Rinsing out electrical after flood

[scottwnuwer]

After Hurricane Milton, we are experiencing several homes along the coast that have had load centers/main breakers either just above, at, or below the level of flood waters. Sometimes only the enclosure or cabinet received flooding (without submerging the load side wiring), and sometimes the bottom few breaker spaces on the busbar received flooding. First, I would like to know thoughts on trying to salvage the busbar and main breaker if only the bottom of the enclosure received flooding. Second, if the flood water did make it up to the few bottom breaker spaces, what is everyones thought on attempting to flush out the busbar and blow it out. Almost all of the flood damaged equipment is copper tinned bus, and the enclosure is located on the gulf of Mexico anyways. Typically the outdoor electrical enclosure only lasts 5-15 years anyways. I read the NEMA article mentioning reconditioning of panelboards, which I imagine would require a recertification. My thought is to flush out the enclosure, blow dry, hilco lube the connections, and recommend total replacement within 90 days. It has only been a little over a week from the storm and most connections seem solid. I only mention this possible approach because I am becoming overwhelmed with customers, and would like to provide a temporary solution to restore power so they can return home and live in the upstairs portion, and guarantee a panel change for the future. Thoughts?

 

[ron]

This reference is often used for this situation https://www.nema.org/docs/default-s...ctrical-equipment-guide.pdf?sfvrsn=7034f9b6_2

 

[petersonra]

I think the problem is that as long as customers have power the ninety days would end up being indefinite.

Personally, I would be inclined to rinse the cabinet out with a hose and clean water and get the dirt and debris out and then blow dry it overnight with a fan and call it good.

Having said that, I do worry about gfci and afci breakers that may have gotten wet.

I know that is not the official position but there are not going to be enough panelboards available to replace everything that got wet. IMO it is better to get as many people's power back on than to worry about if all the rules are followed.

I know people are going to go crazy wanting know what to do about the wet paper inside NM. I say just leave it for now. What is it going to hurt? If there is wall board that has to be removed it is likely possible to splice in some new NM above where the NM paper got wet.

 

[scottwnuwer]

Thanks for the reference ron. Breakers and devices would need to be replaced for certain. It says all NM needs to be removed if submerged.

My goal is similar, petersonra. Try to get as many people power safely. Also, has anyone ever rinsed/cleaned/flushed out a few of the lower spaces of a busbar that were submerged to temporarily save a relatively new panel? For temporary purposes, what are the rammifications? The power is off, you rinse/flush the salt off, dry the enclosure, spray the connections or busbar with hilco lube or lps2, and move on.
Did anyone deal with home run issues if the NM paper did receive moisture at the main panel? I remembered reading somewhere about NM cable needing to be cut back 10' from the point where the paper got wet. I found it somewhere deep in the rabbit hole.
I dealt with service riser replacements from hurricane Ian, so this is my first time with flooding (Helene and Milton combined).
Needing an education. Thanks.

 

[Fred B]

None of the typical residential breakers will be waterproof. Even IF you could get them to dry out, the damage is done internally, that includes the main breaker. Have been to sites that had water damages and even months later the breakers could have water inside, SD-QO have a window and can see water in the window or rust visible. Seen this sort of damage even without submersion from damaged SE cable allowing water to come into the panel.

Seen completely submerged panel that breakers never even tripped even with water inside. Can't be good

 

[scottwnuwer]

I never

 

[don_resqcapt19]

None of the typical residential breakers will be waterproof. Even IF you could get them to dry out, the damage is done internally, that includes the main breaker. Have been to sites that had water damages and even months later the breakers could have water inside, SD-QO have a window and can see water in the window or rust visible. Seen this sort of damage even without submersion from damaged SE cable allowing water to come into the panel.

Seen completely submerged panel that breakers never even tripped even with water inside. Can't be good

Very difficult to flow enough current so that the thermal element gets hot enough to open the breaker when the breaker is under water.

We did a repair of a panel in the basement mechanical room that had a domestic water line break. The room had a fire door and the room filled to about 7' before the door broke. No one in the restaurant had any idea there was a problem until the door failed. None of the breakers tripped.
Since this was domestic water, the bus was just wiped down and new breakers installed per the manufacturer's engineer.

 

[scottwnuwer]

I can see from my initial post that I was misleading. In certain situations we have been allowing the electrical panel to remain, if the flood waters only submerged the few bottom breakers or less, and the electrical panel is still in very good condition. We simply replace the breakers and spray the bus down that was submerged. If it is a feed through panel, we purchase a main lug kit and replace the lugs if submerged. If the main breaker is submerged, we either replace the breaker or the whole enclosure. I will admit that if it's a particular manufacturer that we like to use, we may be more inclined to "recondition". Meter socket enclosures can also be saved if in very good condition. We have the power company replace meters that were submerged (which thankfully is becoming the standard), and we spray the connections. As mentioned, this is one option we may provide. The alternative is a full replacement of the service. If there are already corroded connections at either the meter or main, it makes perfect sense.
So far, this system has been working well.

As far as replacing the flooded NM cable, it is going to be interesting to see homeowners decisions in this manner. I tell homeowners that any NM cable that was flooded needs to be removed. If you can strip back the NM cable to a point where the paper wrapper is dry and the copper is shiny again, all should be good. I feel that there will be homeowners who will simply drywall over the existing flooded wiring because they want their house put back together so quickly. Has anyone had experience replacing flooded NM cable? Have there been portions that you kept? Or maybe I should ask of the known/experienced consequences for those who did not want to replace portions of flooded wiring.

 

[petersonra]

As for flooded NM wiring.

As I understand it, most NM uses THHN insulation. Now as a practical matter, it is probably the same insulation as used for THHN/THWN single conductors.

If the outer jacket gets wet I don't see it as a big deal. The code allows NM to be used outdoor for temporary wiring, and a flood is a very temporary situation.

If the paper gets wet, what difference does it make? THWN is allowed to be immersed permanently in water and THHN is allowed to be used in damp areas. I don't see how NM that has been flooded can be called wet. Damp maybe if water seeps up into the cable. But it won't ever be "wet".

In a more legalistic sense though, none of this matters unless UL says it can be used in damp or wet locations and UL won't because the NEC does not require it.