The Utility Pole Fan Page

Last updated May 24, 2012


The following are questions that I have about utility poles. Some questions here are more burning than others. There are some questions which may have obvious answers that I just thought were more necessary to bring up. Some of the questions are also based on search queries that people did at search engines, such as Google and Yahoo. There are also answers included that I have received from a few people regarding some of the questions.


What does "P & H" stand for that are engraved with the date on the old gray poles?
The P&H brand you have seen stands for Paige & Hill. They were a pole treating company.
Robert W.

What do the numbers and letters stand for on the engrave marks? For example, two poles near my house have this arrangement of numbers and letters, as shown in the illustration below. (I know that "Koppers" is the name of a wood preservation company, and "78" is the year that the pole was treated and/or manufactured.)
KOPPERS, MO 78, SP C, 4 - 40
The engraved marks on your pole SP relate to Southern Pine the species. 4 40 relates to the fact that the pole is 40 long (set in the ground 10% plus 2 feet or 6 feet). The prefix 4 means that it is a class 4 which refers to its strength or more directly the diameter of the pole at groundline.

Where the total height is indicated on the poles, does this include the part of the pole that is underground?
Yes. We generally use the formula: height of pole top = total height - (total height * 0.1 - 2ft)
Adam K.

What is used to stamp the brandings on the poles?

What do these stampers look like?

Climbing Steps

What was the purpose of the hooks inserted in the sides of the poles?
Hooks were put into poles to assist the telephone/catv man to get to the cables. Nowadays, they use ladders to access them. If you notice, none of those hooks reach beyond the phone/catv. Then only "hooks" that do reach higher are the step bolts on a transmission tower and the climbers we use to climb the pole when a pole is inaccessible to a bucket truck.
These were originally used for poles that were going to be climbed frequently. (OCR poles, tie points between feeders) They saved wear and tear on the poles.

Why were the hooks discontinued?
Hooks in the poles were discontinued due to liability of kids climbing the poles. Especially with all of the bucket trucks, climbing a pole is a rare event.
With more bucket trucks being used they [the hooks] stopped being used.

Why do some poles have the climbing hooks while other ones don't?
The ones with the pole steps (proper term for "hooks") were where the linemen would have to climb often (such as to operate a switch) and to save wear and tear on the pole from the climbing hooks linemen use.
David D.

General Specifications

How tall is a telephone pole?
The poles we use typically are 40' for secondary (house current) circuits and phone only, 45', 50', 55', 60' for Distribution Primary Circuits (5Kv, 15Kv, 25Kv) 70' for Transmission Circuits (however this is rare as most transmission will be on metal towers)
Adam W.A.

What is the standard height of a telephone pole?
The average height, most commonly used for Distribution, is 45' Class 3
Adam W.A.

How deep is a telephone pole buried into the ground?
A pole is buried according to this formula: 10% of the poles height + 2 Feet. eg. For a 45' Pole, the pole would be buried in a hole 6'6" deep.
Adam W.A.

What is the length between poles when they are set?
There is no set distance. Utility distribution poles average about 200 feet from pole-to-pole but that spacing can be longer in some cases and, more commonly, shorter where pole loadings are higher or the line needs to be stronger for storm hardening.
Dave C.

How far should a utility pole be from the road?
As close as you can get it without destroying the curb is generally fine. For sensitive equipment such as if you had a pad mounted transformer near the road, you would use bollards to protect it from cars. However for line of sight reasons, we maintain a clearance of 1.5 metres from driveways, corners, etc.
Adam K.

How far from the pole should the guy wire be installed?
Depends on the results of force calculations. It will be different everytime.
Adam K.

Why don't electric companies use metal poles?
Because they are generally conductive. We use them for streetlighting where there is no electrical plant on the pole. If a wire were to break and a phase touched a metal pole and you were near it, you would likely be hurt.
Adam K.

What is the weight of a telephone pole?
The average pole (45' C3) is about 1200 pounds
Adam W.A.

What kind of wood are utility poles made of?
Most of the poles that we use are Ceder, however I have seen pine and tamarack used.
Adam W.A.

What is the typical diameter of a utility pole, based on class?
This does depend somewhat on height but c3 poles are typically ~18" in Diameter, c2 ~20", c1 24"... this isn't 100% of the time
Adam W.A.

How much does a utility pole cost?
By the time you've removed the pole, replaced it with a new one, reinstalled the framing and installed the components, you are looking at anywhere from $6,000 to over 10,000 on average (canadian dollars)
Adam K.


When were the very first poles erected?
The first poles were put up in 1844 when Morse built his famous telegraph line.
David D.

