"If it's not grounded, it's not dead" - This is an important concept that we need to communicate to both first responders and to the public. Just this week, following a storm, I was "sitting on a wire" (watching a downed primary wire to make sure no one got to too close while waiting for the local utility to respond) and I had a police officer tell me "it's ok - it's dead". Power had been out for 5 hours and, on just that street, a half dozen homes had generators operating. Throughout the neighborhood about 30 residences were out. If just one homeowner's generator is mis-wired and back-feeding, the downed wire could be at thousands of volts.
U R SO right, last Feb around 5 in the afternoon a cold windy day the lights went out, all up the street too. First thing I did was to go out to the pole and put the MAINS breaker in OFF. same with MAINS in the house. Only then when that was done did I fire up old Sparky the generator to the dryer. Otherwise voltage would have gone up the service drops and using what is normally the transformer's secondary of 240 volts, It now became a primary and the ordinarily primary was acting as a secondary boosting 240 volts to 7200, stupidity and/or ignorance it does not matter. A linesman gets juiced and they find who back-fed, someone's ass will be legally fried.
I have seen a person get hit by 9.6Kv to ground twice and not even take a ride on EMS *Twice* Not tried it myself but did get hit by small engine spark coil in youth enough times to know what if feels like
@@ChiDraconis If those people didn't take a ride on EMS, then they didn't get the full 9.6kV between the line and ground. They might have gotten an inductive tingle, or grounded some small stored charge. There is absolutely no comparison between being hit by a small engine spark plug and a 9.6kV primary line. One has a power of about 36 watts behind it. The other has about a million watts. The arc flash from the spark plug "might" burn a tiny spot on your finger. The arc flash from the primary would seriously mess you up. Pretty close to this: ruclips.net/video/Pf8cPGtZbbw/видео.html
@@stargazer7644 Okay - be certain that I understand "inductive tingle" and how a 1 amp at that voltage places me in the wrong but answer me this since you bothered to reply ~ moments before one of them was throwing plasma fireballs 10" diameter ~ 3 ' and when asked why he did not get off of it reported his muscles were spasm and locked so that he could not move ~ this is through work-wear but I have been hit with 277 enough times to wonder just what happened with the other guy - as you know 277 is instantly deadly so do not accuse me of lying what I want to know is if the overhead primary was laying on the ground and I could hear the heavy humm of line loaded pulling amperage then it seems to me he could have backed off of it with torso as that was working → since we cannot meter what happened then how do we get the heavy humm of loading
@@ChiDraconis I'm not accusing you of lying, I'm just saying if they walked away unharmed, they didn't get the full 9.7kV. Seeing as how I don't know anything about the circumstances of what you're describing, I can't help you with an explanation beyond this: If the resistance between the person and the ground, or between the person and the line was high, then they didn't get the full 9.6kV. If the line is drawing a heavy current to ground, the voltage on the line will be closer to ground potential. If it went through work wear, that's normally not a bad insulator, but not a great one at 9.7kV since it'll blow a hole in it. If you're standing near a downed line, you don't have to even touch it to be shocked by the voltage gradient in the ground. How much of a differential you get across determines how bad the shock is. It only takes about 90VAC to lock your muscles. If you're hearing a heavy hum, that's telling you that a large current is flowing through a resistance, and therefore there's a large voltage drop as well. For example, if you bond a primary line to ground, it'll still be close to ground potential even if you connect it to 9.6kV. That's why linemen do it on an outage - so hopefully someone mistakenly closing a switch can't kill the folks working on the line.
I drive a tow truck and we have two different police contracts for towing. We constantly have to deal with vehicles that hit hydro polls and bring hydro lines down. I always request that they call hydro before I touch the vehicle or go nearby the area. Even when I’m told the power is off! I can see some of the first responders irritated or that look like I’m being a wimp! But I know better then to go near the lines! I want someone from hydro that is experienced and has the proper equipment on location to tell me it’s safe to proceed!! Thanks for the informative video it makes me feel a little better that I’m not being to overcautious! Cheers!
Oh man! I'm so glad to be reading this right now 👊. You are 100% correct in not going near a vehicle near downed wires. Induction or backfeed on a "dead" line can be deadly. It may also be on a reclosing device or remotely switched on. Keep doing what your doing 🤝. I'd rather hear about dirty or irritated looks then hear of someone not making it home to their family 🙌
This is great info for everyone especially in this day where it seems everyone has solar panels on their roofs, and battery banks or power walls. All it takes is one of those solar electric generating homes to not have their solar isolated from the grid and it can easily backfeed into the lines killing anyone who touches them. Not grounded, not dead, and if you're not sure whether or not its grounded DON'T TOUCH IT!
Thank you for the information. I'm preparing to take the CAST Test as first step in a hiring process for my local utility company. I found your channel a little while back. I'm hoping to learn more from your videos as I begin a career as a lineman apprentice.
Awesome ! I love hearing feedback like this 👊👊 Linework is a great trade , and you will learn a lot ! Don't ever be scared to ask questions ! Better to ask then get yourself into a dangerous situation. Best of luck!
Backfeeding is extremely dangerous for both linemen and customers, someone I know once backfed their generator using a double male extension cord plugged into the clothes dryer outlet, he at least isolated his house from the mains by turning off the main breaker to prevent the utility transformer from becoming energized. However once the power had been restored, he flipped the main breaker on without first shutting off the generator and unplugging it, next thing he knew there was a loud explosion outside. The generator was completely engulfed in flames, fortunately it was far enough away from the house that nothing else caught fire and nobody was injured. Ended up having to replace the generator (which I’m sure wasn’t cheap) and installing a transfer switch after that. The only “legal” backfeeding is if you have grid connected solar panels, as these use inverters which ride off the grid frequency and will shut down if there is a power outage. Plus I think grid tie inverters wait a few minutes after power comes on before they go back online.
nothing wrong with backfeeding done properly, in areas where its covered by code, a physical interlock is required, preventing use of mains with backfeed engaged or the other way around, essentially it has to ensure a situation is impossible, also prevents your generator getting burnt out when they ground the 7200v line youre ``feeding``
He mentioned that there was 3 phase loads downstream of the break. In a three phase motor all phases are interconnected within the motor thoughthe windings allowing voltage to back feed from the still live phases through the load and transformer back on to the "dead" line.
