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2103 Secondary Surge Protector

Installation Guide

Overview

Teledyne Isco’s 2103 Modem Module has internal 

protection for differential voltages and large current 
flows on the tip and ring conductors of a phone line. 
However, since the 2103 is powered by batteries, it lacks 
a ground reference and does not have protection from 
common mode voltages. In certain situations, such as a 
lightning strike, large currents could be sent through the 
2103 and attached 2150 down to the probe and into the 
stream, resulting in damage to the equipment.

Installation of the 2103 Secondary Surge Protector 

provides additional protection against a close proximity 
lightning strike. It does this by using a low impedance 
Ground Equalization Conductor (GEC), which equalizes 
the ground potential at the 2150’s probe with that at the 
primary earth ground.

Installation

The Surge Protector Kit (P/N 60-5314-493), shown in 

Figure 1, contains the following items:

30

Cable tie fasteners

2

5/16” #4-40 flat head screws

2

1/4” #4-40 flat head screws

50 foot Ground Equalization Conductor

1

Secondary Protector

Figure 1: Secondary Surge Protector Kit  

CAUTION

The surge protector kit is not to be installed in an 
environment that is classified as a Hazardous Location. 
This kit has not been certified to be safe or to make 
equipment safe in environments defined as hazardous.

The preferred configuration is shown in Figure 2, 

which shows a site where the 2103 is within twelve feet 
(cable route) of the primary earth ground.

Figure 2: Preferred Installation Configuration  

If the 2103 is more than twelve feet from the primary 

ground, an additional earth ground will be needed. This 
second grounding point should be as close to the 2103 
as possible, but outside of the manhole. When using this 
configuration, the secondary protector and the GEC 
should be connected to the secondary ground instead of 
the primary ground.

Note

To prevent an excessive amount of energy from being 
dissipated through the manhole, the primary earth 
ground must be of highest quality.

Follow the steps below to install the secondary surge 

protector:

1. Remove the 2150 and 2103 from the manhole.

2. Extract the mounting ring with probe from the 

sewer. Remove the old cable ties holding the 
probe to the mounting ring and remove the 
probe from the ring. Clean off the ring, probe, 
and cable

3. Mount the GEC to the probe, as shown in Figure 

3. Use the longest set of screws in the kit to 
securely mount the GEC and probe to the mount-
ing ring, as shown in Figure 4.

Secondary 
Protector

Ground Equalization 
Conductor and 
Connector

Cable Ties 
and Screws

Battery

Ground
Equalization
Conductor

Outside Manhole

Inside Manhole

2103

2150

Mounting

Ring

Probe

T elephone

Line

Stream

Protector

Protector

1st

2nd

Primary Earth

Ground

Instruction Sheet

Revision C, September 18, 2009

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