Our church is installing a security system, and we are creating notification signs for the entrances. We want to use the word "premises" on the sign.

I realize that the etymology of this word shows that it is the plural of "premise." However, in practical use, is the word singular or plural?

Which wording should I use?

• This premises is under video surveillance.
• These premises are under video surveillance.

To me, the singular use makes more sense.

This question is not a duplicate of Is "premises" always plural? because that question is about the use of "premises" vs. "premise." My question deals with whether or not to treat the word "premises" as singular or plural.