Richard Hiskett Any phase to phase load can do it. A motor is one, but a 208V heater can backfeed between a live and dead phase. In a 600-208/120Y system where the 600 is delta but 208/120 is Y, even a 120V phase to ground load on the panel side of the transformer can appear as a phase to phase load on the input, causing the same thing - a phase to phase backfeed.
In Europe, if you want to run your house in island-mode, you need breakers that communicate with a PV-inverter and are operated by a motor so they trip in the event of power-loss, while your inverter keeps running ánd you need a special inverter. Every PV-inverter installed in Europe is usually not capable of running in island-mode. As the use of generators is rather rare (as are powercuts) backfeed is not such a big risk (although the wiremen do test for it first of course)
Hey bob, love your videos you’re an amazing creator and linemen. Just graduated high school this past year and your videos have helped me get into the trade more more. Please don’t ever stop doing what you’re doing!!!
Thanks for the awesome feedback! That's awesome that's you've taken an interest in the trade right out of high school! It's a great career and you will learn a ton of its something you choose to pursue 👊
Great educational for the everyone! I really appreciate your channel as I share your videos to people who are not lineman but also I also share to customers I deal with everyday that work in the power utility world as most engineers do not understand what the field crews do... This is a great example of why DERs and back-feeding generators are very dangerous. I sell the only tool in the world to measure direction of flow for these exact issues, to keep you safe and make sure you go home to your family everyday. Be safe and keep up the great work!! #thankalineman
I remember an ice storm in Arkansas that brought down lines, and some homeowners fired up their generators after the power went out. Only problem was, their transfer switch was set wrong, and the generator power was backfeeding onto the mains, threatening the guys trying to fix the wires!
That reminds me of when a line in the opposite lane of the road I was driving became live and arced to the road and scared me half to death. I got out there really quick. Nothing happened to me or my car but I was not about to get out of my car as I'm more protected in my car then on foot. That was scary
Madness💥 is there not any kind of regulation on generation sets running in parallel with the supply to a customer. In the UK we’d have a changeover switch in place to prevent this from happening. Have only just started watching you videos makes a difference to the day job of being a commercial and residential electrical here in. the UK. Oh by the way, the Canadian East coast is a lovely place to live IMO
There's regulations here as well, most setups have a blocking mechanism on the transfer switch. There's always a sketchy install here and there, but generally speaking a certified electrician won't risk his job for an improper setup. And your right! It's a beautiful place to live! Pretty quiet here most of the time! Cheers!
@@Bobsdecline What's really worrying is the number of video's on RUclips uploaded by folks showing people how to use a generator to power your home in the event of an outage. There's me hoping they're using a proper power cable, a proper inlet and a transfer switch....but no. They're making suicide cables with Edison's at either end and connecting generators into drier/stove outlets. Even more worrying is; some are even trying to excuse their stupidity and incompetence by saying "if you don't know what you're doing, don't do this". If they knew what they were doing, they wouldn't entertain doing it... Power outages where I am in the UK are rare, so I haven't bothered with a transfer switch; a portable generator in the garden with a power cord through a slightly opened window works for me and provides enough power for the essentials.
Question does that mean that the pole is dangerous to touch it? If it's smoking I assume power is running threw it? If so wow if anyperson happens to touch it before the public knows is it deadly? Your videos just amaze how dangerous power lines are thanks for sharing would really like too know keep them coming stay safe young men and iam sure women
What is the procedure if you determine the cause of the backfeed is a generator? I assume if you can hear it you'd try to find it and shut it down, but what if you have no idea? Do you just ground the live phase on the generator side and move on?
@@joshuabest100 You will NOT blow up the generator unless it is some home made POS. All factory made units I have ever seen have breakers just like house. Short it and and all you are going to do is trip the units beaker
@@joshuabest100 Yes, that is why the linemen ground everything before they start to work. I work in a small engine repair shop. In over 40 years I have only seen one generator that was damaged due to backfeed. During a storm the power got knocked out this man hooked his generator up wrong. Lightening hit the line and ran back into the generator. When your generator gets hit by lightening it is time to buy a new generator.
Hearing you describe rangers of working with electricity in this video made me double take👀. Ya described rangers of my job, hydrogen fuel cell technician. HE is odorless, colorless, invisible. When ignited it's only visible in low light conditions and virtually noiseless (your truck idling is louder) it will suffocate, frostbite, and 3rd degree burn you in the same second 😱. Some days I'd rather be a lineman 😆
hi Bob. thank you so much. would it be pissble for you to please one day show us how you put the primary wires back up( or new wire if the old wire is burned).I just want to see how you retension the lines when adding auto splice.Do you still pull the cable using comealong? thank you @bobsdecline
A couple of weeks ago, when I was doing some janitorial work for a small apartment complex, a large flock of birds landed on the overhead power lines. When the birds took off, two of the lines hit each other with an incredibly loud bang, a big spark, and a cloud of acrid smoke (swing short?), which knocked the power out momentarily. I also noticed that the two power lines which collided with each other lost chunks of insulation. Is this dangerous?
