A Field Guide To The North American Utility Pole | Hackaday

We live under the umbrella of an intricate and fascinating web of infrastructure that enables every aspect of modern technology. But how often do we really look at it? I’ve been intrigued by utility poles for years, and I’ve picked up a thing or two that I’d like to share. Bear in mind these are just my observations from the ground in my area; I’m sure utility professionals will have better information, and regional practices will no doubt lead to very different equipment arrangements. But here’s a little of what I’ve picked up over my years as a pole geek.

Very few utility poles are used for just one utility. Poles that house multiple services, like power, telephone, and cable, are called joint poles and are covered by strict safety rules that separate the utilities spatially. In general, the most dangerous things on a utility pole are at the top. That makes sense – get the scary stuff as far away from the humans as possible. This is known as the supply space, and it’s where you’ll find both the primary lines, which distribute high voltage, and the secondary circuits, which have been stepped down by distribution transformers. If there are streetlights or traffic signals attached to a pole, this is where they’ll live. Power Distribution Cabinet

A Field Guide To The North American Utility Pole | Hackaday

The space closest to the ground is reserved for the low-voltage utilities and is called the communications space. Telephone is usually the lowest on the pole, with cable TV right above it. Telephone lines are generally thick cables and usually have junction boxes on one or both sides of the pole. Cable lines are generally thinner, usually silver or light-colored, and have distinctive D-shaped expansion loops next to each pole. They often have inline equipment like amplifiers; those are easy to spot by the obvious heatsinks on the enclosures. It’s worth noting that sometimes cable lines are at the bottom of the communications space rather than telephone, at least in my area.

In some cities there are still dedicated wires for fire and police signaling, like fire pull boxes and police patrolman’s call boxes. Businesses used to have dedicated lines for burglar alarms that went right to the local precinct house, but those days are gone and their space on joint poles has largely been reclaimed. You might find optical fiber cables in the communications space as well, if your local providers are using fiber as a backbone, or if you’re lucky enough to live where fiber directly connects to customers.

Between the supply space and the communication space is the neutral space or safety zone space. It’s an area reserved for telco and cable workers to safely perform maintenance and make connections to their service. In the US it’s a minimum of 40″ at the pole – that’s not much, so the communications workers still need to be careful up there.

There’s one more really important circuit on every pole – the ground circuit. Tied into the supply neutral and extending from the bottom of the supply space to a rod driven into the ground next to the pole, the ground circuit provides a potentially lifesaving path to the earth for any stray current.

Up in the supply space is where things get interesting. That’s where the primary and secondary wiring lives, along with all the safety and distribution equipment. Near the top of a typical pole you’ll often see one or more crossarms, which are stout wooden timbers bolted to the pole and braced diagonally. These act as spreaders to keep the wires of the primary circuits separated. Power is distributed from substations at anywhere from 7,200 volts to 34,500 volts. You can get a general idea of how high the voltage is by looking at the insulators used – the longer the insulator, the higher the voltage.

The crossarm will have anywhere from two to four wires on it, depending on how many phases are being distributed. Power companies generate electricity in three phases 120° apart, which gives them many options for connecting secondary and distribution equipment. Three-phase distribution requires four wires, one for each phase and a neutral. If you see three wires on a crossarm and one wire on the pole in the supply space, you’ll know you’re looking at a three-phase circuit. Poles in some rural areas like mine don’t have crossarms and only have a single conductor on an insulator at the very top of the pole along with the neutral. In this case a single phase is being distributed.

The supply space is also where power companies put their safety gear. To protect against short circuits, cutout fuses are often installed between distribution lines and secondary equipment, like transformers. Cutouts are easy to spot – they’re wide insulators with a light-colored tube running between contacts. The tube contains a fuse with an explosive charge that kicks the cutout open quickly and dramatically. The dangling fuse body can be removed and replaced with a hot stick, although sometimes there’s still a line fault when the cutout is reconnected:

Some circuits have reclosers instead of cutouts. Reclosers are basically automatically resetting circuit breakers that look a little like small transformers. They’re used in circuits that see a lot of nuisance trips due to foliage or animal activity, opening when a fault is detected and reclosing after a time delay, on the assumption that the short-circuit has cleared. They’ll try to reconnect several times before giving up.

Secondary equipment in the supply space is dominated by transformers. Usually in the form of a large gray barrel, transformers step the primary voltage down to secondary voltages suitable for end customers. Residential customers in North America generally get a 240/120 volt service, with two 120 volt circuits relative to neutral. Service drops from the transformer to residences (one transformer usually services multiple customers) is often in the form of triplex cable, with two insulated conductors wrapped around a bare center conductor. The bare wire serves as both neutral conductor and physically supports the two 120 volt conductors.  Commercial customers often benefit from three-phase service, in which case you might see three transformers mounted on a pole, one for each phase.

There’s another very important part of the power system that you’ll occasionally see on a pole – the lineworkers. As I write this, a bizarre winter storm is raging outside. It was 10 below zero yesterday with snow, and now it’s 50 degrees with heavy rain and wind. It’s weather that’s tailor made for tearing apart infrastructure, and I know there’s a good chance that a tree limb will come down somewhere and tear down wires. When it happens, lineworkers need to get out there and fix it. If you want a taste for what it takes to be a lineworker, check out this series of videos from the Southeast Lineman Training Center. It’s both physically and mentally demanding work, and the fact that these men and women will be out cleaning up the mess created by this storm tonight is comforting.

