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Control/Dimming Help me identify this?

Discussion in 'Lighting and Electrics' started by Charc, Jun 2, 2008.

  1. Charc

    Charc Well-Known Member

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    So, I am sitting in the booth in the (oldest space) for an assembly, and decided to pop open a breaker type thing... The exterior metal plaque is nearly impossible to read, but I think I've worked out 30 Amps, 250 Volts, and that's about it. There is a lockable metal handle on the right. Inside there appear to be some fuses, and some sort of knife switch. The gauge of wire seems to be pretty substantially low. I've included a picture, which I took with my MBP iSight, so it's backwards.
     
    Last edited: Nov 28, 2008
  2. Dustincoc

    Dustincoc Active Member

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    Looks like a really old fusebox. The switch thing is probably the main disconnect for the panel. The wiring looks like standard household wiring. It's probably solid wire so it can handle a bit more power than a twisted wire(i think).
     
  3. SteveB

    SteveB Well-Known Member

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    It's 2 pole, fused disconnect.

    SB
     
  4. SteveB

    SteveB Well-Known Member

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    Ampacity and thus capacity for solid or stranded wiring is the same = 5 - 10 - 50 - 200 amps, whatever.

    The diameter of stranded will be larger due to greater surface area of multiple wires, which makes stranded more flexible and useful in some scenarios.

    Steve B.
     
  5. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    NFPA 70E specifies certain levels of PPE based on Risk Category, as determined by potential Voltage/Amperage present. You WERE wearing the appropriate PPE before you opened that panel, RIGHT? Did anything turn off when you turned off the switch? Is this by any chance near a kitchen?
     
  6. thirdoctive

    thirdoctive Member

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    It could have been used as a show power disconnect for when the Beatle's played there.
     
  7. Charc

    Charc Well-Known Member

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    At appears to be a hot and neutral, non grounding. This is correctly named "two pole"?

    I'm surprised that the ampacity is so high on the fusebox, as it feeds a solitary L5-15R in a junction box mounted directly above the fusebox. Question, is the switch isolated? Because it looks like metal on metal = hot switch.
     
  8. Van

    Van CBMod CB Mods Premium Member

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    Oddly enough, to my eyes, it appears that the Neutral is switched and the hot is a straight feed through. As a matter of fact it sorta looks like there is nothing fedding the Supply side of the hot fuse, yet there appears to be a 12 ga wire on the load side. Or are these old eyes decieving me? Either way, Yeah it's just a standard disconnect, probably not rated for more than 30amps max
     
  9. Charc

    Charc Well-Known Member

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    How would the arcing be on this guy if disconnecting under load?
     
  10. Van

    Van CBMod CB Mods Premium Member

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    Those switches are designed to be connected and disconnected under load. One of the main reasons most disconnects now days are "spring loaded" is to reduce acring, ie the faster the knife blades move the less time for an arc. Since the box has to be close for you to engage the load, the arc in contained. If you can move the switch handle whilst the box is open then it is truly dangerous. Even at a maximum 30 amp load you'd have to be moving pretty darn slow to get a significant arc, remember Arcing is a symptom of high Voltage not amperage and at 120v it takes a steady hand to maintain an arc for long.
     
  11. Charc

    Charc Well-Known Member

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    Nothing I saw indicated the door needed to be closed to throw the switch.
     
  12. Van

    Van CBMod CB Mods Premium Member

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    Just remember, Don't cross the streams.
     
  13. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    For your own, as well as others', safety; close the dam door and stay away from it. You have no reason to be opening anything you don't understand, including Pandora's Box Media Server.

    Just because one wire is white and it's wired to an L5-15R, doesn't mean it can't be a 220V, single-phase, supply. If it is 110V, the fused neutral is a bad thing. And if the fuses are 30A, and the downstream wire is #12, and the single receptacle is 15A, that's several other bad things.
     
    Last edited: Jun 2, 2008
  14. SteveB

    SteveB Well-Known Member

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    Once upon a time, oh maybe 50 years ago ?, it was common practice to fuse and switch the neutral. Usually on systems that were single phase, single pole, which is long before the advent of everything in a house needing electricity.

