lighting strikes
- Thread starter fritts
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Re: lighting strikes
Never seen any supporting data to support that statement. In fact ANSI/IEEE states around 95% of all lightning damage occurs on the primary side of the service transformers. I would highly doubt it since most Telco/CATV services are either under ground or located underneath the electric utility sharing the same right-of-way and poles.
However, in a lot of instances the Telco and CATV protectors are connected to an isolated ground rod not bonded to the service GES, or remotely located from the service. That would difinetly cause a lot of problems and make it appear it came from the Telco or CATV, when in reality it came from POCO and improper bonding of services.
[ October 27, 2005, 11:53 AM: Message edited by: dereckbc ]
Never seen any supporting data to support that statement. In fact ANSI/IEEE states around 95% of all lightning damage occurs on the primary side of the service transformers. I would highly doubt it since most Telco/CATV services are either under ground or located underneath the electric utility sharing the same right-of-way and poles.
However, in a lot of instances the Telco and CATV protectors are connected to an isolated ground rod not bonded to the service GES, or remotely located from the service. That would difinetly cause a lot of problems and make it appear it came from the Telco or CATV, when in reality it came from POCO and improper bonding of services.
[ October 27, 2005, 11:53 AM: Message edited by: dereckbc ]
jtester
Senior Member
- Location
- Las Cruces N.M.
Re: lighting strikes
It is nearly impossible for lightning to come through a transformer and into a building on the hot secondary conductors. I believe that most lightning enters the home, business, well motor, etc., through the neutral and or ground.
I have cut up many pole mounted distribution transformers to observe lightning damage, and in many cases, the damage can be seen as a small hole through the paper insulation within a few primary turns of the hv side or the neutral side, but never more than a few turns into the coil. There is just too much impedance in a transformer for lightning to go through it in any quantity.
Jim T
It is nearly impossible for lightning to come through a transformer and into a building on the hot secondary conductors. I believe that most lightning enters the home, business, well motor, etc., through the neutral and or ground.
I have cut up many pole mounted distribution transformers to observe lightning damage, and in many cases, the damage can be seen as a small hole through the paper insulation within a few primary turns of the hv side or the neutral side, but never more than a few turns into the coil. There is just too much impedance in a transformer for lightning to go through it in any quantity.
Jim T
bphgravity
Senior Member
- Location
- Florida
Re: lighting strikes
The lightning itself doesn't have to physically enter the structure or physically travel through a transformer or over conductors. Lightning that strikes or is near to conductive systems will generate a surge into that system that can and will cross over transformers and possibly "surge" the incoming voltage.
I think people have a general misconception that lightning always acts as a separate entity that flows over the system. While this is true in some cases, many more times it is nothing more than surge voltage and surge current that has been induced by lightning.
The lightning itself doesn't have to physically enter the structure or physically travel through a transformer or over conductors. Lightning that strikes or is near to conductive systems will generate a surge into that system that can and will cross over transformers and possibly "surge" the incoming voltage.
I think people have a general misconception that lightning always acts as a separate entity that flows over the system. While this is true in some cases, many more times it is nothing more than surge voltage and surge current that has been induced by lightning.
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