The question was:

"The code places a maximum open circuit voltage in or on homes. This maximum voltage is (600) (750 (1000). Circle the correct answer.

Where in NEC is this voltage referenced?"

The answer was given as 1000 volts and NEC 410.80(B).

Since the wiring used is listed as 600 volts, I selected 600. When I went to check the code site, it is non existent.

So where in the NEC is this voltage referenced? I ask this because I cannot find it anywhere in the code book.

Here you go:

From the 2008 Edition of the NEC, page 70-276

XIV. Special Provisions for Electric-Discharge Lighting Systems of More Than 1000 Volts

410.140 General.
(A) Listing. Electric-discharge lighting systems with an open-circuit voltage exceeding 1000 volts shall be listed and installed in conformance with that listing.
(B) Dwelling Occupancies. Equipment that has an opencircuit voltage exceeding 1000 volts shall not be installed in or on dwelling occupancies.

Thank you.

I had found 410.130(A) but the cite you gave gives the prohibition.

Either cite tells me to give up the fight (metaphorically speaking)

I do not see the answer you seek in Section 410.130(A).