A few things to consider for this installation:
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[*] Larger Size Transformer,
[*] Split-Coil Transformer - with a slightly higher output Voltage,
[*] Placing the Transformer in the center of the runs - as mentioned before,
[*] Running several low voltage branch circuits to different areas, to reduce total load current on each circuit,
[*] Running low voltage multi-wire branch circuits.
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For the first option, a larger Transformer, or multiple Transformers will reduce the loading effects on the Secondary Winding.
The second option would be to use a typical Isolated Transformer (like one used for Buck/Boost applications), which has Secondary Voltages of 16/32 VAC.
Third option already mentioned by members.
Fourth option would be to run several two-wire low voltage circuits out from the Transformer to the Lighting Fixtures, and break up the load currents into multiple runs.
Fifth option combines options #2 and #4, but the low voltage branch circuitry would be several 3-wire runs, which would be 16/32 VAC 1Ø 3 Wire.
Possibly, a combination of all listed items will work best.
My suggestions would be to go with two Split-Coil Transformers - sized larger than calculated loads, with 16/32 VAC Secondaries, and connect the low voltage Lighting to several 3-wire branch circuits - using #12 cu minimum.
Feel free to ask for more information if needed.
Scott35
