ECN Forum Forums Photo Discussion Forums Violation Photo Forum UL Listed Plywood

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How can you tell if this plywood is UL listed?

(Click on thumbnail image)

Perhaps a flame spread test?

A very ... interesting .... way to remodel a bath! Perhaps the last panel rusted apart?

Irreverent comment follows: There actually IS such a thing as "UL Listed plywood!" UL does list some plywood for surface fire resistance, as evaluated by a flame-spread test (E-84).

Still ... the UL standard for panels states plainly at its' beginning (materials) that wood shall not be used in the construction.

Reno:
What you are refering to is 'FRP" rated/labeled plywood. That's the designation 'grade stamp on each sheet, I do not know if 'FRP' is the UL nomenclature.

The only FRP I know about is "Fiberglass Reinforced Panel". The stuff I saw was more of a plastic thing than plywood.
They use it in commercial kitchens and public bathrooms in tough spots. It handles hosing down well. I am not sure about flame.

Here's a couple of links that may explain some things:

http://www.plywoodcompany.com/application/common/store/itemdetails.aspx?categoryid=39&itemid=500

http://www.hectorshardware.biz/shop/product.asp?dept_id=428&sku=100390&

that second link looks like what they make those industrial freezers out of

No, Hotline, I am NOT referring to FRP, or the partitions they have inside gear.

I am describing actual, ordinary plywood that has been pressure-treated for fire resistance. It does exist - good luck finding it, though!

The UL label oneach sheet will contain numbers representing ratings for flame spread and smoke developed. You can find similar labels on rolls of household insulation.

Reno,

The first link I posted above leads to all the information on type FRS fire resistant plywood, including a picture of the labeling.

It's commonly required for telco backboards in the 3/4" size, as well as specified for the mounting of electrical equipment & is readily available.

Yes, it does, Scott! And, yes, telco backer boards is exactly where I have encountered the specification.

I had inferred that the other comments thought I was referring to the red-fiber stuff you find in switchgear. That "FRP" stuff commonly found in commercial kitchens is another material altogether.

Thanks for the good links!

Reno:
Sorry...I meant "FRS", but...typed 'FRP'

John, it's nothing personal - or even really aimed at you at all.

I haunt a number of forums, and it's amazing some of the misconceptions and mis-identifications that are out there. Sometimes I get overly detailed in my posts, because I'm thinking of some bits of confusion I've encountered elsewhere.

Hey, isn't that a 3 phase panel? Is this a commercial location? It's one thing to find that in a residence, but in a commercial facility!!!!

I wouldn't be at all surprised to see this in a non-residential setting.
That's generally where the attitude of "get it done NOW" and "get it done CHEAP" are all too common.

I seem to remember a posting on this board about an electrical closet with a transformer that was fed by cables laying on the floor that were fed by an open panel with 'protective cardboard' over the live bus...and THAT particular installation was many months old.

If it is a 3 phase panel, another issue is the use of white for grounds or the tieing of the green ground wire to the neutral block.

Good eye, Gus!

Yes, it is a 3-phase panel. The arrangement of the neutral buss leads me to suspect that this is a dayed panel; it looks like a "Myers" panel I encountered on another job, which would use Cutler-Hammer breakers as replacements.

This was probably installed long before there even were ground wires. I would suspect that the wall is masonry, and the back of the panel simply rusted apart. The wood is a repair.