A customer has a building that is to be torn down in the future and they are going to install a 12 pair underground cable. What kind of lightning protection do you guys recommend on each end?

You can't go wrong with Porta-Systems now a Tii product.

Ditto on the Tii brand. They are pretty much the standard for Verizon and most other large telcos and for a good reason. Their stuff is good.

I'd encourage them to run 25 pair minimum. The cable costs a tiny bit more, but the protection options that offer telco-grade standards start at the 25 pair count. Just make sure that any protection hardware meets BellCore (Telecordia) standards and you'll be fine.

"A customer has a building that is to be torn down in the future"

How large a building is replacing it? What will it be used for? How many people will work out of it?

I'm a pessimist I'd go 50 pair.

The new building will not be in the same spot. A 12 pair should be good. Thanks

Our company exclusively uses Circa products for this use.

Please check out the following:
https://www.circaent.com/telecom/products/view/278-25-pair-bix-connector-with-cover-splice-chamber

Never had a problem with Circa -- great products.