What is combustible?

[gregorsc]

A question on a practice journeyman's test asked " The code permits a _____ '' maximum space between the panel enclosure and the panel cover installed in a metal stud wall with (2) layers of 5/8'' sheetrock?"
My answer would be that it should be flush because the wall material is combustible.
312.3 for cabinets doesn't list sheetrock as noncombustible.314.20 for boxes does list sheetrock as noncombustible.
Should I tell my students that because it tells us in 314.20 it is noncombustible that they should know that for any other application and the answer is 1/4" and it is just a situation of inconsistency in the code book?

 

[rcarroll]

I think I would still go with the 1/4" just because of the "other noncumbustible material". Somewhere in the back of my mind, when I was studying for my other building inspector certs, sheetrock is not defined as combustible or noncombustible. JMHO. :smile:

 

[raider1]

In my humble opinion in regards to 312.3 I would say sheetrock would be a noncombustible material.

Chris

 

[dnem]

..... it is just a situation of inconsistency in the code book?

Is it the NEC that's being inconsistent or is it you ?

Where is the inconsistency in the code on this issue ?

 

[gregorsc]

Inconsistency...

Inconsistency...

If the code states in 312.3 walls of concrete,tile or other noncombustible...and in 314.20 it states surfaces of concrete,tile and gypsum,plaster....and both articles are trying to clarify a situation as to when the box is allowed to be not more than 1/4" or flush. If I read both articles I would think gypsum is noncombustible. If I just read 312.3 and not 314.20 I would think gypsum is combustible. Thinking of this from the apprentice's point of view and preparing for a journeyman's test I would want to know if I should apply the article on junction boxes to the question asking about a panel cabinet.

 

[dnem]

If I just read 312.3 and not 314.20 I would think gypsum is combustible.

Even 312.3 says, "or other noncombustible material"
314.20 adds a further clarification by using the word, "gypsum"
It seems clear to me.

Even the cheapest drywall/sheetrock has a 15 minute flash rating, right ?
I guess in reality it's combustible resistant and classified by the NEC as noncombustible for application of code rules.

 

[ryan_618]

When a building is deemed noncombustible (Type I or Type II) sheetrock is still permitted. I see it as being noncombustible.

 

[stars13bars2]

I wish I could help you on the combustible/noncombustible thing but I am still
trying to figure out the difference between flammable and inflammable.

 

[shwazqrt]

Even 312.3 says, "or other noncombustible material"
314.20 adds a further clarification by using the word, "gypsum"
It seems clear to me.

Even the cheapest drywall/sheetrock has a 15 minute flash rating, right ?
I guess in reality it's combustible resistant and classified by the NEC as noncombustible for application of code rules.

sounds logical... at least to me .. .. ..!!

 

[ryan_618]

I wish I could help you on the combustible/noncombustible thing but I am still
trying to figure out the difference between flammable and inflammable.

LOL. A big pet peeve of mine with the english language is that flammable and inflammable mean the same thing.

 

[JohnE]

Sheetrock is noncombustible. I posted on this a while ago, I'll try to find the post.

 

[JeffD]

A standard sheetrock partition gives you a 1 hour fire rating. If you want a 2 hour partition you just add more sheetrock. I take this to mean sheetrock is noncombustible.
Wood paneling would be something that is combustible.

 

[petersonra]

Years ago the place I worked at got a new president. He had his office remodeled. The city required that the walls be non-combustible so had to use sheet metal studs instead of 2x4's.

The city did not care that on the inside of the drywall, he had wood paneling installed.

 

[iwire]

Years ago the place I worked at got a new president. He had his office remodeled. The city required that the walls be non-combustible so had to use sheet metal studs instead of 2x4's.

The city did not care that on the inside of the drywall, he had wood paneling installed.

That would be standard procedure for fire rated construction.

We did a seven story steel and cement building for an insurance company's headquarters. It was like a mansion inside all Stained Cherry or painted poplar raised panels from floor to ceiling but under all that wood was a metal stud wall with 5/8" fire code sheet rock taped and compounded.

Wood finish or not the sheet rock contains the fire .... for a while.

 

[Pierre C Belarge]

You will find the combutible rating of sheet rock (I think it is designated as X, XX, XXX, etc..) at the gypum website.

 

[JeffD]

Wood finish or not the sheet rock contains the fire .... for a while.

Agreed, I was thinking of someone paneling with just wood paneling, no drywall subsurface, like finishing a rec room.

What other combustible wall systems can anyone think of?

 

[zog]

Agreed, I was thinking of someone paneling with just wood paneling, no drywall subsurface, like finishing a rec room.

What other combustible wall systems can anyone think of?

The first 2 of the 3 little pigs wall systems.

 

[zog]

Its not so much the material but the formit is in, see gran elevator explosions.

Ever pour powder coffe creamer over a flame? That kept us entertained on our submarie for about a week when we figured that one out.

 

[hillbilly]

I wish I could help you on the combustible/noncombustible thing but I am still
trying to figure out the difference between flammable and inflammable.

I asked my 6th grade teacher why flammable and inflammable meant the same thing, and she didn't know.

45 years later.......I still don't.

steve

 

[lbwireman]

The first 2 of the 3 little pigs wall systems.

Au contraire, mon frere. The ASTM E-119 test gives a plastered straw bale wall a two hour fire rating.