Security Sales & Integration October 2021 - 56

SMARTS & PARTS
Tech Talk by Bob Dolph
Grounding
Essentials
TOOL OF THE MONTH
This month I have selected
the new DTK-120X12 SPD
solution from Ditek for fi re
alarm systems. It can connect
up to 12 low-voltage circuits.
Status of circuits can be
monitored by dry contacts.
Onsite fi eld replacement
modules makes for an easy
service call.
▶ EVERY ESSENTIAL SKILLS repertoire
should begin with a fi rm foundation. In this case
I am referring to ground. Small word, but a very
important concept for every serious professional
systems technician. Th is month we are going to
build on our essential skills library by drilling
down and understanding the concepts of ground.
You will fi rst notice that I have been somewhat
Bob Dolph has served
in various technical
management and advisory
positions in the security
industry for 30+ years. To
share tips and installation
questions, email Bob at
bdolph.ssi@gmail.com. Access
content from his 15+ years as
Tech Talk columnist by going
online at securitysales.com/
author/bdolph.
56
vague about the term ground. Th at is because
there are many types of grounds. Earth ground
is physical connection to the earth itself. Th is can
either be a ground rod or some other buried metal
conductor. All grounds theoretically are at zero
volts. Th e third, middle round prong in an electrical
outlet is considered earth ground. Th e large
fl at prong is considered the neutral connection;
however, it is actually connected to ground in the
facility for electrical safety. If you have equipment
with metal enclosures they will typically be connected
to earth ground. Th is will protect anyone
from being shocked from a wiring error.
Equipment should be grounded at a common
point in the facility to avoid what is referred to as
ground loops. Circuit ground is the common connection
in electronic circuits. Th is can be for both
digital and analog circuits. Care should be taken
as analog signals can interfere with digital signals.
Ground symbols can be confusing because some
are diff erent and can mean the same, and some are
the same but can mean diff erent. It is best to know
the purpose of the type of ground you are working
with and the rest will fall into place.
Since we are in this arena you may have heard
the term bonding. Bonding joins noncurrent-carrying
conductive materials, such as cabinets
and raceways, in order to establish an eff ective
ground-fault path. Th ere are some good, free online
references for learning more about grounding
and bonding. I would recommend starting
with the free Mike Holt video series, " Electrical
Safety Fundamentals. " Old-timers may even fi nd
it a good review. Another good Holt video is
" Understanding Utility Neutral-to-Earth (NEV)
AKA Stray Voltage. " Find them on YouTube.
Yes, much of what we do is in the low-voltage
Security Sales & Integration OCTOBER 2021
bdolph.ssi@gmail.com
world, and one might ask, " What does high-voltage
and utility power have to do with me? " Well
for starters, if grounding and bonding is not performed
properly it can seriously aff ect the performance
of your system with things like audio hum
or signal interference. Now is a good opportunity
to take the time to understand and master these
grounding concepts. After all, it is in the NEC
code (Article 250) as well.
Once a proper grounding system is in place, then
we can discuss the important function of lightning
surge suppression. No one knows lightning protection
better than residents of Florida, including
yours truly. I would like to point out Ditek, a surge
protection solutions manufacturer that has been
based in Florida for more than 30 years. Being the
experts they are, I thought I would relay some of
their advice on what are best practices.
1. Most surge protection plans begin from
the outside and work in. While outside devices
such as cameras are in danger from lightning, it is
the inner heart of the system that needs planned
surge protection as well. Surges may also not
come directly from lightning.
2. Grounding is the fi rst line of defense
when it comes to surge protection. Centralized
grounding is very important. It can help reduce
interference and line noise, improve power factors,
reduce the risk of accidental electrocution and
help decrease potentially damaging harmonics.
3. Make sure the SPD is properly installed.
An improperly installed surge protection device
(SPD) will not perform at maximum effi ciency.
Proactive measures are strongly encouraged for
security systems and fi re alarm panels. Installation
of SPDs should be done by professionals and not
DIY personnel. Th e conductor length between
the SPD and protection equipment should be a
minimum of 3 feet. Th is allows for the SPD to
react and protect the equipment. Protected and
unprotected wires should be in separate conduits.
Install a solid metal grounding bus bar.
4. Be aware of additional sources of power
surges. Establish plans to mitigate outside power
surges and spikes. Some potential threats are wired
connections to outdoor cameras, signaling and
notifying circuits in fi re alarms systems, phone
lines connected to fi re and security control panels,
ATMs, and point-of-sale devices. A suggestion is
to simply install SPDs on both ends of wire runs.
Find additional tips in the online version of this
colum.
securitysales.com
COURTESY OF DITEK
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