User's Guide

We continue to elaborate on these recommendations in the following sections.
G.1.4 Ethernet Surge Protection
An Ethernet cable provides a path for a power surge to enter a BreadCrumb. The longer the cable, the
more susceptible it is to picking up surges. In case of a lightning strike, the cable will act as an antenna
and absorb the electro-magnetic wave caused by the strike even from a long distance. Surges through
the Ethernet port can be suppressed by an Ethernet surge protector.
Selecting Ethernet Surge Protectors
There are several aspects to consider when selecting an Ethernet surge protector:
• It is important to know how large a surge the protector can handle and how many strikes it can with-
stand before needing to be replaced.
• Be sure that the surge protector supports passive PoE. Installing the wrong surge protector on the
PoE line can prevent the BreadCrumb from getting enough power to turn on.
• The surge protector will cause a voltage drop in the PoE power carried over the Ethernet cable. The
voltage drop should be small enough so that enough power reaches the BreadCrumb.
• The surge protector will cause some degradation to the Ethernet data signal. Be sure that the degra-
dation to the signal does not severely impact Ethernet throughput, especially on longer Ethernet ca-
ble runs.
Rajant recommends the L-Com ALS-CAT6HPW Ethernet surge protector ( www.l-com.com, P/N: ALS-
CAT6HPW) (see Figure 1).
Figure 1: L-Com ALS-CAT6HPW Ethernet Surge Protector
The features of this device are:
• Designed to meet the GR-1089 Intra-Building surge protection requirements.
• Weatherproof ABS enclosure with gasketed cover and PG16 cable glands for outdoor operation.
• External ground clamp to provide a tie point for earth ground.
• Compatible with 10/100/1000 Base-T equipment.
• Compatible with CAT5, CAT5e and CAT6 cables.
• Robust, two-stage TVS diode and differential gas tube suppression.