What did the old and gray poles originally look like when they were first erected years ago?
If the poles that are now gray were treated with creosote, they would have been dark brown. Creosote was used as far back as the 1910's and maybe further.
David D.
When they were treated at the pole treating plants, they were the blond color of new wood since the bark had just been peeled off. However, poles usually lie around in pole yards for awhile before they are set, so many of the cedar poles had probably begun to go gray on the side that was facing up in the pole yards by the time that they were set. I have seen pictures that show them when they were new, and even though the pictures are black and white, the wood appears to be a very light color, so they probably did not weather very much. Incidentaly, one of the pictures of a new cedar pole I have seen shows the wood ground wire molding (all poles with transformers have ground wires running down the side of them. Wood ground wire molding was used by WMECO until about 1968) to be just as dark as the creosoted butt of the pole, so the ground wire molding was probably creosoted.
Robert W.

Are records kept on the utility poles, such as when a pole was replaced or first erected?
Yes, but such information is not generally made public. It's done so that the utilities know what equipment is on each pole.
David D.

Do utility companies take pictures of the poles, such as for records?
As a rule of thumb no we don't take pictures of every pole. However whenever the engineering department goes out to look at a job or field check specific poles, we often take a camera and take many many pictures. I myself have taken hundreds of pictures in the last eight months. I can't speak for other departments. We keep all these pictures on reference for various reasons such as 1) not having to always go in the field to check everything 2) refreshing memory in the office while working on a job 3) evidence of a certain condition 4) to see the way something is configured so we can reference it again when doing a similar job.
Adam K.

Were there less poles erected than usual during WWII?
Very likely yes. Any construction not absolutely essential was put off until the war's end.
David D.

Is there such a thing as a museum which relates to utility/telephone poles?

When did utility bucket trucks become common?

I.D. Numbers

What is the exact purpose of the metal numbers hammered on the poles?
Some #'s denote a poles # in the line, some are switch #'s and if there is a piece of equipment on the pole it serves to ID the equipment.
The only purpose the letters and numbers serve is to ID the pole.
David D.

How long ago was it when metal numbers were first used to ID the poles?

What do the following metal letters stand for on the poles?
In the WMECO system, there are several suffixes that are added to numbers that have specific meanings. One is the suffix "B" which is added after the route number. (For instance, you might run across a pole numbered 154B/3). The suffix "B" refers to the side of the street the pole is on. The side that the majority of poles are on is side "A" and receives no suffix. All poles on the side opposite, ( with a few exceptions I can explain later) receive the suffix "B" after the route number. Thus, on a given street, route number 154, lets say there are three poles. Poles 1 and 2 are on the north side of the street and are numbered 154/1 and 154/2. Pole 3 is on the south side and is numbered 154B/3.
Robert W.

The suffix "M", which appears after the pole number (for example, 164/2M) means that the pole is an "intermediate" pole which was set in between two existing poles after the line was numbered. Pole 164/2M would be between 164/2 and 164/3. Other companies sometimes use the suffix 1/2. This is common practice with Massachusetts Electric. If a pole is set between poles 6 and 7, it will be numbered 6-1/2. For awhile, Massachusetts Electric used the decimal system for these poles, so instead of 6-1/2 the pole would be numbered 6-50. When two poles are set in-between two existing poles (this is a rare occurrence, but it does happen) I have seen Massachusetts Electric number the first pole 1/2 and the second 3/4. For example, between poles 6 and 7 would be 6-1/2 and 6-3/4 or in the decimal system, 6-50 and 6-75. When Western Mass Electric does this, the second intermediate pole would get the suffix M1. thus between poles 164/2 and 164/3 would be 164/2M and 164/2M1.
Robert W.

Push Brace (Source: The Lineman and Cableman's Handbook, Sixth Edition)
Stub (Source: The Lineman and Cableman's Handbook, Sixth Edition)

Why is there a serif "S" hammered on the side of a pole sometimes?

Why would a number get skipped in a sequence now and then?
It is not unusual to find numbers missing in a sequence. Thus, on a given street, the numbers may jump from pole 5 to pole 7 with no pole 6. This almost invariably means that pole 6 was removed at some point. One of the reasons that Western Mass Electric renumbered their poles was to rectify this situation, and restore a logical sequence. Of course, in the years after 1955, poles were removed as well, so you can still see jumps in the sequences. By the way, utility officials don't often speak of renumbering poles. What we would call renumbering is referred to as "restenciling" because at the turn of the century, before metal numbers were used, the numbers were painted on with stencils. This practice was discontinued, because the painted numbers wore off. Metal numbers are more permanent.
Robert W.

Have there ever been various sized sans serif numbers and letters used by certain companies just like with the serif ones?
I doubt fonts and materials matter much to the utilities, only that it stands up to the weather.
David D.

Are there any utility companies that still use sans serif numbers and letters today?

