how do I do this?

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petersonra

petersonra

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Location
Northern illinois
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engineer
I have a type 4 cabinet with an XP horn mounted on the outside.

the CL of the threaded opening for a 3/4 fitting on the bottom of the horn is no more than an inch from the wall of the box.

there will be a seal on the bottom of the horn, and then it has to turn into the box and enter through a hub of some sort.

is there some combination of fittings that I can do this with that will allow me to mount the horn flush to the side of the box? or will it need to be spaced away from the side of the box?
 
Does the horn have a swivel on it ( adjustable)so it can be taken apart at that point? If not can you get an angle or adjustable adapter for it. Maybe something like this

jbc100.jpg
 
I mounts flush to the side of the cabinet.

It is not even my project. Somehow I got stuck fixing it. I was kind of surprised the horn did not come with an internal seal but the instructions make no mention of it and it does not appear to be potted.
 
I am not going to screw around with it any more. It is going on the side near the bottom and piping around the corner and into the bottom of the enclosure as suggested by an earlier poster, as I cannot think of anything better.
 
It has occurred to me that maybe only the stuff starting at the seal has to be XP and whatever is run back into the box does not given the box is pressurized. Not that it makes all that much difference.
 
petersonra,
the seal must be within 18" of the entry point of the enclosure. i do not have my code book or project notes with me to cite the code.
regards,
james
 
james_mcquade said:
petersonra,
the seal must be within 18" of the entry point of the enclosure. i do not have my code book or project notes with me to cite the code.
regards,
james
Click to expand...

I was aware of that requirement.

My meandering thought was why does it need to be XP between the box and the seal other than as best I can tell it is required by code. The pressurized inside of the box feeds into the conduit leading to the seal, so there is no chance of a hazard there, and the seal keeps the horn from introducing a hazard.

It just does not seem necessary, even though it appears to be required by the code.

We don't do much work in classified areas so I have to look everything up because we do so little of it. We used to do more, but over time went away from it. I think maybe because UL changed the way they list control panels for classified areas.
 
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I 'm not sure an external seal is required at all even tho the horn may be listed as Explosionproof.Cooper C-H AC horns do not have any arcing contacts and the DC horns the leads are hermetically sealed and construction is flame tight. The seal requirement may be to maintain a positive pressure on the CL 4 enclosure,SWAG. I know others are similar Appleton,Federal etc.A seal is oft times required in Group B atmospheres

Who is the manufacturer of this unit maybe you can look up a spec sheet.


dick
 
dicklaxt said:
I 'm not sure an external seal is required at all even tho the horn may be listed as Explosionproof.Cooper C-H AC horns do not have any arcing contacts and the DC horns the leads are hermetically sealed and construction is flame tight. The seal requirement may be to maintain a positive pressure on the CL 4 enclosure,SWAG. I know others are similar Appleton,Federal etc.A seal is oft times required in Group B atmospheres

Who is the manufacturer of this unit maybe you can look up a spec sheet.


dick
Click to expand...

It is already done. Its a Federal Signal unit. 31X.
 
What is the classification of the hazardous location?

I am confused about needing an explosion proof horn, explosion proof seal and only a type 4 cabinet? The entry into the cabinet doesn't appear to be an explosion proof method either. Plus the mounting of the horn is just bolts through the cabinet wall. If this were an environment requiring explosion proof methods you do not drill holes into enclosures and still maintain the explosion proof rating.

If this is a class 2 hazardous location - the horn will need CL 2 rating - and the one pictured may be rated both CL 1 and CL2, but should not need the sealing fitting, no hazardous gas will be inside the raceways or enclosures for class 2 installations, which is what the seal fittings are for.

Simple duct sealant is sufficient for sealing raceways when leaving a class 2 environment.
 
kwired said:
What is the classification of the hazardous location?

I am confused about needing an explosion proof horn, explosion proof seal and only a type 4 cabinet? The entry into the cabinet doesn't appear to be an explosion proof method either. Plus the mounting of the horn is just bolts through the cabinet wall. If this were an environment requiring explosion proof methods you do not drill holes into enclosures and still maintain the explosion proof rating.

If this is a class 2 hazardous location - the horn will need CL 2 rating - and the one pictured may be rated both CL 1 and CL2, but should not need the sealing fitting, no hazardous gas will be inside the raceways or enclosures for class 2 installations, which is what the seal fittings are for.

Simple duct sealant is sufficient for sealing raceways when leaving a class 2 environment.
Click to expand...
Class I, Div 2, Grp C&D.

It is a type Z pressurized/purged enclosure. The mounting bolts have washers on the back side under the nuts inside the enclosure to maintain the environmental rating, although how water or anything else could get into a pressurized enclosure like this through the tiny opening there escapes me.

The hole you see the elbow going thru below the seal is actually thru the side wall of a leg stand, not the enclosure. There is another elbow on the left side of the floor stand kit that turns up and enters the enclosure thru an XP sealing hub.

I think you need a real XP seal between the enclosure and the horn, since the horn is only rated for CL 1, Div 1.

They make a CL 1 Div 2 horn but the guy that started the job did not buy that one. I think with that style of horn you might well be allowed to use some other sealing method, although why it would need to be sealed at all escapes me other than that the code would appear to require some kind of seal between a Cl1 D2 area that is the outside of the box, and the unclassified area inside the enclosure.

I do not do enough of this kind of thing to know the cheapest solution to this type of problem so did what I was sure would work. The fiber dam and sealing material cost more than the fittings did.
 
petersonra said:
Class I, Div 2, Grp C&D.

