Thank you Mike, this is a great reference video. I am an EE who designs broadcast facilities and I know all about this issue. But I am also a hobbyist audio enthusiast and I spend time on several consumer high end audio forums. Many times the suggestion comes up to run a separate ground rod to all your AV components to reduce noise. That invokes the specific lightning danger you cite here as well as a fire hazard. I tell people if you insist on doing that you must run a minimum #6 between the "audio" ground rod and the main service ground. I get a lot of push back from people who have absolutely no understanding of electrical systems. Also you explained the difference between bonding and grounding. The IEEE has also recently discussed this difference. The Earth is not some magical sewer where you can dump electrical noise. It does work somewhat on low frequency radio interference as that uses the Earth as a return path. But noise created within the electrical system will not be corrected by simply Earthing the systems return. I often ask those people how does you highly complex cell phone work without an Earth ground? How does all the electronics on a plane, your car, function properly without an Earth ground?
This comment made my day! Finally the IEEE is going to start thinking about the differences between bonding and grounding. I love the cell phone analogy.
I love the way you explained how the current will always find a way back to the source. I can visualize the 20 amps smoking the small conductor of the telephone bonding. The fact that it was there to take the load imbalance for just a minute or two, may have given the home owner just enough time to kill the main before the law of series circuites wiped out his electronics.
I'm all for being safe and understand the reasons for bonding and grounding. As for the open-neutral danger causing current flow on the cable TV and phone conductors, all you need to do is put a CT over the connection from the IBT to the GEC and have it trip the main disconnect if it sees more than a few amps. Something like 230.95 large services where you detect current on the MBJ to trip the main. This might also save your equipment that gets over-voltage due to the imbalance if it trips quick enough. Sadly, this becomes yet another expense when putting in a new service for something that (fortunately) rarely happens. Waiting to see if they require it in the 2026 code now that I've mentioned it.
I love your videos they are great learning tools. My question is how about fiber runs from one service pole to the next or fiber communications in general. I see old RV parks grounding systems that really suck. I see poles without and bonding lugs or ground rods. Then they wonder why peoples RV power system gets fried.
At 22:00 Trust this, Hams have studied and engineered grounding systems forever, and way beyond anyone else on earth. This is maybe the single most discussed subject in all of ham radio. Books galore printed on the subject. My original statement holds true, grounding is a form of black magic lol, especially when we talk about RF grounds..
We have an Intersystem Bonding Terminations for our home with #10 bonding jumpers until the Cablevision company installed new equipment and removed all of the bonding jumpers for phone box and a phone company TV signal system we previously used. I didn't notice until after they had left but I'm going to call and try to find out why this bonding connection was removed. I'm wondering if discharge units are required for some of the connections but I haven't reached the end of your video. I'm installing 2 new 10 foot copper clad ground rods for our home. We raised a rancher style home in 96 with a 100A service and installed a 200A service and changed the 100A panel to a sub plus installed another 100A sub panel for the garage. The resistance between the service grounding conductor and the 10 foot galvanized ground rod had increased to 6.1k ohms over the years. I'll check everything I can think of as we create the new ground connection and share it here later. We've been trying to eliminate as much electrical noise as we can which already resulted in noticing the grounding system change. Interesting video as always.
Adding ground rods does not do anything to reduce 'noise' whatever that is (what is noise?), nor will the two extra ground rods improve anything as it relates to the bonding of communications systems together. The resistance of the ground is a moot point, that is why the NEC does not have any specific value.
Regarding the ADU on antenna's and the "where required" comment. You may run into the situation where you have multiple antenna feeds off the same assembly. Or more commonly in rural America both a UHF and VHF antenna that runs into a combiner amplifier. The ADU will ground the signal conductor in the presence of high voltage usually via a plasma tube that will not conduct normally. Mainly it's there to shunt wind generated static discharge that builds up on the array. I just put the ADU after the combiner amplifier and called it a day, Sure it may toast the amplifier but eh the TV's and other electronics are protected. But as you said some guys are nuts, I've seen some crazy setups where a guy had a quad UHF moveable array! Fun fact there are no remaining manufacture's of listed ADU's anymore. Most simply install a grounding block and call it a day, which from a safety perspective is fine as only the ground sheath becoming energized would be the risk, the center signal conductor is electrically isolated. That said I though the viewer's comment about a fuse on the telco and catv connections wasn't a bad idea. What are your thoughts on that?