If the answer to the above question is "yes," then do any of these utility companies still use the old sans serif style (such as the "3" being flat-topped)?

What metals are the metal numbers made of? Have they ever been made of other various materials in the past?
I'll bet that most of these tags and letters/numbers are aluminum.
David D.

What makes some nails of a metal number/letter/company name tag stick out after a certain period of time?
Probably expansion and contraction of the wood over time?
David D.

Why is an electric company name tag up higher than necessary over an ID number sometimes?
Name tag up higher than necessary.

If not called "sequence numbers" (that each correspond with a street), then what are these numbers really called?
Within the company they are referred to as route numbers. The route numbering system has been in use since 1955. In 1955, Western Mass Electric took an inventory of all the poles in their system. Young engineering students were hired for the summer to measure the distance between poles, note the height, class and species of a pole, and to take note of all services attached to the pole. Services are wires that run from the pole to houses, businesses, etc. This raw data was used to create a card file. Each pole had a card, and the cards were filed by the pole's number. The card contained the following information: distance of the pole from the pole before it, number of primary (high voltage) wires, the size and kind of the wires (for example: #2 copper), the same information for secondary (low voltage, usually 120/240v) and street lighting wires (I'll have to save that one for an explanation of the history of street lighting systems). It was decided that with the new cards would come a new numbering system. The streets in the town were assigned route numbers in alphabetical order. (For example, in Amherst, Adams Street is route 1, and Woodside Avenue is route 162). Thus, the first pole on Woodside Avenue would be thereafter known as 162/1, not just 1, as was the previous practice. (You will note a difference in how the pole number is written and how it appears on the pole. On the pole, under the WMECO tag, would be 162, and below that 1. But this is written as 162/1 on the cards.) The old numbers were written in pencil near the new numbers just for reference sake. When a new street was added in any town after 1955, it was assigned the next number available in the sequence, regardless of its place in alphabetical order. Thus, for more recent streets, you could have an Apple Lane, but its route number might be 352. So the WMECO route numbering system is alphabetical by street name for streets existing in 1955, and sequential by the date the street was put in for streets built after 1955. I would expect that this is the case in other systems that have used this route numbering system, unless they deliberately skipped numbers to leave room for future streets.
Robert W.

Are there any other electric companies, besides Western Mass. Electric, that use route numbers based on alphabetical order of streets?
(The answer seems to be "yes," according to an observation that I have written here.)

Does the Massachusetts Electric Company use route numbers, although it doesn't seem to indicate on the poles in their area?

When NET&T Co. merged with a New York phone company to become NYNEX in the mid-1990's, why did the design of the ID numbers go through a major change?

I have seen utility company name tags up for auction at the eBay site. But I am curious, though: Have there ever been ID numbers up for auction at eBay?


Are there special names for the different types and lengths of crossarms?
I’m not aware of names for different are lengths but there are slang terms for different crossarm configurations.
Buck Arm – two sets of crossarms at 90 degrees to each other, usually used to change direction of the line.
Alley Arm-an arm used for off-center (sticking to one side) on the pole, usually used in alleys or places with reduced clearance on one side of the pole.
Dave C.

How is it determined what crossarm(s) and/or insulator holders to put on the poles?
Utilities will typically have a book detailing various types of construction for different applications. The correct term for "insulator holder" is pin.
David D.

Why are two crossarms (one on each side) fastened on a pole sometimes instead of just one?
Utilities will add the second crossarm where there is expected to be additional strain, such as in the following situations: line going around a curve, where the line crosses a street or railroad, and most importantly at the end of the line where the pull is the greatest.
David D.

What are the metal parts of the crossarms called?
metal parts
You are referring to the crossbraces. They are not always metal, as sometimes wooden crossbraces with metal ends are used.
David D.

What is/was the purpose of the little angle-shaped piece with a loop that appears on the metal parts of the crossarms fastened to the side?
The little bracket on the long crossbrace shown is a step for the linemen to get out to the end of the crossarm. This type of construction is referred to as "alley-arm" construction.
David D.

What are among the things that happen to old crossarms (and insulators) after they are removed from old poles?
Old crossarms and insulators will be either thrown out, saved for collectors (insulators), or sold at a surplus auction.
David D.

What is the purpose of the brown head extenders fastened on top of certain poles?
This is where a line is upgraded and the original height of the pole was inadequate. I've seen 2 crossarms used on either side of the pole for the same results.
David D.

What is the reason for the new design of crossarm braces (in which parts of them are wooden)?