    This particular box "might" have an interlock, hard to tell, there's some sort of mechanism in the lower left side of the box (is the photo reversed ?), but the typical door interlock has a protruding locking tab near the switch handle, and I don't see that here. Thus I'm assuming the box is over 30 years old or so.

    I also have seen way to many wiring jobs that used white color coded wire as a hot, and failed to mark the wire with a correct color code - I believe every inch of the wire in the box needs to be wrapped in tape of an appropriate color (black, blue, red) if used as a hot , or green if a ground, etc..., thus I'm guessing it's not a switched but simply a bad installation.

    Steve B.
     
  15. Charc

    Charc Well-Known Member

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    %$#!, I thought about that darn near 5 minutes until I got the reference...
     
  16. Charc

    Charc Well-Known Member

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    Yes, yes, well, how was I to know the insides were gonna be all dangerous and such? Besides, I was bored...:twisted: But no, there is some rhyme to my reason: Unless I'm mistaken, that L5-15R is where we connect one of the venue's followspots. It hasn't be used in that theater since it was disconnected, and we'll likely have to reconnect it again soon, and run power from the booth. However, I couldn't
    remember the position of that switch originally, wether or not it got disconnected. That box is giving me the creeps, I might conveniently disappear if/when we have to run power from the booth.

    I can't see why that disconnect would have a 15A fuses, given gauge of wire, and old-awesomeness of disconnect. But it's possible the fuses were switched to 15A, and the illegible riveted metal label never changed, I'm just not trying to poke around and find out.

    Can you give me some backstory on the fused neutral? Why? I assume this has fallen out of practice 'cause if the neutral fuse goes first, then you just have a hot dangling around? (Technical description)

    Yes, I took the photo with a webcam, it is reversed, I'm really doubting there is a mechanism that requires the door closed.

    Bad installation? I don't follow.
     
  17. JD

    JD Well-Known Member

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    Wow. The fact that we are talking about this thing as if it's a relic from long long ago is making me feel WAY too old! I remember back in the early days when half my tie-ins were done into such a contraption. (One mounted above an open beer compressor in the basement of a club that had a standing foot of water to trudge through comes to mind. I think it was the 70's.)

    Well, I guess I am going to go pick out my coffin now. Feeling really really old...
     
  18. SteveB

    SteveB Well-Known Member

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    If the white colored wire is being used as a hot, it's supposed to be color coded appropriately - I.E. with black, red or blue tape. Leaving it white leads to confusion, as white is reserved for neutral, just as green is ALWAYS a grounding wire (typical USA code here).

    I'm guessing that the age of the box is not old enough for the white wire to be a fused neutral, thus if it's a hot, it needs to be color coded as such. It's not, thus it's a bad installation, but note that I am making assumptions.

    SB
     
  19. Charc

    Charc Well-Known Member

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    I think it is fused neutral, I suppose it's possible it isn't, I just don't see why I'd have, what, two phase power supply there?... then running a 1kW FEL?...
     
  20. JD

    JD Well-Known Member

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    (returning from my coffin hunt)

    Ok, most often this box was used if there was an "add on" to an old service that was 220v without a neutral, such as a water heater. Yes, if the white is hot, it should be painted or have marker tape on it, but I can't remember ever seeing any that were! There is no neutral block in this box, just what looks like a ground wire. To make things worse, the power input (or what should be the power input) does not even have a ground! It even looks like the primary wiring is that funky old cloth covered rubber romex that was used in the 1940s! (I hope I'm wrong. I used to call that stuff "bomb wick" as it often ended in a fire.)

    Now, you mentioned an FEL, so if this is feeding a device that is 120v, the "neutral" is running through the fuse that was intended for the second hot. I haven't seen something this far from code since Frankenstein's Castle! (ahh.. correction there, the Playpen in 1980, but that's another story.

    Best way to address this box: Wrap yellow "Caution" tape around it and RUN ! ;)
     

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