Emt to liquidtite roof penetration Support HELP

[jssegaloff]

i am installing multiple roof top exhaust fans on a flat rubber roof. Units came came pre-assembled with weather proof disconnects on the outside. to feed these, i understand future maintance requires these to be able to be taken off to be cleaned without having to physically disconnect any conduit. i currently have holes drilled about 16" away from the curb of the unit. it is impossible to go into the curb. my question is as follows: can i stub up the emt thru the flat roof with no supports other then a 3 inch piece of strut cut with a strut clip pressed down against the base of the penetration and tight to the roof (inside the witches hat), with also another strut clip, supported from framing members below roof line; then, change over to liquidtite above the witches hat and not then support until within a foot from the disconnect. there would be about 2 feet of emt sticking up and then no more then 5 feet of liquidtite????

 

[renosteinke]

Personally, I've always transitioned to rigid in such situations - at least for the part that goes through the roof deck. Then I usually have an LB or a box atop the 'mast,' where I change to the liquitite.

 

[Smart $]

i am installing multiple roof top exhaust fans on a flat rubber roof. Units came came pre-assembled with weather proof disconnects on the outside. to feed these, i understand future maintance requires these to be able to be taken off to be cleaned without having to physically disconnect any conduit. i currently have holes drilled about 16" away from the curb of the unit. it is impossible to go into the curb. my question is as follows: can i stub up the emt thru the flat roof with no supports other then a 3 inch piece of strut cut with a strut clip pressed down against the base of the penetration and tight to the roof (inside the witches hat), with also another strut clip, supported from framing members below roof line; then, change over to liquidtite above the witches hat and not then support until within a foot from the disconnect. there would be about 2 feet of emt sticking up and then no more then 5 feet of liquidtite????

IMO, it is not required to have the EMT secured at the roof line as long as the support below is within 10' of where you secure the LT. The requirement for securing EMT 3' or less from terminations is just that, and the transition to LT is not a termination unless you install a conduit body or a box.

That said, doing a sound installation versus meeting code requirements is not always the same.

Don't forget you have to use a wet-location listed fitting on the EMT above the roof.

 

[nhfire77]

I would recommend bending the EMT 130 degrees in a gooseneck configuration. Of course rigid is better, but not needed.

 

[jusme123]

I would recommend bending the EMT 130 degrees in a gooseneck configuration. Of course rigid is better, but not needed.

I have never seen it done that way, usually you just stub up and convert to sealtite right from the conduit

 

[glene77is]

I would recommend bending the EMT 130 degrees in a gooseneck configuration. Of course rigid is better, but not needed.

I like that, a hand-made weather-head. I have seen pictures.
I think RMC rigid & Unistrut may be required for proper support,
similar to a mast structure.

Maybe use a Navy Water-Tight Plug-&-Receptical,
salt-water proof, like ones on the aircraft carriers.
(that's a little joke)

 

[jssegaloff]

thanks for all of your responses and i'm probably going to stub up with emt, and at the top of the witches hat using a compression connector to a ridgid coupling to changeover to LT. i'll go with a "mast style" support inside with strut. thanks again! - in addition to the person with the gooseneck configuration. could you describe in a bit more detail? i'm curious

 

[Smart $]

thanks for all of your responses and i'm probably going to stub up with emt, and at the top of the witches hat using a compression connector to a ridgid coupling to changeover to LT. i'll go with a "mast style" support inside with strut. thanks again! - in addition to the person with the gooseneck configuration. could you describe in a bit more detail? i'm curious

While the gooseneck bend sounds interesting, consider that it may incite the need for another pull point due to the 360? bend restriction in the run and also introduce a violation of the following section...

225.22 Raceways on Exterior Surfaces of Buildings or
Other Structures. Raceways on exteriors of buildings or
other structures shall be arranged to drain and shall be
raintight in wet locations.

