Fall 2007
AgriCulture
Energy information for the agricultural community
Time to Check
Waterers and Heating
W
ith winter around the
corner, now is a good
time to check your farm’s
waterers to make sure
your livestock get the water they need
through the cold days ahead.
The Straight Up Facts
About Utility Poles
Did you know:
• There are approximately 170 million utility
poles in North America.
• Most utility poles are made of wood and
pressure-treated with some type of preservative to keep away woodpeckers, insects,
fungi, fires and rotting.
• Western red cedar is a popular wood type
because of its natural insecticidal properties
and durability.
• Utility poles are divided into 10 classes.
• A class one utility pole has a minimum top
circumference of 27 inches.
• The higher the class number, the skinnier a
pole. Utility pole lengths start at 16 feet and
increase by two-foot steps to 22 feet, then by
five-foot steps from 25 feet to 90 feet.
• A 90-foot, class one western red cedar pole
weighs about 6,600 pounds. A 16-foot pole
weighs only about 700 pounds.
• Poles are spaced about 100 feet to 300 feet
apart, with 250 feet being typical.
Making sure your waterers are running
smoothly is crucial to the health of your
animals. The amount of water consumed by animals has a direct effect
on body tissue growth, weight gain and
health, and their ability to digest and
use food. If the liquid in your waterers
is frozen, your livestock can’t drink the
water they need for growth.
Your fall checkup of electrically heated
waterers should include making certain your waterer is properly fused and
bonded to your electric system. It’s
important to ensure that the grounding
conductor is bonded to the case of the
waterer. The electric circuit running
to your waterers should be checked
for damaged insulation and broken or
missing box covers.
All the conduits (the steel or plastic
pipe that wires run through) should be
in good condition and not rusted out or
broken. Make certain that conduit connections are tight.
Performing a complete check of electrical connections to heated waterers will
help prevent costly loss of livestock due
to electric shock from shorts. It also
will prevent frozen, broken pipes and
the costly replacement of waterers.
Besides checking your waterers,
remember to check the heating tape
wrapped around your water pipes.
Check the tape for deterioration or
cracked electric insulation and any
sign of overheating. You may need to
remove insulation to check for hidden
damage. Also examine all electrical
connections for deterioration and overheating. And don’t forget to make sure
your barn lighting system and grain
dryers are working properly this winter.
If extension cords were used last year,
a ground fault circuit interrupter should
be installed with approved wiring
material for the conditions. Proper wiring methods will reduce fire hazards
and possible electric faults, which could
cause dangerous shock conditions.
Make sure to call a qualified electrician
for any needed repairs.
For more information on checking heat
tape and livestock waterers, fill out the
enclosed postage-paid card, and circle
EQ-2 and mail it to Consumers Energy.
Four-Wire Services: What Are They And Why Are They Important?
M
ost single-phase electric
services are a 3-wire
arrangement, using two hot
conductors and a neutral
wire. But in some cases, particularly
where stray voltage could affect animals
or where dedicated grounding of equipment is needed, an arrangement called a
4-wire system may be needed. Because
this service arrangement is becoming
more widely recommended, we are providing the description and illustration
below to help our readers understand the
basics of 4-wire single-phase services.
The fundamental difference between
a standard 3-wire single-phase service
and one with 4-wires is installation
of an additional equipment grounding
conductor to create a separate dedicated
path for ground faults to return to earth.
This is shown by the dashed line in the
illustration. The addition of this fourth
wire reduces the potential for specific
sources of stray voltage in livestock
confinement facilities. Because installation of a 4-wire service adds little to the
overall cost of new electric services, and
standard 3-wire services can be easily
upgraded in most cases to 4-wire, this
new arrangement has emerged as a cost-
effective solution to certain stray voltage
problems.
Referring to the illustration, a standard
3-wire service from a pole would include
all wires shown except the equipment
grounding conductor (dashed line). The
absence of this wire in a 3-wire service
means that at the building’s panel (right)
the incoming neutral is connected alongside the grounding conductor to a common terminal block, just like it is at the
meter pole. Therefore, in 3-wire systems,
there will always be some current on the
neutral. This results in a voltage drop
along the farmstead’s neutral, which can
be a source for stray voltage. In fact,
voltage drop along this neutral is one of
the most common causes of stray voltage
on farms. In cases where 120 volt loads
on a 3-wire system cannot be evenly balanced between Line 1 and 2, or when
long runs to buildings create high voltage drop on the neutral, a 4-wire service
can reduce the problem.