Yes, please contact your electric utilities provider and have them inspect the transmission lines. The reason for the cost of your energy bill is not only for your power consumption, but also to maintain the service, as well. By the way, you may want to report it to your management, as this can cause a serious issue. Good luck!
@2:57 " If it's not grounded, it's not dead". How do you guys ground it? Also, if we come across a downed wire, can we use a multimeter to see if its live?
There's a great chance you won't get close enough to be able to use the multimeter. As you walk towards an energized downed line, the voltages involved can be strong enough to go through your shoes. And you make a better conductor than the ground. So if your feet are at different voltage potentials by being a different distance away, there's an excellent chance you'll get electrocuted through your legs. This is why they teach you to hop, feet together, away from downed lines, if it's not safe to stay where you are, like if you were in an accident and your car caught fire. If the car didn't catch fire, staying in it until the lines have been shut is vastly safer. Oh, and don't touch the car and the ground at the same time, because the tires are insulators, and you are not.
Is your "multimeter" rated to 139kv? Is it on the end of a 6+ foot insulated stick? Is your PPE (gloves) rated to 250kv? I'm pretty sure the answer to both is h*** no. Just stay away from it and let the linemen do their thing.
Walking up to a downed distribution line with a multimeter is a good way to get electrocuted. You don't want to be that close to a downed line if you aren't a lineman with all the proper knowledge and PPE.
Education, it all comes down to education. Obvs we can't all be expert in the ins and out of power and gas distribution and there is no need, but we can all be brought to the point where we know we do not know enough to proceed. This should be taught at schools along with basic swimming class... OK maybe not together, that could get toasty :D Herp - Derp a wire fell off the top of that pole, it's not sparking, let me coil it up < should not be a thought that enters anyone's head. Yet it is.
If someone used broken. concrete. Instead of fill dirt In yard and depletes the the soil of minerals could this prevent the earth ground for pannel and house frm working properly ?
So do I understand that the other 2 phases were feeding the "dead" phase back thru the load and down the line to the break in the line? I understand kind of standard house wiring but not 3 phase. Well, that's not entirely true. I do understand 3 phase motorcycle alternators, regulators, and battery systems. But not this. On a motorcycle you can lose a phase but the diodes in the regulator prevent back feed so the dead phase reads out 0 volts ac and infinity ohms at the alternator. While it will still charge, albeit at about half rated capacity its still bad. Be safe.
An induction motor with multiple phases only needs a single phase to run, but will do so with reduced torque and efficiancy and can not start up without all phases present or external circuitry. The remaining phases will then act as a generator, outputting full line voltage. That is how phase converters work. In this case the motor was already running, and just became a phase converter when they lost a phase, thus backfeeding the line through the transformer.
probably or it was someone who just plugs thier generator into thier dryer outlet, mightve covered two phases so 2 people dong that and all three phases are covered.
It was an open phase. A 3 phase load will send voltage back up the open phase from the two still connected phases. Remember, in a 3 phase motor, all of the phases are connected together by three inductors.
Star Gazer Any phase to phase load like a 208V heater can do the same thing. A spinning three phase motor will do it, too, but a stalled one would probably trip the overload in a few seconds or a few minutes. Also in a 600/208 system, even a 120V load can be reflected as a phase to phase load through the panel transformer if your building has a 600V feed and transformers to get 208/120 out of 600.
If you look into rotary phase converters and how they work, you will understand how this happens.An RPC uses single phase power and capacitors to get a 3 phase motor running which then functions as a generator. The motor provides the 3rd leg to run other 3 phase loads.
Wow, that was not the type of "back feeding" I was thinking of when I read the title! Never would have thought of a 3 phase load generating power on a missing phase...
Another statement. Related to last.night,s reply...car hits pole, breaks the phase that fed us. Electrons were back-feeding through the primaries & secondary of 3-phase transformer banks. As a result, the house lites we're glowing dimly..just.like a big Inductor coil.
Question for you. Do the residential smart meters prevent back feeding in the case of a power outage and someone connects their generator to their home without first opening their main breaker?
Just found your channel and I find it fascinating. What was the 3-phase load back feeding power onto the load side of the break? I'm layman so I'm not familiar with these sorts of things. Only thought I had was maybe a 3-phase motor that was spinning down, acting like a generator, but that wouldn't be likely for over 20 minutes.
Brian Hawkins A three phase transformer can do that, depending on the loads on that transformer, but even a simple system without separate panel transformers can do it, too. If there are phase to phase loads (600V or 208V) across the live to dead phase, or in delta to Y 600/208Y system, even a 120V load can cause a backfeed. Either case can backfeed from the live phase to the dead phase. So can a stalled motor, but usually the overload would trip before twenty minutes.
In a three-phase load (particularly a motor, but true for all such loads), all three phases are physically connected through the working elements (in the motor example, the inductive coils), so if you lose a leg, the power returning from the other two phases will keep the downed line at a high potential, despite not being visible from the point of the line break. Imagine the motor wires all joining together in a Y shape, where each arm of the Y is one of the coils.
You should do a video for young linemen and apprentices on how not to be total goofs. How not to think that their the sweetest dude on the line and bash everyone else. Think how much deadlier (in a good way) the trade would be if everyone was down to earth and modestly got along......
To guarantee that there is no voltage potential difference between ground and the wires they are working on. If somehow a generator or whatever is back feeding, their step down transformer will act as a step up transformer and send thousands of volts back up the downed power lines. By grounding them out, you guarantee that any voltage that would have gotten onto the lines is not going to be able to hurt a lineman while they repair the lines.
Backfeed? So some idiot was powering his home with a generator, during a power outage, but forgot to isolate the incoming 120/240volt lines before running the generator, so he ended up (via the stepdown transformer, now acting as a stepup transformer) powering the high voltage line that SHOULD have been deenergized? One of the linemen should have just grounded that backfeed anergized HV line, causing a short that would have been magnetically coupled via the transformer, back into the guy's house, and fried his generator. That would have taught that idiot a lesson.
