposed and easily shorted. Also a great way to cause fires or death.

    7)Crispy. Again, unsure, but I have a feeling that thing was wired poorly.
     
  14. ship

    ship Senior Team Emeritus Premium Member

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    Photo 18: What was the cause of this lamp failure?
     

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  15. ship

    ship Senior Team Emeritus Premium Member

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    See something new just about every day.
     
  16. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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    Well, how many are you going to submit to our collective brain power in this serving?
     
  17. ship

    ship Senior Team Emeritus Premium Member

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    Done for now. (some of it has been posted before.)

    Much of what I see is under negotiation and not public knowledge out of say "your plugs suck," what are you going to do about it - take these dimmer racks back and give us a loaner while you re-do them, or send a tech person out to fix them? The connectors have issues, this new rubber used in the Socapex-compatible panel mount connector to retain the sockets is a wee bit more soft than used to be used. It's allowing pins to pushed in which if they than don't engage a plug sufficiently will have a wee bit of resistance. Resistance is heat, heat means that if solder type instead of crimp connection of wire to pin means we now could have melted solder that than means liquid electricity in shorting between hot/neutral and worse yet, between phases.

    Or, here is a hundred lamps of this type with pinch cracks in the pinch seal. Is this a problem that should be corrected? This much less on some of the lamps style, pinch bubbles around the electrodes that as they approach the pinch crack could leak and explode in an expensive way. More of a concern to solve design-wise? Something to be concerned about? What's this about warranty also covering the lighting fixture installed in, say to replace the reflector and other components that lamp in exploding took out?

    Ok, basic electricity says the "skin effect" (Question of the day - another one, what is the skin effect.) On these very high wattage (and expensive) xenon lamps, some out of the factory have a sort of wire rope that is tightly twisted leading to the envelope pinch of the lamp. Others at random have one side that has somewhat un-twisted, others have up to both sides so seriously un-twisted that they sort of mushroom out of the lamp base. Given the skin effect of wire, can this un-twisting of the lead in wire play a role in lamp failure?


    But I digress... yep, wall of shame with lots of stuff, a whole 'nother wall of shame ready to go once I get about building it. On a day to day basis, it's more like stuff like gee, some manufacturer attached a 1Kw Mogul Screwbase metal halide lamp directly to a fan guard for their lighting fixture. Seems that a fan guard is not really rated for mounting a heavy lamp vertically off it and one fan guard broke. Lamp then melted into the side of the plastic fixture once the power cord was all holding it in place. This much less pulse rated 1Kw lamp, no grounding and no isolation between fan grill and lamp base terminals. Lots of issues abound by way of how this company did it - even ran the fans backwards in keeping them cool. Fan quits, lamp over heats and its supports fan, lamp base and lamp now melt through the plastic mountings for them. We now have the fixture wiring cords holding up these things that otherwise drop on those below or explode in already having melted through the 200F plastic guard for them. Long story, some production company is in negotiation with where I work to correct all these and other issues for them. Fascinating stuff constantly.
     
    Last edited: Dec 5, 2007
  18. Hughesie

    Hughesie Well-Known Member

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    number 16, i have sitting on my desk currently for others to see what not to do when changing a globe, what has happened is when the person changed the globe they put their greasy fingers around the globe and it created a hotspot and died (sometimes they smash quite violently)

    oh yes, i know a small about lighting:cool:
     
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  19. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Sorry, Hughesie89, but I think you're wrong. While I can't tell what lamp to which you're referring, none of the three failed lamps pictured above are the cause of fingerprints, in my opinion. Hint: Note that two lamps are short-arc, and one is incandescent (All T/H lamps are incandescent, but the converse is not true).

    [Ship, PLEASE in the future post these one at a time, and/or label the pix with a number or letter!]
     
  20. Hughesie

    Hughesie Well-Known Member

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    we the image is rather low quality in that area, from the globe that i have which has glass fragments that have expanded
    [​IMG]

    that's my one
     

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