Tell someone or document it before you close it up.
Equipment tag against print not checked
Before connecting duct to equipment, verify the equipment tag against the print. Similar units in the same area can look identical, and location alone is not proof.
Do not connect duct until the equipment tag and print match.
Check
Find the equipment tag on the unit, curb, cabinet, or nameplate.
Find the matching equipment tag on the mechanical drawing, equipment schedule, or shop drawing.
Confirm the tags match exactly before making the connection. Similar nearby units are a common source of wrong tie-ins.
If the tag is missing, unreadable, or does not match the print, do not connect. Photograph the unit tag/nameplate and the drawing callout.
In crowded mechanical rooms or large floors with repeated units, physically walk the equipment and trace the route before final connection.
Steps
Find the equipment tag on the unit, curb, cabinet, or nameplate.
Find the matching equipment tag on the mechanical drawing, equipment schedule, or shop drawing.
Confirm the tags match exactly before making the connection. Similar nearby units are a common source of wrong tie-ins.
If the tag is missing, unreadable, or does not match the print, do not connect. Photograph the unit tag/nameplate and the drawing callout.
In crowded mechanical rooms or large floors with repeated units, physically walk the equipment and trace the route before final connection.
Say this to your foreman
I am about to connect to the unit at [location]. The unit tag reads [tag] and the drawing shows [tag] at this location. They [match / do not match / are unclear]. Can you confirm I am at the right unit before I connect?