How 4-Wire Systems Differ
In the illustration, a fourth wire (equipment grounding) is added at the distribution point, and run to any building on
the premises containing livestock. (A
standard 3-wire system can still be run
to other buildings). At the facility supplied with 4-wire service, the neutral is
connected to a separate neutral terminal
block in the panel. It is NOT connected
to the metal enclosure of the panel.
Therefore, the neutral is not grounded at
the building panel.
The added grounding conductor is run to
a separate equipment grounding terminal
block in the panel. It IS required to be
connected to the metal panel (using a
bonding screw or jumper), and grounded
to the earth for safety.
With this 4-wire service, secondary neutral current from operation of loads in
the building cannot reach the grounding
terminal in the building service panel
and therefore cannot get to components
that livestock might touch. Even under
conditions of high neutral current and
high resistance on the neutral, the potential for stray voltage is dramatically
reduced with the 4-wire service. It will
not, however, protect the farm from all
stray voltage sources, only those associated with high neutral-to-earth voltage
originating from the building’s neutral
system.
(Continued on flap)
Line 1
Isolated Neutral Bus
Line 3, Neutral
Line 2
Line 1
Line 2
Line 3, Neutral
Line 4, Equipment Grounding Conductor
Bonding Screw/Jumper
Page 2
Grounding Bus
Staying Grounded: Farm Safety and
Neutral-to-earth Voltage
Understanding Stray
Voltage, A Working
Definition
What is stray voltage?
Stray voltage is an electrical current, generally less than 10 volts,
measured between two points that
a farm animal may touch at the
same time. If this occurs, a current may flow through the animal
between those points.
People seldom perceive these voltage levels. The amount of current
depends on the voltage and total
resistance of the circuit. Livestock
respond to the resulting current
flow, not to voltage.
Information taken from “Stray
Voltage” questions and answers,
produced by the Michigan
Agricultural Electric Council. Visit
its Web site at http://www.egr.msu.
edu/age/MAEC.
E
lectric safety on the farm
continues to be of paramount
concern to Consumers Energy
and farmers statewide.
Most farms employ a three-wire,
single-phase service that includes a
neutral wire grounded to the earth and
two ungrounded wires.
From the neutral to either of the
ungrounded wires is 120 volts. From
one ungrounded wire to the other
(Leg A to Leg B) is 240 volts.
Other farms may use a four-wire system. However, when installing a fourwire service to a farm building, it is
necessary to add separate equipment
grounding wire and grounding terminal block to the electrical panel.
The neutral terminal block must be
isolated from the metal panel by
removing the bonding screw and moving all of the bare grounding wires to
the newly added equipment grounding
terminal block. Failure to correctly add
the fourth wire can result in a dangerous condition.
“A dangerous voltage can develop
on equipment in a building if the
equipment grounding wire is omitted, forcing fault current to flow
through the earth,” wrote Michigan
State University researchers Jonathan
Althouse and Truman Surbrook in a
paper for the Michigan Agricultural
Electric Council titled, “Dangers
of Total Separation of Equipment
Grounds and Neutral,” Nov. 1999.
However, “The earth is never permitted to be the only equipment grounding conductor,” the wiring experts
report, paraphrasing the National
Electrical Code, Section 250.32(B).
The National Electrical Code (NEC) is
a booklet containing a set of minimum
standards for the safe installation and
use of electricity in residential, commercial, industrial and agricultural
structures.
It is published by the National Fire
Protection Association. The NEC
2005 softbound edition ($65) is about
725 pages. The NEC 2005 Handbook
($119.95) is an expanded hardbound
reference guide with about 1,250
pages. Both are available at http://
www.necdirect.org or by calling
(800) 344-3555.
Page 3
Four-Wire Services (Continued from page 2)
The 2005 Natural Electrical Code (NEC) includes specific wording about the 4-wire services as part of Article
547, Agricultural Buildings. The provisions of NEC 547.9
(B)(3) explain the installation requirements if 4-wire
systems are used in livestock buildings. A concern with
the 4-wire system is the dependence on a single connection between the neutral and the grounding conductor
at the main disconnect (meter pole). In a building with
4-wire service, if the neutral were opened, none of the
120 volt loads would operate. However, if the grounding
conductor (fourth wire) opened, the only way it would
be evident is after current caused harm to equipment,
animals or people. For this reason, the NEC requires the
fourth wire to be made of copper and covered (insulated)
if installed underground. This helps reduce corrosion.
The rules for 4-wire systems were first added to the NEC
in 1987. Because the concept and use of 4-wire services
is relatively new, there has been some confusion among
electricians and inspectors regarding proper installation.
