PCL for helicopters question

Hi all,

Sorry haven't been participating much lately, "free time" has become
just a figure of speech for me lately.  Quick question: I'm not a
helicopter pilot, so I don't have any first-hand experience with this. 
A family member is an electrician and works at a hospital where they're
thinking of overhauling the PCL system at the helicopter pad.  According
to them, when the helicopter pilot on approach activates the lights,
different colored lights blink in a certain pattern.  They need to know
what procedures need to be followed when overhauling the system.  All
I've been able to find so far is AC 70/7460-1K which talks about putting
up obstruction lighting, but it doesn't seem to address their question. 
Has anyone come across anything like this?  Thanks in advance.