And let’s not forget the guys even further behind the scenes – the circuit managers. We had a cutout near our house that was regularly blowing and knocking us offline. I complained to the utility company, and to my complete surprise I got a call from a very nice gentleman who was very upset that one of his circuits was causing trouble. He promised action, and within a few days a tree crew was out removing hazards from the area. We haven’t had a problem since then, and I was really impressed by the level of craftsmanship exhibited by this guy. He took it seriously – personally, even. I really didn’t expect that from what I’d always assumed was a faceless corporate monopoly.

The point is, real people built the grid, and real people keep it alive for the benefit of everyone. So every once in a while, it’s not a bad idea to spend a little time looking up and admiring the handiwork that we so often take for granted.

“The tube contains a fuse with an explosive charge that kicks the cutout open quickly and dramatically.”

oh boy and how. I worked in underground utility construction for 17 years and I never got used to the sound of a fuse blowing when a line got cut. The worst was when it happened near the base of the pole (mislocated lines) and the damn thing was directly overhead. Like a 12 gauge going off right neat to your ear and the fun of dodging falling molten metal…YAY!

That’s why they call them shotgun fuses. :)

That is not strictly true. The fuse is held in position by sprung mechanism that is retrained by the fuse. The fuse element itself is designed to break the fault current. Once the fuse has blown the spring is not restrained and the fuse drops outs so that an operator can see the fuse has operated. If the fuse were to be swung open at the exact time the fault occurred. A large arc would be drawn between the contacts. Which potentially could go phase to phase at the top of the pole basically detroying the equipment up there and tripping the next layer of protection back.

In the uk it is unusual you would find an operator closing a fuse onto a suspect fault because fuses have a lower fault making ability compared to circuit breakers, so it is usually safer to reenergise via other means

What is not strictly true?

They are called shotgun fuses, I don’t understand why your explanation negates that or what you are explaining. The spring is to increase the air gap faster than the spark can expand so that the fuse has a very large breaking capacity. Nothing will go phase to phase at the top of the pole when you have an overcurrent spark on one phase.

Tbh, it was supposed to be a reply to the other post you replied too. Yes they are called shotgun fuses. Because you guessed it. They sound like a shotgun going off

However, the point I was making in my post was the fuse dropping out does nothing to break the fault current. The fuse element does that within the fuse carrier.

I don’t know what fuse carriers you have used, however all the ones I have ever used,( which look very similar to the one in the video) the spring does not force the carrier out of the holder. It mearly frees it from its locking mechanism. Allowing gravity to pull it out. Which in the grand scheme of things is really slow…..

and yes a large ball of ionised gas at the top of pole could lead to phase to phase fault. Especially when your staging has failed because the fuse has Been withdrawn before the element has had time to operate…

The noise is the hot air meeting the relatively cool air when the fuse burns up (think lightning). If the fuse were not contained in a barrel there would be no noise (think gun barrel). The shorter sticks used to close them out of a bucket or on the pole are called “shotgun sticks”. The fuses are called, …fuses. The spring allows the barrel to drop down by releasing when the fuse burns up. If not the barrel would stay in the closed position when the fuse blew. It drives me nuts when newscasters talk about all the “transformers blowing”……yeah ok… just revealed your ignorance. John, I have to disagree with you on the phase to phase not happening when one fuse blows. I witnessed the very thing one night on a single phase dip that was out. We installed fault indicators on the underground loop and gave the fuse “a drink.” The pole was framed with a 3 phase crowfoot fiberglass bracket which put the three phases of 13.8 fairly close together. A friend of mine had warned me about this very same dip as he had been there before. When the fuse blew there was a calm second and then the prettiest cross phase and sweet ball of aquamarine blue fire that ran two spans before going out when the phases spread to crossarm construction. The way the cutout was hung would let the ionized hot air from the blown fuse rise up through the phases and thus the AIR became Conductive. We reframed the pole and No Problem since.

I use a copper grappling hook with 0 gauge wire to get free power from the lines outside my house.

The CIA is going to pay your family members to be discontent and attempt to overthrow you as the head of household to dissuade the spread of socialism..

I use a copper grappling hook with 0 gauge wire to get free power from the lines outside my house.

In other words a typical Third-world service drop

You’re not wrong – when I lived in Mexico the utility company would drive by once a week with a long wooden pole and knock off all of the wires that people had hung from the (120v) power lines. Before the truck got to the end of the block people would start to come back out to re attach their wires.

Out of curiosity, what city do you live in?

The one where my house is

Cheyenne, Wyoming judging by his Facebook profile

Don’t believe everything you read on the internet.

Including your claim of using grappling hooks to to draw power from the gird. Perhaps in some third world country. Even there the thieves wouldn’t use something so obvious and unreliable. Any way that’s enough troll feeding from me.

That’ll get you killed one day. If you insist on using such a ram-shackle system, at least do the electricians the decency of moving the rig with an RC drone from a nice, safe distance.

Around here, the crows run a “free” electricity racket.

For a modest one time charge, they’ll hook you up. They’ll take just about anything, Visa, tin foil, Discover, half-empty cans of cat food, AmEx, cigarette butts. Oh yeah, and bitcoin. Whatever you’ve got, they’ll trade it to someone else for something they want.

are there “crows” in the Punta Gorda Florida area??? Lol

This article was far more interesting than I thought it would be. Great job!

I always get a kick out of watching unsuspecting onlookers as a lineman replaces a fuse and it blows. I’m usually standing back covering my ears. The lineman has ear muffs on. Then you have one person without a clue excited their power is going to be back on. It scares the crap out of them. Does it make me a bad person to not warn them?

Nah. That’s good entertainment.