 

[glene77is]

thanks for all of your responses and i'm probably going to stub up with emt, and at the top of the witches hat using a compression connector to a ridgid coupling to changeover to LT. i'll go with a "mast style" support inside with strut. thanks again! - in addition to the person with the gooseneck configuration. could you describe in a bit more detail? i'm curious

Jss,
There is a picture/drawing of one in the '05 Handbook,
but it is for a type of service mast install.
Pay attention to codes relating to your specific design.

 

[don_resqcapt19]

IMO, it is not required to have the EMT secured at the roof line as long as the support below is within 10' of where you secure the LT. The requirement for securing EMT 3' or less from terminations is just that, and the transition to LT is not a termination unless you install a conduit body or a box.
...

I see the transition to flex as an "other tubing termination" and triggering the requirement for a support within 3'.

 

[nhfire77]

I have never seen it done that way, usually you just stub up and convert to sealtite right from the conduit

The gooseneck reduces the infiltration of water, I know it's supposed to be water tight already. It also reduces the strain on the connector, depending on the application. I've found it to reduce long term problems with weather damage.

I've seen it on the roof of walmarts, although I wouldn't shop there.

 

[Smart $]

I see the transition to flex as an "other tubing termination" and triggering the requirement for a support within 3'.

I was wondering if and how long it would take for someone to counter my comment

I can see how the requirement can be interpretted either way. One point in favor of your interpretation is the use of the word tubing. The argument for the other side of the coin is that it is not a termination, but rather a transition from one type of conduit to another. How would you view it if it were EMT to RMC or IMC?

 

[don_resqcapt19]

I was wondering if and how long it would take for someone to counter my comment

I can see how the requirement can be interpretted either way. One point in favor of your interpretation is the use of the word tubing. The argument for the other side of the coin is that it is not a termination, but rather a transition from one type of conduit to another. How would you view it if it were EMT to RMC or IMC?

That is a good point and I would look at that differently, the other raceway can provide the required support, but the flex cannot. That being said, it would be my opinion that the code language requires a support within 3' of each side of the change between conduit types.

 

[Smart $]

That is a good point and I would look at that differently, the other raceway can provide the required support, but the flex cannot. That being said, it would be my opinion that the code language requires a support within 3' of each side of the change between conduit types.

Since when, speaking strictly according to code, does conduit ("the other raceway") provide support? You'll note that in my original comment I did state that a sound installation and a code-required installation are not always one and the same.

If you are going to interpret (quite strictly) that the EMT requires "securing" within 3' of the transition, then the strictest interpretation of securing the flex would put it at not more than 12" from the transition... Is this what you are proposing? If that be the case, just think of how many existing violations there are!

As mentioned previously, the requirement for EMT uses the word tubing. What if we were using RMC instead. The requirement for it and flex (e.g. LFMC) both use the word conduit? Remember, this is according to code, not necessarily providing a sound installation.

 

[don_resqcapt19]

Since when, speaking strictly according to code, does conduit ("the other raceway") provide support? You'll note that in my original comment I did state that a sound installation and a code-required installation are not always one and the same.

I don't think there is any section of the code where it says one conduit can support another. I just would not have an issue at a transition between conduits or tubings that are rigid, even though it would be a code violation.

If you are going to interpret (quite strictly) that the EMT requires "securing" within 3' of the transition, then the strictest interpretation of securing the flex would put it at not more than 12" from the transition... Is this what you are proposing? If that be the case, just think of how many existing violations there are!

I agree that the code requires both supports, unless the flex is being installed per 348.30(A) Exception #2.

As mentioned previously, the requirement for EMT uses the word tubing. What if we were using RMC instead. The requirement for it and flex (e.g. LFMC) both use the word conduit? Remember, this is according to code, not necessarily providing a sound installation.

The reference in the respective xxx.30 sections is to the conduit that is covered by the scope of that article and does not include conduits that are covered by scopes of other articles.

 

[Smart $]

I don't think there is any section of the code where it says one conduit can support another. I just would not have an issue at a transition between conduits or tubings that are rigid, even though it would be a code violation.