As a low volt cable installer it is critical you understand the concept of ground potential changing with distance and electrical systems. This is particularly true if you work on large commercial or industrial campuses many of which maybe old construction. I have seen ground potential differences smoke network switches and all the equipment hooked to them. Fiber optic cable is a wonderful way to run network circuits to remote buildings and not have to worry about all this.
I have worked for the cable company for 39 years and I have seen homes that have lost or had a bad neutral and the coaxal cable becomes the neutral, it does give off a bad smell and smoke due to the coaxial cable melting
The only place outside other then the house that telephone grounding that is bonded is at a pole where the messenger is bonded to ground wire at pole from electric co. The sheathing on buried telephone service wire is aluminum or copper based.
So the condition that this person experience makes sense and is fairly interesting in the fact that the sheath of the buried service wire is directly attached to the bonding bar where the ground/bonding wire is attached inside the network interface device, if you have an aerial service you probably have a non-metallic cable and therefore would not be an issue. as for the pedestals there's no ground rods at them, the enclosure typically (and in this case is the culprit the fire) acts as a grounding Source but modern pedestals are usually plastic and so the bonding bar inside of them is simply bonded and not grounded to other buried service wires and the cable sheath. Generally you don't want the cable sheath being bonded to neutrals except at the ends of the aerial cabling which is why aside from cost they typically use non-metallic supported drop wires. very cool scenario to break down, never would have even thought of it.
Heres another fly in the ointment. The elaborate ground system we install for RF systems such as ham radio. This ground ststem is a much lower impedance path to ground (return path) than the service ground.
Mike, I will like to buy some of your books, what package (books) do you think I should get, i am planning to do only residential, I already have some good books but I really will like to get some of you books
Many internet services are provided via fiber today. My fiber internet service is buried cable. The fiber cable has a joined conductor attached to the side of the cable. My service provider did not bond this to my house service. When I questioned them, they said it is not required but they would do it for me.
Funny you brought up the broken service neutral issue. For years I knew it was going to happen at some point and then it did. I had the same problem at a customers house over a year ago. The messenger cable broke but the line conductors stayed in tact. The coax cable caught on fire along with the woman's house. She stood outside in bare feet pouring pots of water on it to put it out. When I arrived I immediately turned off the main breaker. I tried for a while to explain to the power company what was wrong based on my findings but they did not believe me until they finally found the break. lol They believed that the ground rods would keep that from happening. lol Another thing, I would never mix conductor sizes or materials between phases. Even though you can compensate for the impedance difference (voltage drop under full load) by adjusting the sizes, It's just a poor practice. Why would you do it? Cost? If so put the correct pipe size in and use all aluminum. Thank you both for being a wealth of knowledge and such assets to the industry!
The other aspect of matching the conductor length has to do with phase matching. Not ABC, but the waveform of the 60Hz power carrier. TL;DR; it doesn't matter in 99% of cases. At 60Hz your waveform is about 19ft long. So those numbers you listed off actually work in your favor because the waveform peaks will arrive roughly at the same time. Now what if the wire is half that wavelength off? The worse case. Well your power will be a little smoother because the peaks will be offset in phase. Now none of this matters because you're carrying power. However, if you're carrying information on those lines then that becomes a big deal. Think of the conductors from the antenna on a 5G tower or terminations in a phased array radar receiver. At nano meter wavelengths a half centimeter will completely destroy or distort the transmission. That's not to say go wild because impedance mismatch will start to mess with transformers efficiency, especially if you try to parallel them but that's more a utility problem not a user.
