We are required to install a shut-off switch for furnaces at the top of the basement stairs, or entrance to a utility room.
Does anyone know what mechanical or building code, and applicable article (if any) mandates this switch?

Here in Ma it is the state building code i believe. I understand it to apply to oil fired equipment only and the switch must be outside of the room that the equipment is in. Which means outside the utility room or outside of the basement which ever applies to a situation.

One of the things that drives me crazy is when codes regulate things beyond their scope. Example: The IMC now requires a flexible electrical cable for an upblast type fan. I have submitted at the state level to change this to "approved flexible wiring method".
The NEC says you can run NM cable through a plenum if perpindicular, but not parrellel. Whoe cares? The IRC and the IMC does not. They don't care WHAT you put in a residential plenum! You have have a 4" PVC in it!!!

Sorry about the gripe...It's just that I think the code applicable to the installation should should govern the installation. All right I'll quite complaining now!

In NY State, the building code requires that gas fired burners have the shutoff located remote from the burner, by the entrance to the burner room. Sometimes this is at the top of the stairs at a basement. Oil fired burners are not required to have this shutoff.
We have a new building code as of January, and I am not sure if this has changed.

Pierre