What were the insulators made of over the years?
Insulators have been made out of a variety of materials. From wikipedia: glass, porcelain, or composite polymer materials. Porcelain insulators are made from clay, quartz or alumina and feldspar, and are covered with a smooth glaze to shed dirt. Insulators made from porcelain rich in alumina are used where high mechanical strength is a criterion. Porcelain has a dielectric strength of about 4-10 kV/mm.[1] Glass has a higher dielectric strength, but it attracts condensation and the thick irregular shapes needed for insulators are difficult to cast without internal strains.[2] Some insulator manufacturers stopped making glass insulators in the late 1960s, switching to ceramic materials. Recently, some electric utilities have begun converting to polymer composite materials for some types of insulators. These are typically composed of a central rod made of fibre reinforced plastic and an outer weathershed made of silicone rubber or EPDM. Composite insulators are less costly, lighter in weight, and have excellent hydrophobic capability. This combination makes them ideal for service in polluted areas. However, these materials do not yet have the long-term proven service life of glass and porcelain.
Adam K.

Why are there certain instances in which two straight-shaped insulator holders are screwed on across from each other on the pole, in which a bolt is also holding them together, and that one of these holders does not have an insulator on it?
straight holders on both sides

Other Poles

Why do certain poles have another pole leaning against it?
The slanted poles are to reinforce against unbalanced sideways pressure. This occurs when a line ends (maybe goes underground) or turns a corner.
Those are called push poles and they support the pole they are "pushing." This is used when there isn't sufficient room for a down guy.

Why are there certain occasions that a pole is placed across the road of another pole? What is the purpose of these poles?
The illustration shows the use of an overhead guy. They are primarily used when there isn't room to put a down guy directly down from the pole. For instance, if the road in your illustration curved to the left, there wouldn't be room for a D/G. So we run it across the road to a pole and down.
These are span guys and are used when there is not enough room to install a normal guy to offset an unbalanced load on the pole. (pole too close to sidewalk or roadway)

When were push brace poles first used?

When were stub poles first used?


What is the detailed process of deciding which poles should be replaced?
I am currently working on refining this process for our company. Generally the process begins in two places/ways. 1) Engineering department - We keep records of poles in the city, their installation date, height and class. Because it is in our best interest to replace a pole before it fails, we have consultants conduct rolling inspections of poles in the city. They note observations on things such as mechanical condition, overall condition, probable remaining life. They also provide detailed information such as the butt treatment and wood species. We use this information to target areas of the system to be rehabilitated. Issues such as rot below the groundlevel, major cracks, leaning poles, hollow poles or carpenter ant or termite damage aremajor reasons to replace a pole. The other reason we may decide to replace poles (aside from age and mechanical condition), is that as standards are changed, what was once acceptable may no longer be. Sometimes we have higher voltage system on a pole that is not of adequate height, or perhaps we are adding telephone or cable attachments to the pole and this may be over the strength specifications of that class of pole. Either way system can be upgraded at the same time as replacement and this is often the reason why we replace certain poles. 2) Line department - they used to kick poles with their spurs or hit them with hammers to listen and determine if poles were hollow or unsafe to climb. Also a screwdriver is thrust at the pole and if it penetrates, the hole is soft or hollow.
Adam K.

How is it determined which poles should be replaced?
There is a test called osmosis done to determine if the pole is rotten inside. Also, if the pole is not tall enough to support a new specification.
The poles are butt checked roughly every 5 years. If they are rotten, they are marked for replacement.

How is it decided which utility company should put up a new pole?
In some towns, such as Hadley and Deerfield, you will see new WMECO poles that are not green. This is because in those towns, the telephone company sets the poles and they get to choose the pole species and treatment. From the mid 70's until 2001, they set penta treated poles. This year, 2002, Verizon has begun setting creosoted poles again. These are the first creosoted poles to be set in this area in more than 20 years. You can spot them instantly by their coal black appearance.
Robert W.

How are poles marked for replacement?
(I may be answering my own question here.)

How is it decided how a pole should be marked ("X," arrow, stick, etc.)?
If you are talking about marking where we want the pole. Generally after the engineer or technician/technologist designs the system for an area, they go out with stakes, a hammer and spray paint. We place a stake at the centre point of where we want the new pole and spray paint a circle around that. Then we place a stake where we want a guy anchor to enter the ground and spray paint an x with the stake at the centre.
Adam K.

Why is the down arrow used most often for marking poles?

After wires are transferred from the old pole to the new one, why is the head cut off the old pole?
The old pole top is cut off to make it easier to remove the old pole. It may also be done to increase the clearance of existing conductors.
Sometimes, especially in the winter, a six foot piece is left sticking out of the ground. In the winter the ground is frozen, poles are hard to pull and backfill is also frozen. It is quite easy to remove the six foot stub in the spring without having to worry about clearance to energized lines.

How long ago was it when the practice of cutting off a top of a pole began?

Why is the bottom part of a replaced pole cut off sometimes?

