I need to splice a 2 wire #18 thermostat wire. Does this spice need to be accessible? This is in a garage that is going to have a fire rated ceiling installed over the splice.

Although the code doesn't require the splice to be in a box or remain accessible, it is a darn good idea.

As Ron said...
the 'Code' of common sense' should prevail, and the splice should be accessable.

Think about if you may have to return!!!

John

A nail on box and a blank cover ($ 1.50)
would be worth it