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Preformed loops are installed by the GC when the concrete for the drive-thru is poured.
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Most GCs do not have experience installing the preformed loop and will do it incorrectly.
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Preformed loops are installed on pegs and should sit two inches under the concrete slab.
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Most common trouble with a preformed loop is that it is installed too deep.
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Will have trouble detecting higher vehicles.
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The wire going into the ground is the same color as the wire coming out of the ground.
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Every tech should carry and know how to use an ohm meter and a LCR meter.
It is impossible to properly troubleshoot a loop without these tools.
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An ohm reading should be zero or almost zero (short).
An infinite ohm reading indicates an open (broken wire) and a loop that has failed.
A high ohm reading will result in high inductance and indicated a loop going bad.
An inductance reading should be less than 100 micro Henrys.
A high inductance reading indicated a loop that is starting to fail.
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Loops are expensive to put in. Be sure a loop is bad before having a store replace it.
