1740_install.pdf — page 1

1740 Series
Coaxial Surge Protector
INSTALLATION INSTRUCTIONS
Speciﬁ cations are subject to change without notice.
The device characteristics and parameters in this data sheet can and do vary in different applications and actual device performance may vary over time.
Users should verify actual device performance in their speciﬁ c applications.
Bourns® Model 1740-15 (150V), 1740-23 (230V) and 1740-35 
(350V) provide surge protection for coax cable.
The protector may be installed indoors or outdoors, without or 
within a compatible UL Listed enclosure. If located outdoors, 
the protector should be oriented so the F connectors face down. 
Rubber ‘boots’ or weatherproof male connectors should be used. 
Video equipment protection will be improved if the protector is 
installed close to the main electrical service panel (where the 
power neutral is grounded). 
The protector must be installed on the output side (video equip-
ment side) of any Network Interface Device (NID) provided and 
installed by the cable company (generally at the service entry 
point of the cable into the building). This NID is used only when 
network-powered broadband voice/data/video services are deliv-
ered to the subscriber. This NID does not refer to the simple box 
wherein the provider’s cable ends and the building cable takes 
over, nor does it refer to a cable modem connecting a PC to an 
unpowered CATV network.
The protector can be secured to the mounting surface (wall, 
joist, stud, etc.) employing the #10 AWG (5 mm) self-tapping 
screw supplied with the protector.
The protector is symmetric and bidirectional, so either end may 
be used for connection to the input and output cables. The con-
necting cables should be 75 ohm impedance with solid center 
conductors, and with Type F male connectors.
General
Where to Install
How to Install
If the protector is installed further than approximately 30 feet 
(10 m) from the cable service entry point, the overall protection 
level to the video equipment can be improved if the cable shield 
is grounded at the cable service entry. Refer to NEC 820-33 for 
grounding of the shield basically, the grounding conductor should 
be insulated copper wire, #14 AWG or larger, and should connect 
to the electrical service grounding electrode system (a grounded 
interior metal water pipe, building steel, electrical service 
equipment enclosure, ground wire, or ground bar).
The cable on the service side of the protector should be RG-
59B/U or RG-59/U with a center conductor size of #22 or #23 
AWG  with a diameter of .025 inches (.065 mm) or smaller. (Note 
that RG-59/U is available with a range of center diameters from 
#20 to #23). If the protector is installed at the service entry point, 
then the restriction on center conductor size would apply to the 
service provider’s cable drop.  Note: Most recent and new cable 
service drops utilize RG-6/U which has a larger center diameter.   
If the protector is located further downstream, then the restriction 
on size can apply either to the cable drop or to the cable between 
the service entry point and the protector. To ensure the proper 
failsafe coordination with the protector, if the upstream center 
conductor diameter(s) are larger than this, a 12 inch (300 mm) 
or longer stub of RG-59B/U, or RG-59/U with a #22 or #23 sized 
center conductor should be added in line, on the service side of 
the protector.  
The cable from the protector to the video equipment can be any 
75 ohm cable of any center diameter (RG-59/U, RG-59B/U, 
RG-6/U, or RG11/U).
IMPORTANT: The Protector(s) described in this Installation 
Instruction shall be installed in accordance to the applicable 
requirements described in the National Electric Code, ANSIINFP 
A 70, Article 800, Section C.