Hey man! The very first step upon my arrival was opening the remaining two phases and grounding the line. This was done before any footage was taken. Your absolutely right in that most cases when you come across a situation like this, it's the result of an improperly installed generator. This is why grounds and bonds are always installed before any work is to commence. In this particular case it was actually backfeed from a three phase load. - the moment I opened the other two phases the arcing stopped. The back feed from the other phases would travel back up through the tx in the exact way you described. The smoke you see in the video is a result of the residual burn of the pressure treated wood. The easiest way to see backfeed in action is to test the "dead" phase of a house that loses 1 leg and you will find voltage there if the breaker is still closed in and meter on. I should have mentioned the scenario you just described.It's very pertinent information to the situation in this video! Thanks man for bringing up the generator scenario! It can be very dangerous to us out there! Cheers!
Bobsdecline - Lineman blogger Makes sense. We had that at work once. We had a 208 feed to the shop, but one 600 volt air compressor with a step up from 208 to 600. One phase of the 208 blew the fuse just before the meter box. Two phases were fine but the third phase was backfeeding from the (stalled) air compressor motor and the 208 to 600 transformer, giving about 75 volts to neutral on the tripped phase. The voltage changed when we kicked the compressor off, and went away without the 208 to 600 transformer. We added a phase monitor to open the compressor contactor on phase loss so it wouldn’t burn the motor out again, but a step up or down three phase transformer (208 to 600 or 600 to 208) can backfeed, depending on the load and whether the transformer is delta-wye or not. We’ve since moved to a bigger shop where we have 600 coming in with the normal 600 to 208Y setup, but we still keep that phase monitor on any automatic start three phase motor like the air compressor.
I read it that this was backfeed from a three phase load still energized from one phase. In principle couldn't it happen through a two phase load too (like losing one side of a 240v household feed)? If this rogue feed is shorted out / grounded, it won't "fry" his generator, but it will pop its main breaker.
@@Bobsdecline I would guess one likely mitigating factor if some miswired generator attempts to feed the grid would be that the load still there at the neighbors (sans generators) would probably be high enough to kick the generator's main breaker. And if more than one miswired generators are feeding, they'll probably short each other out due to unsynchronized phases. But I'm pretty sure the rules for repairing these lines are written so as to avert such dangers, right? Even if it shorts out the rogue feed.
Ram-n_dodge Three phase loads can backfeed. A 208 volt single phase load (wired phase to phase) will backfeed if one of the two phases feeding it is out. A spinning motor will backfeed if it has enough torque to keep spinning its load with one phase missing. And a 600/208 distribution system common in larger buildings can backfeed just because of a 120 volt load because a phase to ground load at 120V is transformed into a phase to phase load in the 600/208 volt transformer.
Ram-n_dodge A delta to Y transformer can produce this backfeed indefinitely, it is basically a continuous load but wired from phase to phase. A motor that was spinning before the phase blew out can continue to backfeed as long as the motor runs which it could do if it isn’t loaded enough that a phase loss doesn’t trip the overload.
I have seen absolute morons who go and make a male to male cable. and plug their generator into an outlet then backfeed their whole house and rely on the main breaker to isolate it from the grid.
Well, if they WILL open their main breaker before such a hick connection, and disconnect the connection before closing the main breaker again, it won't energize the drop, let alone the grid, but neither will they know that the line power is back except by observing or hearing from the neighbors. Also there would be a theoretical chance that due to relative AC phase, the voltage across the main breaker could be up to twice what it normally is when open, resulting in arcing when the line power is back.
@ damn you're right I was a bit quick to assume nothing could go wrong (although everything would be tested blah blah blah). The power would be incredibly low (
"If it's not grounded, it's not dead" - This is an important concept that we need to communicate to both first responders and to the public. Just this week, following a storm, I was "sitting on a wire" (watching a downed primary wire to make sure no one got to too close while waiting for the local utility to respond) and I had a police officer tell me "it's ok - it's dead". Power had been out for 5 hours and, on just that street, a half dozen homes had generators operating. Throughout the neighborhood about 30 residences were out. If just one homeowner's generator is mis-wired and back-feeding, the downed wire could be at thousands of volts.
U R SO right, last Feb around 5 in the afternoon a cold windy day the lights went out,
all up the street too. First thing I did was to go out to the pole and put the MAINS
breaker in OFF. same with MAINS in the house. Only then when that was done did
I fire up old Sparky the generator to the dryer. Otherwise voltage would have gone up
the service drops and using what is normally the transformer's secondary of 240
volts, It now became a primary and the ordinarily primary was acting as a secondary
boosting 240 volts to 7200, stupidity and/or ignorance it does not matter. A linesman
gets juiced and they find who back-fed, someone's ass will be legally fried.
