Small conflict

[zigmark]

Ok electrical people out there lend me a hand with this.

Condition: New SFR in coastal V zone with a Design Flood Elevation of 12'-0". Home is elevated on concrete piles. Breakaway walls surround a portion of enclosed grade level with a door to exterior. In this jurisdiction we do not inspect electrical the State department of L&I does. We use the 2012 editions of codes. State uses NEC 2008.

The IRC does not permit the attachment of any electrical to the breakaway wall. IRC Section 322.3.4

The NEC requires that electrical outlets be no more than 6-1/2' above grade.

Questions: What is the acceptable installation for the electrical box requirement at the exterior grade level door?

Does the NEC address FEMA requirements?

Thanks for the help.

ZIG

 

[gfretwell]

Piling house?

Mount it on a piling.

I also see service disconnects set up that way.

A lot of AHJs want a ground level SD.

 

[Gregg Harris]

Ok electrical people out there lend me a hand with this.Condition: New SFR in coastal V zone with a Design Flood Elevation of 12'-0". Home is elevated on concrete piles. Breakaway walls surround a portion of enclosed grade level with a door to exterior. In this jurisdiction we do not inspect electrical the State department of L&I does. We use the 2012 editions of codes. State uses NEC 2008.

The IRC does not permit the attachment of any electrical to the breakaway wall. IRC Section 322.3.4

The NEC requires that electrical outlets be no more than 6-1/2' above grade.

Questions: What is the acceptable installation for the electrical box requirement at the exterior grade level door?

Does the NEC address FEMA requirements?

Thanks for the help.

ZIG

A little more clarity is needed.

Are you referencing the 6.6 to the service meter height?

All electrical should be above the lowest elevated floor.

 

[gfretwell]

A little more clarity is needed.Are you referencing the 6.6 to the service meter height?

All electrical should be above the lowest elevated floor.

You are still not relieved of the need for 120v receptacles at grade in front and back

As I said we also have AHJs who want the service disconnect accessible at grade (for the firemen)

 

[north star]

+ + +

zigmark,

See Article 682.10 [ `08 NEC ] for requirements of electrical equipment

near natural & artificial bodies of water.

+ + +

 

[zigmark]

Thanks for the responses. I don't have an NEC and I do not enforce the NEC. I'm being told that the State electrical inspector is requiring an electrical outlet outside the man doors at grade level. In this situation grade level is below the design flood elevation (underwater in a flood event).

gfretwell- What are you typically seeing for this application as far as materials? Is this required to be water tight or weather proof? Is there any reference in the NEC about applications in areas prone to flooding? I have found some FEMA references about this but was wondering if they were in conflict with the NEC because the reference seems to elude to that and has a note about talking to the AHJ, which in this case would be the State. I was hoping to have an idea about the answer before asking the question.

Thanks again,

ZIG

 

[rnapier]

The only thing I Know of in the NEC is in ARTICLE 682— NATURAL AND ARTIFICIALLY MADE BODIES OF WATER which defines the datum plain as listed below

Electrical Datum Plane. The electrical datum plane as used in this article is defined as follows:

(1) In land areas subject to tidal fluctuation, the electrical datum plane is a horizontal plane 600 mm (2 ft) above the highest tide level for the area occurring under normal

circumstances, that is, highest high tide.

(2) In land areas not subject to tidal fluctuation, the electrical datum plane is a horizontal plane 600 mm (2 ft) above the highest water level for the area occurring

under normal circumstances.

(3) In land areas subject to flooding, the electrical datum plane based on (1) or (2) above is a horizontal plane 600 mm (2 ft) above the point identified as the prevailing

also

682.10 Electrical Equipment and Transformers. Electrical equipment and transformers, including their enclosures, shall be specifically approved for the intended location. No

portion of an enclosure for electrical equipment not identified for operation while submerged shall be located below the electrical datum plane.

682.11 Location of Service Equipment. On land, the service equipment for floating structures and submersible electrical equipment shall be located no closer than 1.5 m (5 ft) horizontally from the shoreline and live parts shall be elevated a minimum of 300 mm (12 in.) above the electrical datum plane. Service equipment shall disconnect when the water level reaches the height of the established electrical datum plane.

682.12 Electrical Connections. All electrical connections not intended for operation while submerged shall be located at least 300 mm (12 in.) above the deck of a floating or

fixed structure, but not below the electrical datum plane. high water mark or an equivalent benchmark based on seasonal or storm-driven flooding from the authority having jurisdiction.

There other requirements that you might find pertinent.

 

[north star]

$ ~ $

zigmark,

Article 682.10 [ in the `08 NEC ] requires that any electrical equipment installed

and intended for use below the electrical datum to be rated for use "while

submerged".

