system must also be durable
under actual field conditions. The markers need
to be made of a substance that will last outdoors for
decades, enduring the harsh environment of ultraviolet
radiation from the sun, the corrosive chemical attack
of today’s pollution, the effects of temperature
extremes (the freeze/thaw and dry/wet cycles), and vandalism.
A final consideration in choosing a
pole marking system is the cost
of its acquisition and ownership – its life cycle
cost. Often overlooked, yet undeniable, is the
fact that the labor and overhead involved in attaching
pole markers and maintaining them far outweighs the cost
of buying the markers in the first place.
No pole marker on the market is a perfect
fit for all of these requirements. Those individual who
must choose a pole marking system will have to endure
trade-offs between legibility, durability and economy.
Let’s look at each aspect in more depth.
human eye needs light and contrast (field and ground)
in order to see, to discern objects. As we all know,
vision acuity varies from person to person. In general,
humans can discern larger objects better than small ones.
This is true of pole markers. As a rule of thumb, a person
with 20-40 vision can see a 1” tall marker from
28 feet, a 2” marker from 56 feet, etc.
During the day the light we need to
see comes from the sun. Yet, as we all have experienced,
the sun can be too bright at times. A flat pole
marker made of a shiny substance (mylar, aluminum or
reflective sheeting, for example) often reflects the
sun’s rays too well, making the marker impossible
to read. The solution to this problem is to look for
a marker that is not flat, but made so that it contains
more than one plane – that is, a marker that is embossed,
stamped or de-bossed. A simple color contrast (black
on yellow, for instance) on a flat surface is not enough
to guarantee legibility.
At night we see less well because the
strength and angle of our light source is no match for
the sun. Often a street lamp, headlight or flashlight
is all that we have as a source of light. Whether these
sources of light are strong enough to see a pole marker
is a function of the distance of the marker from the
source of light and the weather conditions (clear, rain
or snow, etc.). The angle between the source of light
and the marker relative to our eye is also a contributing
factor to how legible a marker is at a given time. The
use of reflective glass
beads or reflective sheeting in the manufacture of a
pole marker will enhance legibility, but only if the
source of light is strong, focused, and at an angle that
approaches ninety degrees to the marker from the eye
of the beholder. This angle of incidence, as it is called,
is critical. Reflectivity is simply light bouncing back
to the viewer. A six-foot tall lineman pointing a strongly
focused beam of light held at eye level at a reflective
pole marker that is placed at a six-foot height on a
pole will have a greater chance of reading that pole
marker than if he were to shine a light from waist height
at a marker attached twelve feet up the pole. Too much
reflectivity can result in an illegible marker, as the
letter or number is surrounded by an aura that makes
reading the character difficult. To read more about reflectivity
markers can be made of a single substance, they can be
laminates/composites, or they can be printed or painted
products. While plastics have been touted as the answer
to society’s need for new materials, with some
being advertised as “stronger than steel,” it
is a fact that all plastics are polymers. Polymers are
simply linked chains of monomers, and any polymer is
vulnerable to UV (ultraviolet) radiation from the sun.
The sun’s UV rays “cut through” the
bonds of the polymer, reducing the plastic to monomeric
molecules. We experience this process as fading, cracking,
and the embrittlement of plastic markers.
been field proven over the last century to last outdoors
without degradation from UV radiation. Steel
markers rust, and brass markers are expensive. Bronze
and zinc markers are easily bent and broken. Aluminum
has proven itself as a material suitable for outdoor
use, as it does not rust and has good tensile strength.
Aluminum oxidizes upon exposure to the air, yet this
thin layer of aluminum oxide actually acts as a protective
layer against further reaction. To read more about
aluminum click here.
Paints and inks provide contrast on
certain pole markers. Both inks and paints are comprised
of a pigment and other substances. When applied and dried,
the pigment is bonded to the surface of a substrate material.
Layers of ink are generally thinner than layers of paint,
and ink’s bonding strength (its coefficient of
adhesion) is less than paint. Paints themselves are of
varying quality, as each of a paint’s components
(from pigment to plasticizers, solvents and UV inhibitors)
is an economic choice its manufacturer makes. In general,
the more expensive the paint the better it lasts outdoors.
Equally important factors in the outdoor durability of
either a painted or inked marker are the care and skill
of those who apply the paint or ink and the cleanliness
of the facility in which it is applied.
mentioned, the (fully burdened) labor cost to attach
and maintain any pole marking system is far greater than
the acquisition cost of the markers themselves. From
this perspective one would want to specify and purchase
the marking system that will last the longest and require
the least amount of maintenance. Yet it is an irony of
many an electric utility’s operation that initial
acquisition cost and purchasing budgets are all that
are considered when buying a pole marking system. (Perhaps
that is why there are only three manufacturers of porcelain
steel signs left in the entire United States.)
all the facts presented in the discussion above there
are choices to be made. If you want reflectivity you
will have to put up with a shorter field life of your
marker (even 3M, the inventor and largest supplier of
reflective sheeting, only guarantees its product for
7 years of outdoor use). If you want high contrast and
choose a painted product, make sure the paint used is
the best and that it is applied by people who know what
they are doing. But realize that even the best paint
will fade, for UV radiation is stronger than any paint
made by man. If you want economy, go with inexpensive
plastic, heat stamped markers. But realize that these
markers will peel, crack and fade within a matter of
a few years. If you need to assemble complex, multi character
alphanumeric coded markers, then go with a slide-in system
and make the markers up before they go to the field.
But realize that human error and mistakes will happen
and some of those markers will be wrong, and some will
never get to the field.
So, what is the best marker,
given all these trade-offs? Simple. It is the Premax
embossed, solid aluminum letter or number, nailed to
the pole with a Premax bright galvanized steel nail.
The marker will stay put for the life of the pole. It
is made of aluminum and will not rust, crack, fade, or
become illegible. It is embossed, and it will reflect
the sun’s rays or a flashlight’s beam from
multiple angles: it will never blind you as a mirror
We have 82 years experience with
this type of pole marker. We have made over 800 million
of these markers – all of them in the good old
United States of America.