"It can't be seen, heard, or touched." I'm pretty sure you can always detect it by touch. Only once though.
yeah i can hear those 550kv lines 60hz buzz,, visual is seeing sparks or arcs
I have seen a person get hit by 9.6Kv to ground twice and not even take a ride on EMS
*Twice*
Not tried it myself but did get hit by small engine spark coil in youth enough times to know what if feels like
@@ChiDraconis If those people didn't take a ride on EMS, then they didn't get the full 9.6kV between the line and ground. They might have gotten an inductive tingle, or grounded some small stored charge. There is absolutely no comparison between being hit by a small engine spark plug and a 9.6kV primary line. One has a power of about 36 watts behind it. The other has about a million watts. The arc flash from the spark plug "might" burn a tiny spot on your finger. The arc flash from the primary would seriously mess you up. Pretty close to this: ruclips.net/video/Pf8cPGtZbbw/видео.html
@@stargazer7644 Okay - be certain that I understand "inductive tingle" and how a 1 amp at that voltage places me in the wrong but answer me this since you bothered to reply ~ moments before one of them was throwing plasma fireballs 10" diameter ~ 3 ' and when asked why he did not get off of it reported his muscles were spasm and locked so that he could not move ~ this is through work-wear but I have been hit with 277 enough times to wonder just what happened with the other guy - as you know 277 is instantly deadly so do not accuse me of lying what I want to know is if the overhead primary was laying on the ground and I could hear the heavy humm of line loaded pulling amperage then it seems to me he could have backed off of it with torso as that was working → since we cannot meter what happened then how do we get the heavy humm of loading
@@ChiDraconis I'm not accusing you of lying, I'm just saying if they walked away unharmed, they didn't get the full 9.7kV. Seeing as how I don't know anything about the circumstances of what you're describing, I can't help you with an explanation beyond this: If the resistance between the person and the ground, or between the person and the line was high, then they didn't get the full 9.6kV. If the line is drawing a heavy current to ground, the voltage on the line will be closer to ground potential. If it went through work wear, that's normally not a bad insulator, but not a great one at 9.7kV since it'll blow a hole in it. If you're standing near a downed line, you don't have to even touch it to be shocked by the voltage gradient in the ground. How much of a differential you get across determines how bad the shock is. It only takes about 90VAC to lock your muscles. If you're hearing a heavy hum, that's telling you that a large current is flowing through a resistance, and therefore there's a large voltage drop as well. For example, if you bond a primary line to ground, it'll still be close to ground potential even if you connect it to 9.6kV. That's why linemen do it on an outage - so hopefully someone mistakenly closing a switch can't kill the folks working on the line.
I drive a tow truck and we have two different police contracts for towing. We constantly have to deal with vehicles that hit hydro polls and bring hydro lines down. I always request that they call hydro before I touch the vehicle or go nearby the area. Even when I’m told the power is off! I can see some of the first responders irritated or that look like I’m being a wimp! But I know better then to go near the lines! I want someone from hydro that is experienced and has the proper equipment on location to tell me it’s safe to proceed!! Thanks for the informative video it makes me feel a little better that I’m not being to overcautious! Cheers!
Oh man! I'm so glad to be reading this right now 👊. You are 100% correct in not going near a vehicle near downed wires. Induction or backfeed on a "dead" line can be deadly. It may also be on a reclosing device or remotely switched on.
Keep doing what your doing 🤝. I'd rather hear about dirty or irritated looks then hear of someone not making it home to their family 🙌
Man I really admire your passion for your trade. It seems like you really love your job and I love seeing that
Retired IBEW journeyman electrician. Enjoy your video's. I highly respect you linemen. Thank you for your service .
This is great info for everyone especially in this day where it seems everyone has solar panels on their roofs, and battery banks or power walls. All it takes is one of those solar electric generating homes to not have their solar isolated from the grid and it can easily backfeed into the lines killing anyone who touches them. Not grounded, not dead, and if you're not sure whether or not its grounded DON'T TOUCH IT!
Thank you for the information. I'm preparing to take the CAST Test as first step in a hiring process for my local utility company. I found your channel a little while back. I'm hoping to learn more from your videos as I begin a career as a lineman apprentice.
Awesome ! I love hearing feedback like this 👊👊 Linework is a great trade , and you will learn a lot ! Don't ever be scared to ask questions ! Better to ask then get yourself into a dangerous situation. Best of luck!
@@Bobsdecline Thank you!
Two rules: "Always treat a line as hot." Rule #2: Never forget rule #1.
That's why I chopped off one of my fingers and replaced it with a Fluke 2AC. ⚡️
Backfeeding is extremely dangerous for both linemen and customers, someone I know once backfed their generator using a double male extension cord plugged into the clothes dryer outlet, he at least isolated his house from the mains by turning off the main breaker to prevent the utility transformer from becoming energized. However once the power had been restored, he flipped the main breaker on without first shutting off the generator and unplugging it, next thing he knew there was a loud explosion outside. The generator was completely engulfed in flames, fortunately it was far enough away from the house that nothing else caught fire and nobody was injured. Ended up having to replace the generator (which I’m sure wasn’t cheap) and installing a transfer switch after that. The only “legal” backfeeding is if you have grid connected solar panels, as these use inverters which ride off the grid frequency and will shut down if there is a power outage. Plus I think grid tie inverters wait a few minutes after power comes on before they go back online.
nothing wrong with backfeeding done properly,
in areas where its covered by code, a physical interlock is required, preventing use of mains with backfeed engaged or the other way around, essentially it has to ensure a situation is impossible, also prevents your generator getting burnt out when they ground the 7200v line youre ``feeding``
I have an “Inter-lock” on my breaker panel so it impossible to back feed. That’s the point... of course.
I don't think this was a case of a generator backfeeding. It looks like one phase broke and was laying across one or two of the other phases.
He mentioned that there was 3 phase loads downstream of the break. In a three phase motor all phases are interconnected within the motor thoughthe windings allowing voltage to back feed from the still live phases through the load and transformer back on to the "dead" line.
Richard Hiskett Any phase to phase load can do it. A motor is one, but a 208V heater can backfeed between a live and dead phase. In a 600-208/120Y system where the 600 is delta but 208/120 is Y, even a 120V phase to ground load on the panel side of the transformer can appear as a phase to phase load on the input, causing the same thing - a phase to phase backfeed.