Well it’s the power utility’s employees job to give warnings. Although as I recall they aren’t really very loud when the blow, not to my ears anyway and there was nothing wrong wrong with my ears

Its great entertainment to clear a front porch of five or six people shooting a fuse. Its even better if they run into the shrubbery when they come off the porch. Hi-flipping-larious!!! Ever seen someone trying to pull Aunt Ethel out of the azalea bushes!?!? LOL!!!!

no it doesnt make you a bad person…i usually get giggle out of it myself …except i just had a pole pig in my backyard go off and it scared the crap out of me, and i retired with 30 years makeing power in the Hydro Electric world

Now do underground power distribution!

My neighbor is a lineman. Wonder if I can arrange a tour of an underground vault? Or better yet, a substation!

“Hey, what does this button d….”

You don’t get to into a live vault unless you have proper training and proper PPE. You can already see most of what’s in a vault by just staring down through a grate.

I have. I’ve been, a, living, at my present address in an NYC apartment building, and I’ve done both, study the ConEd gang at work replacing its guts, and even studying it at work. Amazing stuff. Especially when you consider that GE happens to be one of the largest supplier of the stuff on utility poles for power.

Remember: if the right-wrong-thing happens, anything in the substation can be a projectile: some guy from a company I’m indirectly associated with almost got hit by a door that got blown off a building in a substation due to some sort of electrical “incident”.

Ask to see a regulator in action. When you do, try bypassing it off neutral…

Hint: Lights will go out.

And its guts will come untanked….dangerous as heck.

A couple of years ago pin flags and grass paint showed up in our front yard. Then a notice was taped to our front door that utility work would soon commence. A day or two later a truck towing a trailer with a small backhoe arrived and they proceeded to dig near the epicenter of the pinflags. I arrived after the hole had been dug and chatted with the workers. IIRC, the conversation went like this… Get off my lawn! Seriously, they explained that they were fixing a defect. They had rerouted our neighborhood feed through an alternative set of cables to allow them to work on that section. They found a small hole ~6mm in diameter burned through the insulation of a 25mm cable. Lightning damage they surmised. They were able to localize the defect using a ”thumper” as marked by the herd of pinflags. They replaced about a 3 decimeter section of the cable (only single phase in my neighborhood) and refilled the hole. I watched them reconnect the main feed at the utility boxes (using the long stick) over in my neighbor’s yard. The next day sod was placed over the patch in the yard and I had to water it for the few weeks. They said the lightning that damaged it could have been quite a distance away. Although there is a flagpole about 2 meters away.

Decimeters – now that’s a unit I haven’t seen in a while.

He REALLY didn’t want to say “a foot”.

Even us Australians who love all things Metric (except for birth weight.. what gives!) don’t use decimeters… Millimeters to Centimeters to Meters

Decimeters aren’t used regularly in Canada either, in fact deci/deka anything isn’t used regularly in any of those countries that converted from Imperial after WWII, however they are in quite common use in Europe.

Decimeters is a very common unit of distance in Sweden, used all the time. I thought we’re the only ones…. But we’re also using “mil” for 10 kilometers, like: It’s 4.5 mil between Stockholm and Arlanda airport.

We use furlongs and elbows.

My car gets 302400 rods to the hog’s head and that’s the way I like it

Without giving us the average speed in furlongs per fortnight, your value tells us nothing.

We use rock throws or rifle shots.

That explains a lot. Any society afraid to measure their own damn foot and see how it compares to the King’s foot is bound to get into a lot of trouble.

Longer power lines also have phase correction capacitors to make the power factor closer to 1. (Balancing the induction of the transmission line.)

Yeah, there’s a LOT of stuff up there that I didn’t have space to cover, and I left the bit on capacitors on the cutting room floor, as it were. The little tidbit that got me is the fact that power lines are essentially massive capacitors – long skinny conductors separated by a dielectric (air). To deal with the capacitative effects, large inductors called shunt reactors are installed from line to ground. But those are usually at the substation, not on the poles.

The capacitors bit is what’s actually interesting, because they’re so rarely mentioned and there’s little information on how they really work.

Do a part 2 on all the weird stuff that gets attached to the lines! There’s a bunch of things I’ve noticed and wondered about. Sheet metal squares, folded diagonally, hanging over wires (best guess: they make water drip off more easily). Thick wires twisted around the distribution lines (best guess: they inductively steal a little power to get warm and prevent icing). Weird little boxes hanging from the power line, tapped into the line a couple feet away on either side (best guess: line monitoring device, powered by the tiny voltage drop across those few feet, possibly communicating home over the power line). Funny knobby things attached near the insulators (TIL: stockbridge dampers).

The metal double-triangles hanging on the line are vibration dampers, to reduce fatigue on the lines from high winds (and prevent wires from touching as they bounce around). There are also giant orange balls (and sometimes neon tubes) that double as visible warnings for aircraft. The knobby things may be to prevent birds from landing where they will get electrocuted, hard to tell without more details.

Personally, I found it astounding to see a water truck spraying the insulators to clean them. It was de-ionized water, but still makes me cringe.

Transformers that are black instead of gray like normal??

I think you have it backwards. The line inductance is corrected by capacitors that can be at substations or on poles. The capacitors look like transformers. They have similar tanks and insulators. Search power factor correction capacitors.

Andy, I had a similar thought. But then I did 5 minutes of G-search (research by Googling).

I think you should start with a search for “shunt reactors”. The ABB ones that come up near the top of my search look quite familiar from substation yards, and are rated in the 800kW range. The Eaton power factor correction capacitor banks that come up (similar searching) are rated in the 1-4kW range.

This would suggest that Dan is more likely correct and what I suspected: the high power rating of shunt reactors indicate they are used for major substation work (long high voltage lines), and the lower rating indicate that cap banks are for correction in more local settings: e.g. heavily industrial areas with a lot of motors running.

There will no doubt be exceptions in this, but it looks like Dan had it right, and you were correct but in a different application.

