Rotary Phase Converters, Transformers, Subpanels and Grounding - Page 2
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  1. #21
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    Apropos of nothing much.., save "multiple idler" RPC.

    My 7 1/2 HP "New, Old Stock" Reliance Dutymaster was shipped by klewless amateurs - no screws or bolts to the mini-pallet, just two steel bands.

    Which failed.

    Arrived with a dented fan bell impinging on the plastic fan, but only just barely. No big deal. I've done plenty of auto body work. Otherwise decent folks, so they get anonimity.

    By contrast:

    Minutes ago, UPS dropped-off it's 3 HP Reliance E-Master "NOS" kid brother bought from one of my more "usual suspects", "NRI-Industrial".. whether via eBay - OR "direct" off their own website.

    - Large standard pasteboard carton.
    - Motor inside, lower third, had been plastic wrapped, foamed in place.
    - Upper third plastic wrapped, foamed in place as well.

    Opened right up, upper two-thirds of the resultant "clamshell" lifted out cleanly, no stray "angel turd",

    Motor in perfect condition. Of course!

    Not new news. NRI are professionals, AND NOT "amateurs".

    I've had GREAT service from NRI for long years arredy. Never yet set a foot wrong.

    2CW

  2. #22
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    Quote Originally Posted by thermite View Post
    More than 35 years ago, now.. but "GFCI" duplex outlets must still have cost the very Earth.. as the PO of this home put a grand total of THREE in a 3 to 4 bedroom three-level split with about 1,200 SF of 2 1/2 car garage / workshop / annex.

    Talk about insane wiring runs? Kitchen fridge, lighting, or appliances go dark, trek upstairs and try to remember which bathroom's GFCI is the one daisy-chained.. etc.

    Several ten-pack boxes of new GFCI duplex outlets later, the only "daisy chain" NOW is in the quad outlet boxen I've added for "puter & printer/scanner convenience, master & slave side-by-side, same box - no confusion likely.

    All others are stand-alones.

    Even BETTER NEWS?

    The "clean-up project" had me discover where the pure fool had "saved money" four branch circuits, by ignorant "dry" wire-nutting many feet of shiney-wood cable so that Proper-Copper appeared at box end and load center end.

    HIDING that silly "house ignitor" shit in the middle potentially far the more dangerous lie than running shiney-wood end-to end so yah at least could see "at once" it had been f**ked-up.

    Utility mains gurus, OTOH, know which shiney-wood alloy actually WORKS and how to terminate it properly for VERY long and trouble-free life.

    About 35 years and counting on the Square-D QO 200 A service entrance panel, here, and nary a shiney-wood issue with the mains feed at all.

    I did mention it pays to know yer s**t?

    Ah, yes. AS/NZS 2.6.3.1
    Additional protection by RCDs with a maximum rated residual current of
    30 mA shall be provided for final subcircuits supplying—

    [snip]
    Where protection of final subcircuits is required, RCDs shall be installed at
    the switchboard
    at which the final subcircuit originates.
    We generally only use the integrated ones for retrofits (where it is only the extension that needs protecting) or medical. One of the many things that surprises me about US rules is that they don't do the same.

  3. #23
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    Quote Originally Posted by SomeoneSomewhere View Post
    One of the many things that surprises me about US rules is that they don't do the same.
    Could was we ain't as foolish?

    You want safe handling of power, yah go to the Yanks or the Japanese.

    As is coming to pass, even if a hundred years LATE:

    Construction - Electrical safety in buildings industry health & safety

    Extract:

    Tools, plugs and cables designed for DIY and domestic use are not suitable for site conditions. You should use cordless tools or those that operate from a 110V centre tapped to earth (CTE) supply system so that the maximum voltage to earth does not exceed 55V.
    "110 VAC" huh?

    Mind .. yah FIRST have to get down to where the USA and Japan are ALREADY! 2XX VAC "split phase" center-tap to Earth for that "1XX".



    Anywhere else on-planet?

    For the most part, saving on spend for Copper

    2XX above Earth..

    ...has been deemed more important than saving human lives.

    1XX above Earth.., is bad enough...


    "Shocking" choice, wasn't it?


  4. #24
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    That's a UK thing. It means the voltage to ground is low enough that it's very unlikely to cause serious harm even if you touch it. It does require transformers more-or-less at point of use though.

    Some older workshops around here have 230:230 isolating transformers for the above-bench sockets, predating RCDs.

    My post was more about being able to find the one that's tripped, though.

  5. #25
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    Quote Originally Posted by SomeoneSomewhere View Post
    That's a UK thing. It means the voltage to ground is low enough that it's very unlikely to cause serious harm even if you touch it. It does require transformers more-or-less at point of use though.
    The 60 V -minus does, yes.

    1XX is easier as they are built-in to the grid, arredy.

    We typically put about four residences on each 240 VAC split-phase or 120-0-120 nominal @ 200 A nominal, each.

    Then again, when all this was going-down North America had already been a net exporter of Copper since before the Bronze Age.

  6. #26
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    I'm more saying that once you're at a voltage that can be lethal, you might as well do it properly.

  7. #27
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    Quote Originally Posted by thermite View Post
    Several ten-pack boxes of new GFCI duplex outlets later, the only "daisy chain" NOW is in the quad outlet boxen I've added for "puter & printer/scanner convenience, master & slave side-by-side, same box - no confusion likely.
    All others are stand-alones.
    GFI receptacles suck. They're too large as retrofits into existing wall boxes. They're basically consumer grade crap.
    Actual GFI breakers cost more, true. Because they're worth it.

    Is anyone going to help this man get the transformer he needs?

  8. #28
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    If you have a corner-grounded derived delta system on the secondary side of a transformer, make sure there is no fuse or untied CB in the grounded leg. Otherwise, if you get a fault between one of the other (high) legs and the grounded leg, the fuse on the grounded leg could open before the fuse on the high leg opens, leaving the high leg hot. You want the high leg to disconnect and want to keep the grounded leg connected to ground at all times. The same principle applies to the secondary side of a single-phase control transformer feeding, say, a 120-V machine lamp. The derived neutral needs to stay grounded in case of a fault from any high source.

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