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Author Topic: Some Post-Harvey Cautions  (Read 2319 times)
W6EM
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Posts: 1642




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« on: August 31, 2017, 05:57:48 AM »


Our son and his family who live in suburban Houston were luckily spared catastrophe, but he joined a group doing some drywall removal in a home that was flooded.  He did so without thinking about risks of electrical shock.  Luckily, the waters had only risen about 6 inches above the flooring and did not reach the outlets in the home.

I left a message on his phone, and this is what I cautioned him about if he was out to do it. 

First, if power is on in a home that has been flooded and water receded, turn off power to the receptacles before touching the drywall.  Why?  Because the outlets and boxes are probably still wet and may energize the wet drywall surrounding the outlet.  And by even touching or separating it to remove it could result in being shocked or electrocuted.  Don’t rely on things like GFIs and AFCIs to have interrupted stray ground currents.  Why not?  GFCIs normally were not required for anything but bathrooms,  kitchens and outside receptacles in the late 1900s.  And, AFCIs on all inside circuits were not required unless homes were built before the early 2000s.  So, chances are, enough fault current didn’t occur on outlet circuits to trip branch circuit breakers.

I’ve heard stranded people on the media say that they are thankful that power is on.  It scares me to think they or someone else will walk through a house with live receptacles under water.  An invitation to electrocution.  Kill the power before it kills you.  I saw on CNN a nursing home with power on in a hallway, with floodwater within an inch of receptacles and nurses were splashing water as they walked down the hallway.  For God’s sake, turn off the power at the breaker panel and do it with something non-conductive like a plastic rod or a dry kitchen utensil like an all plastic spatula or spoon if the panel is still above water level.  Otherwise, get out.

CNN has stories of persons found deceased from walking through floodwaters and a man who was electrocuted from coming near a high voltage wire submerged in floodwater.  If you don’t have to walk through flooded areas, don’t.  At least in a boat, any stray voltage will be distributed and current won’t flow through your body, at least while in the boat..

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W6EM
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Posts: 1642




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« Reply #1 on: August 31, 2017, 06:56:47 AM »

I meant to say that AFCIs, which combine arc sensing and ground fault sensing were not required on all inside branch circuits until after the early 2000s.  Even so, they shouldn't be relied upon.

At this stage of things, I can't understand why utilities haven't cut power on purpose to flooded areas.  Not safe where water has risen above floor level and can reach outlets.

Even if they can't get to substations, they can trip source transmission remotely.

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W9FIB
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Posts: 2097




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« Reply #2 on: August 31, 2017, 12:45:28 PM »

Same precaution for gas. Water can move things around and cause gas leaks. If at all possible gas should be turned off at the service valve at the meter.
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Happy being an Amateur Extra!
Nothing says CB on my printed license.
Ares/Races but no lights or crown vic.
KG7LEA
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Posts: 34




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« Reply #3 on: September 03, 2017, 08:30:12 AM »

Turn off gas if you smell gas otherwise you might wait weeks for the gas company to restore service. My family made that mistake in 1989 in San Francisco. We were a week without hot water.
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W9FIB
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« Reply #4 on: September 03, 2017, 12:51:07 PM »

Turn off gas if you smell gas otherwise you might wait weeks for the gas company to restore service. My family made that mistake in 1989 in San Francisco. We were a week without hot water.

The leaking gas contributed to the many fires after the quake. A week of no hot water is better then burning down a house or a neighborhood. Not to mention the same wrench you used to turn it off can be used to turn it back on if everything is ok after the flood cleanup.
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Happy being an Amateur Extra!
Nothing says CB on my printed license.
Ares/Races but no lights or crown vic.
W6EM
Member

Posts: 1642




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« Reply #5 on: September 03, 2017, 02:56:09 PM »

Turn off gas if you smell gas otherwise you might wait weeks for the gas company to restore service. My family made that mistake in 1989 in San Francisco. We were a week without hot water.


The leaking gas contributed to the many fires after the quake. A week of no hot water is better then burning down a house or a neighborhood. Not to mention the same wrench you used to turn it off can be used to turn it back on if everything is ok after the flood cleanup.
Yes, better than the alternative.....that is, an explosion and fire.  If people evacuate, and leave the gas on, they are taking a big, big risk that mother nature won't send Hurricane-strength lightning nearby (to poke holes in flexible steel gas appliance tubes).  And they won't be home to douse the fire before it spreads.  Also, a retired fire chief friend told me that not all water heater pilots have thermocouple safety shut offs, meaning, if the pilot should be snuffed by a back puff of air down the vent, that the pilot gas supply will cut off as the thermocouple cools.  Pilot gas and no flame equates to explosion and fire.
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