Was at a residence the other day were the utility primary and grounded conductor broke at two diferent locations. With this it sent HV to the service equipment energizing the neutrel and equipment grounds in the house. A fire started at the oil furnace burner. The grounding electrode system was intact. The voltage in the ground even burnt the metal expation joint in garage floor. Any comments on what more to do to prevent this in the future?
HV on grounded conductor
- Thread starter mach1
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charlie
Senior Member
- Location
- Indianapolis
Re: HV on grounded conductor
The insurance company's attorney might take a look at the fusing scheme of the serving electric utility.
We use the overcurrent protection to protect the line, not the equipment. However, we do step our protection somewhat. If it can be proven that the utility was at odds with accepted standards, they may be able to recover some of the costs and force the utility to update their system.
On the other hand, the electric utility's system was, as you said, damaged. With circuit damage, things do not work as designed. Therefore, proof of poor engineering would be difficult to prove.
The insurance company's attorney might take a look at the fusing scheme of the serving electric utility.
We use the overcurrent protection to protect the line, not the equipment. However, we do step our protection somewhat. If it can be proven that the utility was at odds with accepted standards, they may be able to recover some of the costs and force the utility to update their system.
On the other hand, the electric utility's system was, as you said, damaged. With circuit damage, things do not work as designed. Therefore, proof of poor engineering would be difficult to prove.
Re: HV on grounded conductor
I am surprised that more homes were not zapped and smoked, by this event.
Apparently the high voltage cable fell across the MGN. The multi-grounding is to force a burn clear at the contact point.
The amount of current flow on the home service ground depends on the resistance value relative to the other ground electrodes.
I am surprised that more homes were not zapped and smoked, by this event.
Apparently the high voltage cable fell across the MGN. The multi-grounding is to force a burn clear at the contact point.
The amount of current flow on the home service ground depends on the resistance value relative to the other ground electrodes.
charlie
Senior Member
- Location
- Indianapolis
Re: HV on grounded conductor
Bennie, the MGN was broken. It is interesting to note that people have been killed where they have stolen the pole ground wire for scrap.
Our most dangerous type of installation is where a single phase primary goes down an easement to a single transformer and the MGN comes down. If the grounding electrode system at the home goes bad and the pole ground is cut, there will be open primary voltage across the open parts of all the grounding points. When this happens, we may not ever know it because everything continues to work properly.
It is because of the same principal that we treat an open neutral as a primary conductor.
Bennie, the MGN was broken. It is interesting to note that people have been killed where they have stolen the pole ground wire for scrap.
Our most dangerous type of installation is where a single phase primary goes down an easement to a single transformer and the MGN comes down. If the grounding electrode system at the home goes bad and the pole ground is cut, there will be open primary voltage across the open parts of all the grounding points. When this happens, we may not ever know it because everything continues to work properly.
It is because of the same principal that we treat an open neutral as a primary conductor.
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