If I missed something, please comment.

You are correct. Not many utilities use shunt reactors on distribution (down your street to your home) lines. Capacitors can be installed at the sub and at the load center on the distribution circuit to counteract voltage drop caused by inductive reactance when motors fire up. Capacitors do not produce voltage but store it. They do however cause a slight unregulated voltage rise when put online.

Capacitive reactance…inductance is caused by motors on the circuit starting up at different times….ever seen your lights dip when your ac unit fires up? There you go. Capacitors counteract inductance.

Normally underground cables are capacitive. The “long skinny conductors” separated with wide air gaps are more inductive. But most powerful loads (say ‘motors”) are inductive, therefore most compensation is capacitive.

I thought the practice was to compensate for motors at the point of use, ie the factory or whatever.

Please do another article covering the additional material. This is a fascinating topic.

I was unaware that power factor was an issue on transmission lines. However I understand it’s an issue on the secondary side of things. In the oilfield all the power lines are constructed owned and maintained by the oil company. Because the load is mostly electriv motors capacitors are used to balance the inductive reactance. That is an issue for farmers that irrigate as well using electric motors to power the pumps. Seem to be a service charge issue. Customer who down resolve the power factor on there side have the bill adjusted according to the power factor. Power factor, apparent power, real power can be difficult to wrap one’s mind around and easily forgotten after one does so. My power bill has a line for the power factor, but because I’m the typical residential load there is no entry on that line.Yet scammers make money selling people power factor correcting devices to reduce their electrical bill. Sheet

IIRC (and it’s been decades), some manufacturing operations are PF “sinks” and the power companies just love them since they keep things balanced out.

“Three-phase distribution requires four wires, one for each phase and a neutral.”

Not necessarily. Over long hauls, the neutral is omitted to save copper, and the whole thing is running on delta instead of wye transformers.

Yeah, should have made that clearer, but I didn’t want to get into the whole delta vs. wye thing.

Well, there’s an interesting and rather important bit on why use delta instead of wye for transmission, because a delta transformer basically shorts out any third harmonic currents which are caused by imbalanced and unmatched loads, and so prevent the third (sixth, 12th…) harmonics from propagating up the transmission line, which improves power quality.

Moreover the 3rd phase can be rendered “safe” by tying it to ground, therein making what is known as a ‘grounded delta’ where each active phase has equal potential between both each other AND ground. This is actually becoming somewhat of a thing in my area.

Above LV they do not run neutral with the three phases, they use star – delta transformer to make the neutral and tie that to ground but there is no neutral at all for the MV.

And then again for high voltage long distance transmission, they again use star connection because there’s less of a voltage difference between the wires, so they don’t need such a large physical separation.

voltage difference is the same – at least if you want to transmit the same amount of power.

On some low, medium, and high voltage lines neutral is included to carry currents caused by uneven phase loading.

As I understand it, I’m no linesman.

Back where my parents used to live was a utility pole that should have been labeled “Squirrel Bait.” At least once a year, some fool squirrel would decide to stand on two terminals on the transformer, a loud bang would occur, and a crispy squirrel would be leaking smoke at the bottom of the pole. We always thought it was the transformer blowing, but it must have been a fuse.

um, I think it was the squirrel that blew

It was probably a 100amp squirrel on a 400amp circuit.

Literally LOLed at that and almost choked on leftover Thai food!!! Thanks.

I’n sur I’d wasn’t to run into a 400 amp squirrel.

Usually they substitute a 750 amp raccoon into the circuit.

It could be worse. I once got shown a place where three or four went in a single week, jumping from branches close enough that they could form a physical short: suffice to say, that got some special treatment.

That’s an interesting read, thanks!

I’ve been idly comparing it with what we have on our poles here in the UK. Here we have relatively few shared poles, on the whole telephones and power each have their own. Cable telly is normally underground. Our high voltage at the neighbourhood level is usually 11kV delta-connected three-phase and has its own poles, it never shares with our 240v domestic supply. We don’t have 3-phase in our houses. In my part of the UK, they seem to have spent a lot of time over the last decade replacing copper overhead 240v cable with insulated aluminium. It’s certainly cut down the power cuts from tree branches. If we have shotgun fuses I’ve never encountered one, instead we have more conventional fuses in ceramic holders at the top of some poles.

All of which is probably more boring than what you’d find on an American street.

“Shotgun fuses” (I’ve only heard them called “explusion fuses”, but whatever) are necessary for high voltages but not for 240 or even 480v. The need arises from arcing – if you blow a fuse on the 50KV side, current will arc through the plasma from a blown fuse, and the current will continue to flow as the air ionizes. An expulsion fuse uses the charge to blow out the arc – literally blowing hot gasses through it to break it up. Ours have boric acid in them, so when they pop at night you get what will be reported as “green lightning”. And a nice, throaty “ka-boom”.

They do have shotgun fuses in the UK but nowhere near as many as the US. The US distribute MV and the LV circuits are very small (about 100 metres maximum) In the UK the LV distribution can be one km or even more in rural areas so you don’t see the MV as much plus we have a lot more MV underground than most places apart from Scandinavia. Shotgun fuses are not used on LV.

All UK supplies can be three phase, I have three phase in my house. The reason that you don’t see as much three phase in the UK is that the network will deliver much more power on single phase than most other places in the world. A normal UK domestic LV supply will deliver 100 amps at 230 volts, that compares to three phase at around 16 amps for europe

The power utility do not share the poles with comms either. This was discussed a while ago but it was generally thought to be a bad idea because the comms companies generally do not have the understanding that the power companies do. If you take a sample of say 100 poles in the UK and measure how vertical they are they will all be within a few degrees but in the US (and other places) they come out at all sorts of angles and that is because the rules are generally ignored if you add stuff after initial design. I think that the legislation for comms companies to use utility poles is in place but the utility have to do the work and that is way too expensive for the comms companies due to the safety aspect.

