Tree Fall on Overhead Service Mast

[juventus]

Hello to all.

Very informative forum.

I am wondering if the interior wiring in a home (downstream of the main circuit breaker panel) can be damaged due to overhead electrical service wires shorting at the exterior mast/weather head after a tree fell on service wires? After the tree fall incident on the service mast, a minor fire occurred at the main service panel in the basement, charring some wiring near the panel only. Also wondering if re-wiring of entire house would be necessary, as the homeowner is claiming.

Finally, would questionable pre-existing bonding and grounding details at the main service panel have an effect on the house wiring as a result of the incident and the path of the fault current that occurred.

Thanks.

 

[charlie b]

I have exchanged messages with the OP. This issue is not about legal disputes or placing blame. So it is not outside forum rules. The essential issue is properly pricing a repair project, based on the required work scope.

 

[GoldDigger]

The fact that a fire started in the panel is direct evidence that either overcurrent due to overvoltage or an arc (also due to overvoltage) was present.
At a minimum all connected devices need to be examined, and possibly replaced. Surge suppressors in particular are likely to have been damaged. Also GFCI or AFCI or receptacles and breakers.

Beyond that, I would say that additional physical inspection of wires and junctions would be be wise. Megger testing of disconnected wires could be reassuring.
And, yes, the design and workmanship of the EGC/GES system could have affected the outcome if an overcurrent device should have tripped but did not, or tripped too slowly.
Remember though that modern electronics constitute devices that will blow or burn to protect breakers and fuses from damage.

Tapatalk!

 

[LEO2854]

Hello to all.

Very informative forum.

I am wondering if the interior wiring in a home (downstream of the main circuit breaker panel) can be damaged due to overhead electrical service wires shorting at the exterior mast/weather head after a tree fell on service wires? After the tree fall incident on the service mast, a minor fire occurred at the main service panel in the basement, charring some wiring near the panel only. Also wondering if re-wiring of entire house would be necessary, as the homeowner is claiming.

Finally, would questionable pre-existing bonding and grounding details at the main service panel have an effect on the house wiring as a result of the incident and the path of the fault current that occurred.

Thanks.

Sure poor grounding could have a bad effect in such a case,however,was it done right at the time it was installed?

Checking each circuit with a mega-ohm-meter will determine whether or not the wiring is good .

Welcome to the forum.

 

[curt swartz]

If the service drop was the only thing involved with the tree there should not be any damage to the wiring. The worst case voltage would be 240 volts which is well below the maximum rating of the wiring so I don't really see a need to Megger the wiring. As said above any electronic devices (dimmers, GFCI's, AFCI's, etc.) may have been damaged and need to be evaluated.

If the tree hit a pole holding both primary and secondary voltages the wiring may have been hit with a much high voltage than it is rated for. In that case a much more thorough inspection of the wiring is needed including Megger testing.

 

[GoldDigger]

If there was no other voltage involved, the most likely, AFAIK, reason for the fire would be if the wires were pulled loose from the panel.

Tapatalk!

 

[juventus]

Thanks for the input guys.

 

[mgookin]

I've seen plenty of bent masts from service drops being impacted by trucks (garbage trucks are notorious), trees, etc. There could be a pinch in the mast and/ or it could pull on the connections at the lugs in the meter can. But I can't see anything beyond the lugs in the meter can being impacted.

 

[kwired]

I've seen plenty of bent masts from service drops being impacted by trucks (garbage trucks are notorious), trees, etc. There could be a pinch in the mast and/ or it could pull on the connections at the lugs in the meter can. But I can't see anything beyond the lugs in the meter can being impacted.

Should the grounded conductor become opened you could have high fault current through equipment beyond the meter, especially if you have a low impedance path back to the source like a water pipe grounding electrode that is common to other services. Some current will take this path anyway but if the grounded conductor of the service drop is open then it all has to go an alternate route.

 

[jxofaltrds]

Hello to all.

Very informative forum.

I am wondering if the interior wiring in a home (downstream of the main circuit breaker panel) can be damaged due to overhead electrical service wires shorting at the exterior mast/weather head after a tree fell on service wires? After the tree fall incident on the service mast, a minor fire occurred at the main service panel in the basement, charring some wiring near the panel only. Also wondering if re-wiring of entire house would be necessary, as the homeowner is claiming.

Finally, would questionable pre-existing bonding and grounding details at the main service panel have an effect on the house wiring as a result of the incident and the path of the fault current that occurred.

Thanks.

I think that you should have the AHJ get involved. Not knowing the 'wiring' in place I can see where you could have problems if you have to replace 'sections' of wiring. AFCI for one comes to mind.

With the information at hand this reminds me of one of those home improvement shows where every time they touch something they go "oh we did see that coming". Not meant as an insult to you. I mean that most here are experts and if there would know the correct answer to give you. Probably in 10 minutes or so.

If I was replacing the panel I would want to be able to AFCI protected the 15 & 20 AMP circuits before I would put my name on the job. Or Megger.

What would you do if this was your home?

 

[kwired]

If I was replacing the panel I would want to be able to AFCI protected the 15 & 20 AMP circuits before I would put my name on the job. Or Megger.

What would you do if this was your home?

Not all of us have the same faith in AFCI technology even if it is in the code.

My house? Maybe sell it as quick as possible, kind of depends on some unknown facts. But I don't have an overhead service drop for a tree to fall on either. Last fall we even got rid of the POCO overhead line between the transformer pole and the meter pole so now it goes from the transformer down that pole, and all the rest is underground except where it emerges to hit the meter then goes underground again to get to the house and other buildings on the site.