Bonding Conduit At Utility Pole
- Thread starter romeo
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charlie
Senior Member
- Location
- Indianapolis
Re: Bonding Conduit At Utility Pole
Maybe. It depends on the size of the ground fault, the impedance of the arc, the amount of neutral conductor from the riser to the transformer, the size and type of primary fuse, etc.
Maybe. It depends on the size of the ground fault, the impedance of the arc, the amount of neutral conductor from the riser to the transformer, the size and type of primary fuse, etc.
jtester
Senior Member
- Location
- Las Cruces N.M.
Re: Bonding Conduit At Utility Pole
romeo
I can't picture the installation you are describing. Does the conduit house primary cable, secondary cable, etc.? Could you give me a little more detail?
Jim T
romeo
I can't picture the installation you are describing. Does the conduit house primary cable, secondary cable, etc.? Could you give me a little more detail?
Jim T
highkvoltage
Senior Member
Re: Bonding Conduit At Utility Pole
Code requires schedule 80 PVC for the first setcion coming out of the ground if used? If the utility requires GRS if metal conduit is used wouldn't you have to size your grounding jumping acording to the requirements of the NEC? When bonding the conduit I connect to the downground on the pole verses the neutral,electrically the same but I just prefer it. Also what makes the difference what the voltage is? Personally I use PVC for all pole risers reguardless of the voltage unless specified differently by the Engineer or customer.
Code requires schedule 80 PVC for the first setcion coming out of the ground if used? If the utility requires GRS if metal conduit is used wouldn't you have to size your grounding jumping acording to the requirements of the NEC? When bonding the conduit I connect to the downground on the pole verses the neutral,electrically the same but I just prefer it. Also what makes the difference what the voltage is? Personally I use PVC for all pole risers reguardless of the voltage unless specified differently by the Engineer or customer.
charlie
Senior Member
- Location
- Indianapolis
Re: Bonding Conduit At Utility Pole
I am making the assumption that this is a secondary service lateral and the customer is required to install the riser on the pole. The electric utility requires the conduit to be RMC or RNC and if it is RMC, it is also required to be bonded. 250.102(E) Exception permits the section of metal conduit to be bonded to the grounding system on the pole if the pole owner will permit the bonding.
I am making the assumption that this is a secondary service lateral and the customer is required to install the riser on the pole. The electric utility requires the conduit to be RMC or RNC and if it is RMC, it is also required to be bonded. 250.102(E) Exception permits the section of metal conduit to be bonded to the grounding system on the pole if the pole owner will permit the bonding.
charlie
Senior Member
- Location
- Indianapolis
Re: Bonding Conduit At Utility Pole
If you are bonding the electric utility system neutral, the transformer tank or primary equipment, you are correct. However, this is on the secondary side of the transformer and needs to be larger than #6.
Highvoltage, your days as a lineman is showing. The downground is usually #6 SD Br. Cu. and the bonding jumper will be sized in accordance with 250.66. If this is a 200 ampere or larger service, the bonding jumper will be larger than the #6 and could burn off the #6.
If you are bonding the electric utility system neutral, the transformer tank or primary equipment, you are correct. However, this is on the secondary side of the transformer and needs to be larger than #6.
jtester
Senior Member
- Location
- Las Cruces N.M.
Re: Bonding Conduit At Utility Pole
Thanks Charlie for the clarification. Clearly the answer to romeo's question is "maybe". The concern about touch potential is tougher. If you can protect against touch potential, it would seem like you'd have a pretty solidly grounded system, which would help operate a high side fuse anyway.
Jim T
Thanks Charlie for the clarification. Clearly the answer to romeo's question is "maybe". The concern about touch potential is tougher. If you can protect against touch potential, it would seem like you'd have a pretty solidly grounded system, which would help operate a high side fuse anyway.
Jim T
- Location
- Illinois
- Occupation
- retired electrician
Re: Bonding Conduit At Utility Pole
Charlie,
Don
Charlie,
In this area the riser is normally installed by the utility and I have never seen the rigid metal conduit riser bonded. The NEC does not apply if the riser is installed by the utility, so does the NESC also require bonding?
Don
charlie
Senior Member
- Location
- Indianapolis
Re: Bonding Conduit At Utility Pole
Romeo, I have copied your last post from the new thread to this one and closed that one. I assume you wanted it here. To post a reply, go to the bottom of the thread and look for this button
. That will open a window so you can post another reply in the same thread.
From Romeo:
Jim T This conduit is the secondary of the transformer extending 10ft. up the pole from the underground service lateral. Many electricians are driving a ground rod and think that they have a effective return path I am an inspector and require them to bond to the utility neutral. I do not have much knowledge with high voltage that is why I am asking if this method will trip the primary cut outs. I know that a ground rod won't do it.My concern is how do we prevent touch voltage if the conduit becomes energized?