The reason why UK households can do with a single phase service is because households in the UK typically use very little electricity. The biggest load most of the time is a tea kettle, and everything else is running on gas. The typical UK household energy consumption is about 22,000 kWh a year, but only 3,500 kWh electricity which is about 400 Watts average per household.

The situation is reversed especially in the nordics where almost nobody uses gas for anything.

I used 2,500 kw in one month this winter. granted something is wrong, which I’m still tracking down but its only like $200. I gotta do my part to support the coal miners.

You lucky prick.. I used 800 kwh in one month during December, and it’s $300 for that month alone… Oh yeah guess a country.

Hint: Vikings sailed around and drank all day long because they couldn’t afford to power anything electrical.

In the US isn’t rare to see three phase connected to residences; with single phase being supplied to,most US residences?. I have at the main disconnect for my property 250 apmp at 240 VAC available.. Like many places in the US I could have three phase run to mt property, cut I’d have to sign a contract that would insure the cost of doing so would be paid

I did mean to say it’s rare to see to see three phase at single home residential properties or to residences

It’s pretty rare to see electricity or even telephones above ground in urban areas of the UK, at least where I am. (Excepting, of course, the huge pylons for long-distance high voltage runs). Some older areas have phones above ground, can’t think of anywhere locally with power above ground to the building, though I imagine it’s more common in the sticks? Seems a lot safer and less prone to damage from trees etc. – can’t remember when we last had a power cut. Why isn’t this standard in the US? Is it cost?

I’ve seen several power poles with a kind of throw switch near the bottom, connected by a long wooden rod up to…something at the top. Is that a total cutout, or a switchover of some kind?

Its a disconnect. It is just a huge knife switch to shut off power to one small section of line. They also use them in dual feed systems where they can switch from one feed to another for maintenance.

It’s a little more complicated, usually they also have some way of drawing the arc away from the contacts, the ones I know have a bit of wire above the contacts which serves that purpose.

So, something I’ve always wondered about…. what are the black plastic “belts” stapled around the base of the pole (about 3-5′ up)? The belts are about 14″-20″ tall.

They are to stop animals climbing the poles.

I’m probably not from your country, but it sounds like something we have here: a sheet metal belt to stop animals climbing up the pole and into the wires.

Sometimes they use those not only as animal deterrents, but also to shore up damaged poles that are in danger of breaking. I’ve seen numerous poles with very obvious splitting get bandaged like this. One time the utility pole in front of my old work was hit by a school bus, the utility company brought in a truck to sink a second pole, and strapped the old pole to it as a temporary fix until a couple days later they moved the high voltage supply to the new pole, and informed the low voltage utilities to move their stuff within a week, as the remnants were going to be removed.

Takes me back to studying for my NCTI exams.

Older rural area may still have crossarm with single phase 2 lines and ground (mainly for lightning) in the middle. The 2 outside line are connected to a transformer then to a service line to my house. The middle line has a wire running down every pole to the ground. When the local company replaces damaged pole, they usually don’t put crossarm back on and just run all the wires on the side.

Practice depends on company, span-specific conditions, etc. They might have run the wires along the side to, just as an example, cut down on the tree pruning they need for their reliability goals. A cross-arm for single-phase does seem a little silly, though.

There is a pole in nearby Goleta Ca that has a welding tank attached at ground level. I was told by someone who may (or may not know) that it contained helium. Any idea what may be going on?

If the tank is much larger than the diameter of the pole, it is probably nitrogen. And it is probably connected to underground service to force moisture out.

Pulp-insulated telephone cable is often pressurized to keep water out. Using a tank of nitrogen at the pole to pressurize the cable is done because of a leak somewhere, such that the pressure that is generated at the central office is not sufficient to pressurize the entire run of cable. Probably the next step is going to be an entire cable replacement with plastic insulated cable. Pulp-insulated telephone cable is no longer made and most of the people that knew how to work on it have retired.

Maybe this is related to that :

It is nitrogen, I assure you.

When I was a kid we lived on the coast, and there was regular outages when there was windy conditions. It was caused by sea salt buildup on the insulators, and I recall we used to go out and watch the spectacular arcing this lead to. They used remotely operated automatic fuses, and they would turn on after 30 seconds, then wait for 5 minutes, and then 30 minutes if it tripped a 3rd time. This was public knowledge so people would not go near downed wires etc, but where I lived it eventually ended up setting a substation on fire, leaving us with no power for 2 weeks :P

Also grew up in a coastal town. The local utility would water blast the connectors on a regular basis to prevent arcing. As it was getting close to the time to clean again the wires would crackle and glow on foggy nights.

Thanks! Now I have Glen Campbell’s “Wichita Lineman” stuck in my head.

The “report comment” link is for comments like this? (hehe)

We lost the neutral line on our service drop in a storm last year. The transient took out every power transformer in the house — doorbell, furnace, kitchen range ($750), telephones, audio, etc. I had a few surge protecteors around but basically, if there was any inductance, it blew. According to my insurance it wasn’t storm damage so I never collected a nickel.

