Appropriate Use of Possessive Plurals?

Question

We have a debate on whether it should be "classes" or "classes'" in the sentence below. Your wisdom is appreciated.

Sentence: This rebalancing of customer classes’ impacts on the system means there will be uneven impacts to rates the first year.

For reference, there are five customer classes (e.g. residential, non-residential, etc.) being referenced in the sentence. Thanks for your feedback! Aaron

Answer 1

The quoted example is gramatically correct, but poorly written.

The reason for this, and your confusion, is the word "impacts": it can be read as both a noun (the effects of the thing) and a verb (creates an effect). The sentence, as written, forces your reader back-track and re-parse your sentence to see if "impacts" is a functioning as a verb or noun (apostrophes are easily missed, and often misused).

To prevent your meaning being carried by a tiny punctuation mark, I would suggest this re-wording:

• This rebalancing of the impacts of customer classes on on the system means there will be uneven impacts on rates the first year.

Note also that one cannot have an impact to something, only on or upon that thing. It's also pretty poor writing to use "impacts" twice in once sentence - "effects" is probably the noun you're looking for for in one of the two cases.