UPDATE 1-UK agency says faulty wiring likely caused Dreamliner fire

NEW YORK, June 18 (Reuters) - A fire that scorched the top of a Boeing Co 787 Dreamliner at London Heathrow airport last summer was likely caused by faulty wiring in an emergency rescue beacon that led to "an uncontrolled discharge" from a lithium-ion battery, the UK aviation safety agency said on Wednesday.