Why does a very short stump of a pole remain now and then, and not get pulled out of the ground?
[It is] likely the line department never got around to removing the stub as this is not of high priority. in odd circumstances we have removed the top of a pole and removed the distribution from it but left telephone attachments on for instance, and in that case we do not bother removing the stub.
Adam K.

Why are there a few instances in which a tiny part of an older pole remains hanging in the air and still holding wires?
We do this on occasion as a way to keep wires separated, it is a bit of a lazy trick, and not often done for safety reasons.
Adam W.A.

What devices are used to erect a new pole into the ground?
An auger mounted on the line truck is typically used to bore out the hole for the pole.
David D.
In addition to the auger we now use (almost exclusively) what is called a vacuum truck. the vacuum truck can excavate the soil to make a hole for the pole without damaging any gas lines, etc under the ground. We use a boom truck to place the pole in the hole while linemen direct the pole. In the old days, (really old) they used what are basically sticks with an end like a yoke to push the pole up, while someone stood under the pole with an x shaped brace to keep it from falling back down on them all.
Adam K.

What devices are used to pull an old pole out of the ground?
A clamp on the line truck's boom is used to pull the poles out.
David D.

What are among the things that happen to old poles once after they have been removed?
When old poles are removed, if they are in good enough condition, they are recycled. The old grey, weathered wood is scraped off of the outside of the pole, and the pole is re-preserved. Other than that, I have no idea, though locally I have seen that old poles are sold to those that see a use for them. I have seen more than one fence made out of old utility poles, with all the pole line hardware still screwed into the wood :)

What is the purpose of the orange padding on a new pole that is just erected?
This is an insulating sleeve to protect the groundman in case the pole makes contact with the primary circuits while being set.
Adam W.A.


What is/are the reason(s) that poles, years ago, were made with a double slant at the top?
The angle cut(s) on the top is to shed water and snow.
The double slant is called a roof. The old poles were roofed to shed water and snow.
The double slant was intended to reduce rottening at the top of the pole by creating a "roof" to drain the water so it would not puddle on top.

Why was/were the double slant(s) discontinued?
It may be considered superfluous with more advanced rot proofing.
Because the treatments for today's poles are better.
New treatments eliminate this need along with the fact that the slates weaken the pole.

Street Lights

What do the black numbers stand for on the yellow stickers?
streetlight number sticker
The numbers represent wattage, and the background color represents the type of lamp installed (mercury, high or low-pressure sodium, metal halide).
David D.

When were the very first streetlights installed?

When were fluorescent streetlights first made and installed?

When were fluorescent orange streetlights first made and installed?

How high up should a street light be from the road?
There are formulas that specify the cone of light that must be produced, this combined with standards of each distribution company's height of lowest attachment usually dictates the height it will be installed at. For instance ours are generally around 24 ft from ground level.
Adam K.


What was the purpose of the little brown round tags with two-digit numbers? Could they be old inspection tags from many, many years ago? (Illustrations of examples directly below, displaying close to actual size of tags.)
29 tag 36 tag
These are called "date nails" and these were made of copper. Typically, they represent year of erection.
David D.
When you look at old poles in the Massachusetts Electric Company system, there is one interesting thing about the dating nails that they used. You mentioned some poles with 29 dating nails in Shutesbury. Well, in 1932, it became the practice in this system to use two dating nails, one for the length of the pole, the other for the year set. The dating nail used for the height of the pole has raised numerals. The dating nail for the year set has recessed numerals. Thus you will often see combinations such as 32 35 for a 35' pole set in 1932, or 40 41 for a 40' pole set in 1941. For 35 foot poles set in 1935, you see two 35 dating nails, one with raised numerals, the other recessed, as mentioned above. These dating nails are almost always right next to each other, usualy quite close to the ground, but sometimes they appear at the height of the aluminum pole numbers. For poles with recognizable brands, dating nails were not used during these years. Starting in 1942, the second dating nail for the height of the pole was dropped. Thus this rather unique system only seems to have existed between 1932 and 1941. In one instance, I saw a piece of steel conduit attached to a pole with a dating nail. This was a 34 dating nail seen on a 1933 cedar pole in Northampton (yes, I have noticed that there are a few cedar poles in Massachusetts Electic's territories. Those in Northampton seem to mostly date from the years 1928-30. The newest I have seen was 1935.) This steel conduit appears to have been used for an underground electric service to a house. The dating nail may have been used to record the date that the underground service was installed. If you ever run into one of these, take note of it if you can. It would be very interesting to find out if the structure that that underground service runs to was built in the year indicated by the dating nail.
Robert W.