$ = $

 

[gfretwell]

The elevation at grade is going to be >"2 ft above the highest tide level for the area occurring under normal" so the datum plane in 682 is not relevant. We are usually talking about things that happen in a hurricane and a little water in the box is the least of your worries.

They use garden variety NEMA 3R stuff.

 

[north star]

= ~ = ~ = ~

gfretwell,

Doesn't FEMA's designation of the area as a "V Zone" establish the entire

area as being subject to being totally submerged; even if it is only occasionally ?

They did this along the Gulf Coastal areas after Hurricane Katrina, so that

the communities could get funding......FEMA tied the "money purse strings"

with new area designations of the "V Zone", and the redefining of Design

Flood Elevations further inland.

$ | $ | $

 

[zigmark]

North-

The "V-Zone" is FEMA's velocity zone typically adjacent to a large body of open water and is one designation in coastal high-hazard areas. Here it would be along the Pacific Ocean. The designation doesn't carry landward very far before the designation changes. The V-Zone is part of areas subject to wave heights in excess of 3 feet or high velocity wave action and erosion and wave born debris. The important thing about V-Zones is that FEMA designates an elevation on their maps that homes have to be elevated above. FEMA has recently introduced new mapping all across the Country and changed some of their designations. With the advent of LIDAR mapping of flood prone areas FEMA has been able to produce more accurate maps than they previously used which in some areas has extended the flood prone areas further landward while in others decreased them. If you live in a flood prone area FEMA offers multiple scholarships for training at their Emmitsburg, MD headquarters where they provide some great training. They travel, house, feed and educate you at not cost to your jurisdiction and it is well worth the time spent.

ZIG

 

[gfretwell]

I don't think what FEMA says about storm surge and wave action is addressed in any way in the electrical code. As I said, if a hurricane is pushing waves over the island, water in the boxes is the least of your worries and you should be long gone by then anyway.This house was built to the 150 MPH code and nothing under the FF was left.

View attachment 900

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[north star]

~ ~ +

gfretwell [ and others ],

Does the designation of an area of potential for flooding; and in this case

a Velocity Wave Action Zone, require the electrical equipment to be rated

for submersion ?......[ Example: the area is designated a "V Zone"......In a

weather event, water only comes up high enough to submerge the electrical

equipment, but not require evacuation of the structure / premises ].

The occupants are able to stay in their structure.......Should their electrical

services [ if still functioning ] be NEC required to be safe & operable ?

Lot's of "ifs" I know, ...but it is still technically possible to occupy a

structure in flood waters " IF " utility services are still functioning,

and most people do not want to leave their homes, regardless if they

have utilities functioning or not.

+ ~ ~

 

[gfretwell]

I am not sure about upland flood areas but down here they have mandatory evacuations of beach and low lying areas near the beach when we have a hurricane. You can stay if you want but it is strongly discouraged and you are on your own. Don't bother calling 911, they ain't coming. The power will be off.

 

[zigmark]

We have annual storm events here that do not meet hurricane standards but still have high tidal surges causing flooding and scour. Typical winds in the 40-60mph range for these events. We had one a couple weeks back. There is no mandatory evacuation for these events. Advisable, yes, but not mandatory. I realize that electrical boxes are the least of occupants worries in an event but still need to know what is permitted/required for construction. Incorrect construction practices and disregard for the code create much worse results for occupants and owners after the fact. It would be interesting to know the year built and standards used for the one structure still standing versus those no longer in the picture.

Thanks for each of your input,

ZIG

 

[gfretwell]

I know of no code that requires greater than NEMA 3R for this situation. I am not even sure where you would find NEMA 6 enclosures or how you would actually use them. In the case of a service disconnect I doubt you will ever find a NEMA 6 enclosure that you could open or operate without tools.

Even when you have a high tide from a tropical storm, does it actually go a couple feet above grade at the base of the house? If so I am surprised it was ever permitted.

 

[zigmark]

I'm not sure I would call them tropical... 45 degrees and winds 40-60 mph. Anyhow, when we do have these larger storm events and they hit on the days with higher tides in the fall and winter months we do regularly get flooding in and around these structures. In several of our coastal towns we have had extremely large surf coupled with high tides that has complete swamped portions of cities that exists behind a seawall or jetty. 12 foot waves with high tides and then added wind pushes the water up the beach further than most expect. I'll post a picture if I can find it, they may be at home.

ZIG

 

[gfretwell]

How often do you get water under the piling houses and how high up does it go?

If you can make the case to the AHJ that a receptacle at grade will be submerged I imagine you can get a variance from the code but it might get the house condemned.

Insurance will certainly be an issue