... I have no clue what you just wrote, but since it has nothing to do with the NEC, I'm good. I'm guessing maybe what you wrote makes sense to someone.
@@MikeHoltNEC It's the science behind the 310.10(G)(2) section of the video. Does it matter from an electrician's point of view no. However length matching is a thing that very much matters in Data or RF systems. It may matter a little bit for motors, but it's handled on the design side. The point is from an electrician's perspective tolerance is super wide to allow for installation drift, bends in conduit that as long as you try to make them match it'll be good enough as to not matter. More posting if you were curious why people who sometime interact with engineers and hear us commenting on it, where those types of questions come from. That said thank you for this video it's a well thought out and easy to understand explanation. I send it to friends who have questions about their antenna setups and give a plug to take your courses.
Hey this may sound like a dumb question. I have a tower with tree ground round one for each leg and I have a 4g wire that runs to my copper pipes. Is that bonded? My main panel is tied to the copper pipes as well
My new service provider for broadband just installed a fiber optic cable into the residence. Since its fiber optic cable does it need to be bonded to the other service cables? Thank you in advance. Really enjoy the videos and is very informative and educational for me. Brian
A little off topic, is there a code for service coming off the power pole transformer going into an underground conduit? The reason I'm asking is I see this all over the place where I live, underground power off the power pole without having a weather head on it. Now because I know its burial cable I know that it's not really necessary for weather protection but I do see a lot of wire chafing where the wires rub against the conduit with wind action.
I am building a home. Meter on a pedestal 200'+ away. I will land some ground rods there. The communications pipe will come right into the basement. Would I put a bonding bridge in the house, attached to the Ufer? I would think yes....or maybe I can just bring their bonding jumper to my main breaker panel. The pedestal will not host the communications conduit.
Mike, thank you for all the great videos. If I may, one advice is if you have someone translate and have your videos available in Spanish audio, you will make a fortune! Just take a look at any job site in the U.S. and compare the ratio of Spanish speaking electricians to any other single language, including English. God bless
I feel that electricians is in the US, need to learn how to speak, read, and write in English. So for that matter we don't have any plans to translated any of our products into Spanish.
I'm glad you enjoyed it and I apologize for the audio drops. We were learning about the ins and outs of live streaming during the lockdowns and had some audio issues.
The grounding around a ham radio tower or antenna is not an electrical ground, it's an RF ground. If an operator does not disconnect from that antenna when it's not in use, he or she deserves what they get. RF burns are nasty.
![Purpose of the NEC [90.1, 2020 NEC]](http://i.ytimg.com/vi/cOFAl_1Utkg/mqdefault.jpg)
![Purpose of the NEC [90.1, 2020 NEC]](/img/tr.png)
Thank you Mike, this is a great reference video. I am an EE who designs broadcast facilities and I know all about this issue. But I am also a hobbyist audio enthusiast and I spend time on several consumer high end audio forums. Many times the suggestion comes up to run a separate ground rod to all your AV components to reduce noise. That invokes the specific lightning danger you cite here as well as a fire hazard. I tell people if you insist on doing that you must run a minimum #6 between the "audio" ground rod and the main service ground. I get a lot of push back from people who have absolutely no understanding of electrical systems. Also you explained the difference between bonding and grounding. The IEEE has also recently discussed this difference. The Earth is not some magical sewer where you can dump electrical noise. It does work somewhat on low frequency radio interference as that uses the Earth as a return path. But noise created within the electrical system will not be corrected by simply Earthing the systems return. I often ask those people how does you highly complex cell phone work without an Earth ground? How does all the electronics on a plane, your car, function properly without an Earth ground?
This comment made my day! Finally the IEEE is going to start thinking about the differences between bonding and grounding. I love the cell phone analogy.
I work for a former Bell System company. I can assure you that we still run twisted wire to buildings.
I love the way you explained how the current will always find a way back to the source. I can visualize the 20 amps smoking the small conductor of the telephone bonding. The fact that it was there to take the load imbalance for just a minute or two, may have given the home owner just enough time to kill the main before the law of series circuites wiped out his electronics.
