Ecobee ecobee3 lite - Step 20: Secure PEK Wiring at Thermostat; Step 21: Manage Excess Wires at Wall

TIP:
When a wire has been connected correctly, the lever on that
block will lower.
STEP 20
Tug on the wires gently to ensure they are
securely connected.
PEK
W2
W1
R
H
C
Carefully push any excess wire back into the
hole and ensure there are no drafts coming
from the hole(s) in the wall.
STEP 21
TIP:
Large holes behind your thermostat will affect temperature readings.
Prevent drafts by covering the hole(s).