GE PGP990DENBB Owner's Manual & Installation Instructions page 21

When installing a double bay downdraft cooktop
in combination with another downdraft cooktop,
maintain the minimum spacing between units as
shown below. Installing them too close will affect
cooking performance.
14.6 cm
5 "
3 4
I
1
25"
(63.5 cm)
36"
(91.4 cm)
Avoid placing cabinets above the cooktop unit, if
possible, in order to reduce the hazards caused by
reaching over heated surface units.
If the cabinets are installed above the cooktop,
allow a minimum 30" (76.2 cm) clearance between
the cooking surface and the bottom of the cabinet.
A non-combustible material must be installed on
the under side of the cabinet. Use a flame retardant
millboard at least 1/4" (6.3 mm) thick, or gypsum
board at least 3/16" (4.7 mm) thick, covered with 28
gauge sheet steel or 0.020" (.5 mm) thick copper.
The maximum depth of cabinets above the cooktop
is 13" (33 cm).
Installation of a listed microwave
oven or cooking appliance over the cooktop shall
conform to the installation instructions packed with
that appliance.
Working areas adjacent to the cooktop should have
an 18" (45.7 cm) minimum clearance between the
countertop and the bottom of the cabinet. If the
clearance is less than 18" (45.7 cm), the adjacent
cabinets should be at least 8" (20.3 cm) from the side
of the cooktop.
21
30" min
(76.2 cm)
13"
(33 cm)
30"
18"
(76.2 cm)
(45.7 cm)
8" min to wall
(20.3 cm)
8" min to wall
(20.3 cm)