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Connecting 3 x 240mm Single Cores to terminal on an Automatic Transfer Switch

Colin Low

One of our electrical contractors did not advise the manufacturer of automatic transfer switches that 3 x 240mm single core cables where being connected to each of the phase and neutral terminals so the ATS was not manufactured to accommodate this. The contractor proposes to replace the bolts on L1, L2, L3 & N with a longer bolt to accept the cables.  

We asked for the contractor to confirm with the manufacturer of the ATSs that this was acceptable to them and received confirmation of same. However, the end user customer is not accepting this and has referred us to a British Standard that does not permit this. 

We are seeking your advice and position on this and look forward to hearing from you.

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    Hmmm… 

    What torque setting are you proposing, on what basis? Will there be spacers or other washers?

    There *are* standards available for making off compression lugs etc including specifying use of washers and torque settings (though I’m at home so don’t have one to hand) and I suspect that this may be where the customer is going. I’d be interested to see which one is being called on.

    Given the size, I suspect significant current even if installation method or volt drop is having an impact.

    I presume you’re not literally thinking of three palms stacked face down in series on the bar, rotated to fit and slotting the bolt through the lot!

    I would be asking the manufacturer for extended terminals or as Alan suggests an external BBC onto which cables can be terminated before a more manageable connection is made.

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  • 0

    Hmmm… 

    What torque setting are you proposing, on what basis? Will there be spacers or other washers?

    There *are* standards available for making off compression lugs etc including specifying use of washers and torque settings (though I’m at home so don’t have one to hand) and I suspect that this may be where the customer is going. I’d be interested to see which one is being called on.

    Given the size, I suspect significant current even if installation method or volt drop is having an impact.

    I presume you’re not literally thinking of three palms stacked face down in series on the bar, rotated to fit and slotting the bolt through the lot!

    I would be asking the manufacturer for extended terminals or as Alan suggests an external BBC onto which cables can be terminated before a more manageable connection is made.

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