24 Generac®Power Systems, Inc.
• If flexible metal conduit is used, it must be sealed
internally at the end where it terminates inside the
compartment’s electrical junction box.
NOTE:
Flexible metal conduit, due to its unique construc-
tion, is NOT vapor tight along its entire length.
• Seams and joints of the galvanized steel (whether
used as a liner or for the compartment itself) must be
lapped and mechanically secured. Such seams may
be manufactured, welded, bolted, riveted or screwed.
Manufactured lock seams are shown in Figure 2.6.
Installer constructed compartments typically utilize a
standard lap joint.

Figure 6.6 – Types of Lock Seams

• After the compartment has been metal lined and
vapor sealed, line the compartment interior walls and
ceiling with an approved, nonflammable sound insu-
lating material. See Section 2.2.3.
Do not install any flammable material directly
above or around the compartment. Heat,
transferred through the compartment structure,
may be sufficient to ignite, char or discolor
seat cushions, fiberboard and other flammable
materials. You may need to use approved
nonflammable insulating materials in high
temperature areas.
6.2.3 SOUND INSU LATING MATERIALS
Once installers have determined that a compartment is
properly constructed and metal lined, they can add
acoustical material. This may include additional sealant
or insulating material, to reflect noise away from the
vehicle interior.
Sound insulating materials should be of a nonflamma-
ble type. One excellent insulating material is a 1-inch
(25 mm) thick fiberglass having a 2-pound density.
When fiberglass is used, its coated side should face
toward the compartment interior.
Do not install sound insulation or any absorbent
material on the compartment floor interior. Such
materials will become soaked with combustible or
explosive vapors and liquids and will become a
fire hazard.
Using a combination of sound insulating materials can
often reduce noise more effectively than a single mater-
ial. For example, a sheet of lead or visco-elastic materi-
al, along with a layer of other acoustical material, is
more effective than when a single material is used.
6.2.4 ACOUSTICS
For additional noise abatement, the installer may wish
to consider the following:
• Using special sound insulating materials.
• Construction of a special noise abatement
compartment.
NOTE:
Any method used to reduce noise must not adverse-
ly affect the flow of cooling and ventilating air into or
out of the compartment.
In addition to the effective use of sound insulating mate-
rials, construction of a special noise abatement com-
partment might be considered to reduce noise levels.
Such a compartment might be constructed as follows
(Figure 2.7):
• Use 5/8-inch thick or 3/4-inch thick plywood in the
compartment.
• Construct the compartment floor of a double thick-
ness of 5/8-inch or 3/4-inch plywood.
• Line the compartment interior walls and floor, as well
as the underside of the floor, with 26-gauge galva-
nized steel.
• Vapor seal all compartment seams and joints.
• Over the galvanized steel lining, install a combination
of acoustical materials as mentioned in Section 2.2.3.
To prevent fire or explosion, do not install any
insulation or other absorbent materials on the
interior or underside of the compartment floor.
• Seal all compartment door edges to prevent noise
leakage around the door perimeter.
• Line the compartment door interior (except for air
openings) with suitable, fireproof sound insulation
(such as 1-inch (25 mm) thick fiberglass with a 2-
pound density).
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Section 6 – Installation
PRIMEPACT 55G and 55LP Recreational Vehicle Generators