Technical Information

How many volts come in from the pole to the breaker box?
Normal household electrical service in North America is 120 and 240 volts, carried on two "hot" wires and a neutral. The voltage from either hot wire to neutral is 120, while the voltage between the two hot wires is 240. 3-phase industrial power is different, with 120/208 being quite common, but various voltages can be used, including 277 and 480. Most power will be dual voltage, even with 3 phase systems.

How many volts do telephone pole cables carry?
Telephone circuit voltages vary depending on the type of service, distance from the central office equipment, and the type of equipment on the line. The most common is a standard loop-start telephone circuit, consisting of a twisted pair of copper wires. When the phone is on the hook, the voltage is low, only a few volts, say 9 or 12. When the phone is off-hook, the voltage increases to about 48 volts DC. Ringing voltage is around 70 to 90 volts AC. Other types of phone circuits such as digital multiplexing circuits (T1 lines are common, so are various kinds of DSL) may use more than 100 volts DC to power line repeaters. They can't carry much more than 150 volts or so because of insulation limitations. Current flow is limited, but can still be dangerous if you should happen to contact it.

Railroad Poles

What type of use do the railroad poles have?
These poles fulfilled several purposes: telephone, telegraph, railway signalling, and railway power.
David D.

Why do train track poles appear more crooked (at least in the case of the older ones)?
Railroads rarely go straight, and the line follows the track. Except where it was absolutely needed, the poles were seldom braced or double-armed.
David D.

What type of company works on the train track pole wires?
The railways do their own maintenance on their lines.
David D.

Why have some train track poles and wires been removed?
With radio equipment being far easier to install and maintain, the pole lines were no longer needed.
David D.

Why are railroad poles shorter?
The voltage of the line determines the minimum safe height. Rarely does a railroad line have more than 600V on their lines (and the high voltage lines are always at the top crossarm).
David D.

Why are railroad poles not given metal ID numbers like other poles?
The sheer number of poles would make it prohibitive (3x or 4x as many poles per mile as power and consider the number of miles each railway owns).
David D.

What are old railroad telephone pole wires made of?

[NOTE: I have found newsgroup messages from alt.railroad that may contain answers to some of the questions that I have asked in this section.]


Where was the first pole transformer installed and when?

What was inside the first pole transformers?

What is inside a utility pole transformer?
A pole mount transformer generally consists of:
However if you are talking about poletrans thats something different, where the transformer is integrated into the inside of a metal pole - dangerous for line crew
Adam K.

What is the tiny red light that appears on the transformers?
It's an overload indicator, it comes on generally when the tranformer is loaded to 110% or greater
Adam K.

When is a transformer put on a utility pole?
After the new pole is framed and I believe after the stringing of the line is done. Or if the pole is existing, then it is installed when designs call to have one installed.
Adam K.

How do telephone pole transformers operate?


What type of treatment was/is given to the old and gray poles? to the dark brown poles? to the orange poles? to the green poles? Also, are the looks of a pole based on what type of treatment it receives and/or type of tree it was made out of?
The color is treatment to preserve the wood. Used to be that poles were not treated. They didn't last long unless they were locust or some other type of naturally durable wood. Then came creosote treatment, the dark color and pungent aroma. Green poles are usually CCA treatment. Another treatment is copper naptanate(sp).
The only untreated poles I ever saw were along the Long Island Rail Road. They were short poles and carried telegraph wires at one time. They were taken down several years ago. The grey ones may be creosoted ones that have had the creosote on the outside leached out of them by the sun and the rain. (Creosote is not water soluble.) CCA would have kind of a green tint. Creosote would be brown to black. Orange could be copper naphanate (sp).
The looks of a pole is dependent on the species of timber and the treatment. Treatment can be CCA (a copper based chemical; hence the green color) or penta (similar to creosote) or creosote. Species include southern yellow pine, douglas fir, and western red cedar.
When poles began to be set along New England streets, in the late 19th century, the species of choice was chestnut, because it grew locally and had a natural resistance to decay. In the early days, the poles were completely untreated. Poles in downtown sections were painted a dark color, usually brown or green, but poles on country roads, and poles on private property were usually left unpainted. These untreated poles, despite the decay resistance of the wood, didn't last particularly long. Companies began to apply creosote with a brush to the portion of the pole that was set in the ground, but a pole treated this way would only last about twenty years or so, still not long enough to prevent frequent replacements. In the early 20's the Chestnut blight began killing off the chestnut native to the east coast, and electric and telephone companies had to find different species to use that did not come from this area. Cedar and Southern Yellow Pine were the species chosen by the majority. In 1925, the Amherst Gas Company, predecessor to Western Mass Electric in Amherst, began to set cedar poles. The cedar poles came from the great lake states and the pacific northwest. They were "butt treated poles", with creosote applied by the pole treating companies to the portion to be set in the ground only. Those old gray poles with brown bottoms that you have seen in Greenfield and Montague are cedar. They were never brown on the upper portion because the upper portion was never treated. The vast majority of poles set in Amherst between 1925 and 1943 were butt treated cedar. Western Mass Electric preferred these poles because of their appearance. It was felt that the untreated wood, which weathered to a nice blue gray color, was more attractive than the brown of the pole that had a full length creosote treatment. The other pole species in use at this time in New England was Southern Yellow Pine. Southern yellow pine is always given a full length treatment because untreated it is extremely prone to decay. It is also very strong, about twice as strong as cedar. The companies that were to become Massachusetts Electric preferred creosoted southern yellow pine poles to cedar during this same period. Thus, it is quite unusual to see a cedar pole in a territory served by Massachusetts Electric. During and after WWII, southern yellow pine replaced Cedar in the lines of Western Mass Electric. In the late 40's cedar was used only for 40' and longer poles, and poles class 2 and above. (the lower the class number, the heavier the pole). Since 1971, the use of cedar has been restricted to poles 55' in length or longer. The southern yellow pine poles purchased by Western Mass Electric were creosoted up until about 1979. From 1979 to 1982, Western Mass Electric set Southern Yellow Pine treated with Pentaclorophenol (penta). These are the "orange" poles you speak of. Massachusetts Electric still sets these. In 1983, Western Mass Electric started to use the green CCA treated poles they still use today.
Robert W.

