[stomachmonkey]

For in ground sprinklers I would not get a permit.

In your case I would get a permit.

Apart from the CYA building codes do change over time.

If you do everything the way it should be done to be code compliant and don't have a permit you run the risk of needing to get a permit at a later date, like if you sell the house and someone picks up on it.

If code changes you could be forced to get it upgraded to current code which may cost a bundle or may not even be possible.

I came very close to having to knock down an entire detached garage because the PO extended it 4 ft without a permit and the setbacks changed during the time I owned it. If the garage had not changed from the original permitted structure I was grandfathered. Had he pulled a permit I was grandfathered. The way he did it made the entire structure, not just the additional 4 ft illegal.

YMMV.