Romeo, I have copied your last post from the new thread to this one and closed that one. I assume you wanted it here. To post a reply, go to the bottom of the thread and look for this button
From Romeo:
Jim T This conduit is the secondary of the transformer extending 10ft. up the pole from the underground service lateral. Many electricians are driving a ground rod and think that they have a effective return path I am an inspector and require them to bond to the utility neutral. I do not have much knowledge with high voltage that is why I am asking if this method will trip the primary cut outs. I know that a ground rod won't do it.My concern is how do we prevent touch voltage if the conduit becomes energized?
charlie
Senior Member
- Location
- Indianapolis
Re: Bonding Conduit At Utility Pole
Don, the NESC requires the riser conduit to be bonded to the system neutral and we also furnish the riser conduit. We do not bond our riser conduits either, we use schedule 80 so our guys can't mess it up.
Don, the NESC requires the riser conduit to be bonded to the system neutral and we also furnish the riser conduit. We do not bond our riser conduits either, we use schedule 80 so our guys can't mess it up.
- Location
- Illinois
- Occupation
- retired electrician
Re: Bonding Conduit At Utility Pole
Charlie,
Our utility uses rigid steel conduit for the first 8' out of the ground and then switches to PVC. They also don't use any type of adapter fitting between the two raceway types. They use the PVC with the built-in bell type coupling and just slip that over the steel conduit as they continue up the pole.
Don
Charlie,
Our utility uses rigid steel conduit for the first 8' out of the ground and then switches to PVC. They also don't use any type of adapter fitting between the two raceway types. They use the PVC with the built-in bell type coupling and just slip that over the steel conduit as they continue up the pole.
Don
charlie
Senior Member
- Location
- Indianapolis
Re: Bonding Conduit At Utility Pole
I hope they have deep pockets if someone gets hurt on their riser.
I hope they have deep pockets if someone gets hurt on their riser.
highkvoltage
Senior Member
Re: Bonding Conduit At Utility Pole
Charlie. I also shows that you have never preformed linework. Most primary neutrals are alum. and are way under sized to meet our sizing standards. What makes the difference if you bond to a # 6 downground, most are #4 in case you didn't know, or #4 or #2 alum. If I have build the riser pole I size my downground according to NEC code to a 3/4" ground rod. Also MOST transformers today have one primary bushing and share the HO/XO or H2/X2 bushing whether pole mounted or padmount and bond there. By the way the way you stated "Your days as a lineman" I find somewhat offensive. I hear this all the time. They usually change their tone when they find out I the man running the job and they are back on unemployment. I have no proplem putting ignorant people out of work.
Charlie. I also shows that you have never preformed linework. Most primary neutrals are alum. and are way under sized to meet our sizing standards. What makes the difference if you bond to a # 6 downground, most are #4 in case you didn't know, or #4 or #2 alum. If I have build the riser pole I size my downground according to NEC code to a 3/4" ground rod. Also MOST transformers today have one primary bushing and share the HO/XO or H2/X2 bushing whether pole mounted or padmount and bond there. By the way the way you stated "Your days as a lineman" I find somewhat offensive. I hear this all the time. They usually change their tone when they find out I the man running the job and they are back on unemployment. I have no proplem putting ignorant people out of work.
- Location
- Massachusetts
Re: Bonding Conduit At Utility Pole
Here we (the electricians) provide and install the riser to the power company specifications.
We must use steel to at least 8' above grade.
The specifications also require a bonding bushing on the top of the riser.
We do provide it but I can not remember a time when this bonding bushing was used.
This bothers me as once we get in the ground we run PVC so the metal riser is nicely isolated.
What will that do for you on the secondary side of the transformer?
Here we (the electricians) provide and install the riser to the power company specifications.
We must use steel to at least 8' above grade.
The specifications also require a bonding bushing on the top of the riser.
We do provide it but I can not remember a time when this bonding bushing was used.
This bothers me as once we get in the ground we run PVC so the metal riser is nicely isolated.
Re: Bonding Conduit At Utility Pole
I am not trying
to beat a dead horse. But I really did not get a answer to my question. We read about City utility boxes and also light poles killing people and animals caused by poor bonding to a equipment bonding conductor.Can't the same thing happen if a metal riser conduit from a underground service lateral become energized?
The district utility engineer
tells me that they are not required to to bring a bonding conductor sized in accordance with 250.66 up the pole and many times the linemen do not do that and the bonding conductor is left at the pole with no connection.
I am
here looking for support to show him how important bonding the conduit to the
nutral is. I recommend that the electrician cut a window ( remove the insulation from the grounded conductor
going up the pole and bug a jumper from it to the conduit . Or leave a coil of bonding wire long enough to reach the utility nutral.
My question is will this provide an effecive current return path and trip the transformer primary fuses ?