Are there any utility companies that currently erect butt-treated cedar poles, or have regularly done so since after the mid-1940's?
All the poles that EPCOR uses are treated with creosote on the butt end only (only about 10' of treatment)
Adam W.A.

Why does the amount of brown color vary so much among the orange-colored poles?

When was the orange-colored treatment first used?
Penta was first used about the year 1941 on cedar poles in the midwest. Penta treated southern yellow pine poles appeared about a year later, and the use of penta as a preservative gradually spread throughout the country.
Robert W.

When was the CCA (green-colored) treatment first used?
CCA was invented and patented in India in 1933. Bell Telephone conducted the first large-scale CCA treatment of utility poles in 1938.
Source: This seems to be in conflict with the generally accepted first use of utility poles in Morse’s 1844 telegraph line.
Dave C.

What material, if any, was used to wrap around the ground level of a pole before there ever was anything made out of plastic?

How frequently are poles tested for their conditions?
General recommendations is to test poles at the groundline every 5 years. Depending on the weather conditions. Poles in the southwest and in Alaska do not tend to rot and are not treated.
What we do is split the city into 4 sections (north ,east, south, west) and do one per year, then the fifth year we retest random samples and repeat the cycle. I believe a 5 year cycle is indeed common.
Adam K.

Is it possible that round-sided diagonal-placed wood in a pole and/or a nail sticking out of the bottom of a pole have anything to do with the inspection of a pole?
Yes, typically these are plugs where the pole has been drilled into to determine if the core is rotten.
Adam W.A.

Why are poles that only have telephone wires not checked like the poles with the electric wires?
The answer is mainly due to risk level. Poles with primary circuitry are far more hazardous than phone-only poles, and as a result are given greater attention and priority.
Adam W.A.

Do some poles decay faster than others?
Yes. How fast a pole decays will depend on many factors including environmental conditions (wetter is worse), the treatment type, and wood species. Pole decay rates are usually considered by Zone based on the zone’s climate – wetter environments cause faster decay. You can find a decay zone map here:
Dave C.

What are some of the names of various preservation companies of the past and present? (Examples: Koppers and Mereduc are among such companies.)
The P&H brand you have seen stands for Paige & Hill. They were a pole treating company. Other brands that you might run into on old poles are as follows:
Robert W.

What makes cedar go gray?
Because the cedar pole is no longer living, it does not replenish the outer cells and natural oils and it’s natural color fades with exposure. Ultraviolet light (from the sun) is the main culprit but exposure to water and mold growth also act to fade the cedar to gray.
Dave C.

What type of wood is a telephone pole made of?
The main wood species for utility/telephone poles are Southern Pine, Douglas Fir, Western Red Cedar, Lodgepole Pine, and Red Pine.
Dave C.

How are utility poles made?
The basic process is that the trees are harvested, limbed/shaped, cut to length, treated, and certified. Poles are graded based on their straightness, taper, grain orientation, knots, and defects.
Dave C.


What is the purpose of the orange padding placed on the wires?
This orange sleeving is used where the wire may come in contact with an object that could cause a short.
David D.

