240 vac 3 phase bull dog box no power between the a and b phase.
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  1. #1
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    Default 240 vac 3 phase bull dog box no power between the a and b phase.

    I'm having a problem getting 240vac on all three phases to my machine at the top of the box I get 240vac between all three phases after the fuse I don't have 240v across the a and b phase I changed all three fuses ohm them out and still get the same result could someone tell me what to check next. 100 amp blade fuses

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    Tighten all connections with power off. Check switch.

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    Quote Originally Posted by toolfood View Post
    I'm having a problem getting 240vac on all three phases to my machine at the top of the box I get 240vac between all three phases after the fuse I don't have 240v across the a and b phase I changed all three fuses ohm them out and still get the same result could someone tell me what to check next. 100 amp blade fuses
    I simply check for a "Square-D" logo. If absent, furnish a box that has such.

    End of problem.

    Bulldog?

    Not as fortunate?

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    Square D is no panacea these days. I have a recall notice on my desk for some. Seems as though some of them don't shut off with the handle. 30 and 60A 240V models.

    Bulldog from the 50's, has the clamp-matic contacts, now part of Siemens, one of the best switch designs in the business.

    Both brands originated in Detroit, for the automotive industry, now located in France and Germany, likely crafted in Asia.

    I would suspect the fuse clips, missing a tension spring, or a bad fuse. Clamp-matic switch contacts going bad is extremely rare.

    SAF Ω

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    You have all three phases at the incoming terminals to the disconnect and have lost a phase at the outgoing, is this correct? If so, simply check the voltage at each joint from top to bottom.

    Tom

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    Quote Originally Posted by SAF View Post
    Square D is no panacea these days. I have a recall notice on my desk for some. Seems as though some of them don't shut off with the handle. 30 and 60A 240V models.
    Nuthin's perfect that has to sell for affordable prices.

    I'll research that, thanks.

    Happens the 60 A I have more than one of. So far, so good - 600-Volt class. Canadian-market surplused, used but good. "So far" being mid 1950's onward, around when Dad, a Seniour Inspector, Corps of Engineers at the time, started backitting "QO" to our extended family's farm & homes.

    Useful skill to do several of those "hot", not pull the meter. Not that I recommend it. Just useful to know how and not have any sort of issue.

    For the 300 Volt class, new or NOS is about as cheap as used, "optimistic" as so many eBayer's can be on the worth of things.


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