An improperly installed or maintained 4-wire system
may not provide all the intended benefits in reducing
stray voltage. It also creates safety concerns. A common
problem in many 4-wire systems is interconnection of the
neutral and equipment grounding wires in circuits within
the building. These interconnections, whether intentional
or accidental, will defeat the purpose of the 4-wire system. Therefore, it is important that electricians and others
(Continued on other side)
Publication Order Form
To help us serve your energy needs, please include the following:
Your six-digit customer number as listed on the mailing label:
H
Fall 2007
Name
Address
City
Zip
Telephone
I am planning to install new electric equipment. Please call me to help
determine the correct electric rate and adequate size of electrical facilities.
Please circle the FREE publication you would like to receive:
EQ2 Livestock Waterers: Selection and Use
W6 Electric Fencing Basics
EQ5 Four-wire Electrical Service for Farm Buildings (MAEC)
“Understanding the Basics of Electric
Fence Energizers”
EQ7 Dangers of Total Separation (MAEC)
“Keeping the Current Flowing on an
Electric Fence”
EQ8Is Your Farm an Energy Hog or a Lean
Machine (Hoard’s Dairyman)
“Protecting an Energizer from Lightning”
AV1 Understanding Neutral-to-earth and Stray
Voltage
“Constructing an Earth Return System”
AV2 Equipotential Planes
W10 Customer Generation Connections
AV3 E ffects of Electrical Voltage/Current on
Farm Animals
W1 Agricultural Wiring Handbook
W2 E lectrical Wiring for Livestock and Poultry
Structures
W3 A Guide to Electric Fencer Safety
W4 Farm Safely with Electricity
W9 Farming Safely & Efficiently with Electricity
W11 Safety Tips Before You Build — A Quick
Guide
W13 Sizing and Selecting Your Standby
Generator
W14 Safe and Effective Electric Fences
W15 Standby Power
Four-Wire Services (Continued from other side)
doing wiring in the building clearly understand the 4-wire
system.
Remember, the 4-wire system is not a solution to every
stray voltage problem. It does not prevent neutral voltage
from other on-farm buildings or off-farm sources from
appearing as stray voltage. It only prevents stray voltage problems caused by operation of unbalanced 120 volt
loads and long secondary neutrals in the building with the
4-wire service. This type of service can, however, be a
very cost-effective way to prevent stray voltage problems
that originate from these two specific sources in confined
livestock buildings.
AGRICULTURAL SERVICES PE-A100
CONSUMERS ENERGY
ONE ENERGY PLAZA
JACKSON, MI 49201-9939
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Note: This story appeared in the December 2005 issue
of Current Marketing, a newsletter of the National Food
and Energy Council. It has been reprinted with permission from the authors, Richard Hiatt and Greg L. Stark.
Hiatt, president and executive manager of the National
Food and Energy Council, has his master’s degree in Ag
Engineering. Stark is a P.E., consulting engineer and
half-time lecturer at Texas A&M University.
Farm Energy Partner
For the past decade, Ron Mason has
been a key link between Consumers
Energy and Michigan farmers.
An account manager in Consumers
Energy’s corporate communications
department, Mason has helped produce this newsletter and community image advertisements, and supported the company’s agriculture
services department at Michigan
Ag Expos and FFA conferences.
“It is a distinct honor to serve
the communication needs of the
agricultural community,” Mason
on
Ron Mas
said. “Being a city boy, I have a newfound
respect and appreciation for the day-to-day workº of our
Michigan farmers.”
Mason graduated from Wayne State University in 1984 with
a bachelor’s degree in journalism.
Call Us for Help
As your farm operation changes and grows, so will your
­electrical needs. By planning and anticipating power demands,
you can ensure your electrical system won’t be overloaded. New
construction or renovations also give you an opportunity
to install safe and efficient energy measures.
If you are in the planning, remodeling or expansion stage, call
the Agricultural Services department for recommendations at
(800) 252-8658.
And if you wish to upgrade, request new electric service or are
already under construction call (800) 477-5050.
Free Checkup Protects
Livestock
If you have a concern about animal contact voltage, call
Consumers Energy at (800) 252-8658.
We’ll conduct a free evaluation of your farm and provide an
illustrated booklet that describes animal contact voltage sources,
detection and maintenance steps to help prevent them from
affecting your livestock.
Page 4
Visit us on the Internet: www.consumersenergy.com/farm
Agricultural Services Department, PE-A100
Consumers Energy
One Energy Plaza
Jackson, MI 49201