It is a type Z pressurized/purged enclosure. The mounting bolts have washers on the back side under the nuts inside the enclosure to maintain the environmental rating, although how water or anything else could get into a pressurized enclosure like this through the tiny opening there escapes me.

The hole you see the elbow going thru below the seal is actually thru the side wall of a leg stand, not the enclosure. There is another elbow on the left side of the floor stand kit that turns up and enters the enclosure thru an XP sealing hub.

I think you need a real XP seal between the enclosure and the horn, since the horn is only rated for CL 1, Div 1.

They make a CL 1 Div 2 horn but the guy that started the job did not buy that one. I think with that style of horn you might well be allowed to use some other sealing method, although why it would need to be sealed at all escapes me other than that the code would appear to require some kind of seal between a Cl1 D2 area that is the outside of the box, and the unclassified area inside the enclosure.

I do not do enough of this kind of thing to know the cheapest solution to this type of problem so did what I was sure would work. The fiber dam and sealing material cost more than the fittings did.
Click to expand...

As far as the horn being rated CL 1 D 1, 501.10(B)(1)(1) permits D 1 equipment and methods to be used in D 2 locations. So the horn is CL1 D2 as far as this application is concerned.

The only reason to put a seal between the enclosures in D 2 location is if one of them is required to be explosion proof, or when leaving the classified area. The pressurized cabinet is not explosion proof. Explosion proof enclosures are designed to contain an explosion if one should occur in them, the pressurized cabinet is preventing the explosive gas from entering in the first place. I don't know if a pressurized cabinet is required to have seals in entering raceways to limit the pressurized space or not. Are there seals in other raceways entering the cabinet? Is there any arcing components in the horn? If not it likely is not required to be explosion proof.
 
kwired said:
As far as the horn being rated CL 1 D 1, 501.10(B)(1)(1) permits D 1 equipment and methods to be used in D 2 locations. So the horn is CL1 D2 as far as this application is concerned.

The only reason to put a seal between the enclosures in D 2 location is if one of them is required to be explosion proof, or when leaving the classified area. The pressurized cabinet is not explosion proof. Explosion proof enclosures are designed to contain an explosion if one should occur in them, the pressurized cabinet is preventing the explosive gas from entering in the first place. I don't know if a pressurized cabinet is required to have seals in entering raceways to limit the pressurized space or not. Are there seals in other raceways entering the cabinet? Is there any arcing components in the horn? If not it likely is not required to be explosion proof.
Click to expand...

The pressurized enclosure is an unclassified area. The horn is outside the enclosure in the C1D2 area. Some kind of boundary seal is required, although what purpose it actually serves in this case is beyond me.

It seems to me that since we chose to use a horn that is not rated for C1D2 it is thus required to be XP and thus needs an XP seal.

In this case it was not a hugely expensive thing one way or the other.
 
petersonra said:
Some kind of boundary seal is required, although what purpose it actually serves in this case is beyond me.

Peter,boundary seals are not required between pieces of equipment that have different listings within a classified area if thats what you are alluding to,,,,,,they are required between different area classifications.

dick
Click to expand...
 
petersonra said:
The pressurized enclosure is an unclassified area. The horn is outside the enclosure in the C1D2 are. Some kind of boundary seal is required, although what purpose it actually serves in this case is beyond me.

It seems to me that since we chose to use a horn that is not rated for C1D2 it is thus required to be XP and thus needs an XP seal.

In this case it was not a hugely expensive thing one way or the other.
Click to expand...

If the seal is not between the cabinet and the horn, then the horn is pressurized also. Is there anything that would disallow doing it that way?

Just because the horn is rated division 1 does not mean it must be used as if it were in division 1 location. Division 1 equipment is permitted to be used in division 2 locations - effectively making them division 2 equipment for the application.

If the application does not require it to be explosion proof, then the seal is not required. I can agree if leaving a classified area then a boundary seal is required. So question may be, did we leave a classified area?
 
kwired said:
If the seal is not between the cabinet and the horn, then the horn is pressurized also. Is there anything that would disallow doing it that way?

Just because the horn is rated division 1 does not mean it must be used as if it were in division 1 location. Division 1 equipment is permitted to be used in division 2 locations - effectively making them division 2 equipment for the application.

If the application does not require it to be explosion proof, then the seal is not required. I can agree if leaving a classified area then a boundary seal is required. So question may be, did we leave a classified area?
Click to expand...

The area inside the enclosure is unclassified. That is why we can use general purpose stuff there. The area outside the enclosure where the horn is located is CID2. It thus seems to follow that there is a boundary seal required between the enclosure and the horn.

In any case, a closer look at the sealing requirements in NFPA496 and Art 500 seem to imply no seal is actually required here.
 
petersonra said:
The area inside the enclosure is unclassified. That is why we can use general purpose stuff there. The area outside the enclosure where the horn is located is CID2. It thus seems to follow that there is a boundary seal required between the enclosure and the horn.

In any case, a closer look at the sealing requirements in NFPA496 and Art 500 seem to imply no seal is actually required here.
Click to expand...

If there is no seal then the pressurized system is extended to the horn. I haven't looked into whether or not that is something that is code compliant, but if there is no seal that is what happens, that pressure doesn't just stop because it is not in the cabinet anymore.

So if that is what is done then the interior of the horn is also unclassified. That may not mean you can use any old horn. If there is external moving parts that could cause arcing or develop high surface temperatures, they still may not be allowed in the classified area.
 
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