What determines how many electric wires appear at the top of a pole (the number seems to range from zero to three)?
To answer a couple questions on your page, the reason why the wires tend to max out at 3 on the top crossarm is that the typical distribution system uses 3 phase wires (each 120 degrees out of step with each other). Whether 1, 2, or 3 wires are used depends on the load - lines close to the substations or in areas with many 3-phase loads (like business districts) will always have 3 wires. 2 wires are used in some residential areas that may have a business or two or where the residential load is too heavy so they tap alternate phases to spread the load out a bit. Single wire lines are used for short lines into residential areas. In some older areas that have not been upgraded, you will sometimes see a fourth wire... this is always the neutral.
David D.
That isn't always a completely true statement [underlined in David D. reply above]. In some parts of Maine, especially Lewiston Maine along the Androscoggin, and in Westbrook Maine along the Presumpscot river. The Sappi paper mill in Westbrook still has some 2 phase power distribution. Next time I am near there I will try to take a few pictures. The 2 phase power is 11kv at the street if memory serves me right. I worked in the mill that is supplied a couple of times. The indoor substation I spent a lot of time in consisted of: 2 phase 440v 750amp open bus with Frankenstein like wood handled knife switches as disconnects at eye level. 2300v 3 phase at 8 feet off the floor and 11kv at 10 feet. All of which is packed in a room that is 20x20. Not to mention the 1000a 240v slate board lighting panel. Its an electrical nightmare. An indoor substation built like that particular one would never fly with the NEC code today. I am glad as an electrician that I never had to work in any particular situation as dangerous as that energized.
2 phase power will commonly have 2 or 4 energized wires, less commonly 2, 3 or 5 wires depending on the arangement of the transformers, and the various ways the system can be grounded. A 2 wire 2 phase system is electrically 180 degrees apart. A 3 wire 2 phase system has 2 90 degree seperated armatures if memory serves me right, and one common conductor. The single line is generally 1.414 times larger than the 2 other line conductors. Think of a T where the vertical meets the horizontal as the common, and either side of that intersect is a phase. 4 wire 2 phase is two single phase center tapped transformers. Think of it as an X A 5 wire system is much like a 4 wire system except that there is a common tap "neutral" shared between the 2 phases.
It is a very antiquated system, it went out in the 1920s. The original generators at Niagra falls were 2 phase generators, that powered a Scott T connected transformer to feed a 3 phase line to buffalo. Westinghouse was the pioneer of 3 phase, Tesla pioneered 2 phase.
Josh M.

How come there are seldom more than three electric wires at the top of a pole?
Power is distributed as a three phase system. each primary circuit consists of three phases (although they can be separated out for single phase runs) so you will generally see either multiples of 3 (such as 6 in a double circuit pole), or just one if its a single phase section.
Adam K.

In medium to heavily populated downtown areas, why is there underground wiring instead of poles with wires?
Because of the complexity of the system in these areas, and the lack of space for poles, and the desire for beautification, it makes sense to use underground system. Although overhead system is cheaper, the underground system means you don't need room for downguys, poles (except streetlights) and can feed all the buildings from underground without having wires all over the place. It is a pain to work in these areas due to traffic considerations and since underground is more difficult to work on in places where they frown upon you digging up the ground.
Adam K.

Why do cable TV wires have a loop at each pole?
The loop at each pole is to allow for expansion and contraction of the tubular aluminum coaxial cable. From hot summer days to cold winter ones, aluminum coax can change its length a great deal. These loops assure that the cable will not pull itself apart from the strain of cold weather shrinkage.

Do the wires on a telephone pole need to be covered?
High voltage utility wires do not need to be covered. They are held off the pole by insulators. Even covered utility conductors are not truly insulated (the cover is not sufficient nor relied on to insulate the conductor from ground). A bare high voltage conductor may or may not result in a fault if in direct contact with a wood pole. Lower voltage communication lines and utility secondary wires (120/240/480 volts) are insulated.
Dave C.

What wires are attached to outside utility poles?
The wires at the very top are usually the high voltage primary conductors (1,000’s of volts). The next lower set are utility secondary wires (100’s of volts) and the system neutral. Below those are communications (TV, telephone, fiber optic, and so on).
Taller utility poles may contain even higher voltages near the top. Circuits with transmission (on top) and distribution (lower) on the same pole are called over-built poles because the transmission is over-built on the distribution. Here is a good diagram of the pole space:
Dave C.

What is the standard for placing lines on a utility pole?
Pole design, including line clearances, is described in the National Electric Safety Code. The clearance requirement is a function of line voltage, distance between poles (span), wire tension, and other factors. The size, or class, of a pole is determined by the design loads carried by it. These loads include horizontal wind loads; vertical loads associated with the conductors, transformers, and other equipment mounted on the pole; expected ice accumulation; and unbalanced loads due to wire tension on angle structures. The minimum loads required to be considered are specified in the NESC.
Dave C.