Top Heavy Safe Harbor Match Plan w/ Prevailing Wage

If a Top Heavy Plan has only deferrals, safe harbor matching contributions, and prevailing wage contributions, does it lose it's free pass?

I know that it gets a pass if only deferrals and the safe-harbor contributions are made, but does the prevailing wage contributions blow that up or is there another exception for those contributions?

Now, what happens if the eligibility for prevailing wage is immediate and the other contributions are 21 & 1 YOS? Usually that would blow it up too, but again I don't know if there is an exception for prevailing wage contributions. 

Thanks in advance!! 

Yes. A safe harbor plan is considered not top heavy only if it consists solely of deferrals and safe harbor contributions (see 416(g)(4)(H)). Once you start adding in other contributions you are subject to the regular top heavy rules.

One option would be to add a second plan just for the PW contributions. As long as no key employees are eligible in the PW plan, the two plans would not have to be aggregated for top heavy.