Definition of jack chain in US English:

jack chain

noun

  • A chain of links each consisting of a double loop of wire resembling a figure of eight, but with the loops in planes at right angles to each other.

    • ‘Jack chains are used for hanging light fixtures.’
    • ‘Allform Products manufactures chain products like double jack chains, single jack chains, id loop chains, ball chains, curb chains, chandelier chains.’