Always surprised at how informative these videos are. Thanks!
Chris, Pats Electric
This is amazing timing. I have my California VDV state certification next week. Thank you Mr Holt!
I'm all for being safe and understand the reasons for bonding and grounding. As for the open-neutral danger causing current flow on the cable TV and phone conductors, all you need to do is put a CT over the connection from the IBT to the GEC and have it trip the main disconnect if it sees more than a few amps. Something like 230.95 large services where you detect current on the MBJ to trip the main. This might also save your equipment that gets over-voltage due to the imbalance if it trips quick enough. Sadly, this becomes yet another expense when putting in a new service for something that (fortunately) rarely happens. Waiting to see if they require it in the 2026 code now that I've mentioned it.
Mostly fiberoptic around here which doesn't conduct electricity so would be no need.
I love your videos they are great learning tools. My question is how about fiber runs from one service pole to the next or fiber communications in general. I see old RV parks grounding systems that really suck. I see poles without and bonding lugs or ground rods. Then they wonder why peoples RV power system gets fried.
I love to see your videos. I have your books too. Thanks for your inputs. I'm getting ready to become electrician in Québec Canada. Best regards sir!
At 22:00 Trust this, Hams have studied and engineered grounding systems forever, and way beyond anyone else on earth.
This is maybe the single most discussed subject in all of ham radio. Books galore printed on the subject.
My original statement holds true, grounding is a form of black magic lol, especially when we talk about RF grounds..
What am I suppose to trust?
We have an Intersystem Bonding Terminations for our home with #10 bonding jumpers until the Cablevision company installed new equipment and removed all of the bonding jumpers for phone box and a phone company TV signal system we previously used. I didn't notice until after they had left but I'm going to call and try to find out why this bonding connection was removed. I'm wondering if discharge units are required for some of the connections but I haven't reached the end of your video.
I'm installing 2 new 10 foot copper clad ground rods for our home. We raised a rancher style home in 96 with a 100A service and installed a 200A service and changed the 100A panel to a sub plus installed another 100A sub panel for the garage. The resistance between the service grounding conductor and the 10 foot galvanized ground rod had increased to 6.1k ohms over the years. I'll check everything I can think of as we create the new ground connection and share it here later. We've been trying to eliminate as much electrical noise as we can which already resulted in noticing the grounding system change.
Interesting video as always.
Adding ground rods does not do anything to reduce 'noise' whatever that is (what is noise?), nor will the two extra ground rods improve anything as it relates to the bonding of communications systems together. The resistance of the ground is a moot point, that is why the NEC does not have any specific value.
Regarding the ADU on antenna's and the "where required" comment. You may run into the situation where you have multiple antenna feeds off the same assembly. Or more commonly in rural America both a UHF and VHF antenna that runs into a combiner amplifier. The ADU will ground the signal conductor in the presence of high voltage usually via a plasma tube that will not conduct normally. Mainly it's there to shunt wind generated static discharge that builds up on the array. I just put the ADU after the combiner amplifier and called it a day, Sure it may toast the amplifier but eh the TV's and other electronics are protected. But as you said some guys are nuts, I've seen some crazy setups where a guy had a quad UHF moveable array!
Fun fact there are no remaining manufacture's of listed ADU's anymore. Most simply install a grounding block and call it a day, which from a safety perspective is fine as only the ground sheath becoming energized would be the risk, the center signal conductor is electrically isolated.
That said I though the viewer's comment about a fuse on the telco and catv connections wasn't a bad idea. What are your thoughts on that?
As a low volt cable installer it is critical you understand the concept of ground potential changing with distance and electrical systems. This is particularly true if you work on large commercial or industrial campuses many of which maybe old construction. I have seen ground potential differences smoke network switches and all the equipment hooked to them. Fiber optic cable is a wonderful way to run network circuits to remote buildings and not have to worry about all this.
