seal and enclusure

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HOGO.

Member
Location
IRAN
hi

I want to install a contractor(ignition source) inside an dust tight enclosure(electrical panel) in C2D2 group G.
but do I need to add ex proof seal to the enclosure?also Can I use NEMA 4 enclosure as dust tight enclosure???
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
hi

I want to install a contractor(ignition source) inside an dust tight enclosure(electrical panel) in C2D2 group G.
but do I need to add ex proof seal to the enclosure?also Can I use NEMA 4 enclosure as dust tight enclosure???

I have often wanted to install a contractor in an enclosure as well. :)

NEMA standards no longer really apply for enclosures. They have been taken over by UL. Many (UL) type 4 enclosures are also rated as type 12. Type 12 is dust tight, type 4 is not.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
hi

I want to install a contractor(ignition source) inside an dust tight enclosure(electrical panel) in C2D2 group G.
but do I need to add ex proof seal to the enclosure?also Can I use NEMA 4 enclosure as dust tight enclosure???

Explosion-proof seals are never required for a Class II area. Some type of seal is required to prevent the dust from entering the enclosure. I have often seen the standard Class I seals filed with duct seal used for this application.
 

HOGO.

Member
Location
IRAN
Explosion-proof seals are never required for a Class II area. Some type of seal is required to prevent the dust from entering the enclosure. I have often seen the standard Class I seals filed with duct seal used for this application.

thank you .
ok, I will use Class 1 sealing fiting with he sealing compound because its rated class 1 and class II.
but is there another types of seals for class II?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I am not aware of seals made for Class II installations. I have also seen duct seal used in conduit bodies for that purpose and the Article permits a 10' of horizontal conduit or 5' of vertical conduit running out of the bottom of the enclosure to act as the required seal.
 

HOGO.

Member
Location
IRAN
I have often wanted to install a contractor in an enclosure as well. :)

NEMA standards no longer really apply for enclosures. They have been taken over by UL. Many (UL) type 4 enclosures are also rated as type 12. Type 12 is dust tight, type 4 is not.
OK,according to nec code
''The term dusttight is typically used in conjunction with Enclosure Types 3, 3S, 3SX, 3X, 5, 12, 12K, and 13.''
also when I go to TABLE 110.28 ,I think type 4 has higher protection and can be used as dusttight.
what is your opinion??
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
You need to re-read Section 502.15 VERY carefully. Dusttight and dust-ignitonproof are not the same thing. Only dust-ignitionproof (Type 9) is ever required to be sealed at all ? and not always.
Section501.15 (1) through (4) lists the acceptable ways of ?sealing? dust-ignitionproof enclosures.

Unlike IEC IP designations, a higher number does not necessarily mean a higher degree of protection. I?ve told you before ? quit trying to apply IEC concepts. EDIT ADD: I HATE TRYING TO USE THIS EDITOR
 
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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
You need to re-read Section 502.15 VERY carefully. Dusttight and dust-ignitonproof are not the same thing. Only dust-ignitionproof (Type 9) is ever required to be sealed at all ? and not always.
Section501.15 (1) through (4) lists the acceptable ways of ?sealing? dust-ignitionproof enclosures.

Unlike IEC IP designations, a higher number does not necessarily mean a higher degree of protection. I?ve told you before ? quit trying to apply IEC concepts. EDIT ADD: I HATE TRYING TO USE THIS EDITOR

Perhaps you meant 502.15?

I have seen people use expanding foam. That seems like it ought to be compliant with method (1).

What the heck does (4) mean?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Perhaps you meant 502.15?

I have seen people use expanding foam. That seems like it ought to be compliant with method (1).

What the heck does (4) mean?
Some AHJs have an issue with any of the foam products unless there is some documentation that says the foam will not damage the conductor insulation.
I really don't know what (4) means....maybe a raceway that runs both horizontally and vertically. 2' horizontally and then 5' vertically down or something like that.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Perhaps you meant 502.15?

I have seen people use expanding foam. That seems like it ought to be compliant with method (1).

What the heck does (4) mean?
Yes - I meant 502.15 :ashamed1: I'm having so much trouble with the editor. I lost track.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
...