In Europe, if you want to run your house in island-mode, you need breakers that communicate with a PV-inverter and are operated by a motor so they trip in the event of power-loss, while your inverter keeps running ánd you need a special inverter. Every PV-inverter installed in Europe is usually not capable of running in island-mode. As the use of generators is rather rare (as are powercuts) backfeed is not such a big risk (although the wiremen do test for it first of course)
@@kcgunesq "lying"
your channel is my new favorite obsession! Thank you for these. I love power distribution for some reason.
Hey bob, love your videos you’re an amazing creator and linemen. Just graduated high school this past year and your videos have helped me get into the trade more more. Please don’t ever stop doing what you’re doing!!!
Thanks for the awesome feedback! That's awesome that's you've taken an interest in the trade right out of high school! It's a great career and you will learn a ton of its something you choose to pursue 👊
Didn't know I wanted to learn about that.
Good that I did.
Great educational for the everyone! I really appreciate your channel as I share your videos to people who are not lineman but also I also share to customers I deal with everyday that work in the power utility world as most engineers do not understand what the field crews do... This is a great example of why DERs and back-feeding generators are very dangerous. I sell the only tool in the world to measure direction of flow for these exact issues, to keep you safe and make sure you go home to your family everyday. Be safe and keep up the great work!! #thankalineman
Who is bob and why is he in decline? Great videos keep up the good work thanks
He never explains that. Perhaps it's an inside joke only shared with Canadians.
Bob was his choice of online alias, the decline was his favourite band
I remember an ice storm in Arkansas that brought down lines, and some homeowners fired up their generators after the power went out. Only problem was, their transfer switch was set wrong, and the generator power was backfeeding onto the mains, threatening the guys trying to fix the wires!
Did someone try to run a house on a potable generator without a way of being sure the main was off?
That reminds me of when a line in the opposite lane of the road I was driving became live and arced to the road and scared me half to death. I got out there really quick. Nothing happened to me or my car but I was not about to get out of my car as I'm more protected in my car then on foot. That was scary
Great video! Can you provide a single line diagram of feed?
I just saw this comment now ! Sorry I missed it ! I'll include a line diagram in a future video
Madness💥 is there not any kind of regulation on generation sets running in parallel with the supply to a customer. In the UK we’d have a changeover switch in place to prevent this from happening.
Have only just started watching you videos makes a difference to the day job of being a commercial and residential electrical here in. the UK.
Oh by the way, the Canadian East coast is a lovely place to live IMO
There's regulations here as well, most setups have a blocking mechanism on the transfer switch. There's always a sketchy install here and there, but generally speaking a certified electrician won't risk his job for an improper setup.
And your right! It's a beautiful place to live! Pretty quiet here most of the time! Cheers!
@@Bobsdecline What's really worrying is the number of video's on RUclips uploaded by folks showing people how to use a generator to power your home in the event of an outage. There's me hoping they're using a proper power cable, a proper inlet and a transfer switch....but no. They're making suicide cables with Edison's at either end and connecting generators into drier/stove outlets. Even more worrying is; some are even trying to excuse their stupidity and incompetence by saying "if you don't know what you're doing, don't do this". If they knew what they were doing, they wouldn't entertain doing it... Power outages where I am in the UK are rare, so I haven't bothered with a transfer switch; a portable generator in the garden with a power cord through a slightly opened window works for me and provides enough power for the essentials.
Question does that mean that the pole is dangerous to touch it? If it's smoking I assume power is running threw it? If so wow if anyperson happens to touch it before the public knows is it deadly? Your videos just amaze how dangerous power lines are thanks for sharing would really like too know keep them coming stay safe young men and iam sure women
What is the procedure if you determine the cause of the backfeed is a generator? I assume if you can hear it you'd try to find it and shut it down, but what if you have no idea? Do you just ground the live phase on the generator side and move on?
Probably short it out to blow up the generator
@@joshuabest100 You will NOT blow up the generator unless it is some home made POS. All factory made units I have ever seen have breakers just like house. Short it and and all you are going to do is trip the units beaker
@@davidhenderson3400 then shorting the line would be ideal to shut off the back feed
@@joshuabest100 Yes, that is why the linemen ground everything before they start to work. I work in a small engine repair shop. In over 40 years I have only seen one generator that was damaged due to backfeed. During a storm the power got knocked out this man hooked his generator up wrong. Lightening hit the line and ran back into the generator. When your generator gets hit by lightening it is time to buy a new generator.
@@davidhenderson3400 Unless some nut has removed the breaker. (a lot more common that you might think.)
Hearing you describe rangers of working with electricity in this video made me double take👀. Ya described rangers of my job, hydrogen fuel cell technician. HE is odorless, colorless, invisible. When ignited it's only visible in low light conditions and virtually noiseless (your truck idling is louder) it will suffocate, frostbite, and 3rd degree burn you in the same second 😱. Some days I'd rather be a lineman 😆
hi Bob. thank you so much. would it be pissble for you to please one day show us how you put the primary wires back up( or new wire if the old wire is burned).I just want to see how you retension the lines when adding auto splice.Do you still pull the cable using comealong? thank you @bobsdecline
This is the best video ever made.
Lol Thanks man ! 👊🙃
A couple of weeks ago, when I was doing some janitorial work for a small apartment complex, a large flock of birds landed on the overhead power lines. When the birds took off, two of the lines hit each other with an incredibly loud bang, a big spark, and a cloud of acrid smoke (swing short?), which knocked the power out momentarily. I also noticed that the two power lines which collided with each other lost chunks of insulation. Is this dangerous?
Yes, please contact your electric utilities provider and have them inspect the transmission lines. The reason for the cost of your energy bill is not only for your power consumption, but also to maintain the service, as well.
By the way, you may want to report it to your management, as this can cause a serious issue.
Good luck!
@@ParabolicNorth Did the lines collided the the electricity arc through the insulation?