I have worked for the cable company for 39 years and I have seen homes that have lost or had a bad neutral and the coaxal cable becomes the neutral, it does give off a bad smell and smoke due to the coaxial cable melting
The only place outside other then the house that telephone grounding that is bonded is at a pole where the messenger is bonded to ground wire at pole from electric co. The sheathing on buried telephone service wire is aluminum or copper based.
So the condition that this person experience makes sense and is fairly interesting in the fact that the sheath of the buried service wire is directly attached to the bonding bar where the ground/bonding wire is attached inside the network interface device, if you have an aerial service you probably have a non-metallic cable and therefore would not be an issue. as for the pedestals there's no ground rods at them, the enclosure typically (and in this case is the culprit the fire) acts as a grounding Source but modern pedestals are usually plastic and so the bonding bar inside of them is simply bonded and not grounded to other buried service wires and the cable sheath. Generally you don't want the cable sheath being bonded to neutrals except at the ends of the aerial cabling which is why aside from cost they typically use non-metallic supported drop wires. very cool scenario to break down, never would have even thought of it.
Heres another fly in the ointment.
The elaborate ground system we install for RF systems such as ham radio. This ground ststem is a much lower impedance path to ground (return path) than the service ground.
Mike, I will like to buy some of your books, what package (books) do you think I should get, i am planning to do only residential, I already have some good books but I really will like to get some of you books
Please call 352.360.2620 and my staff will get you taken care of!
@@MikeHoltNEC I ordered some of your books last week, looks like they will arrive tomorrow, very excited
@@alvilla701 Be sure you also ordered the digital video downloads that match the books. God Bless and I'm excited for you!
Many internet services are provided via fiber today. My fiber internet service is buried cable. The fiber cable has a joined conductor attached to the side of the cable. My service provider did not bond this to my house service. When I questioned them, they said it is not required but they would do it for me.
That's not a bonding wire, it's a toning wire for locates much like gas lines and non-metallic water lines need.
Funny you brought up the broken service neutral issue. For years I knew it was going to happen at some point and then it did. I had the same problem at a customers house over a year ago. The messenger cable broke but the line conductors stayed in tact. The coax cable caught on fire along with the woman's house. She stood outside in bare feet pouring pots of water on it to put it out. When I arrived I immediately turned off the main breaker. I tried for a while to explain to the power company what was wrong based on my findings but they did not believe me until they finally found the break. lol They believed that the ground rods would keep that from happening. lol
Another thing, I would never mix conductor sizes or materials between phases. Even though you can compensate for the impedance difference (voltage drop under full load) by adjusting the sizes, It's just a poor practice. Why would you do it? Cost? If so put the correct pipe size in and use all aluminum.
Thank you both for being a wealth of knowledge and such assets to the industry!
Thank you for sharing this story.
One of only a couple code articles that allow a 5' ground rod instead of 8'.
The other aspect of matching the conductor length has to do with phase matching. Not ABC, but the waveform of the 60Hz power carrier. TL;DR; it doesn't matter in 99% of cases. At 60Hz your waveform is about 19ft long. So those numbers you listed off actually work in your favor because the waveform peaks will arrive roughly at the same time. Now what if the wire is half that wavelength off? The worse case. Well your power will be a little smoother because the peaks will be offset in phase. Now none of this matters because you're carrying power. However, if you're carrying information on those lines then that becomes a big deal. Think of the conductors from the antenna on a 5G tower or terminations in a phased array radar receiver. At nano meter wavelengths a half centimeter will completely destroy or distort the transmission. That's not to say go wild because impedance mismatch will start to mess with transformers efficiency, especially if you try to parallel them but that's more a utility problem not a user.
... I have no clue what you just wrote, but since it has nothing to do with the NEC, I'm good. I'm guessing maybe what you wrote makes sense to someone.
@@MikeHoltNEC It's the science behind the 310.10(G)(2) section of the video. Does it matter from an electrician's point of view no. However length matching is a thing that very much matters in Data or RF systems. It may matter a little bit for motors, but it's handled on the design side. The point is from an electrician's perspective tolerance is super wide to allow for installation drift, bends in conduit that as long as you try to make them match it'll be good enough as to not matter. More posting if you were curious why people who sometime interact with engineers and hear us commenting on it, where those types of questions come from.
