Electrical safety in aftermath of flood

[LMAO]

Hi guy, I apologize if it is not the appropriate forum for this question. A friend has had about 3" standing water in her home for about 3 days. They have since left the house, and before leaving, they turned off main power. They are now about to return to assess damage. She asked me if it is OK to close the breakers feeding upstairs while they are cleaning up downstairs. I said as long as breakers are dedicated to upstairs (not feeding anything on the lower level) it should be OK. I also said closing GFCI breakers (or breaker dedicated to GFCI receptacles) downstairs should be OK.
Can you let me know if I was missing anything? Do you agree with my advice?

Also, what is a good way to check the safety of downstairs receptacles? Can they measure the resistance/voltage from hot to ground?

As you know hiring a electrical contractor is really not an option here in Houston unless they are willing to wait weeks.

Thanks,

 

[topgone]

Hi guy, I apologize if it is not the appropriate forum for this question. A friend has had about 3" standing water in her home for about 3 days. They have since left the house, and before leaving, they turned off main power. They are now about to return to assess damage. She asked me if it is OK to close the breakers feeding upstairs while they are cleaning up downstairs. I said as long as breakers are dedicated to upstairs (not feeding anything on the lower level) it should be OK. I also said closing GFCI breakers (or breaker dedicated to GFCI receptacles) downstairs should be OK.
Can you let me know if I was missing anything? Do you agree with my advice?

Also, what is a good way to check the safety of downstairs receptacles? Can they measure the resistance/voltage from hot to ground?

As you know hiring a electrical contractor is really not an option here in Houston unless they are willing to wait weeks.

Thanks,

Best to hire an electrician and megger all the lines first before putting on.

 

[Sahib]

Won't POCO people there lend a helping hand in the case of immediate nonavailability of other electricians?

 

[Sierrasparky]

3 inches of water and Slab on grade home. I would think ok.

3 inches of water with a crawlspace or basement absolutely not. You have no idea what has been submerged.

What blows my mind was those elderly folks sitting in 2 feet of water with the power obviously on. crazy. :?

 

[Jraef]

Won't POCO people there lend a helping hand in the case of immediate nonavailability of other electricians?

In a few months, maybe years, sure...
The magnitude of this situation is beyond the ability of any PoCo to keep up with. They will be starting with their distribution system and go down stream from there. It will be a long long time before they can get to each and every individual end user.

 

[ggunn]

In a few months, maybe years, sure...
The magnitude of this situation is beyond the ability of any PoCo to keep up with. They will be starting with their distribution system and go down stream from there. It will be a long long time before they can get to each and every individual end user.

Actually, the situation is not as bad as it was after Hurricane Ike. Ike knocked down thousands of trees onto overhead services; my friend in Garden Oaks was without power for seven or eight weeks. This time it's just water.

 

[Ingenieur]

An electrician should be able to do a fairly quick check
open main
close all branches
unplug everything, turn lights off, etc
measure
N-G
L1-G
L2-G
L1-L2
if anything is shorted open branches until it clears
pull that cb until it meggers ok

 

[Coppersmith]

Won't POCO people there lend a helping hand in the case of immediate nonavailability of other electricians?

I can only speak for my part of the country: POCO does not do anything beyond their service drop/lateral. They will tell you to call an electrician.

 

[topgone]

I can only speak for my part of the country: POCO does not do anything beyond their service drop/lateral. They will tell you to call an electrician.

Agree.

 

[junkhound]

1. assuming 'rainwater' and not storm surge salt water.
If storm surge salt water, then anything submerged needs to at least have all connections redone.

So assuming non-salt water.
Due to liability, no one will give 'go ahead and power it up advice, eh?

However-- IF water has receded:
In own house would have no concern powering all 120V circuits once water has receded. At 170V peak, a breaking water film does not sustain an arc, but 340 Vp will.
But be sure water has receded below any control panels. Even at 120Vac, if wet conditions still exist, there can be enough leakage current across something like a 120V t-stat to pull in the contactor on an AC or similar.

240V circuits line to line has the potential for arcing, and best to megger lines with loads disconnected; or, since few electricians have a megger at least check open circuit current draw with meter that can read down to a few mA. Can take weeks to 'dry out', paper in NM wicking water is a concern.

At 240V, as a water film boils off and 'breaks', the small arc-break can create a track path across insulators. I would clean all 240V appliance terminals and contactors that have a surface between conductors (terminal strips, etc) before powering up.
The flood waters probably are muddy?, so just getting mud out of everything is part of cleanup.