@@the_expidition427 There is no insulation on the high voltage powerlines. They are insulated by air space.
@2:57 " If it's not grounded, it's not dead". How do you guys ground it? Also, if we come across a downed wire, can we use a multimeter to see if its live?
There are three ways to tell if a line is live:
1: It is
2: Just get a lineman don't do anything yourself
3: Even if it isn't, it is.
There's a great chance you won't get close enough to be able to use the multimeter. As you walk towards an energized downed line, the voltages involved can be strong enough to go through your shoes. And you make a better conductor than the ground. So if your feet are at different voltage potentials by being a different distance away, there's an excellent chance you'll get electrocuted through your legs.
This is why they teach you to hop, feet together, away from downed lines, if it's not safe to stay where you are, like if you were in an accident and your car caught fire. If the car didn't catch fire, staying in it until the lines have been shut is vastly safer. Oh, and don't touch the car and the ground at the same time, because the tires are insulators, and you are not.
Is your "multimeter" rated to 139kv? Is it on the end of a 6+ foot insulated stick? Is your PPE (gloves) rated to 250kv? I'm pretty sure the answer to both is h*** no. Just stay away from it and let the linemen do their thing.
Walking up to a downed distribution line with a multimeter is a good way to get electrocuted. You don't want to be that close to a downed line if you aren't a lineman with all the proper knowledge and PPE.
Education, it all comes down to education. Obvs we can't all be expert in the ins and out of power and gas distribution and there is no need, but we can all be brought to the point where we know we do not know enough to proceed. This should be taught at schools along with basic swimming class... OK maybe not together, that could get toasty :D
Herp - Derp a wire fell off the top of that pole, it's not sparking, let me coil it up < should not be a thought that enters anyone's head. Yet it is.
If someone used broken. concrete. Instead of fill dirt
In yard and depletes the the soil of minerals could this prevent the earth ground for pannel and house frm working properly ?
So do I understand that the other 2 phases were feeding the "dead" phase back thru the load and down the line to the break in the line? I understand kind of standard house wiring but not 3 phase. Well, that's not entirely true. I do understand 3 phase motorcycle alternators, regulators, and battery systems. But not this. On a motorcycle you can lose a phase but the diodes in the regulator prevent back feed so the dead phase reads out 0 volts ac and infinity ohms at the alternator. While it will still charge, albeit at about half rated capacity its still bad. Be safe.
An induction motor with multiple phases only needs a single phase to run, but will do so with reduced torque and efficiancy and can not start up without all phases present or external circuitry. The remaining phases will then act as a generator, outputting full line voltage. That is how phase converters work. In this case the motor was already running, and just became a phase converter when they lost a phase, thus backfeeding the line through the transformer.
What’s the “decline” in your handle?
Unfortunately now. People think of power as a USB port and a wifi connection.
Did you ever find what was causing the back feed? You mention it was 3 phase so maybe it was a backup gen where the inter-lock failed?
probably or it was someone who just plugs thier generator into thier dryer outlet, mightve covered two phases so 2 people dong that and all three phases are covered.
It was an open phase. A 3 phase load will send voltage back up the open phase from the two still connected phases. Remember, in a 3 phase motor, all of the phases are connected together by three inductors.
Star Gazer Any phase to phase load like a 208V heater can do the same thing. A spinning three phase motor will do it, too, but a stalled one would probably trip the overload in a few seconds or a few minutes. Also in a 600/208 system, even a 120V load can be reflected as a phase to phase load through the panel transformer if your building has a 600V feed and transformers to get 208/120 out of 600.
If you look into rotary phase converters and how they work, you will understand how this happens.An RPC uses single phase power and capacitors to get a 3 phase motor running which then functions as a generator. The motor provides the 3rd leg to run other 3 phase loads.
Wow, that was not the type of "back feeding" I was thinking of when I read the title! Never would have thought of a 3 phase load generating power on a missing phase...
Another statement. Related to last.night,s reply...car hits pole, breaks the phase that fed us. Electrons were back-feeding through the primaries & secondary of 3-phase transformer banks. As a result, the house lites we're glowing dimly..just.like a big
Inductor coil.
Question for you. Do the residential smart meters prevent back feeding in the case of a power outage and someone connects their generator to their home without first opening their main breaker?
No, but they would enable the electric provider to be aware of such especially if there was no solar net metering setup.
Ain't got to tell me to leave down power lines alone.
sadly some have to
Electrician told me he lost two helpers on the job. I asked what happened. He said, "Electricity."
My cousin’s son was a lineman until a close friend was electrocuted on the job. He quit and changed careers just like that.
Just found your channel and I find it fascinating. What was the 3-phase load back feeding power onto the load side of the break? I'm layman so I'm not familiar with these sorts of things. Only thought I had was maybe a 3-phase motor that was spinning down, acting like a generator, but that wouldn't be likely for over 20 minutes.
Brian Hawkins A three phase transformer can do that, depending on the loads on that transformer, but even a simple system without separate panel transformers can do it, too. If there are phase to phase loads (600V or 208V) across the live to dead phase, or in delta to Y 600/208Y system, even a 120V load can cause a backfeed. Either case can backfeed from the live phase to the dead phase. So can a stalled motor, but usually the overload would trip before twenty minutes.
In a three-phase load (particularly a motor, but true for all such loads), all three phases are physically connected through the working elements (in the motor example, the inductive coils), so if you lose a leg, the power returning from the other two phases will keep the downed line at a high potential, despite not being visible from the point of the line break. Imagine the motor wires all joining together in a Y shape, where each arm of the Y is one of the coils.
You should do a video for young linemen and apprentices on how not to be total goofs. How not to think that their the sweetest dude on the line and bash everyone else. Think how much deadlier (in a good way) the trade would be if everyone was down to earth and modestly got along......