Those crappy little “surge protectors” won’t do shit against an actual storm induced surge. Proper protection has several layers, starting in the inlet box, continuing in the breaker box and finally ends with surge protectors that look similar to the cheap crap normally sold as surge protectors… All that fancy hardware (and the installation work) is fairly expensive, so it’s not very common as the installation price would usually exceed the cost new appliances several times…

You know, having lived half of my life in Belgium, I finally figured out the #1 reason that US streetscapes look so much messier than most European ones: all those damn poles and wires all over the place! I think most European countries tend to put a lot more of their infrastructure underground…

Buried is more expensive, more difficult to repair, in some ways easier to accidentally hit, and experiences slightly higher losses due to the greater proximity to mass, so it tends to only get used over here for high density (New York City used to use poles: you should go look for some pictures), or if the customer pays extra.

I don’t know if there’s a rate-hike for underground service.

As for appearance, a lot of older towns that haven’t been redeveloped run theirs through alleys: after a year of experience, I’ve decided that residential streets should be required to look semi-industrial, with all the nice cushy stuff in the backyard (and as little front-yard as is safe), that way all the nice cushy stuff won’t be CONSTANTLY causing problems for the utilities for the entire freaking town. The utility companies don’t prompt your neighbors to sue you every time your pet vines and trees kill the neighborhood’s utility services, so don’t let your pet vines and trees anywhere near the utility easements (or rights-of-way, or whatever else it is in the half of town that you live in).

Harder to repair, yes, but doesn’t need repairing, because trees don’t hit cables burried underground… In the UK the positions of underground cables and pipes are well known, so you’ve got to be *really* negligent to hit one by accident. Given the stories here about power regularly going for people in the US, Id be surprised if it wasn’t cheaper in the long run to put them underground?

That’s not true necessarily. Underground faults still occur regularly in older neighborhoods (before 1980). I have gotten outages at least once a year, all UG faults ( except for one nearby, which I ended up reporting before power went out). The US also has a true grid on MV lines, meaning the power company just flips a switch or two and the power’s back up (ok, more complicated than that but you get what I mean). And plus, in idaho we have some of the cheapest power in the world thanks to overhead lines and renewable energy.

They’ve buried the lines in the last 3 houses I’ve lived in (all northern Utah). Here its the old streets that still have the poles.

There’s probably still a few, though it’s certainly not guaranteed. I’ve seen a lot of line, and in most places you can find an occasional grounding wire that just isn’t as visible (or convenient) as the others, and thus got left behind.

Here in remote rural Australia we have a significant number of utility poles with a *single* wire…

For runs of several tens of kilometres and a sparse number of users (in the order of 10 or less), the utility runs a single 11KV line. At each residence a transformer is connected between the 11KV and ground to give 240volts. I don’t know if the transformers are auto-tapping or of the ferro-resonant variety, but surprisingly there doesn’t seem to be much of an issue with voltage fluctuation, even when you (or a neighbour) is welding.

I’ve also seen distribution lines of a *single* conductor (again 11KV) running off the main line to service single residence farms “nearby” to small towns. In my experience this was done at the farm owners expense, and the cost was usually in the order of 10 thousand dollars per kilometre (1980’s price). In my situation the toss up between off-grid (solar + batteries or diesel generator + 10 years fuel) and grid-connect was a big question. It ended up being very close to the same price (about $30K), but perceived reliability and ability to handle large surge loads selected grid-connect.

30 years later the now owner is still paying not only for electricity, but also “distribution fees” (despite the fact the poles & wires were *not* paid for by the utility company).

It is a bug-bear in rural Australia where utility companies are now charging very high (unreasonably high?) “service fees” for infrastructure that the land owner had to originally pay for. In a lot of cases the fee is still applied regardless of electricity usage : even if you disconnect, you are still slugged a ‘service fee’.

But the second owner (or later) doesn’t pay again for the infrastructure when it comes time to replace it. Right?

Of that I am not too sure. Replacement would likely be poles only (they were all wood back in ’80 – now quite a few are concrete). Wires would not need replacing, and surprisingly I’ve not ever seen a broken insulator. Either they are as-tough-as, or broken ones are replaced so fast. Most designs seem to be somewhat redundant so the loss of an insulator means the adjacent poles support the wire (now hanging down quite a bit more than usual), the wire drops onto the crossbar, or the internal structure (metal?? skeleton) of the insulator still holds the wire. The pole/crossbar being wood or concrete is not terribly conductive, at least when dry! No immediate fault, no ’emergency’ callout.

I don’t think I’ve *ever* seen a metal post used for power distribution, although I have seen metal poles used for telephone alongside railway tracks. Mind you, this is something *long* gone, but sometimes you can spot a lonely pole with insulators on it.

On your question, I’d have to dig up someone who has had the (probably unpleasant) experience to give you an accurate answer.

Ooops! Just realised, most of the really high voltage stuff (over 100KV) are held by very large metal towers! Only the “low” voltage stuff seems to be exclusively concrete or wood.

I had to laugh when I read your comment. At work (a nuclear power plant), in our switchyard, we have 2 different voltages we supply to the grid: 500 KV and 230 KV. We call the 230 KV the low voltage. I suppose, it’s all relative.

I moved from the Netherlands, where there are no overhead lines at all, to semi-rural Queensland and was a bit shocked about the electrical standards here (and how much they charge for it all).

We are responsible for the maintenance from the first pole on our property; when you apply for a connection the power company will charge you for installing the transformer and the bit of wire from the road to the first pole (and they will maintain that too, for which you pay handsomely every 3 months) but any faults past that point are the property owners problem. We had a wire break just behind the pole and had to find a contractor to fix it, Energex wouldn’t help (they did show up with a truck to cut the power but that was about it).

Interesting enough they’ve recently changed all the cross-bars on the street poles from timber to galvanized steel, Guess that’s to improve the fireworks when an insulator fails?

Of course Australian 230V/50Hz is much more dangerous than the same voltage in Europe, you need an electrical trades licence or you can’t legally do as much as put a new plug on an extension cord (no matter what your other electrical qualifications may be).

