Why does the plumbing get installed first into a new construction over the electrical work?

There are two reasons why plumbing is installed first in new construction projects:

1. Plumbing can get wet, but electric wires cannot. So, plumbers have to start before the building is watertight. This means they start before the windows and doors are in, even before the roof is on and complete. Electricians have to wait until everything else is done before they can start work.

2. Wires are easier to move around than pipes and heating ductwork. So, electricians go after the plumbing pipes and ductwork is in and works around them. If they have pipes to install, they do need to check ahead and sometimes coordinate with the plumbers and HVAC people.