Debatable... IMO, the vernacular of the requirements are not explicit enough for this to be an absolute conclusion. I'm not saying yours is a wrong interpretation, but the wording leaves a gray area.

I agree that the code requires both supports, ...

Same as above.

The reference in the respective xxx.30 sections is to the conduit that is covered by the scope of that article and does not include conduits that are covered by scopes of other articles.

If we go with this premise, then transitioning to another type excludes each mutually from the other's xxx.26 (360? bends in one run) requirement... right???

 

[cycotcskir]

Terminator

Terminator

I agree with Don. The EMT and the Sealtight must be supported. The EMT within 3' and the LFMC within 12"

I think the issue here is the issue of "termination". NOT the termination of the conductors, but the termination of the CONDUIT or TUBING.

Does the EMT end? Does the LFMC begin and end?


358.30(A) Securely Fastened. EMT shall be securely fastened in
place at least every 3 m (10 ft). In addition, each EMT run
between termination points shall be securely fastened within
900 mm (3 ft) of each outlet box, junction box, device box,
cabinet, conduit body, or other tubing termination.

350.30(A) Securely Fastened. LFMC shall be securely fastened
in place by an approved means within 300 mm (12 in.) of
each box, cabinet, conduit body, or other conduit termination
and shall be supported and secured at intervals not to
exceed 1.4 m (41⁄2 ft).

ter?mi?nate adj \ˈtər-mə-nət\
Definition of TERMINATE
: coming to an end or capable of ending

 

[don_resqcapt19]

The reference in the respective xxx.30 sections is to the conduit that is covered by the scope of that article and does not include conduits that are covered by scopes of other articles.

If we go with this premise, then transitioning to another type excludes each mutually from the other's xxx.26 (360? bends in one run) requirement... right???

That would be correct. That is not the intent, but is the effect of placing the rule in each of the raceway sections. The rule probably should be in Article 300.

 

[Smart $]

I agree with Don. The EMT and the Sealtight must be supported. The EMT within 3' and the LFMC within 12"

I think the issue here is the issue of "termination". NOT the termination of the conductors, but the termination of the CONDUIT or TUBING.

Does the EMT end? Does the LFMC begin and end?


358.30(A) Securely Fastened. EMT shall be securely fastened in
place at least every 3 m (10 ft). In addition, each EMT run
between termination points shall be securely fastened within
900 mm (3 ft) of each outlet box, junction box, device box,
cabinet, conduit body, or other tubing termination.

350.30(A) Securely Fastened. LFMC shall be securely fastened
in place by an approved means within 300 mm (12 in.) of
each box, cabinet, conduit body, or other conduit termination
and shall be supported and secured at intervals not to
exceed 1.4 m (41⁄2 ft).

ter?mi?nate adj \ˈtər-mə-nət\
Definition of TERMINATE
: coming to an end or capable of ending

The way I read it, the wording "other xxx termination" should be taken in the context of the preceding list members. In such context, each implies pull-point type of terminations only.

 

[cycotcskir]

In such context, each implies pull-point type of terminations only.

I see the sentence more as pretty much exhausting the former (pull-point types) and adding a catch-all for all other types of conduit terminations including other pull-type terminations.

I think either readings of the sentence could potentially be valid. I do think that one has to TRY to see it the way you propose, rather than just reading it tha way that it is.

As is typical in the english language, when one creates a list such as this, it is contained within the predicate of the sentence, which explains what is being said about the subject of the sentence.

"Run" is the subject, "EMT" and "between termination points" modify the subject, and "fastened" is the verb beginning the predicate.

In addition, each EMT run
between termination points shall be securely fastened within
900 mm (3 ft) of each outlet box, junction box, device box,
cabinet, conduit body, or other tubing termination.

All that was to say that the list within the predicate need not be confined to directly relating to one another, they need only to directly relate to the subject.

Sub. Portion Pred.
RUN Securely Fastened
Termination Points outlet box, junction box, device box,

cabinet, conduit body, or other tubing termination.