I think it will if I am wrong how do we prevent touch voltage should the conduit be energized ??thank all of you and Charlie for such a wonderful service for those of us who care.
Way to go RED SOX romeo from Massachusetts
I am not trying
to beat a dead horse. But I really did not get a answer to my question. We read about City utility boxes and also light poles killing people and animals caused by poor bonding to a equipment bonding conductor.Can't the same thing happen if a metal riser conduit from a underground service lateral become energized?
The district utility engineer
tells me that they are not required to to bring a bonding conductor sized in accordance with 250.66 up the pole and many times the linemen do not do that and the bonding conductor is left at the pole with no connection.
I am
here looking for support to show him how important bonding the conduit to the
nutral is. I recommend that the electrician cut a window ( remove the insulation from the grounded conductor
going up the pole and bug a jumper from it to the conduit . Or leave a coil of bonding wire long enough to reach the utility nutral.
My question is will this provide an effecive current return path and trip the transformer primary fuses ?
I think it will if I am wrong how do we prevent touch voltage should the conduit be energized ??thank all of you and Charlie for such a wonderful service for those of us who care.
Way to go RED SOX romeo from Massachusetts
charlie
Senior Member
- Location
- Indianapolis
Re: Bonding Conduit At Utility Pole
Highvoltage, I didn't mean to ruffle your feathers and no insult was intended. Obviously, I did insult you and for that I apologize.
You are correct, I have never been a lineman but I have written or checked work orders for the line department for 35 years. I have a bit more than a passing knowledge of the NESC so lets go through your litany.
Most modern primary and neutral conductors are aluminum except for the wire that goes from the stirrups to the cutouts, lightning arresters, primary bushings, etc. For the current the phase and neutrals normally carry, they are way oversized in most cases. The sizes we use are for the physical strength and not for ampacity. This changes on the secondary side of the transformer where ampacity is the major consideration.
The pole down grounds are required by the NESC to be #6 Cu. and some electric utilities will oversize the pole ground. We use #6 and will use #4 on transmission poles for the static down ground. Some electric utilities have started using a larger size copperweld down ground but I don't know how large it is. Copperweld is a steel wire with a copper welded on the outside of the steel and is no different than a copperweld ground rod. This keeps thieves away from the ground wire.
The importance of grounding to a #4 for a 200 ampere service is to be able to carry the fault current if there is a ground fault in the conduit. The physics are the same whether the ground fault is in the service conduit on the side of a home or on a pole. You have to go to 250.66 to size your grounding jumper and if it is attached to a #6, why bother using the #4 from the table? If it a 400 ampere service, now you are talking about 1/0 and that #6 will be way too small.
If you are building a riser, you could be using a ? X 8" listed Copperweld rod and #6 Cu. running to it (that also is acceptable in the NESC).
I agree with you about the transformer configurations.
I hope we can disagree with each other without getting mad. As I said before, I had no intention of insulting you.
Highvoltage, I didn't mean to ruffle your feathers and no insult was intended. Obviously, I did insult you and for that I apologize.
You are correct, I have never been a lineman but I have written or checked work orders for the line department for 35 years. I have a bit more than a passing knowledge of the NESC so lets go through your litany.
Most modern primary and neutral conductors are aluminum except for the wire that goes from the stirrups to the cutouts, lightning arresters, primary bushings, etc. For the current the phase and neutrals normally carry, they are way oversized in most cases. The sizes we use are for the physical strength and not for ampacity. This changes on the secondary side of the transformer where ampacity is the major consideration.
The pole down grounds are required by the NESC to be #6 Cu. and some electric utilities will oversize the pole ground. We use #6 and will use #4 on transmission poles for the static down ground. Some electric utilities have started using a larger size copperweld down ground but I don't know how large it is. Copperweld is a steel wire with a copper welded on the outside of the steel and is no different than a copperweld ground rod. This keeps thieves away from the ground wire.
The importance of grounding to a #4 for a 200 ampere service is to be able to carry the fault current if there is a ground fault in the conduit. The physics are the same whether the ground fault is in the service conduit on the side of a home or on a pole. You have to go to 250.66 to size your grounding jumper and if it is attached to a #6, why bother using the #4 from the table? If it a 400 ampere service, now you are talking about 1/0 and that #6 will be way too small.
If you are building a riser, you could be using a ? X 8" listed Copperweld rod and #6 Cu. running to it (that also is acceptable in the NESC).
I agree with you about the transformer configurations.
I hope we can disagree with each other without getting mad. As I said before, I had no intention of insulting you.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Bonding Conduit At Utility Pole
Almost all the poles I have seen have a #4 solid that runs down the side of it that can be used to bond to with a split bolt? But if the utility fuses like Charlie's does it might not matter as the availble fault current would just blow this connection open.
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