About 20 years ago talked to the folks at a hydro plant where the generator room got flooded. For 'cleanup' big tents over generators with dehumidifiers and heat. Took over a month to get 2 of 3 generators to megger good, they replaced the 3rd generator as could never get a good verification of insulation integrity. IIRC, theses were 25kV generators, so arcing a definite concern. The 'flood' was clean clear fresh water.

 

[kwired]

Best to hire an electrician and megger all the lines first before putting on.

Won't POCO people there lend a helping hand in the case of immediate nonavailability of other electricians?

An electrician should be able to do a fairly quick check
open main
close all branches
unplug everything, turn lights off, etc
measure
N-G
L1-G
L2-G
L1-L2
if anything is shorted open branches until it clears
pull that cb until it meggers ok

5th or 6th largest metro population in the US and you all think all these people are going to wait how ever long it takes for someone qualified to show up?

Having power on will give them at least some "normalcy" feeling at a time when nothing seems normal. And getting anybody to do any kind of work for you is next to impossible so you take things on yourself, at least the friend of the OP had concerns and called someone for advice.

 

[Sahib]

In a few months, maybe years, sure...
The magnitude of this situation is beyond the ability of any PoCo to keep up with. They will be starting with their distribution system and go down stream from there. It will be a long long time before they can get to each and every individual end user.

Here in India many licemced electrician give their details including addresses to the local POCO so that the POCO customers may employ those electricians during a crisis also.

 

[kwired]

Here in India many licemced electrician give their details including addresses to the local POCO so that the POCO customers may employ those electricians during a crisis also.

Getting through to the POCO is likely a task in itself in the Huston area right now. Next major hurdle is just getting them to come to your place - it will not be even a mediocre priority right now. Want a list of electricians to call - if they would happen to give names on the phone it is only going to be the same short list for every caller and you will be waiting a long time.

If you look on web, you should find a much bigger list - but again expect to wait in this situation. Local contractors will have their priorities they go to first, assuming they don't have much devastation of their own to deal with. There is going to be a lot of outsiders helping out, but is still going to be a lot of things going on all at once and you are still likely going to be waiting.

 

[junkhound]

5th or 6th largest metro population in the US and you all think all these people are going to wait how ever long it takes for someone qualified to show up?

Having power on will give them at least some "normalcy" feeling at a time when nothing seems normal. And getting anybody to do any kind of work for you is next to impossible so you take things on yourself, at least the friend of the OP had concerns and called someone for advice.

Amen, +1, etc.

Probably 80+% of folks just left the house after grabbing whatever most important to them, never even occurring to them to throw main breaker(s).
If power on when they get back, they are happy.
If not most will try closing any breakers that are tripped and hope for the best.

A guess would be that 10-20% would have to call a friend to even know to try to reset a breaker.

PS: anyone know what percentage of SE TX is underground distribution ? If one has a pad mounted 5kV xfmr serving their house, the 120/240 house wiring is not the weak link.
copied this pic off the net, HV overhead transmission lines visible, but looks like neighborhood distribution is underground. Not cheap homes in the pic, no water above typical outlet level so mostl likely OK for power inside the houses.

 

[Ingenieur]

Just throw the switch and pray for the best
words to die by

 

[Jraef]

I posted more relevant information here:
http://forums.mikeholt.com/showthread.php?t=186421

 

[Coppersmith]

5th or 6th largest metro population in the US and you all think all these people are going to wait how ever long it takes for someone qualified to show up?

I have heard in the past (I don't remember the circumstances) of licencing rules being relaxed during disasters to allow anybody licensed in another state to come in and do work legally. I'm wondering if Texas will be doing this.

 

[ggunn]

I have heard in the past (I don't remember the circumstances) of licencing rules being relaxed during disasters to allow anybody licensed in another state to come in and do work legally. I'm wondering if Texas will be doing this.

I don't know about the licensing but there are workers from other states coming in.

 

[retirede]

I just read a story about 4 rescue workers were electrocuted today when their boat drifted into power lines.
There were (I think) 3 others in the boat who survived.

 

[kwired]

I have heard in the past (I don't remember the circumstances) of licencing rules being relaxed during disasters to allow anybody licensed in another state to come in and do work legally. I'm wondering if Texas will be doing this.

Is it even possible to monitor all the construction that will be going on with the "usual" local AHJ's and according to the "usual" procedures?

They can have POCO's refuse to energize services without approval - but when enough people are ready but can't get an inspection - the people will protest.