Calendar question - project specific calendar for a small group of resources?

Hi all!

We currently only use a few global calendars for all of our projects.

Mainly we use:

Standard 5 day week with 8hr/day with holidays

4 day week with 10hr/day with holidays (construction guys)

So for a single project, the construction phase will be done on an accelerated 5 day week with 10/hr days.

A co-worker created the new 5 day, 10 hour calendar as global calendar.

I thought I would assign this calendar to the construction activities that only have construction resources.  That sounds pretty straight forward, but....

Questions.

What about activities that have non-construction resources assigned (engineers, techs, etc)?  Those guys work the standard 5 day, 8/hrs per day.