If the transformers are, say, a foot away from the lamps then I can't imagine the transformers "melting" as you say. It would be a serious fire risk if they were melting and a 50W Halogen is unlikely to scorch the outside of a transformer let alone melt it.
If the load the lamps are placing on each transformer is close to, or at the limit of the Wattage rating of the transformers then the transformers may be failing prematurely because of overloading. Just uprate the tansformers and keep them well away from the lamps.
Check the connector blocks of the Halogens - cheap ones fail - buy new connectors and transfromers from a specialist lamp shop. Do the maths first...
Good luck...
Peccavi
May 2009
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