My husband's employer (Pennsylvania business) is taking advantage of him . . . about three nights a week we are awaken by his work telephoning. The third shift calls whenever the machinery breaks down. Sometimes he has goes into the plant to fix the problem and other times he just talks them through it on the phone. This has been going on for the past six months. He is not on salary and only punches the clock during his regular shift (1st).

The problem is that he is not being compensated for troubleshooting. The non-compensation has been discussed but it is quickly dropped with the excuse, "we are looking into it". It would not be a problem but these calls wake both of us up and makes it difficult for either of us to fall back asleep. If he does not fix the machines the company will lose money due to the down time. My position is, do not answer the phone if they will not pay.

I am looking for documentation or support, to prove that this company has an obligation to pay him for his on-call time when he is troubleshooting.

The time he is on the phone trouble-shooting is work time.
http://www.dol.gov/dol/allcfr/ESA/Title_29/Part_785/29CFR785.11.htm

If the employer refuses to pay, your husband can file a claim with the state Dept. of Labor.