What the heck does (4) mean?
Basically, it means that the "unclassified" end, whether open or terminating in an enclosure that doesn't need to be sealed itself, must be below the dust-ignitionproof enclosure. Technically, the total length still needs to be not less than 10' and the vertical portion not less than 5'.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Basically, it means that the "unclassified" end, whether open or terminating in an enclosure that doesn't need to be sealed itself, must be below the dust-ignitionproof enclosure. Technically, the total length still needs to be not less than 10' and the vertical portion not less than 5'.

I don't recall it actually says the other end of the raceway has to be in an unclassified area.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
I don't recall it actually says the other end of the raceway has to be in an unclassified area.
It doesn't; it's a matter of practicality. Unlike cables [Section 502.10(B)(1)(6)],there is no provision for terminating a raceway in a Class II location except in an enclosure, but it isn't always necessary to terminate in an enclosure in an unclassified location; i.e., there are no specified "boundary" requirements, just those between dust-ignitionproof and non-dust-ignitionproof locations
 
Last edited:

HOGO.

Member
Location
IRAN
You need to re-read Section 502.15 VERY carefully. Dusttight and dust-ignitonproof are not the same thing. Only dust-ignitionproof (Type 9) is ever required to be sealed at all ? and not always.
Section501.15 (1) through (4) lists the acceptable ways of ?sealing? dust-ignitionproof enclosures.

Unlike IEC IP designations, a higher number does not necessarily mean a higher degree of protection. I?ve told you before ? quit trying to apply IEC concepts. EDIT ADD: I HATE TRYING TO USE THIS EDITOR

OK.in C2D2, dust tight enclosure is acceptable for relays(sparks,arcs) and Section502.15 (1) through (4) lists the acceptable ways of ?sealing? dust-ignitionproof enclosures.
But I m tryng to find a good way to make effective seal like Section501.15 (1) for the openings in the box.
so ,do you think the foam ,silicon or fiber(that used with sealing compound) will be good for sealing ???:D:D:blink:

also , can I use non sparking fan in C2D2??? Because I read "" 502.125(B) Motors and Generators""the motor shall be totally enclosed nonventilated, but I did not understand the concept!!!:(:(:?:?
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
OK.in C2D2, dust tight enclosure is acceptable for relays(sparks,arcs) and Section502.15 (1) through (4) lists the acceptable ways of ?sealing? dust-ignitionproof enclosures.
But I m tryng to find a good way to make effective seal like Section501.15 (1) for the openings in the box.
so ,do you think the foam ,silicon or fiber(that used with sealing compound) will be good for sealing ???:D:D:blink:

also , can I use non sparking fan in C2D2??? Because I read "" 502.125(B) Motors and Generators""the motor shall be totally enclosed nonventilated, but I did not understand the concept!!!:(:(:?:?
Good for you! You have done your homework and discovered that the contactor enclosure is not required to be dust-ignitionproof in Class II, Division 2 [502.115(B)] in which case no seal is required at all. However, unless you are attempting to use with "nonincendive field wiring" [502.10(B)(3)](which I don't recommend for you) all wiring methods and enclosures inside the Class II, Division 2 location must essentially be dusttight.[502.10(B)]

There are several other enclosure types listed in Section 502.125(B), "totally enclosed nonventilated" is just one of them. Again, unless you are attempting to use the 502.125(B) Exception, any totally enclosed motor with the 500.8(D)(2) external temperature restriction will do.
 

kwired

Electron manager
Location
NE Nebraska
Explosion-proof seals are never required for a Class II area. Some type of seal is required to prevent the dust from entering the enclosure. I have often seen the standard Class I seals filed with duct seal used for this application.

I am not aware of seals made for Class II installations. I have also seen duct seal used in conduit bodies for that purpose and the Article permits a 10' of horizontal conduit or 5' of vertical conduit running out of the bottom of the enclosure to act as the required seal.

I have never used a class I seal in a class 2 location. Always been ordinary general purpose "duct seal" either in a conduit body or in the termination of the raceway itself.

Distance also creates an acceptable seal as mentioned. That dust apparently can only travel so far in a raceway and then just gets tired and stops. Many of installs I have done need sealing anyway because of temperature differences and condensation issues.
 
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