Of course Australian electricity is more dangerous than in europe… So are the spiders, snakes, and everything else… :p This was a fascinating event. Even though I’m in the US, I followed this very closely. Mercury Energy did a really good job of keeping people updated, with updates as frequent as every hour (remember too that the web back in ’98 wasn’t was it is today).

For Europeans, it’s a little strange that the most advanced country in the world has its electrical and IT infrastructure hanging on wooden poles :D For us, it is indeed a bit “messy”, but somehow … stylish ;-)

What’s even more interesting, is that most of Europe, especially ex-soviet states use concrete poles for high-ish voltage rather then wood… The really high voltage stuff is almost always steel.

The really high voltage stuff is always steel (at least here in Germany), that’s correct. But you rarely have wooden (or concrete) poles in the *streets*. Mains voltage, cable, telephone, glas fibre internet … it’ s all underground (well, 99% of it).

But it depends on regions – rural Spain for example has a lot more “open air” infrastructure than middle Europe.

But the pillars are…concrete… no dead trees ;-)

Old telegraph poles in the UK are wood. Still got one at the bottom of our garden; it’s in perfect nick despite not being Used or maintained for over 10 years, probably longer. Street lamps are metal or concrete, depending on the size and region.

Sometimes wood is the best material for the job. My brother-in-law’s company makes railroad ties, mostly out of white oak. I asked him why we still use wood – why not concrete or recycled tires or something. He said wood is still the best material – cheapest, strongest, lightest, and most flexible. And when properly treated and installed it lasts a long time. Same with poles – pressure treated Southern Yellow Pine is incredibly strong, flexible enough to sway in the wind, and has the distinct benefit of being able to be climbed with gaffs. Try that on a concrete or steel pole!

Part of the reason maybe that so much infrastructure in Europe was destroyed during World War II. When it was rebuilt, technology had advanced to the point where putting the cables underground was much more feasible.

Half Million Volt Workers episode of the UK TV series Danger Men. The American company air2 services high power lines from helicopters. I know the grandfather of the guy who in this show sits on the chopper skid while replacing line separators. Here’s part 1, the others are also on YouTube.

This is one of my favorite youtube videos, and it is finally relevant!

If anyone is bored…Google Street View is a great way to look at the utility pole infrastructure in North America. It can be fun to try to track where your power comes from.

A few other interesting widgets that you find around distribution poles are:

1. Lightning Arresters These serve the same purpose as a transient voltage suppression diode. There always installed near sensitive equipment like transformers. When the voltage exceeds a certain level (i.e. lightning) current is shunted away from whatever equipment the arrester is connected to. You can identify an arrester on a service transformer because it will always be installed in parallel with the primary busing.

2. Line Sectionalizers These are always used in conjunction with some type of upstream recloser. Line sectionalizers, count recloser open intervals and open after a set number of intervals. In a sense, they help locate faults because they’ll always open just before the last one or two upstream reclose intervals. That way, the unfaulted circuit remains energized and the faulted portion is de-energized. These are somewhat hard to spot because, depending on the type they can look like transformers or they can look like reclosers. One way to tell is that service transformers and reclosers often have a rating (i.e. 50kVA for transformers, 70A, 100A for reclosers), but a sectionalizer is really marked that way.

3. Faulted Circuit Indicators These also help locate faults. They are unique because the newer ones actually couple power from the line. When the coupled current exceeds the rated value of the FCI, a flag appears or some lights start blinking to show that a fault occured downstream. While not installed on the poles, they often appear near poles and look like black pucks. Since distribution circuits are radial (current only flows one direction), these devices sometimes require that you know where the substation is to find a fault.

While this thread is old in relation to this current post, in case others find this in the future, I feel I should elaborate on the cable TV aspect of this post. I was a employed as a communication engineer for several years for Mastec, and can shed some “light” on this particular aspect.

First of all, the copper ground wires running from the top of the pole to the bottom are called “vertical grounds” with bonds to the neutral cable for a power company’s infrastructure, or to the “strand”(physical supporting cable) in the cable company’s infrastructure. These “verticals” are terminated to the “ground rod” driven into the surface at the bottom, which are supposed to be 6 to 8 feet long. In experience, I have found that many are shorter being due to the fact that the ground rod bottomed out on a rock layer under the surface while being driven, and were sometimes cut off with a saw to save expenditure of time and/or energy(outside of regulation). It is true that the vertical grounds have often been removed by copper thieves.

The cable between locations(poles) is produced in two types: self-supporting, and lashed. Self-supporting cable has the aluminum co-axial cable extruded at the factory with a bonded strand in the same jacket, while lashed cable has a strand cable for support, with the naked co-axial cable being hung below the strand with the two having been lashed together with “lashing wire”(like thin bailing wire) which wraps around both cables using an impressive mechanical device called a “lasher”. This “lasher” uses a mechanism similar to one that would be used to twist rope in production. The same two scenarios apply to telephone infrastructure as well, both copper and fiber.

The coaxial cable for cable TV not only carries the forward and reverse communications for TV and internet, but also a 60 Hz(in the US) power feed between 60 to 90 volts. This applies in all cases except for end-of-line feeds where no further active component requires power, or further active devices are powered from another power feed from the other direction for the further active devices down the line. The power is fed into the coax in-line with a power inserter, and the power supplies that feed them are typically battery backed up, and are similar to a typical UPS, except they are much larger and only provide the previously mentioned 60-90 volts. These power supplies can be seen as the large(usually green in color) metal enclosures mounted to the side of a typical pole.

