Can a policeman handcuff a person without probable cause?

Policemen can handcuff a person based only on reasonable suspicion, if the handcuffing is to avoid the destruction or tampering of suspected evidence.

For example, if somebody has been reported lingering around parked cars for some time, this is enough suspicion to allow the officer to check them for burglary tools, even if a crime has not been reported/committed yet.

Handcuffs are often used for the protection of the officer and no other reason. You do not need to be under arrest for handcuffs to be used. If the officer feels he may be at risk for any reason, handcuffs are considered a reasonable restraint.