Where do you get the ground from
Did you forget about the famous 50 hz hum?
60hz here
Why do you install grounds on the three phases when responding to downed power lines?
To guarantee that there is no voltage potential difference between ground and the wires they are working on. If somehow a generator or whatever is back feeding, their step down transformer will act as a step up transformer and send thousands of volts back up the downed power lines. By grounding them out, you guarantee that any voltage that would have gotten onto the lines is not going to be able to hurt a lineman while they repair the lines.
At 3:00 are those the grounds you install?
Looks like its a lead feeding the single phase side line
Backfeed? So some idiot was powering his home with a generator, during a power outage, but forgot to isolate the incoming 120/240volt lines before running the generator, so he ended up (via the stepdown transformer, now acting as a stepup transformer) powering the high voltage line that SHOULD have been deenergized? One of the linemen should have just grounded that backfeed anergized HV line, causing a short that would have been magnetically coupled via the transformer, back into the guy's house, and fried his generator. That would have taught that idiot a lesson.
Hey man!
The very first step upon my arrival was opening the remaining two phases and grounding the line. This was done before any footage was taken.
Your absolutely right in that most cases when you come across a situation like this, it's the result of an improperly installed generator.
This is why grounds and bonds are always installed before any work is to commence.
In this particular case it was actually backfeed from a three phase load. - the moment I opened the other two phases the arcing stopped. The back feed from the other phases would travel back up through the tx in the exact way you described. The smoke you see in the video is a result of the residual burn of the pressure treated wood.
The easiest way to see backfeed in action is to test the "dead" phase of a house that loses 1 leg and you will find voltage there if the breaker is still closed in and meter on.
I should have mentioned the scenario you just described.It's very pertinent information to the situation in this video!
Thanks man for bringing up the generator scenario! It can be very dangerous to us out there! Cheers!
All that would happen in that case is the breaker in the generator would trip. And maybe the breaker in the panel he was back feeding though.
Bobsdecline - Lineman blogger Makes sense. We had that at work once. We had a 208 feed to the shop, but one 600 volt air compressor with a step up from 208 to 600. One phase of the 208 blew the fuse just before the meter box. Two phases were fine but the third phase was backfeeding from the (stalled) air compressor motor and the 208 to 600 transformer, giving about 75 volts to neutral on the tripped phase. The voltage changed when we kicked the compressor off, and went away without the 208 to 600 transformer. We added a phase monitor to open the compressor contactor on phase loss so it wouldn’t burn the motor out again, but a step up or down three phase transformer (208 to 600 or 600 to 208) can backfeed, depending on the load and whether the transformer is delta-wye or not. We’ve since moved to a bigger shop where we have 600 coming in with the normal 600 to 208Y setup, but we still keep that phase monitor on any automatic start three phase motor like the air compressor.
I read it that this was backfeed from a three phase load still energized from one phase. In principle couldn't it happen through a two phase load too (like losing one side of a 240v household feed)?
If this rogue feed is shorted out / grounded, it won't "fry" his generator, but it will pop its main breaker.
@@Bobsdecline I would guess one likely mitigating factor if some miswired generator attempts to feed the grid would be that the load still there at the neighbors (sans generators) would probably be high enough to kick the generator's main breaker. And if more than one miswired generators are feeding, they'll probably short each other out due to unsynchronized phases.
But I'm pretty sure the rules for repairing these lines are written so as to avert such dangers, right? Even if it shorts out the rogue feed.
How much money do you make per year?
Nice. So someone could of had a 3 phase generator on their property... i have one myself. I was curious if you guys take precautions because of that.
could "have" had...
that's what he said.
What was the cause? Was it a closed-delta bank neutral shift?
The cause was an open supply phase. You're going to get voltage back on the open phase from a 3 phase load when that happens.
Whats up AA Ron and family !
All good on this end 💪! And you?
Were good...
The man upstairs is making me wait for my spot.
Im cool with that lol
🤜🤛
You'll get it man! Just keep doin what your doing! 👊😎
Word.
Gonna appreciate it for sure.
what was back feeding?
The load
Ram-n_dodge Three phase loads can backfeed. A 208 volt single phase load (wired phase to phase) will backfeed if one of the two phases feeding it is out. A spinning motor will backfeed if it has enough torque to keep spinning its load with one phase missing. And a 600/208 distribution system common in larger buildings can backfeed just because of a 120 volt load because a phase to ground load at 120V is transformed into a phase to phase load in the 600/208 volt transformer.
@@dale116dot7 Thanks, I get the transformer and motors but I didn't think these would produce a load for very long.
Ram-n_dodge A delta to Y transformer can produce this backfeed indefinitely, it is basically a continuous load but wired from phase to phase. A motor that was spinning before the phase blew out can continue to backfeed as long as the motor runs which it could do if it isn’t loaded enough that a phase loss doesn’t trip the overload.
Backfeed yes
I have seen absolute morons who go and make a male to male cable. and plug their generator into an outlet then backfeed their whole house and rely on the main breaker to isolate it from the grid.
Well, if they WILL open their main breaker before such a hick connection, and disconnect the connection before closing the main breaker again, it won't energize the drop, let alone the grid, but neither will they know that the line power is back except by observing or hearing from the neighbors.
Also there would be a theoretical chance that due to relative AC phase, the voltage across the main breaker could be up to twice what it normally is when open, resulting in arcing when the line power is back.
she didunt explaining where unt what causes feed backs
generators powering back into the grid
.
@ damn you're right I was a bit quick to assume nothing could go wrong (although everything would be tested blah blah blah). The power would be incredibly low (
@@KingJellyfishII Become certified yourself?
@@GeneralPurposeVehicl uh that might be kinda hard but I guess it would work