The devices seen on these cable lines consist of(in order of priority): – Nodes, which are fiber-fed, and convert light from the fiber to RF(and vice-versa) and feed coax – System Amplifiers and Bridges, which amplify the RF from the node or a previous amplifier and provide multiple outputs – Line Extenders which are single-output amplifiers used to amplify toward the end-of-line – Splitters and Directional-Couplers which send and receive the signal from multiple hard-line coaxial branches – Taps which are simply combinational RF splitters/combiners which break-out and reduce the high-level RF to a level acceptable to send down a drop wire to a subscriber

Amplifiers and Line Extenders typically output anywhere from 40 to 55 decibels of RF depending on the frequency and are usually set with “pads” and “equalizers” to place the top output frequencies at a higher level than the lower frequencies, as cable losses occur more rapidly at higher frequencies. Pads set the ultimate output level, while the equalizers set the delta of the output so the higher(less easily propagated) frequencies will arrive at the input of the next amplifier(after cable-losses) at equal levels to the lower frequency levels. A typical Amplifier or Line Extender requires at least 11dB signal level to be able to accurately reproduce the signal at low noise levels, while 3dB more is usually better. Amplifiers and Line Extenders combined are generally not used in linear cascades of more than 3-6 in a row, to be able to avoid crazy noise-figures.

I didn’t realize that a transformer was used to step down the amount of voltage coming through the lines to make it suitable for customers. I see the gray transformer barrels all the time, and I have always been curious about what they are and what they do. Now I do, so thanks for the information about transformers!

Thanks Dan. That was a good article and it created some great discussion. Nice Job.

Came here for the artwork, who did the top image? I love it! So simple but so great!

DW Found him on you about us page

I live on an old southern road. As the years have gone by I nor my neighbors paid too much attention to the cell tower that was installed on the yard of a commercial trucking company. It set back behind the trucks and building of the private company. The utility poles became burdened with heavy cables that after years hung low enough to touch. I complained about in front of my property referencing the Virginia Code and the lines in front of my house were adjusted to code height. The cable company did not adjust the swagging cable wires on the rest of the street. The cell tower is owned by a company for profit, but not a major cable or communication company.

Originating from the cell tower are the heavy cable lines that run for a mile on utility poles that were installed for less weight. They run about a mile down the road into an under ground box. A well known cell and cable company rents the utility poles from the local electric company.

Question – Is there some helpful site that will answer questions about a fenced cell tower contained within a a fenced private business and possibility an underground utility box a mile down the street appears to be support equipment for the cell tower. If the box is support equipment the issue of the cell tower and underground utility box can be combined in a complaint. Those cable lines that run from the cell tower to the underground cable box have multiple, too many, amplifiers attached. Between poles. Seems like when ever they add cable to a house they add an amplifier. I am assuming it is an amplifier based on my search of utility poles configuration.

I think that being careful is the job of the power utility staff. Warning keeps you safe from various problems. And if this works out cautiously, the electrical lines are be safe.

It’s worth noting that sometimes cable lines are at the bottom of the communications space rather than telephone, at least in my area.

This article was fascinating as we just had a fuse blow on the power pole outside our house (sounded like a shotgun going off) and since we are homeschooling during the quarantine it was like a science lesson!

Some owners had put their own electric line wire up like this few years back. Now it’s gone! They hooked up from their driveway night light to their basement window … they hooked up through the unmetered side …is that stealing full strength it legal or dangerous for close neighbors should they get hit by lighting or for others in that family should they fall over the line on the ground!??…. Also How do you spot reversed electric or a stealing from else where…as we had an extra recorded spike of signal recorded by the electric company they do not know what this is from….and we are still getting spike of lower voltage that is making out lights dim every hour or so! Is tis a hacker hacking us or is this electric signal stalking or micro-waving or other something else activity, but we think something has a bad motor and it is drawing voltage from the area.. and that is what going on!? I but one Huge question: I notice could this be a problem here…I notice right before some real live bigger earthquakes 4.0 – 5.0 or higher over in California and Alaska certain earthquakes, their is a spike also, I have timed it with the live earthquake map monitoring web site!! lands stress from systemic magnetic movement ” waves activity” activity and land stress movement and so much water everywhere in the USA!!!?

Any idea why they would put dry hay under utility poles that deliver power only?

Just a very plebian question: May householders screw clothesline fixtures to power poles? Wouldn’t 4 lines from adjoining neighbours prevent a linesman from climbing said pole?

Wye is an ecological, cattle, and human disaster, due to utility earth currents (“stray voltage”).

Caution to the reader: Expect conflated terms, questionable misquotes, inaccurate “facts,” and manipulation of source material. There is some *valid* concern with poorly managed EM, it’s true, but this muddles the waters so much as to be predatory toward the lay-public, and to push an fact-checking investigative mind away.

Just an aside, in North America you mentioned two 120 V circuits coming into the house plus neutral return. Regular appliances connect between one of the phases and ground. The 120 V circuits are actually 180 degrees out of phase so you can get 240 V using the two phases which is used for high power appliances like electric clothes dryers.

In Israel where I live now, all new installations have 220V 3 phase which is very nice.

It appears most of you folks know way more about this than I do so I am going to put a question out there. I am in New England. I usually identify 3-phase power by the three wires on a cross bar or grouped in a triangle hangar. I have seen the three wires decrease down to two, again, mounted on opposite ends of the crossbar. With no change to any of the other wires attached to the pole. Is the set-up with the two wires still 3-Phase? I have a photo but I couldn’t attach or insert it. Thanks in advance-

A reasonable question I hope Dan or someone will answer, or clarify for the challenged readers like myself if that answer appeared in the original post, or later comments.

Why do telephone poles next to a railroad track have two crossbars?

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A Field Guide To The North American Utility Pole | Hackaday

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