That said thank you for this video it's a well thought out and easy to understand explanation. I send it to friends who have questions about their antenna setups and give a plug to take your courses.
God bless you Mike you make this mKe sense.
Hey this may sound like a dumb question. I have a tower with tree ground round one for each leg and I have a 4g wire that runs to my copper pipes. Is that bonded? My main panel is tied to the copper pipes as well
A ground rod at the antenna tower. Could this not be an auxiliary ground covered in 250.54 ?
Yes
Couldn't hear Brian on the question about parallel cables length (about 45 min of the recording).
Sorry
what about seperate grounding electrode so I do not have ground loop? Can you give some insight on that.
Separate ground rods are not permitted, all systems must be bonded together at one point (IBT).
Thanks for your help Good job
Have you ever heard of a Ham Radio tripping every AFCI breaker in the panel ?
No, but I'm not surprised anymore...
My new service provider for broadband just installed a fiber optic cable into the residence. Since its fiber optic cable does it need to be bonded to the other service cables? Thank you in advance. Really enjoy the videos and is very informative and educational for me. Brian
The NEC does not cover communications wiring installed and supplied by the communications utility.
If the company is installing an outdoor optical network terminal it needs to be bonded however indoor units do not.
A little off topic, is there a code for service coming off the power pole transformer going into an underground conduit? The reason I'm asking is I see this all over the place where I live, underground power off the power pole without having a weather head on it. Now because I know its burial cable I know that it's not really necessary for weather protection but I do see a lot of wire chafing where the wires rub against the conduit with wind action.
This is under the utility scope of work, so it's their specifications/standards that apply.
Usually, the conduit is closed with explaining foam sealant.
Thanks sir your explanation is great
Hey Mike. Is there a high voltage spark gap on transmission lines?
I am building a home. Meter on a pedestal 200'+ away. I will land some ground rods there. The communications pipe will come right into the basement. Would I put a bonding bridge in the house, attached to the Ufer? I would think yes....or maybe I can just bring their bonding jumper to my main breaker panel. The pedestal will not host the communications conduit.
I haven't finished the video yet,
Just bond it like I describe in the video.
Mike, thank you for all the great videos. If I may, one advice is if you have someone translate and have your videos available in Spanish audio, you will make a fortune! Just take a look at any job site in the U.S. and compare the ratio of Spanish speaking electricians to any other single language, including English. God bless
I feel that electricians is in the US, need to learn how to speak, read, and write in English. So for that matter we don't have any plans to translated any of our products into Spanish.
@@MikeHoltNEC I agree. What study guide would you recommend for me to purchase to understand the Do’s and Dont’s for Grounding and Bonding. T.I.A.
@@rudyjauregui5575 Visit MikeHolt.com/Bonding and order my Bonding Library
@@MikeHoltNEC Purchased your “Bonding and Grounding based on 2020 NEC!” Was easier for me to buy through Amazon though. Thanks again!
@@rudyjauregui5575 Did you get the Bonding and Grounding 'Library' with the 'digital platform' that includes the videos?
What about the resistance between phases and unbalanced load?
The current on the phase and neutral conductors have nothing to do with the bonding of communications systems.
The best parts audio cut out...Brian talking about parallel conductor s about 45 minutes in
I'm glad you enjoyed it and I apologize for the audio drops. We were learning about the ins and outs of live streaming during the lockdowns and had some audio issues.
Mike the videos has some default I needs bonding ground check it please
I don't understand.
Kick ass
The grounding around a ham radio tower or antenna is not an electrical ground, it's an RF ground. If an operator does not disconnect from that antenna when it's not in use, he or she deserves what they get. RF burns are nasty.
I don't care what you call it, it's required to be bonded to the building ground.
👍
He's got that Donald Trump tan 😂😂💪👊
It's the lighting I used...